Merge branch 'zstd-minimal' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs

Pull zstd support from Chris Mason:
 "Nick Terrell's patch series to add zstd support to the kernel has been
  floating around for a while. After talking with Dave Sterba, Herbert
  and Phillip, we decided to send the whole thing in as one pull
  request.

  zstd is a big win in speed over zlib and in compression ratio over
  lzo, and the compression team here at FB has gotten great results
  using it in production. Nick will continue to update the kernel side
  with new improvements from the open source zstd userland code.

  Nick has a number of benchmarks for the main zstd code in his lib/zstd
  commit:

      I ran the benchmarks on a Ubuntu 14.04 VM with 2 cores and 4 GiB
      of RAM. The VM is running on a MacBook Pro with a 3.1 GHz Intel
      Core i7 processor, 16 GB of RAM, and a SSD. I benchmarked using
      `silesia.tar` [3], which is 211,988,480 B large. Run the following
      commands for the benchmark:

        sudo modprobe zstd_compress_test
        sudo mknod zstd_compress_test c 245 0
        sudo cp silesia.tar zstd_compress_test

      The time is reported by the time of the userland `cp`.
      The MB/s is computed with

        1,536,217,008 B / time(buffer size, hash)

      which includes the time to copy from userland.
      The Adjusted MB/s is computed with

        1,536,217,088 B / (time(buffer size, hash) - time(buffer size, none)).

      The memory reported is the amount of memory the compressor
      requests.

        | Method   | Size (B) | Time (s) | Ratio | MB/s    | Adj MB/s | Mem (MB) |
        |----------|----------|----------|-------|---------|----------|----------|
        | none     | 11988480 |    0.100 |     1 | 2119.88 |        - |        - |
        | zstd -1  | 73645762 |    1.044 | 2.878 |  203.05 |   224.56 |     1.23 |
        | zstd -3  | 66988878 |    1.761 | 3.165 |  120.38 |   127.63 |     2.47 |
        | zstd -5  | 65001259 |    2.563 | 3.261 |   82.71 |    86.07 |     2.86 |
        | zstd -10 | 60165346 |   13.242 | 3.523 |   16.01 |    16.13 |    13.22 |
        | zstd -15 | 58009756 |   47.601 | 3.654 |    4.45 |     4.46 |    21.61 |
        | zstd -19 | 54014593 |  102.835 | 3.925 |    2.06 |     2.06 |    60.15 |
        | zlib -1  | 77260026 |    2.895 | 2.744 |   73.23 |    75.85 |     0.27 |
        | zlib -3  | 72972206 |    4.116 | 2.905 |   51.50 |    52.79 |     0.27 |
        | zlib -6  | 68190360 |    9.633 | 3.109 |   22.01 |    22.24 |     0.27 |
        | zlib -9  | 67613382 |   22.554 | 3.135 |    9.40 |     9.44 |     0.27 |

      I benchmarked zstd decompression using the same method on the same
      machine. The benchmark file is located in the upstream zstd repo
      under `contrib/linux-kernel/zstd_decompress_test.c` [4]. The
      memory reported is the amount of memory required to decompress
      data compressed with the given compression level. If you know the
      maximum size of your input, you can reduce the memory usage of
      decompression irrespective of the compression level.

        | Method   | Time (s) | MB/s    | Adjusted MB/s | Memory (MB) |
        |----------|----------|---------|---------------|-------------|
        | none     |    0.025 | 8479.54 |             - |           - |
        | zstd -1  |    0.358 |  592.15 |        636.60 |        0.84 |
        | zstd -3  |    0.396 |  535.32 |        571.40 |        1.46 |
        | zstd -5  |    0.396 |  535.32 |        571.40 |        1.46 |
        | zstd -10 |    0.374 |  566.81 |        607.42 |        2.51 |
        | zstd -15 |    0.379 |  559.34 |        598.84 |        4.61 |
        | zstd -19 |    0.412 |  514.54 |        547.77 |        8.80 |
        | zlib -1  |    0.940 |  225.52 |        231.68 |        0.04 |
        | zlib -3  |    0.883 |  240.08 |        247.07 |        0.04 |
        | zlib -6  |    0.844 |  251.17 |        258.84 |        0.04 |
        | zlib -9  |    0.837 |  253.27 |        287.64 |        0.04 |

  I ran a long series of tests and benchmarks on the btrfs side and the
  gains are very similar to the core benchmarks Nick ran"

* 'zstd-minimal' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
  squashfs: Add zstd support
  btrfs: Add zstd support
  lib: Add zstd modules
  lib: Add xxhash module

fs/btrfs/Kconfig

@@ -6,6 +6,8 @@ config BTRFS_FS
 	select ZLIB_DEFLATE
 	select LZO_COMPRESS
 	select LZO_DECOMPRESS
+	select ZSTD_COMPRESS
+	select ZSTD_DECOMPRESS
 	select RAID6_PQ
 	select XOR_BLOCKS
 	select SRCU

fs/btrfs/Makefile

@@ -6,7 +6,7 @@ btrfs-y += super.o ctree.o extent-tree.o print-tree.o root-tree.o dir-item.o \
 	   transaction.o inode.o file.o tree-defrag.o \
 	   extent_map.o sysfs.o struct-funcs.o xattr.o ordered-data.o \
 	   extent_io.o volumes.o async-thread.o ioctl.o locking.o orphan.o \
-	   export.o tree-log.o free-space-cache.o zlib.o lzo.o \
+	   export.o tree-log.o free-space-cache.o zlib.o lzo.o zstd.o \
 	   compression.o delayed-ref.o relocation.o delayed-inode.o scrub.o \
 	   reada.o backref.o ulist.o qgroup.o send.o dev-replace.o raid56.o \
 	   uuid-tree.o props.o hash.o free-space-tree.o

fs/btrfs/compression.c

@@ -704,6 +704,7 @@ static struct {
 static const struct btrfs_compress_op * const btrfs_compress_op[] = {
 	&btrfs_zlib_compress,
 	&btrfs_lzo_compress,
+	&btrfs_zstd_compress,
 };
 
 void __init btrfs_init_compress(void)

fs/btrfs/compression.h

@@ -99,7 +99,8 @@ enum btrfs_compression_type {
 	BTRFS_COMPRESS_NONE  = 0,
 	BTRFS_COMPRESS_ZLIB  = 1,
 	BTRFS_COMPRESS_LZO   = 2,
-	BTRFS_COMPRESS_TYPES = 2,
+	BTRFS_COMPRESS_ZSTD  = 3,
+	BTRFS_COMPRESS_TYPES = 3,
 };
 
 struct btrfs_compress_op {
@@ -127,6 +128,7 @@ struct btrfs_compress_op {
 
 extern const struct btrfs_compress_op btrfs_zlib_compress;
 extern const struct btrfs_compress_op btrfs_lzo_compress;
+extern const struct btrfs_compress_op btrfs_zstd_compress;
 
 int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end);
 

fs/btrfs/ctree.h

@@ -270,6 +270,7 @@ struct btrfs_super_block {
 	 BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS |		\
 	 BTRFS_FEATURE_INCOMPAT_BIG_METADATA |		\
 	 BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO |		\
+	 BTRFS_FEATURE_INCOMPAT_COMPRESS_ZSTD |		\
 	 BTRFS_FEATURE_INCOMPAT_RAID56 |		\
 	 BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF |		\
 	 BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA |	\

fs/btrfs/disk-io.c

@@ -2828,6 +2828,8 @@ int open_ctree(struct super_block *sb,
 	features |= BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF;
 	if (fs_info->compress_type == BTRFS_COMPRESS_LZO)
 		features |= BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO;
+	else if (fs_info->compress_type == BTRFS_COMPRESS_ZSTD)
+		features |= BTRFS_FEATURE_INCOMPAT_COMPRESS_ZSTD;
 
 	if (features & BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA)
 		btrfs_info(fs_info, "has skinny extents");

fs/btrfs/ioctl.c

@@ -296,8 +296,10 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg)
 
 		if (fs_info->compress_type == BTRFS_COMPRESS_LZO)
 			comp = "lzo";
-		else
+		else if (fs_info->compress_type == BTRFS_COMPRESS_ZLIB)
 			comp = "zlib";
+		else
+			comp = "zstd";
 		ret = btrfs_set_prop(inode, "btrfs.compression",
 				     comp, strlen(comp), 0);
 		if (ret)
@@ -1435,6 +1437,8 @@ int btrfs_defrag_file(struct inode *inode, struct file *file,
 
 	if (range->compress_type == BTRFS_COMPRESS_LZO) {
 		btrfs_set_fs_incompat(fs_info, COMPRESS_LZO);
+	} else if (range->compress_type == BTRFS_COMPRESS_ZSTD) {
+		btrfs_set_fs_incompat(fs_info, COMPRESS_ZSTD);
 	}
 
 	ret = defrag_count;

fs/btrfs/props.c

@@ -390,6 +390,8 @@ static int prop_compression_validate(const char *value, size_t len)
 		return 0;
 	else if (!strncmp("zlib", value, len))
 		return 0;
+	else if (!strncmp("zstd", value, len))
+		return 0;
 
 	return -EINVAL;
 }
@@ -412,6 +414,8 @@ static int prop_compression_apply(struct inode *inode,
 		type = BTRFS_COMPRESS_LZO;
 	else if (!strncmp("zlib", value, 4))
 		type = BTRFS_COMPRESS_ZLIB;
+	else if (!strncmp("zstd", value, len))
+		type = BTRFS_COMPRESS_ZSTD;
 	else
 		return -EINVAL;
 
@@ -429,6 +433,8 @@ static const char *prop_compression_extract(struct inode *inode)
 		return "zlib";
 	case BTRFS_COMPRESS_LZO:
 		return "lzo";
+	case BTRFS_COMPRESS_ZSTD:
+		return "zstd";
 	}
 
 	return NULL;

fs/btrfs/super.c

@@ -514,6 +514,14 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
 				btrfs_clear_opt(info->mount_opt, NODATASUM);
 				btrfs_set_fs_incompat(info, COMPRESS_LZO);
 				no_compress = 0;
+			} else if (strcmp(args[0].from, "zstd") == 0) {
+				compress_type = "zstd";
+				info->compress_type = BTRFS_COMPRESS_ZSTD;
+				btrfs_set_opt(info->mount_opt, COMPRESS);
+				btrfs_clear_opt(info->mount_opt, NODATACOW);
+				btrfs_clear_opt(info->mount_opt, NODATASUM);
+				btrfs_set_fs_incompat(info, COMPRESS_ZSTD);
+				no_compress = 0;
 			} else if (strncmp(args[0].from, "no", 2) == 0) {
 				compress_type = "no";
 				btrfs_clear_opt(info->mount_opt, COMPRESS);
@@ -1230,8 +1238,10 @@ static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
 	if (btrfs_test_opt(info, COMPRESS)) {
 		if (info->compress_type == BTRFS_COMPRESS_ZLIB)
 			compress_type = "zlib";
-		else
+		else if (info->compress_type == BTRFS_COMPRESS_LZO)
 			compress_type = "lzo";
+		else
+			compress_type = "zstd";
 		if (btrfs_test_opt(info, FORCE_COMPRESS))
 			seq_printf(seq, ",compress-force=%s", compress_type);
 		else

fs/btrfs/sysfs.c

@@ -200,6 +200,7 @@ BTRFS_FEAT_ATTR_INCOMPAT(mixed_backref, MIXED_BACKREF);
 BTRFS_FEAT_ATTR_INCOMPAT(default_subvol, DEFAULT_SUBVOL);
 BTRFS_FEAT_ATTR_INCOMPAT(mixed_groups, MIXED_GROUPS);
 BTRFS_FEAT_ATTR_INCOMPAT(compress_lzo, COMPRESS_LZO);
+BTRFS_FEAT_ATTR_INCOMPAT(compress_zstd, COMPRESS_ZSTD);
 BTRFS_FEAT_ATTR_INCOMPAT(big_metadata, BIG_METADATA);
 BTRFS_FEAT_ATTR_INCOMPAT(extended_iref, EXTENDED_IREF);
 BTRFS_FEAT_ATTR_INCOMPAT(raid56, RAID56);
@@ -212,6 +213,7 @@ static struct attribute *btrfs_supported_feature_attrs[] = {
 	BTRFS_FEAT_ATTR_PTR(default_subvol),
 	BTRFS_FEAT_ATTR_PTR(mixed_groups),
 	BTRFS_FEAT_ATTR_PTR(compress_lzo),
+	BTRFS_FEAT_ATTR_PTR(compress_zstd),
 	BTRFS_FEAT_ATTR_PTR(big_metadata),
 	BTRFS_FEAT_ATTR_PTR(extended_iref),
 	BTRFS_FEAT_ATTR_PTR(raid56),

fs/btrfs/zstd.c

@@ -0,0 +1,432 @@
+/*
+ * Copyright (c) 2016-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+#include <linux/bio.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/refcount.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/zstd.h>
+#include "compression.h"
+
+#define ZSTD_BTRFS_MAX_WINDOWLOG 17
+#define ZSTD_BTRFS_MAX_INPUT (1 << ZSTD_BTRFS_MAX_WINDOWLOG)
+#define ZSTD_BTRFS_DEFAULT_LEVEL 3
+
+static ZSTD_parameters zstd_get_btrfs_parameters(size_t src_len)
+{
+	ZSTD_parameters params = ZSTD_getParams(ZSTD_BTRFS_DEFAULT_LEVEL,
+						src_len, 0);
+
+	if (params.cParams.windowLog > ZSTD_BTRFS_MAX_WINDOWLOG)
+		params.cParams.windowLog = ZSTD_BTRFS_MAX_WINDOWLOG;
+	WARN_ON(src_len > ZSTD_BTRFS_MAX_INPUT);
+	return params;
+}
+
+struct workspace {
+	void *mem;
+	size_t size;
+	char *buf;
+	struct list_head list;
+};
+
+static void zstd_free_workspace(struct list_head *ws)
+{
+	struct workspace *workspace = list_entry(ws, struct workspace, list);
+
+	kvfree(workspace->mem);
+	kfree(workspace->buf);
+	kfree(workspace);
+}
+
+static struct list_head *zstd_alloc_workspace(void)
+{
+	ZSTD_parameters params =
+			zstd_get_btrfs_parameters(ZSTD_BTRFS_MAX_INPUT);
+	struct workspace *workspace;
+
+	workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
+	if (!workspace)
+		return ERR_PTR(-ENOMEM);
+
+	workspace->size = max_t(size_t,
+			ZSTD_CStreamWorkspaceBound(params.cParams),
+			ZSTD_DStreamWorkspaceBound(ZSTD_BTRFS_MAX_INPUT));
+	workspace->mem = kvmalloc(workspace->size, GFP_KERNEL);
+	workspace->buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!workspace->mem || !workspace->buf)
+		goto fail;
+
+	INIT_LIST_HEAD(&workspace->list);
+
+	return &workspace->list;
+fail:
+	zstd_free_workspace(&workspace->list);
+	return ERR_PTR(-ENOMEM);
+}
+
+static int zstd_compress_pages(struct list_head *ws,
+		struct address_space *mapping,
+		u64 start,
+		struct page **pages,
+		unsigned long *out_pages,
+		unsigned long *total_in,
+		unsigned long *total_out)
+{
+	struct workspace *workspace = list_entry(ws, struct workspace, list);
+	ZSTD_CStream *stream;
+	int ret = 0;
+	int nr_pages = 0;
+	struct page *in_page = NULL;  /* The current page to read */
+	struct page *out_page = NULL; /* The current page to write to */
+	ZSTD_inBuffer in_buf = { NULL, 0, 0 };
+	ZSTD_outBuffer out_buf = { NULL, 0, 0 };
+	unsigned long tot_in = 0;
+	unsigned long tot_out = 0;
+	unsigned long len = *total_out;
+	const unsigned long nr_dest_pages = *out_pages;
+	unsigned long max_out = nr_dest_pages * PAGE_SIZE;
+	ZSTD_parameters params = zstd_get_btrfs_parameters(len);
+
+	*out_pages = 0;
+	*total_out = 0;
+	*total_in = 0;
+
+	/* Initialize the stream */
+	stream = ZSTD_initCStream(params, len, workspace->mem,
+			workspace->size);
+	if (!stream) {
+		pr_warn("BTRFS: ZSTD_initCStream failed\n");
+		ret = -EIO;
+		goto out;
+	}
+
+	/* map in the first page of input data */
+	in_page = find_get_page(mapping, start >> PAGE_SHIFT);
+	in_buf.src = kmap(in_page);
+	in_buf.pos = 0;
+	in_buf.size = min_t(size_t, len, PAGE_SIZE);
+
+
+	/* Allocate and map in the output buffer */
+	out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
+	if (out_page == NULL) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	pages[nr_pages++] = out_page;
+	out_buf.dst = kmap(out_page);
+	out_buf.pos = 0;
+	out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
+
+	while (1) {
+		size_t ret2;
+
+		ret2 = ZSTD_compressStream(stream, &out_buf, &in_buf);
+		if (ZSTD_isError(ret2)) {
+			pr_debug("BTRFS: ZSTD_compressStream returned %d\n",
+					ZSTD_getErrorCode(ret2));
+			ret = -EIO;
+			goto out;
+		}
+
+		/* Check to see if we are making it bigger */
+		if (tot_in + in_buf.pos > 8192 &&
+				tot_in + in_buf.pos <
+				tot_out + out_buf.pos) {
+			ret = -E2BIG;
+			goto out;
+		}
+
+		/* We've reached the end of our output range */
+		if (out_buf.pos >= max_out) {
+			tot_out += out_buf.pos;
+			ret = -E2BIG;
+			goto out;
+		}
+
+		/* Check if we need more output space */
+		if (out_buf.pos == out_buf.size) {
+			tot_out += PAGE_SIZE;
+			max_out -= PAGE_SIZE;
+			kunmap(out_page);
+			if (nr_pages == nr_dest_pages) {
+				out_page = NULL;
+				ret = -E2BIG;
+				goto out;
+			}
+			out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
+			if (out_page == NULL) {
+				ret = -ENOMEM;
+				goto out;
+			}
+			pages[nr_pages++] = out_page;
+			out_buf.dst = kmap(out_page);
+			out_buf.pos = 0;
+			out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
+		}
+
+		/* We've reached the end of the input */
+		if (in_buf.pos >= len) {
+			tot_in += in_buf.pos;
+			break;
+		}
+
+		/* Check if we need more input */
+		if (in_buf.pos == in_buf.size) {
+			tot_in += PAGE_SIZE;
+			kunmap(in_page);
+			put_page(in_page);
+
+			start += PAGE_SIZE;
+			len -= PAGE_SIZE;
+			in_page = find_get_page(mapping, start >> PAGE_SHIFT);
+			in_buf.src = kmap(in_page);
+			in_buf.pos = 0;
+			in_buf.size = min_t(size_t, len, PAGE_SIZE);
+		}
+	}
+	while (1) {
+		size_t ret2;
+
+		ret2 = ZSTD_endStream(stream, &out_buf);
+		if (ZSTD_isError(ret2)) {
+			pr_debug("BTRFS: ZSTD_endStream returned %d\n",
+					ZSTD_getErrorCode(ret2));
+			ret = -EIO;
+			goto out;
+		}
+		if (ret2 == 0) {
+			tot_out += out_buf.pos;
+			break;
+		}
+		if (out_buf.pos >= max_out) {
+			tot_out += out_buf.pos;
+			ret = -E2BIG;
+			goto out;
+		}
+
+		tot_out += PAGE_SIZE;
+		max_out -= PAGE_SIZE;
+		kunmap(out_page);
+		if (nr_pages == nr_dest_pages) {
+			out_page = NULL;
+			ret = -E2BIG;
+			goto out;
+		}
+		out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
+		if (out_page == NULL) {
+			ret = -ENOMEM;
+			goto out;
+		}
+		pages[nr_pages++] = out_page;
+		out_buf.dst = kmap(out_page);
+		out_buf.pos = 0;
+		out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
+	}
+
+	if (tot_out >= tot_in) {
+		ret = -E2BIG;
+		goto out;
+	}
+
+	ret = 0;
+	*total_in = tot_in;
+	*total_out = tot_out;
+out:
+	*out_pages = nr_pages;
+	/* Cleanup */
+	if (in_page) {
+		kunmap(in_page);
+		put_page(in_page);
+	}
+	if (out_page)
+		kunmap(out_page);
+	return ret;
+}
+
+static int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
+{
+	struct workspace *workspace = list_entry(ws, struct workspace, list);
+	struct page **pages_in = cb->compressed_pages;
+	u64 disk_start = cb->start;
+	struct bio *orig_bio = cb->orig_bio;
+	size_t srclen = cb->compressed_len;
+	ZSTD_DStream *stream;
+	int ret = 0;
+	unsigned long page_in_index = 0;
+	unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
+	unsigned long buf_start;
+	unsigned long total_out = 0;
+	ZSTD_inBuffer in_buf = { NULL, 0, 0 };
+	ZSTD_outBuffer out_buf = { NULL, 0, 0 };
+
+	stream = ZSTD_initDStream(
+			ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size);
+	if (!stream) {
+		pr_debug("BTRFS: ZSTD_initDStream failed\n");
+		ret = -EIO;
+		goto done;
+	}
+
+	in_buf.src = kmap(pages_in[page_in_index]);
+	in_buf.pos = 0;
+	in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
+
+	out_buf.dst = workspace->buf;
+	out_buf.pos = 0;
+	out_buf.size = PAGE_SIZE;
+
+	while (1) {
+		size_t ret2;
+
+		ret2 = ZSTD_decompressStream(stream, &out_buf, &in_buf);
+		if (ZSTD_isError(ret2)) {
+			pr_debug("BTRFS: ZSTD_decompressStream returned %d\n",
+					ZSTD_getErrorCode(ret2));
+			ret = -EIO;
+			goto done;
+		}
+		buf_start = total_out;
+		total_out += out_buf.pos;
+		out_buf.pos = 0;
+
+		ret = btrfs_decompress_buf2page(out_buf.dst, buf_start,
+				total_out, disk_start, orig_bio);
+		if (ret == 0)
+			break;
+
+		if (in_buf.pos >= srclen)
+			break;
+
+		/* Check if we've hit the end of a frame */
+		if (ret2 == 0)
+			break;
+
+		if (in_buf.pos == in_buf.size) {
+			kunmap(pages_in[page_in_index++]);
+			if (page_in_index >= total_pages_in) {
+				in_buf.src = NULL;
+				ret = -EIO;
+				goto done;
+			}
+			srclen -= PAGE_SIZE;
+			in_buf.src = kmap(pages_in[page_in_index]);
+			in_buf.pos = 0;
+			in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
+		}
+	}
+	ret = 0;
+	zero_fill_bio(orig_bio);
+done:
+	if (in_buf.src)
+		kunmap(pages_in[page_in_index]);
+	return ret;
+}
+
+static int zstd_decompress(struct list_head *ws, unsigned char *data_in,
+		struct page *dest_page,
+		unsigned long start_byte,
+		size_t srclen, size_t destlen)
+{
+	struct workspace *workspace = list_entry(ws, struct workspace, list);
+	ZSTD_DStream *stream;
+	int ret = 0;
+	size_t ret2;
+	ZSTD_inBuffer in_buf = { NULL, 0, 0 };
+	ZSTD_outBuffer out_buf = { NULL, 0, 0 };
+	unsigned long total_out = 0;
+	unsigned long pg_offset = 0;
+	char *kaddr;
+
+	stream = ZSTD_initDStream(
+			ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size);
+	if (!stream) {
+		pr_warn("BTRFS: ZSTD_initDStream failed\n");
+		ret = -EIO;
+		goto finish;
+	}
+
+	destlen = min_t(size_t, destlen, PAGE_SIZE);
+
+	in_buf.src = data_in;
+	in_buf.pos = 0;
+	in_buf.size = srclen;
+
+	out_buf.dst = workspace->buf;
+	out_buf.pos = 0;
+	out_buf.size = PAGE_SIZE;
+
+	ret2 = 1;
+	while (pg_offset < destlen && in_buf.pos < in_buf.size) {
+		unsigned long buf_start;
+		unsigned long buf_offset;
+		unsigned long bytes;
+
+		/* Check if the frame is over and we still need more input */
+		if (ret2 == 0) {
+			pr_debug("BTRFS: ZSTD_decompressStream ended early\n");
+			ret = -EIO;
+			goto finish;
+		}
+		ret2 = ZSTD_decompressStream(stream, &out_buf, &in_buf);
+		if (ZSTD_isError(ret2)) {
+			pr_debug("BTRFS: ZSTD_decompressStream returned %d\n",
+					ZSTD_getErrorCode(ret2));
+			ret = -EIO;
+			goto finish;
+		}
+
+		buf_start = total_out;
+		total_out += out_buf.pos;
+		out_buf.pos = 0;
+
+		if (total_out <= start_byte)
+			continue;
+
+		if (total_out > start_byte && buf_start < start_byte)
+			buf_offset = start_byte - buf_start;
+		else
+			buf_offset = 0;
+
+		bytes = min_t(unsigned long, destlen - pg_offset,
+				out_buf.size - buf_offset);
+
+		kaddr = kmap_atomic(dest_page);
+		memcpy(kaddr + pg_offset, out_buf.dst + buf_offset, bytes);
+		kunmap_atomic(kaddr);
+
+		pg_offset += bytes;
+	}
+	ret = 0;
+finish:
+	if (pg_offset < destlen) {
+		kaddr = kmap_atomic(dest_page);
+		memset(kaddr + pg_offset, 0, destlen - pg_offset);
+		kunmap_atomic(kaddr);
+	}
+	return ret;
+}
+
+const struct btrfs_compress_op btrfs_zstd_compress = {
+	.alloc_workspace = zstd_alloc_workspace,
+	.free_workspace = zstd_free_workspace,
+	.compress_pages = zstd_compress_pages,
+	.decompress_bio = zstd_decompress_bio,
+	.decompress = zstd_decompress,
+};

fs/squashfs/Kconfig

@@ -165,6 +165,20 @@ config SQUASHFS_XZ
 
 	  If unsure, say N.
 
+config SQUASHFS_ZSTD
+	bool "Include support for ZSTD compressed file systems"
+	depends on SQUASHFS
+	select ZSTD_DECOMPRESS
+	help
+	  Saying Y here includes support for reading Squashfs file systems
+	  compressed with ZSTD compression.  ZSTD gives better compression than
+	  the default ZLIB compression, while using less CPU.
+
+	  ZSTD is not the standard compression used in Squashfs and so most
+	  file systems will be readable without selecting this option.
+
+	  If unsure, say N.
+
 config SQUASHFS_4K_DEVBLK_SIZE
 	bool "Use 4K device block size?"
 	depends on SQUASHFS

fs/squashfs/Makefile

@@ -15,3 +15,4 @@ squashfs-$(CONFIG_SQUASHFS_LZ4) += lz4_wrapper.o
 squashfs-$(CONFIG_SQUASHFS_LZO) += lzo_wrapper.o
 squashfs-$(CONFIG_SQUASHFS_XZ) += xz_wrapper.o
 squashfs-$(CONFIG_SQUASHFS_ZLIB) += zlib_wrapper.o
+squashfs-$(CONFIG_SQUASHFS_ZSTD) += zstd_wrapper.o

fs/squashfs/decompressor.c

@@ -65,6 +65,12 @@ static const struct squashfs_decompressor squashfs_zlib_comp_ops = {
 };
 #endif
 
+#ifndef CONFIG_SQUASHFS_ZSTD
+static const struct squashfs_decompressor squashfs_zstd_comp_ops = {
+	NULL, NULL, NULL, NULL, ZSTD_COMPRESSION, "zstd", 0
+};
+#endif
+
 static const struct squashfs_decompressor squashfs_unknown_comp_ops = {
 	NULL, NULL, NULL, NULL, 0, "unknown", 0
 };
@@ -75,6 +81,7 @@ static const struct squashfs_decompressor *decompressor[] = {
 	&squashfs_lzo_comp_ops,
 	&squashfs_xz_comp_ops,
 	&squashfs_lzma_unsupported_comp_ops,
+	&squashfs_zstd_comp_ops,
 	&squashfs_unknown_comp_ops
 };
 

fs/squashfs/decompressor.h

@@ -58,4 +58,8 @@ extern const struct squashfs_decompressor squashfs_lzo_comp_ops;
 extern const struct squashfs_decompressor squashfs_zlib_comp_ops;
 #endif
 
+#ifdef CONFIG_SQUASHFS_ZSTD
+extern const struct squashfs_decompressor squashfs_zstd_comp_ops;
+#endif
+
 #endif

fs/squashfs/squashfs_fs.h

@@ -241,6 +241,7 @@ struct meta_index {
 #define LZO_COMPRESSION		3
 #define XZ_COMPRESSION		4
 #define LZ4_COMPRESSION		5
+#define ZSTD_COMPRESSION	6
 
 struct squashfs_super_block {
 	__le32			s_magic;

fs/squashfs/zstd_wrapper.c

@@ -0,0 +1,151 @@
+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2016-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * zstd_wrapper.c
+ */
+
+#include <linux/mutex.h>
+#include <linux/buffer_head.h>
+#include <linux/slab.h>
+#include <linux/zstd.h>
+#include <linux/vmalloc.h>
+
+#include "squashfs_fs.h"
+#include "squashfs_fs_sb.h"
+#include "squashfs.h"
+#include "decompressor.h"
+#include "page_actor.h"
+
+struct workspace {
+	void *mem;
+	size_t mem_size;
+	size_t window_size;
+};
+
+static void *zstd_init(struct squashfs_sb_info *msblk, void *buff)
+{
+	struct workspace *wksp = kmalloc(sizeof(*wksp), GFP_KERNEL);
+
+	if (wksp == NULL)
+		goto failed;
+	wksp->window_size = max_t(size_t,
+			msblk->block_size, SQUASHFS_METADATA_SIZE);
+	wksp->mem_size = ZSTD_DStreamWorkspaceBound(wksp->window_size);
+	wksp->mem = vmalloc(wksp->mem_size);
+	if (wksp->mem == NULL)
+		goto failed;
+
+	return wksp;
+
+failed:
+	ERROR("Failed to allocate zstd workspace\n");
+	kfree(wksp);
+	return ERR_PTR(-ENOMEM);
+}
+
+
+static void zstd_free(void *strm)
+{
+	struct workspace *wksp = strm;
+
+	if (wksp)
+		vfree(wksp->mem);
+	kfree(wksp);
+}
+
+
+static int zstd_uncompress(struct squashfs_sb_info *msblk, void *strm,
+	struct buffer_head **bh, int b, int offset, int length,
+	struct squashfs_page_actor *output)
+{
+	struct workspace *wksp = strm;
+	ZSTD_DStream *stream;
+	size_t total_out = 0;
+	size_t zstd_err;
+	int k = 0;
+	ZSTD_inBuffer in_buf = { NULL, 0, 0 };
+	ZSTD_outBuffer out_buf = { NULL, 0, 0 };
+
+	stream = ZSTD_initDStream(wksp->window_size, wksp->mem, wksp->mem_size);
+
+	if (!stream) {
+		ERROR("Failed to initialize zstd decompressor\n");
+		goto out;
+	}
+
+	out_buf.size = PAGE_SIZE;
+	out_buf.dst = squashfs_first_page(output);
+
+	do {
+		if (in_buf.pos == in_buf.size && k < b) {
+			int avail = min(length, msblk->devblksize - offset);
+
+			length -= avail;
+			in_buf.src = bh[k]->b_data + offset;
+			in_buf.size = avail;
+			in_buf.pos = 0;
+			offset = 0;
+		}
+
+		if (out_buf.pos == out_buf.size) {
+			out_buf.dst = squashfs_next_page(output);
+			if (out_buf.dst == NULL) {
+				/* Shouldn't run out of pages
+				 * before stream is done.
+				 */
+				squashfs_finish_page(output);
+				goto out;
+			}
+			out_buf.pos = 0;
+			out_buf.size = PAGE_SIZE;
+		}
+
+		total_out -= out_buf.pos;
+		zstd_err = ZSTD_decompressStream(stream, &out_buf, &in_buf);
+		total_out += out_buf.pos; /* add the additional data produced */
+
+		if (in_buf.pos == in_buf.size && k < b)
+			put_bh(bh[k++]);
+	} while (zstd_err != 0 && !ZSTD_isError(zstd_err));
+
+	squashfs_finish_page(output);
+
+	if (ZSTD_isError(zstd_err)) {
+		ERROR("zstd decompression error: %d\n",
+				(int)ZSTD_getErrorCode(zstd_err));
+		goto out;
+	}
+
+	if (k < b)
+		goto out;
+
+	return (int)total_out;
+
+out:
+	for (; k < b; k++)
+		put_bh(bh[k]);
+
+	return -EIO;
+}
+
+const struct squashfs_decompressor squashfs_zstd_comp_ops = {
+	.init = zstd_init,
+	.free = zstd_free,
+	.decompress = zstd_uncompress,
+	.id = ZSTD_COMPRESSION,
+	.name = "zstd",
+	.supported = 1
+};

include/linux/xxhash.h

@@ -0,0 +1,236 @@
+/*
+ * xxHash - Extremely Fast Hash algorithm
+ * Copyright (C) 2012-2016, Yann Collet.
+ *
+ * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *   * Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above
+ *     copyright notice, this list of conditions and the following disclaimer
+ *     in the documentation and/or other materials provided with the
+ *     distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License version 2 as published by the
+ * Free Software Foundation. This program is dual-licensed; you may select
+ * either version 2 of the GNU General Public License ("GPL") or BSD license
+ * ("BSD").
+ *
+ * You can contact the author at:
+ * - xxHash homepage: http://cyan4973.github.io/xxHash/
+ * - xxHash source repository: https://github.com/Cyan4973/xxHash
+ */
+
+/*
+ * Notice extracted from xxHash homepage:
+ *
+ * xxHash is an extremely fast Hash algorithm, running at RAM speed limits.
+ * It also successfully passes all tests from the SMHasher suite.
+ *
+ * Comparison (single thread, Windows Seven 32 bits, using SMHasher on a Core 2
+ * Duo @3GHz)
+ *
+ * Name            Speed       Q.Score   Author
+ * xxHash          5.4 GB/s     10
+ * CrapWow         3.2 GB/s      2       Andrew
+ * MumurHash 3a    2.7 GB/s     10       Austin Appleby
+ * SpookyHash      2.0 GB/s     10       Bob Jenkins
+ * SBox            1.4 GB/s      9       Bret Mulvey
+ * Lookup3         1.2 GB/s      9       Bob Jenkins
+ * SuperFastHash   1.2 GB/s      1       Paul Hsieh
+ * CityHash64      1.05 GB/s    10       Pike & Alakuijala
+ * FNV             0.55 GB/s     5       Fowler, Noll, Vo
+ * CRC32           0.43 GB/s     9
+ * MD5-32          0.33 GB/s    10       Ronald L. Rivest
+ * SHA1-32         0.28 GB/s    10
+ *
+ * Q.Score is a measure of quality of the hash function.
+ * It depends on successfully passing SMHasher test set.
+ * 10 is a perfect score.
+ *
+ * A 64-bits version, named xxh64 offers much better speed,
+ * but for 64-bits applications only.
+ * Name     Speed on 64 bits    Speed on 32 bits
+ * xxh64       13.8 GB/s            1.9 GB/s
+ * xxh32        6.8 GB/s            6.0 GB/s
+ */
+
+#ifndef XXHASH_H
+#define XXHASH_H
+
+#include <linux/types.h>
+
+/*-****************************
+ * Simple Hash Functions
+ *****************************/
+
+/**
+ * xxh32() - calculate the 32-bit hash of the input with a given seed.
+ *
+ * @input:  The data to hash.
+ * @length: The length of the data to hash.
+ * @seed:   The seed can be used to alter the result predictably.
+ *
+ * Speed on Core 2 Duo @ 3 GHz (single thread, SMHasher benchmark) : 5.4 GB/s
+ *
+ * Return:  The 32-bit hash of the data.
+ */
+uint32_t xxh32(const void *input, size_t length, uint32_t seed);
+
+/**
+ * xxh64() - calculate the 64-bit hash of the input with a given seed.
+ *
+ * @input:  The data to hash.
+ * @length: The length of the data to hash.
+ * @seed:   The seed can be used to alter the result predictably.
+ *
+ * This function runs 2x faster on 64-bit systems, but slower on 32-bit systems.
+ *
+ * Return:  The 64-bit hash of the data.
+ */
+uint64_t xxh64(const void *input, size_t length, uint64_t seed);
+
+/*-****************************
+ * Streaming Hash Functions
+ *****************************/
+
+/*
+ * These definitions are only meant to allow allocation of XXH state
+ * statically, on stack, or in a struct for example.
+ * Do not use members directly.
+ */
+
+/**
+ * struct xxh32_state - private xxh32 state, do not use members directly
+ */
+struct xxh32_state {
+	uint32_t total_len_32;
+	uint32_t large_len;
+	uint32_t v1;
+	uint32_t v2;
+	uint32_t v3;
+	uint32_t v4;
+	uint32_t mem32[4];
+	uint32_t memsize;
+};
+
+/**
+ * struct xxh32_state - private xxh64 state, do not use members directly
+ */
+struct xxh64_state {
+	uint64_t total_len;
+	uint64_t v1;
+	uint64_t v2;
+	uint64_t v3;
+	uint64_t v4;
+	uint64_t mem64[4];
+	uint32_t memsize;
+};
+
+/**
+ * xxh32_reset() - reset the xxh32 state to start a new hashing operation
+ *
+ * @state: The xxh32 state to reset.
+ * @seed:  Initialize the hash state with this seed.
+ *
+ * Call this function on any xxh32_state to prepare for a new hashing operation.
+ */
+void xxh32_reset(struct xxh32_state *state, uint32_t seed);
+
+/**
+ * xxh32_update() - hash the data given and update the xxh32 state
+ *
+ * @state:  The xxh32 state to update.
+ * @input:  The data to hash.
+ * @length: The length of the data to hash.
+ *
+ * After calling xxh32_reset() call xxh32_update() as many times as necessary.
+ *
+ * Return:  Zero on success, otherwise an error code.
+ */
+int xxh32_update(struct xxh32_state *state, const void *input, size_t length);
+
+/**
+ * xxh32_digest() - produce the current xxh32 hash
+ *
+ * @state: Produce the current xxh32 hash of this state.
+ *
+ * A hash value can be produced at any time. It is still possible to continue
+ * inserting input into the hash state after a call to xxh32_digest(), and
+ * generate new hashes later on, by calling xxh32_digest() again.
+ *
+ * Return: The xxh32 hash stored in the state.
+ */
+uint32_t xxh32_digest(const struct xxh32_state *state);
+
+/**
+ * xxh64_reset() - reset the xxh64 state to start a new hashing operation
+ *
+ * @state: The xxh64 state to reset.
+ * @seed:  Initialize the hash state with this seed.
+ */
+void xxh64_reset(struct xxh64_state *state, uint64_t seed);
+
+/**
+ * xxh64_update() - hash the data given and update the xxh64 state
+ * @state:  The xxh64 state to update.
+ * @input:  The data to hash.
+ * @length: The length of the data to hash.
+ *
+ * After calling xxh64_reset() call xxh64_update() as many times as necessary.
+ *
+ * Return:  Zero on success, otherwise an error code.
+ */
+int xxh64_update(struct xxh64_state *state, const void *input, size_t length);
+
+/**
+ * xxh64_digest() - produce the current xxh64 hash
+ *
+ * @state: Produce the current xxh64 hash of this state.
+ *
+ * A hash value can be produced at any time. It is still possible to continue
+ * inserting input into the hash state after a call to xxh64_digest(), and
+ * generate new hashes later on, by calling xxh64_digest() again.
+ *
+ * Return: The xxh64 hash stored in the state.
+ */
+uint64_t xxh64_digest(const struct xxh64_state *state);
+
+/*-**************************
+ * Utils
+ ***************************/
+
+/**
+ * xxh32_copy_state() - copy the source state into the destination state
+ *
+ * @src: The source xxh32 state.
+ * @dst: The destination xxh32 state.
+ */
+void xxh32_copy_state(struct xxh32_state *dst, const struct xxh32_state *src);
+
+/**
+ * xxh64_copy_state() - copy the source state into the destination state
+ *
+ * @src: The source xxh64 state.
+ * @dst: The destination xxh64 state.
+ */
+void xxh64_copy_state(struct xxh64_state *dst, const struct xxh64_state *src);
+
+#endif /* XXHASH_H */

include/uapi/linux/btrfs.h

@@ -255,13 +255,7 @@ struct btrfs_ioctl_fs_info_args {
 #define BTRFS_FEATURE_INCOMPAT_DEFAULT_SUBVOL	(1ULL << 1)
 #define BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS	(1ULL << 2)
 #define BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO	(1ULL << 3)
-/*
+#define BTRFS_FEATURE_INCOMPAT_COMPRESS_ZSTD	(1ULL << 4)
- * some patches floated around with a second compression method
- * lets save that incompat here for when they do get in
- * Note we don't actually support it, we're just reserving the
- * number
- */
-#define BTRFS_FEATURE_INCOMPAT_COMPRESS_LZOv2	(1ULL << 4)
 
 /*
  * older kernels tried to do bigger metadata blocks, but the

lib/Kconfig

@@ -192,6 +192,9 @@ config CRC8
 	  when they need to do cyclic redundancy check according CRC8
 	  algorithm. Module will be called crc8.
 
+config XXHASH
+	tristate
+
 config AUDIT_GENERIC
 	bool
 	depends on AUDIT && !AUDIT_ARCH
@@ -246,6 +249,14 @@ config LZ4HC_COMPRESS
 config LZ4_DECOMPRESS
 	tristate
 
+config ZSTD_COMPRESS
+	select XXHASH
+	tristate
+
+config ZSTD_DECOMPRESS
+	select XXHASH
+	tristate
+
 source "lib/xz/Kconfig"
 
 #

lib/Makefile

@@ -103,6 +103,7 @@ obj-$(CONFIG_CRC4)	+= crc4.o
 obj-$(CONFIG_CRC7)	+= crc7.o
 obj-$(CONFIG_LIBCRC32C)	+= libcrc32c.o
 obj-$(CONFIG_CRC8)	+= crc8.o
+obj-$(CONFIG_XXHASH)	+= xxhash.o
 obj-$(CONFIG_GENERIC_ALLOCATOR) += genalloc.o
 
 obj-$(CONFIG_842_COMPRESS) += 842/
@@ -116,6 +117,8 @@ obj-$(CONFIG_LZO_DECOMPRESS) += lzo/
 obj-$(CONFIG_LZ4_COMPRESS) += lz4/
 obj-$(CONFIG_LZ4HC_COMPRESS) += lz4/
 obj-$(CONFIG_LZ4_DECOMPRESS) += lz4/
+obj-$(CONFIG_ZSTD_COMPRESS) += zstd/
+obj-$(CONFIG_ZSTD_DECOMPRESS) += zstd/
 obj-$(CONFIG_XZ_DEC) += xz/
 obj-$(CONFIG_RAID6_PQ) += raid6/
 

lib/xxhash.c

@@ -0,0 +1,500 @@
+/*
+ * xxHash - Extremely Fast Hash algorithm
+ * Copyright (C) 2012-2016, Yann Collet.
+ *
+ * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *   * Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above
+ *     copyright notice, this list of conditions and the following disclaimer
+ *     in the documentation and/or other materials provided with the
+ *     distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License version 2 as published by the
+ * Free Software Foundation. This program is dual-licensed; you may select
+ * either version 2 of the GNU General Public License ("GPL") or BSD license
+ * ("BSD").
+ *
+ * You can contact the author at:
+ * - xxHash homepage: http://cyan4973.github.io/xxHash/
+ * - xxHash source repository: https://github.com/Cyan4973/xxHash
+ */
+
+#include <asm/unaligned.h>
+#include <linux/errno.h>
+#include <linux/compiler.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/xxhash.h>
+
+/*-*************************************
+ * Macros
+ **************************************/
+#define xxh_rotl32(x, r) ((x << r) | (x >> (32 - r)))
+#define xxh_rotl64(x, r) ((x << r) | (x >> (64 - r)))
+
+#ifdef __LITTLE_ENDIAN
+# define XXH_CPU_LITTLE_ENDIAN 1
+#else
+# define XXH_CPU_LITTLE_ENDIAN 0
+#endif
+
+/*-*************************************
+ * Constants
+ **************************************/
+static const uint32_t PRIME32_1 = 2654435761U;
+static const uint32_t PRIME32_2 = 2246822519U;
+static const uint32_t PRIME32_3 = 3266489917U;
+static const uint32_t PRIME32_4 =  668265263U;
+static const uint32_t PRIME32_5 =  374761393U;
+
+static const uint64_t PRIME64_1 = 11400714785074694791ULL;
+static const uint64_t PRIME64_2 = 14029467366897019727ULL;
+static const uint64_t PRIME64_3 =  1609587929392839161ULL;
+static const uint64_t PRIME64_4 =  9650029242287828579ULL;
+static const uint64_t PRIME64_5 =  2870177450012600261ULL;
+
+/*-**************************
+ *  Utils
+ ***************************/
+void xxh32_copy_state(struct xxh32_state *dst, const struct xxh32_state *src)
+{
+	memcpy(dst, src, sizeof(*dst));
+}
+EXPORT_SYMBOL(xxh32_copy_state);
+
+void xxh64_copy_state(struct xxh64_state *dst, const struct xxh64_state *src)
+{
+	memcpy(dst, src, sizeof(*dst));
+}
+EXPORT_SYMBOL(xxh64_copy_state);
+
+/*-***************************
+ * Simple Hash Functions
+ ****************************/
+static uint32_t xxh32_round(uint32_t seed, const uint32_t input)
+{
+	seed += input * PRIME32_2;
+	seed = xxh_rotl32(seed, 13);
+	seed *= PRIME32_1;
+	return seed;
+}
+
+uint32_t xxh32(const void *input, const size_t len, const uint32_t seed)
+{
+	const uint8_t *p = (const uint8_t *)input;
+	const uint8_t *b_end = p + len;
+	uint32_t h32;
+
+	if (len >= 16) {
+		const uint8_t *const limit = b_end - 16;
+		uint32_t v1 = seed + PRIME32_1 + PRIME32_2;
+		uint32_t v2 = seed + PRIME32_2;
+		uint32_t v3 = seed + 0;
+		uint32_t v4 = seed - PRIME32_1;
+
+		do {
+			v1 = xxh32_round(v1, get_unaligned_le32(p));
+			p += 4;
+			v2 = xxh32_round(v2, get_unaligned_le32(p));
+			p += 4;
+			v3 = xxh32_round(v3, get_unaligned_le32(p));
+			p += 4;
+			v4 = xxh32_round(v4, get_unaligned_le32(p));
+			p += 4;
+		} while (p <= limit);
+
+		h32 = xxh_rotl32(v1, 1) + xxh_rotl32(v2, 7) +
+			xxh_rotl32(v3, 12) + xxh_rotl32(v4, 18);
+	} else {
+		h32 = seed + PRIME32_5;
+	}
+
+	h32 += (uint32_t)len;
+
+	while (p + 4 <= b_end) {
+		h32 += get_unaligned_le32(p) * PRIME32_3;
+		h32 = xxh_rotl32(h32, 17) * PRIME32_4;
+		p += 4;
+	}
+
+	while (p < b_end) {
+		h32 += (*p) * PRIME32_5;
+		h32 = xxh_rotl32(h32, 11) * PRIME32_1;
+		p++;
+	}
+
+	h32 ^= h32 >> 15;
+	h32 *= PRIME32_2;
+	h32 ^= h32 >> 13;
+	h32 *= PRIME32_3;
+	h32 ^= h32 >> 16;
+
+	return h32;
+}
+EXPORT_SYMBOL(xxh32);
+
+static uint64_t xxh64_round(uint64_t acc, const uint64_t input)
+{
+	acc += input * PRIME64_2;
+	acc = xxh_rotl64(acc, 31);
+	acc *= PRIME64_1;
+	return acc;
+}
+
+static uint64_t xxh64_merge_round(uint64_t acc, uint64_t val)
+{
+	val = xxh64_round(0, val);
+	acc ^= val;
+	acc = acc * PRIME64_1 + PRIME64_4;
+	return acc;
+}
+
+uint64_t xxh64(const void *input, const size_t len, const uint64_t seed)
+{
+	const uint8_t *p = (const uint8_t *)input;
+	const uint8_t *const b_end = p + len;
+	uint64_t h64;
+
+	if (len >= 32) {
+		const uint8_t *const limit = b_end - 32;
+		uint64_t v1 = seed + PRIME64_1 + PRIME64_2;
+		uint64_t v2 = seed + PRIME64_2;
+		uint64_t v3 = seed + 0;
+		uint64_t v4 = seed - PRIME64_1;
+
+		do {
+			v1 = xxh64_round(v1, get_unaligned_le64(p));
+			p += 8;
+			v2 = xxh64_round(v2, get_unaligned_le64(p));
+			p += 8;
+			v3 = xxh64_round(v3, get_unaligned_le64(p));
+			p += 8;
+			v4 = xxh64_round(v4, get_unaligned_le64(p));
+			p += 8;
+		} while (p <= limit);
+
+		h64 = xxh_rotl64(v1, 1) + xxh_rotl64(v2, 7) +
+			xxh_rotl64(v3, 12) + xxh_rotl64(v4, 18);
+		h64 = xxh64_merge_round(h64, v1);
+		h64 = xxh64_merge_round(h64, v2);
+		h64 = xxh64_merge_round(h64, v3);
+		h64 = xxh64_merge_round(h64, v4);
+
+	} else {
+		h64  = seed + PRIME64_5;
+	}
+
+	h64 += (uint64_t)len;
+
+	while (p + 8 <= b_end) {
+		const uint64_t k1 = xxh64_round(0, get_unaligned_le64(p));
+
+		h64 ^= k1;
+		h64 = xxh_rotl64(h64, 27) * PRIME64_1 + PRIME64_4;
+		p += 8;
+	}
+
+	if (p + 4 <= b_end) {
+		h64 ^= (uint64_t)(get_unaligned_le32(p)) * PRIME64_1;
+		h64 = xxh_rotl64(h64, 23) * PRIME64_2 + PRIME64_3;
+		p += 4;
+	}
+
+	while (p < b_end) {
+		h64 ^= (*p) * PRIME64_5;
+		h64 = xxh_rotl64(h64, 11) * PRIME64_1;
+		p++;
+	}
+
+	h64 ^= h64 >> 33;
+	h64 *= PRIME64_2;
+	h64 ^= h64 >> 29;
+	h64 *= PRIME64_3;
+	h64 ^= h64 >> 32;
+
+	return h64;
+}
+EXPORT_SYMBOL(xxh64);
+
+/*-**************************************************
+ * Advanced Hash Functions
+ ***************************************************/
+void xxh32_reset(struct xxh32_state *statePtr, const uint32_t seed)
+{
+	/* use a local state for memcpy() to avoid strict-aliasing warnings */
+	struct xxh32_state state;
+
+	memset(&state, 0, sizeof(state));
+	state.v1 = seed + PRIME32_1 + PRIME32_2;
+	state.v2 = seed + PRIME32_2;
+	state.v3 = seed + 0;
+	state.v4 = seed - PRIME32_1;
+	memcpy(statePtr, &state, sizeof(state));
+}
+EXPORT_SYMBOL(xxh32_reset);
+
+void xxh64_reset(struct xxh64_state *statePtr, const uint64_t seed)
+{
+	/* use a local state for memcpy() to avoid strict-aliasing warnings */
+	struct xxh64_state state;
+
+	memset(&state, 0, sizeof(state));
+	state.v1 = seed + PRIME64_1 + PRIME64_2;
+	state.v2 = seed + PRIME64_2;
+	state.v3 = seed + 0;
+	state.v4 = seed - PRIME64_1;
+	memcpy(statePtr, &state, sizeof(state));
+}
+EXPORT_SYMBOL(xxh64_reset);
+
+int xxh32_update(struct xxh32_state *state, const void *input, const size_t len)
+{
+	const uint8_t *p = (const uint8_t *)input;
+	const uint8_t *const b_end = p + len;
+
+	if (input == NULL)
+		return -EINVAL;
+
+	state->total_len_32 += (uint32_t)len;
+	state->large_len |= (len >= 16) | (state->total_len_32 >= 16);
+
+	if (state->memsize + len < 16) { /* fill in tmp buffer */
+		memcpy((uint8_t *)(state->mem32) + state->memsize, input, len);
+		state->memsize += (uint32_t)len;
+		return 0;
+	}
+
+	if (state->memsize) { /* some data left from previous update */
+		const uint32_t *p32 = state->mem32;
+
+		memcpy((uint8_t *)(state->mem32) + state->memsize, input,
+			16 - state->memsize);
+
+		state->v1 = xxh32_round(state->v1, get_unaligned_le32(p32));
+		p32++;
+		state->v2 = xxh32_round(state->v2, get_unaligned_le32(p32));
+		p32++;
+		state->v3 = xxh32_round(state->v3, get_unaligned_le32(p32));
+		p32++;
+		state->v4 = xxh32_round(state->v4, get_unaligned_le32(p32));
+		p32++;
+
+		p += 16-state->memsize;
+		state->memsize = 0;
+	}
+
+	if (p <= b_end - 16) {
+		const uint8_t *const limit = b_end - 16;
+		uint32_t v1 = state->v1;
+		uint32_t v2 = state->v2;
+		uint32_t v3 = state->v3;
+		uint32_t v4 = state->v4;
+
+		do {
+			v1 = xxh32_round(v1, get_unaligned_le32(p));
+			p += 4;
+			v2 = xxh32_round(v2, get_unaligned_le32(p));
+			p += 4;
+			v3 = xxh32_round(v3, get_unaligned_le32(p));
+			p += 4;
+			v4 = xxh32_round(v4, get_unaligned_le32(p));
+			p += 4;
+		} while (p <= limit);
+
+		state->v1 = v1;
+		state->v2 = v2;
+		state->v3 = v3;
+		state->v4 = v4;
+	}
+
+	if (p < b_end) {
+		memcpy(state->mem32, p, (size_t)(b_end-p));
+		state->memsize = (uint32_t)(b_end-p);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(xxh32_update);
+
+uint32_t xxh32_digest(const struct xxh32_state *state)
+{
+	const uint8_t *p = (const uint8_t *)state->mem32;
+	const uint8_t *const b_end = (const uint8_t *)(state->mem32) +
+		state->memsize;
+	uint32_t h32;
+
+	if (state->large_len) {
+		h32 = xxh_rotl32(state->v1, 1) + xxh_rotl32(state->v2, 7) +
+			xxh_rotl32(state->v3, 12) + xxh_rotl32(state->v4, 18);
+	} else {
+		h32 = state->v3 /* == seed */ + PRIME32_5;
+	}
+
+	h32 += state->total_len_32;
+
+	while (p + 4 <= b_end) {
+		h32 += get_unaligned_le32(p) * PRIME32_3;
+		h32 = xxh_rotl32(h32, 17) * PRIME32_4;
+		p += 4;
+	}
+
+	while (p < b_end) {
+		h32 += (*p) * PRIME32_5;
+		h32 = xxh_rotl32(h32, 11) * PRIME32_1;
+		p++;
+	}
+
+	h32 ^= h32 >> 15;
+	h32 *= PRIME32_2;
+	h32 ^= h32 >> 13;
+	h32 *= PRIME32_3;
+	h32 ^= h32 >> 16;
+
+	return h32;
+}
+EXPORT_SYMBOL(xxh32_digest);
+
+int xxh64_update(struct xxh64_state *state, const void *input, const size_t len)
+{
+	const uint8_t *p = (const uint8_t *)input;
+	const uint8_t *const b_end = p + len;
+
+	if (input == NULL)
+		return -EINVAL;
+
+	state->total_len += len;
+
+	if (state->memsize + len < 32) { /* fill in tmp buffer */
+		memcpy(((uint8_t *)state->mem64) + state->memsize, input, len);
+		state->memsize += (uint32_t)len;
+		return 0;
+	}
+
+	if (state->memsize) { /* tmp buffer is full */
+		uint64_t *p64 = state->mem64;
+
+		memcpy(((uint8_t *)p64) + state->memsize, input,
+			32 - state->memsize);
+
+		state->v1 = xxh64_round(state->v1, get_unaligned_le64(p64));
+		p64++;
+		state->v2 = xxh64_round(state->v2, get_unaligned_le64(p64));
+		p64++;
+		state->v3 = xxh64_round(state->v3, get_unaligned_le64(p64));
+		p64++;
+		state->v4 = xxh64_round(state->v4, get_unaligned_le64(p64));
+
+		p += 32 - state->memsize;
+		state->memsize = 0;
+	}
+
+	if (p + 32 <= b_end) {
+		const uint8_t *const limit = b_end - 32;
+		uint64_t v1 = state->v1;
+		uint64_t v2 = state->v2;
+		uint64_t v3 = state->v3;
+		uint64_t v4 = state->v4;
+
+		do {
+			v1 = xxh64_round(v1, get_unaligned_le64(p));
+			p += 8;
+			v2 = xxh64_round(v2, get_unaligned_le64(p));
+			p += 8;
+			v3 = xxh64_round(v3, get_unaligned_le64(p));
+			p += 8;
+			v4 = xxh64_round(v4, get_unaligned_le64(p));
+			p += 8;
+		} while (p <= limit);
+
+		state->v1 = v1;
+		state->v2 = v2;
+		state->v3 = v3;
+		state->v4 = v4;
+	}
+
+	if (p < b_end) {
+		memcpy(state->mem64, p, (size_t)(b_end-p));
+		state->memsize = (uint32_t)(b_end - p);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(xxh64_update);
+
+uint64_t xxh64_digest(const struct xxh64_state *state)
+{
+	const uint8_t *p = (const uint8_t *)state->mem64;
+	const uint8_t *const b_end = (const uint8_t *)state->mem64 +
+		state->memsize;
+	uint64_t h64;
+
+	if (state->total_len >= 32) {
+		const uint64_t v1 = state->v1;
+		const uint64_t v2 = state->v2;
+		const uint64_t v3 = state->v3;
+		const uint64_t v4 = state->v4;
+
+		h64 = xxh_rotl64(v1, 1) + xxh_rotl64(v2, 7) +
+			xxh_rotl64(v3, 12) + xxh_rotl64(v4, 18);
+		h64 = xxh64_merge_round(h64, v1);
+		h64 = xxh64_merge_round(h64, v2);
+		h64 = xxh64_merge_round(h64, v3);
+		h64 = xxh64_merge_round(h64, v4);
+	} else {
+		h64  = state->v3 + PRIME64_5;
+	}
+
+	h64 += (uint64_t)state->total_len;
+
+	while (p + 8 <= b_end) {
+		const uint64_t k1 = xxh64_round(0, get_unaligned_le64(p));
+
+		h64 ^= k1;
+		h64 = xxh_rotl64(h64, 27) * PRIME64_1 + PRIME64_4;
+		p += 8;
+	}
+
+	if (p + 4 <= b_end) {
+		h64 ^= (uint64_t)(get_unaligned_le32(p)) * PRIME64_1;
+		h64 = xxh_rotl64(h64, 23) * PRIME64_2 + PRIME64_3;
+		p += 4;
+	}
+
+	while (p < b_end) {
+		h64 ^= (*p) * PRIME64_5;
+		h64 = xxh_rotl64(h64, 11) * PRIME64_1;
+		p++;
+	}
+
+	h64 ^= h64 >> 33;
+	h64 *= PRIME64_2;
+	h64 ^= h64 >> 29;
+	h64 *= PRIME64_3;
+	h64 ^= h64 >> 32;
+
+	return h64;
+}
+EXPORT_SYMBOL(xxh64_digest);
+
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_DESCRIPTION("xxHash");

lib/zstd/Makefile

@@ -0,0 +1,18 @@
+obj-$(CONFIG_ZSTD_COMPRESS) += zstd_compress.o
+obj-$(CONFIG_ZSTD_DECOMPRESS) += zstd_decompress.o
+
+ccflags-y += -O3
+
+# Object files unique to zstd_compress and zstd_decompress
+zstd_compress-y := fse_compress.o huf_compress.o compress.o
+zstd_decompress-y := huf_decompress.o decompress.o
+
+# These object files are shared between the modules.
+# Always add them to zstd_compress.
+# Unless both zstd_compress and zstd_decompress are built in
+# then also add them to zstd_decompress.
+zstd_compress-y += entropy_common.o fse_decompress.o zstd_common.o
+
+ifneq ($(CONFIG_ZSTD_COMPRESS)$(CONFIG_ZSTD_DECOMPRESS),yy)
+	zstd_decompress-y += entropy_common.o fse_decompress.o zstd_common.o
+endif

lib/zstd/bitstream.h

@@ -0,0 +1,374 @@
+/*
+ * bitstream
+ * Part of FSE library
+ * header file (to include)
+ * Copyright (C) 2013-2016, Yann Collet.
+ *
+ * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *   * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License version 2 as published by the
+ * Free Software Foundation. This program is dual-licensed; you may select
+ * either version 2 of the GNU General Public License ("GPL") or BSD license
+ * ("BSD").
+ *
+ * You can contact the author at :
+ * - Source repository : https://github.com/Cyan4973/FiniteStateEntropy
+ */
+#ifndef BITSTREAM_H_MODULE
+#define BITSTREAM_H_MODULE
+
+/*
+*  This API consists of small unitary functions, which must be inlined for best performance.
+*  Since link-time-optimization is not available for all compilers,
+*  these functions are defined into a .h to be included.
+*/
+
+/*-****************************************
+*  Dependencies
+******************************************/
+#include "error_private.h" /* error codes and messages */
+#include "mem.h"	   /* unaligned access routines */
+
+/*=========================================
+*  Target specific
+=========================================*/
+#define STREAM_ACCUMULATOR_MIN_32 25
+#define STREAM_ACCUMULATOR_MIN_64 57
+#define STREAM_ACCUMULATOR_MIN ((U32)(ZSTD_32bits() ? STREAM_ACCUMULATOR_MIN_32 : STREAM_ACCUMULATOR_MIN_64))
+
+/*-******************************************
+*  bitStream encoding API (write forward)
+********************************************/
+/* bitStream can mix input from multiple sources.
+*  A critical property of these streams is that they encode and decode in **reverse** direction.
+*  So the first bit sequence you add will be the last to be read, like a LIFO stack.
+*/
+typedef struct {
+	size_t bitContainer;
+	int bitPos;
+	char *startPtr;
+	char *ptr;
+	char *endPtr;
+} BIT_CStream_t;
+
+ZSTD_STATIC size_t BIT_initCStream(BIT_CStream_t *bitC, void *dstBuffer, size_t dstCapacity);
+ZSTD_STATIC void BIT_addBits(BIT_CStream_t *bitC, size_t value, unsigned nbBits);
+ZSTD_STATIC void BIT_flushBits(BIT_CStream_t *bitC);
+ZSTD_STATIC size_t BIT_closeCStream(BIT_CStream_t *bitC);
+
+/* Start with initCStream, providing the size of buffer to write into.
+*  bitStream will never write outside of this buffer.
+*  `dstCapacity` must be >= sizeof(bitD->bitContainer), otherwise @return will be an error code.
+*
+*  bits are first added to a local register.
+*  Local register is size_t, hence 64-bits on 64-bits systems, or 32-bits on 32-bits systems.
+*  Writing data into memory is an explicit operation, performed by the flushBits function.
+*  Hence keep track how many bits are potentially stored into local register to avoid register overflow.
+*  After a flushBits, a maximum of 7 bits might still be stored into local register.
+*
+*  Avoid storing elements of more than 24 bits if you want compatibility with 32-bits bitstream readers.
+*
+*  Last operation is to close the bitStream.
+*  The function returns the final size of CStream in bytes.
+*  If data couldn't fit into `dstBuffer`, it will return a 0 ( == not storable)
+*/
+
+/*-********************************************
+*  bitStream decoding API (read backward)
+**********************************************/
+typedef struct {
+	size_t bitContainer;
+	unsigned bitsConsumed;
+	const char *ptr;
+	const char *start;
+} BIT_DStream_t;
+
+typedef enum {
+	BIT_DStream_unfinished = 0,
+	BIT_DStream_endOfBuffer = 1,
+	BIT_DStream_completed = 2,
+	BIT_DStream_overflow = 3
+} BIT_DStream_status; /* result of BIT_reloadDStream() */
+/* 1,2,4,8 would be better for bitmap combinations, but slows down performance a bit ... :( */
+
+ZSTD_STATIC size_t BIT_initDStream(BIT_DStream_t *bitD, const void *srcBuffer, size_t srcSize);
+ZSTD_STATIC size_t BIT_readBits(BIT_DStream_t *bitD, unsigned nbBits);
+ZSTD_STATIC BIT_DStream_status BIT_reloadDStream(BIT_DStream_t *bitD);
+ZSTD_STATIC unsigned BIT_endOfDStream(const BIT_DStream_t *bitD);
+
+/* Start by invoking BIT_initDStream().
+*  A chunk of the bitStream is then stored into a local register.
+*  Local register size is 64-bits on 64-bits systems, 32-bits on 32-bits systems (size_t).
+*  You can then retrieve bitFields stored into the local register, **in reverse order**.
+*  Local register is explicitly reloaded from memory by the BIT_reloadDStream() method.
+*  A reload guarantee a minimum of ((8*sizeof(bitD->bitContainer))-7) bits when its result is BIT_DStream_unfinished.
+*  Otherwise, it can be less than that, so proceed accordingly.
+*  Checking if DStream has reached its end can be performed with BIT_endOfDStream().
+*/
+
+/*-****************************************
+*  unsafe API
+******************************************/
+ZSTD_STATIC void BIT_addBitsFast(BIT_CStream_t *bitC, size_t value, unsigned nbBits);
+/* faster, but works only if value is "clean", meaning all high bits above nbBits are 0 */
+
+ZSTD_STATIC void BIT_flushBitsFast(BIT_CStream_t *bitC);
+/* unsafe version; does not check buffer overflow */
+
+ZSTD_STATIC size_t BIT_readBitsFast(BIT_DStream_t *bitD, unsigned nbBits);
+/* faster, but works only if nbBits >= 1 */
+
+/*-**************************************************************
+*  Internal functions
+****************************************************************/
+ZSTD_STATIC unsigned BIT_highbit32(register U32 val) { return 31 - __builtin_clz(val); }
+
+/*=====    Local Constants   =====*/
+static const unsigned BIT_mask[] = {0,       1,       3,       7,	0xF,      0x1F,     0x3F,     0x7F,      0xFF,
+				    0x1FF,   0x3FF,   0x7FF,   0xFFF,    0x1FFF,   0x3FFF,   0x7FFF,   0xFFFF,    0x1FFFF,
+				    0x3FFFF, 0x7FFFF, 0xFFFFF, 0x1FFFFF, 0x3FFFFF, 0x7FFFFF, 0xFFFFFF, 0x1FFFFFF, 0x3FFFFFF}; /* up to 26 bits */
+
+/*-**************************************************************
+*  bitStream encoding
+****************************************************************/
+/*! BIT_initCStream() :
+ *  `dstCapacity` must be > sizeof(void*)
+ *  @return : 0 if success,
+			  otherwise an error code (can be tested using ERR_isError() ) */
+ZSTD_STATIC size_t BIT_initCStream(BIT_CStream_t *bitC, void *startPtr, size_t dstCapacity)
+{
+	bitC->bitContainer = 0;
+	bitC->bitPos = 0;
+	bitC->startPtr = (char *)startPtr;
+	bitC->ptr = bitC->startPtr;
+	bitC->endPtr = bitC->startPtr + dstCapacity - sizeof(bitC->ptr);
+	if (dstCapacity <= sizeof(bitC->ptr))
+		return ERROR(dstSize_tooSmall);
+	return 0;
+}
+
+/*! BIT_addBits() :
+	can add up to 26 bits into `bitC`.
+	Does not check for register overflow ! */
+ZSTD_STATIC void BIT_addBits(BIT_CStream_t *bitC, size_t value, unsigned nbBits)
+{
+	bitC->bitContainer |= (value & BIT_mask[nbBits]) << bitC->bitPos;
+	bitC->bitPos += nbBits;
+}
+
+/*! BIT_addBitsFast() :
+ *  works only if `value` is _clean_, meaning all high bits above nbBits are 0 */
+ZSTD_STATIC void BIT_addBitsFast(BIT_CStream_t *bitC, size_t value, unsigned nbBits)
+{
+	bitC->bitContainer |= value << bitC->bitPos;
+	bitC->bitPos += nbBits;
+}
+
+/*! BIT_flushBitsFast() :
+ *  unsafe version; does not check buffer overflow */
+ZSTD_STATIC void BIT_flushBitsFast(BIT_CStream_t *bitC)
+{
+	size_t const nbBytes = bitC->bitPos >> 3;
+	ZSTD_writeLEST(bitC->ptr, bitC->bitContainer);
+	bitC->ptr += nbBytes;
+	bitC->bitPos &= 7;
+	bitC->bitContainer >>= nbBytes * 8; /* if bitPos >= sizeof(bitContainer)*8 --> undefined behavior */
+}
+
+/*! BIT_flushBits() :
+ *  safe version; check for buffer overflow, and prevents it.
+ *  note : does not signal buffer overflow. This will be revealed later on using BIT_closeCStream() */
+ZSTD_STATIC void BIT_flushBits(BIT_CStream_t *bitC)
+{
+	size_t const nbBytes = bitC->bitPos >> 3;
+	ZSTD_writeLEST(bitC->ptr, bitC->bitContainer);
+	bitC->ptr += nbBytes;
+	if (bitC->ptr > bitC->endPtr)
+		bitC->ptr = bitC->endPtr;
+	bitC->bitPos &= 7;
+	bitC->bitContainer >>= nbBytes * 8; /* if bitPos >= sizeof(bitContainer)*8 --> undefined behavior */
+}
+
+/*! BIT_closeCStream() :
+ *  @return : size of CStream, in bytes,
+			  or 0 if it could not fit into dstBuffer */
+ZSTD_STATIC size_t BIT_closeCStream(BIT_CStream_t *bitC)
+{
+	BIT_addBitsFast(bitC, 1, 1); /* endMark */
+	BIT_flushBits(bitC);
+
+	if (bitC->ptr >= bitC->endPtr)
+		return 0; /* doesn't fit within authorized budget : cancel */
+
+	return (bitC->ptr - bitC->startPtr) + (bitC->bitPos > 0);
+}
+
+/*-********************************************************
+* bitStream decoding
+**********************************************************/
+/*! BIT_initDStream() :
+*   Initialize a BIT_DStream_t.
+*   `bitD` : a pointer to an already allocated BIT_DStream_t structure.
+*   `srcSize` must be the *exact* size of the bitStream, in bytes.
+*   @return : size of stream (== srcSize) or an errorCode if a problem is detected
+*/
+ZSTD_STATIC size_t BIT_initDStream(BIT_DStream_t *bitD, const void *srcBuffer, size_t srcSize)
+{
+	if (srcSize < 1) {
+		memset(bitD, 0, sizeof(*bitD));
+		return ERROR(srcSize_wrong);
+	}
+
+	if (srcSize >= sizeof(bitD->bitContainer)) { /* normal case */
+		bitD->start = (const char *)srcBuffer;
+		bitD->ptr = (const char *)srcBuffer + srcSize - sizeof(bitD->bitContainer);
+		bitD->bitContainer = ZSTD_readLEST(bitD->ptr);
+		{
+			BYTE const lastByte = ((const BYTE *)srcBuffer)[srcSize - 1];
+			bitD->bitsConsumed = lastByte ? 8 - BIT_highbit32(lastByte) : 0; /* ensures bitsConsumed is always set */
+			if (lastByte == 0)
+				return ERROR(GENERIC); /* endMark not present */
+		}
+	} else {
+		bitD->start = (const char *)srcBuffer;
+		bitD->ptr = bitD->start;
+		bitD->bitContainer = *(const BYTE *)(bitD->start);
+		switch (srcSize) {
+		case 7: bitD->bitContainer += (size_t)(((const BYTE *)(srcBuffer))[6]) << (sizeof(bitD->bitContainer) * 8 - 16);
+		case 6: bitD->bitContainer += (size_t)(((const BYTE *)(srcBuffer))[5]) << (sizeof(bitD->bitContainer) * 8 - 24);
+		case 5: bitD->bitContainer += (size_t)(((const BYTE *)(srcBuffer))[4]) << (sizeof(bitD->bitContainer) * 8 - 32);
+		case 4: bitD->bitContainer += (size_t)(((const BYTE *)(srcBuffer))[3]) << 24;
+		case 3: bitD->bitContainer += (size_t)(((const BYTE *)(srcBuffer))[2]) << 16;
+		case 2: bitD->bitContainer += (size_t)(((const BYTE *)(srcBuffer))[1]) << 8;
+		default:;
+		}
+		{
+			BYTE const lastByte = ((const BYTE *)srcBuffer)[srcSize - 1];
+			bitD->bitsConsumed = lastByte ? 8 - BIT_highbit32(lastByte) : 0;
+			if (lastByte == 0)
+				return ERROR(GENERIC); /* endMark not present */
+		}
+		bitD->bitsConsumed += (U32)(sizeof(bitD->bitContainer) - srcSize) * 8;
+	}
+
+	return srcSize;
+}
+
+ZSTD_STATIC size_t BIT_getUpperBits(size_t bitContainer, U32 const start) { return bitContainer >> start; }
+
+ZSTD_STATIC size_t BIT_getMiddleBits(size_t bitContainer, U32 const start, U32 const nbBits) { return (bitContainer >> start) & BIT_mask[nbBits]; }
+
+ZSTD_STATIC size_t BIT_getLowerBits(size_t bitContainer, U32 const nbBits) { return bitContainer & BIT_mask[nbBits]; }
+
+/*! BIT_lookBits() :
+ *  Provides next n bits from local register.
+ *  local register is not modified.
+ *  On 32-bits, maxNbBits==24.
+ *  On 64-bits, maxNbBits==56.
+ *  @return : value extracted
+ */
+ZSTD_STATIC size_t BIT_lookBits(const BIT_DStream_t *bitD, U32 nbBits)
+{
+	U32 const bitMask = sizeof(bitD->bitContainer) * 8 - 1;
+	return ((bitD->bitContainer << (bitD->bitsConsumed & bitMask)) >> 1) >> ((bitMask - nbBits) & bitMask);
+}
+
+/*! BIT_lookBitsFast() :
+*   unsafe version; only works only if nbBits >= 1 */
+ZSTD_STATIC size_t BIT_lookBitsFast(const BIT_DStream_t *bitD, U32 nbBits)
+{
+	U32 const bitMask = sizeof(bitD->bitContainer) * 8 - 1;
+	return (bitD->bitContainer << (bitD->bitsConsumed & bitMask)) >> (((bitMask + 1) - nbBits) & bitMask);
+}
+
+ZSTD_STATIC void BIT_skipBits(BIT_DStream_t *bitD, U32 nbBits) { bitD->bitsConsumed += nbBits; }
+
+/*! BIT_readBits() :
+ *  Read (consume) next n bits from local register and update.
+ *  Pay attention to not read more than nbBits contained into local register.
+ *  @return : extracted value.
+ */
+ZSTD_STATIC size_t BIT_readBits(BIT_DStream_t *bitD, U32 nbBits)
+{
+	size_t const value = BIT_lookBits(bitD, nbBits);
+	BIT_skipBits(bitD, nbBits);
+	return value;
+}
+
+/*! BIT_readBitsFast() :
+*   unsafe version; only works only if nbBits >= 1 */
+ZSTD_STATIC size_t BIT_readBitsFast(BIT_DStream_t *bitD, U32 nbBits)
+{
+	size_t const value = BIT_lookBitsFast(bitD, nbBits);
+	BIT_skipBits(bitD, nbBits);
+	return value;
+}
+
+/*! BIT_reloadDStream() :
+*   Refill `bitD` from buffer previously set in BIT_initDStream() .
+*   This function is safe, it guarantees it will not read beyond src buffer.
+*   @return : status of `BIT_DStream_t` internal register.
+			  if status == BIT_DStream_unfinished, internal register is filled with >= (sizeof(bitD->bitContainer)*8 - 7) bits */
+ZSTD_STATIC BIT_DStream_status BIT_reloadDStream(BIT_DStream_t *bitD)
+{
+	if (bitD->bitsConsumed > (sizeof(bitD->bitContainer) * 8)) /* should not happen => corruption detected */
+		return BIT_DStream_overflow;
+
+	if (bitD->ptr >= bitD->start + sizeof(bitD->bitContainer)) {
+		bitD->ptr -= bitD->bitsConsumed >> 3;
+		bitD->bitsConsumed &= 7;
+		bitD->bitContainer = ZSTD_readLEST(bitD->ptr);
+		return BIT_DStream_unfinished;
+	}
+	if (bitD->ptr == bitD->start) {
+		if (bitD->bitsConsumed < sizeof(bitD->bitContainer) * 8)
+			return BIT_DStream_endOfBuffer;
+		return BIT_DStream_completed;
+	}
+	{
+		U32 nbBytes = bitD->bitsConsumed >> 3;
+		BIT_DStream_status result = BIT_DStream_unfinished;
+		if (bitD->ptr - nbBytes < bitD->start) {
+			nbBytes = (U32)(bitD->ptr - bitD->start); /* ptr > start */
+			result = BIT_DStream_endOfBuffer;
+		}
+		bitD->ptr -= nbBytes;
+		bitD->bitsConsumed -= nbBytes * 8;
+		bitD->bitContainer = ZSTD_readLEST(bitD->ptr); /* reminder : srcSize > sizeof(bitD) */
+		return result;
+	}
+}
+
+/*! BIT_endOfDStream() :
+*   @return Tells if DStream has exactly reached its end (all bits consumed).
+*/
+ZSTD_STATIC unsigned BIT_endOfDStream(const BIT_DStream_t *DStream)
+{
+	return ((DStream->ptr == DStream->start) && (DStream->bitsConsumed == sizeof(DStream->bitContainer) * 8));
+}
+
+#endif /* BITSTREAM_H_MODULE */

lib/zstd/entropy_common.c

@@ -0,0 +1,243 @@
+/*
+ * Common functions of New Generation Entropy library
+ * Copyright (C) 2016, Yann Collet.
+ *
+ * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *   * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License version 2 as published by the
+ * Free Software Foundation. This program is dual-licensed; you may select
+ * either version 2 of the GNU General Public License ("GPL") or BSD license
+ * ("BSD").
+ *
+ * You can contact the author at :
+ * - Source repository : https://github.com/Cyan4973/FiniteStateEntropy
+ */
+
+/* *************************************
+*  Dependencies
+***************************************/
+#include "error_private.h" /* ERR_*, ERROR */
+#include "fse.h"
+#include "huf.h"
+#include "mem.h"
+
+/*===   Version   ===*/
+unsigned FSE_versionNumber(void) { return FSE_VERSION_NUMBER; }
+
+/*===   Error Management   ===*/
+unsigned FSE_isError(size_t code) { return ERR_isError(code); }
+
+unsigned HUF_isError(size_t code) { return ERR_isError(code); }
+
+/*-**************************************************************
+*  FSE NCount encoding-decoding
+****************************************************************/
+size_t FSE_readNCount(short *normalizedCounter, unsigned *maxSVPtr, unsigned *tableLogPtr, const void *headerBuffer, size_t hbSize)
+{
+	const BYTE *const istart = (const BYTE *)headerBuffer;
+	const BYTE *const iend = istart + hbSize;
+	const BYTE *ip = istart;
+	int nbBits;
+	int remaining;
+	int threshold;
+	U32 bitStream;
+	int bitCount;
+	unsigned charnum = 0;
+	int previous0 = 0;
+
+	if (hbSize < 4)
+		return ERROR(srcSize_wrong);
+	bitStream = ZSTD_readLE32(ip);
+	nbBits = (bitStream & 0xF) + FSE_MIN_TABLELOG; /* extract tableLog */
+	if (nbBits > FSE_TABLELOG_ABSOLUTE_MAX)
+		return ERROR(tableLog_tooLarge);
+	bitStream >>= 4;
+	bitCount = 4;
+	*tableLogPtr = nbBits;
+	remaining = (1 << nbBits) + 1;
+	threshold = 1 << nbBits;
+	nbBits++;
+
+	while ((remaining > 1) & (charnum <= *maxSVPtr)) {
+		if (previous0) {
+			unsigned n0 = charnum;
+			while ((bitStream & 0xFFFF) == 0xFFFF) {
+				n0 += 24;
+				if (ip < iend - 5) {
+					ip += 2;
+					bitStream = ZSTD_readLE32(ip) >> bitCount;
+				} else {
+					bitStream >>= 16;
+					bitCount += 16;
+				}
+			}
+			while ((bitStream & 3) == 3) {
+				n0 += 3;
+				bitStream >>= 2;
+				bitCount += 2;
+			}
+			n0 += bitStream & 3;
+			bitCount += 2;
+			if (n0 > *maxSVPtr)
+				return ERROR(maxSymbolValue_tooSmall);
+			while (charnum < n0)
+				normalizedCounter[charnum++] = 0;
+			if ((ip <= iend - 7) || (ip + (bitCount >> 3) <= iend - 4)) {
+				ip += bitCount >> 3;
+				bitCount &= 7;
+				bitStream = ZSTD_readLE32(ip) >> bitCount;
+			} else {
+				bitStream >>= 2;
+			}
+		}
+		{
+			int const max = (2 * threshold - 1) - remaining;
+			int count;
+
+			if ((bitStream & (threshold - 1)) < (U32)max) {
+				count = bitStream & (threshold - 1);
+				bitCount += nbBits - 1;
+			} else {
+				count = bitStream & (2 * threshold - 1);
+				if (count >= threshold)
+					count -= max;
+				bitCount += nbBits;
+			}
+
+			count--;				 /* extra accuracy */
+			remaining -= count < 0 ? -count : count; /* -1 means +1 */
+			normalizedCounter[charnum++] = (short)count;
+			previous0 = !count;
+			while (remaining < threshold) {
+				nbBits--;
+				threshold >>= 1;
+			}
+
+			if ((ip <= iend - 7) || (ip + (bitCount >> 3) <= iend - 4)) {
+				ip += bitCount >> 3;
+				bitCount &= 7;
+			} else {
+				bitCount -= (int)(8 * (iend - 4 - ip));
+				ip = iend - 4;
+			}
+			bitStream = ZSTD_readLE32(ip) >> (bitCount & 31);
+		}
+	} /* while ((remaining>1) & (charnum<=*maxSVPtr)) */
+	if (remaining != 1)
+		return ERROR(corruption_detected);
+	if (bitCount > 32)
+		return ERROR(corruption_detected);
+	*maxSVPtr = charnum - 1;
+
+	ip += (bitCount + 7) >> 3;
+	return ip - istart;
+}
+
+/*! HUF_readStats() :
+	Read compact Huffman tree, saved by HUF_writeCTable().
+	`huffWeight` is destination buffer.
+	`rankStats` is assumed to be a table of at least HUF_TABLELOG_MAX U32.
+	@return : size read from `src` , or an error Code .
+	Note : Needed by HUF_readCTable() and HUF_readDTableX?() .
+*/
+size_t HUF_readStats_wksp(BYTE *huffWeight, size_t hwSize, U32 *rankStats, U32 *nbSymbolsPtr, U32 *tableLogPtr, const void *src, size_t srcSize, void *workspace, size_t workspaceSize)
+{
+	U32 weightTotal;
+	const BYTE *ip = (const BYTE *)src;
+	size_t iSize;
+	size_t oSize;
+
+	if (!srcSize)
+		return ERROR(srcSize_wrong);
+	iSize = ip[0];
+	/* memset(huffWeight, 0, hwSize);   */ /* is not necessary, even though some analyzer complain ... */
+
+	if (iSize >= 128) { /* special header */
+		oSize = iSize - 127;
+		iSize = ((oSize + 1) / 2);
+		if (iSize + 1 > srcSize)
+			return ERROR(srcSize_wrong);
+		if (oSize >= hwSize)
+			return ERROR(corruption_detected);
+		ip += 1;
+		{
+			U32 n;
+			for (n = 0; n < oSize; n += 2) {
+				huffWeight[n] = ip[n / 2] >> 4;
+				huffWeight[n + 1] = ip[n / 2] & 15;
+			}
+		}
+	} else {						 /* header compressed with FSE (normal case) */
+		if (iSize + 1 > srcSize)
+			return ERROR(srcSize_wrong);
+		oSize = FSE_decompress_wksp(huffWeight, hwSize - 1, ip + 1, iSize, 6, workspace, workspaceSize); /* max (hwSize-1) values decoded, as last one is implied */
+		if (FSE_isError(oSize))
+			return oSize;
+	}
+
+	/* collect weight stats */
+	memset(rankStats, 0, (HUF_TABLELOG_MAX + 1) * sizeof(U32));
+	weightTotal = 0;
+	{
+		U32 n;
+		for (n = 0; n < oSize; n++) {
+			if (huffWeight[n] >= HUF_TABLELOG_MAX)
+				return ERROR(corruption_detected);
+			rankStats[huffWeight[n]]++;
+			weightTotal += (1 << huffWeight[n]) >> 1;
+		}
+	}
+	if (weightTotal == 0)
+		return ERROR(corruption_detected);
+
+	/* get last non-null symbol weight (implied, total must be 2^n) */
+	{
+		U32 const tableLog = BIT_highbit32(weightTotal) + 1;
+		if (tableLog > HUF_TABLELOG_MAX)
+			return ERROR(corruption_detected);
+		*tableLogPtr = tableLog;
+		/* determine last weight */
+		{
+			U32 const total = 1 << tableLog;
+			U32 const rest = total - weightTotal;
+			U32 const verif = 1 << BIT_highbit32(rest);
+			U32 const lastWeight = BIT_highbit32(rest) + 1;
+			if (verif != rest)
+				return ERROR(corruption_detected); /* last value must be a clean power of 2 */
+			huffWeight[oSize] = (BYTE)lastWeight;
+			rankStats[lastWeight]++;
+		}
+	}
+
+	/* check tree construction validity */
+	if ((rankStats[1] < 2) || (rankStats[1] & 1))
+		return ERROR(corruption_detected); /* by construction : at least 2 elts of rank 1, must be even */
+
+	/* results */
+	*nbSymbolsPtr = (U32)(oSize + 1);
+	return iSize + 1;
+}

lib/zstd/error_private.h

@@ -0,0 +1,53 @@
+/**
+ * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of https://github.com/facebook/zstd.
+ * An additional grant of patent rights can be found in the PATENTS file in the
+ * same directory.
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License version 2 as published by the
+ * Free Software Foundation. This program is dual-licensed; you may select
+ * either version 2 of the GNU General Public License ("GPL") or BSD license
+ * ("BSD").
+ */
+
+/* Note : this module is expected to remain private, do not expose it */
+
+#ifndef ERROR_H_MODULE
+#define ERROR_H_MODULE
+
+/* ****************************************
+*  Dependencies
+******************************************/
+#include <linux/types.h> /* size_t */
+#include <linux/zstd.h>  /* enum list */
+
+/* ****************************************
+*  Compiler-specific
+******************************************/
+#define ERR_STATIC static __attribute__((unused))
+
+/*-****************************************
+*  Customization (error_public.h)
+******************************************/
+typedef ZSTD_ErrorCode ERR_enum;
+#define PREFIX(name) ZSTD_error_##name
+
+/*-****************************************
+*  Error codes handling
+******************************************/
+#define ERROR(name) ((size_t)-PREFIX(name))
+
+ERR_STATIC unsigned ERR_isError(size_t code) { return (code > ERROR(maxCode)); }
+
+ERR_STATIC ERR_enum ERR_getErrorCode(size_t code)
+{
+	if (!ERR_isError(code))
+		return (ERR_enum)0;
+	return (ERR_enum)(0 - code);
+}
+
+#endif /* ERROR_H_MODULE */

lib/zstd/fse.h

@@ -0,0 +1,575 @@
+/*
+ * FSE : Finite State Entropy codec
+ * Public Prototypes declaration
+ * Copyright (C) 2013-2016, Yann Collet.
+ *
+ * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *   * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License version 2 as published by the
+ * Free Software Foundation. This program is dual-licensed; you may select
+ * either version 2 of the GNU General Public License ("GPL") or BSD license
+ * ("BSD").
+ *
+ * You can contact the author at :
+ * - Source repository : https://github.com/Cyan4973/FiniteStateEntropy
+ */
+#ifndef FSE_H
+#define FSE_H
+
+/*-*****************************************
+*  Dependencies
+******************************************/
+#include <linux/types.h> /* size_t, ptrdiff_t */
+
+/*-*****************************************
+*  FSE_PUBLIC_API : control library symbols visibility
+******************************************/
+#define FSE_PUBLIC_API
+
+/*------   Version   ------*/
+#define FSE_VERSION_MAJOR 0
+#define FSE_VERSION_MINOR 9
+#define FSE_VERSION_RELEASE 0
+
+#define FSE_LIB_VERSION FSE_VERSION_MAJOR.FSE_VERSION_MINOR.FSE_VERSION_RELEASE
+#define FSE_QUOTE(str) #str
+#define FSE_EXPAND_AND_QUOTE(str) FSE_QUOTE(str)
+#define FSE_VERSION_STRING FSE_EXPAND_AND_QUOTE(FSE_LIB_VERSION)
+
+#define FSE_VERSION_NUMBER (FSE_VERSION_MAJOR * 100 * 100 + FSE_VERSION_MINOR * 100 + FSE_VERSION_RELEASE)
+FSE_PUBLIC_API unsigned FSE_versionNumber(void); /**< library version number; to be used when checking dll version */
+
+/*-*****************************************
+*  Tool functions
+******************************************/
+FSE_PUBLIC_API size_t FSE_compressBound(size_t size); /* maximum compressed size */
+
+/* Error Management */
+FSE_PUBLIC_API unsigned FSE_isError(size_t code); /* tells if a return value is an error code */
+
+/*-*****************************************
+*  FSE detailed API
+******************************************/
+/*!
+FSE_compress() does the following:
+1. count symbol occurrence from source[] into table count[]
+2. normalize counters so that sum(count[]) == Power_of_2 (2^tableLog)
+3. save normalized counters to memory buffer using writeNCount()
+4. build encoding table 'CTable' from normalized counters
+5. encode the data stream using encoding table 'CTable'
+
+FSE_decompress() does the following:
+1. read normalized counters with readNCount()
+2. build decoding table 'DTable' from normalized counters
+3. decode the data stream using decoding table 'DTable'
+
+The following API allows targeting specific sub-functions for advanced tasks.
+For example, it's possible to compress several blocks using the same 'CTable',
+or to save and provide normalized distribution using external method.
+*/
+
+/* *** COMPRESSION *** */
+/*! FSE_optimalTableLog():
+	dynamically downsize 'tableLog' when conditions are met.
+	It saves CPU time, by using smaller tables, while preserving or even improving compression ratio.
+	@return : recommended tableLog (necessarily <= 'maxTableLog') */
+FSE_PUBLIC_API unsigned FSE_optimalTableLog(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue);
+
+/*! FSE_normalizeCount():
+	normalize counts so that sum(count[]) == Power_of_2 (2^tableLog)
+	'normalizedCounter' is a table of short, of minimum size (maxSymbolValue+1).
+	@return : tableLog,
+			  or an errorCode, which can be tested using FSE_isError() */
+FSE_PUBLIC_API size_t FSE_normalizeCount(short *normalizedCounter, unsigned tableLog, const unsigned *count, size_t srcSize, unsigned maxSymbolValue);
+
+/*! FSE_NCountWriteBound():
+	Provides the maximum possible size of an FSE normalized table, given 'maxSymbolValue' and 'tableLog'.
+	Typically useful for allocation purpose. */
+FSE_PUBLIC_API size_t FSE_NCountWriteBound(unsigned maxSymbolValue, unsigned tableLog);
+
+/*! FSE_writeNCount():
+	Compactly save 'normalizedCounter' into 'buffer'.
+	@return : size of the compressed table,
+			  or an errorCode, which can be tested using FSE_isError(). */
+FSE_PUBLIC_API size_t FSE_writeNCount(void *buffer, size_t bufferSize, const short *normalizedCounter, unsigned maxSymbolValue, unsigned tableLog);
+
+/*! Constructor and Destructor of FSE_CTable.
+	Note that FSE_CTable size depends on 'tableLog' and 'maxSymbolValue' */
+typedef unsigned FSE_CTable; /* don't allocate that. It's only meant to be more restrictive than void* */
+
+/*! FSE_compress_usingCTable():
+	Compress `src` using `ct` into `dst` which must be already allocated.
+	@return : size of compressed data (<= `dstCapacity`),
+			  or 0 if compressed data could not fit into `dst`,
+			  or an errorCode, which can be tested using FSE_isError() */
+FSE_PUBLIC_API size_t FSE_compress_usingCTable(void *dst, size_t dstCapacity, const void *src, size_t srcSize, const FSE_CTable *ct);
+
+/*!
+Tutorial :
+----------
+The first step is to count all symbols. FSE_count() does this job very fast.
+Result will be saved into 'count', a table of unsigned int, which must be already allocated, and have 'maxSymbolValuePtr[0]+1' cells.
+'src' is a table of bytes of size 'srcSize'. All values within 'src' MUST be <= maxSymbolValuePtr[0]
+maxSymbolValuePtr[0] will be updated, with its real value (necessarily <= original value)
+FSE_count() will return the number of occurrence of the most frequent symbol.
+This can be used to know if there is a single symbol within 'src', and to quickly evaluate its compressibility.
+If there is an error, the function will return an ErrorCode (which can be tested using FSE_isError()).
+
+The next step is to normalize the frequencies.
+FSE_normalizeCount() will ensure that sum of frequencies is == 2 ^'tableLog'.
+It also guarantees a minimum of 1 to any Symbol with frequency >= 1.
+You can use 'tableLog'==0 to mean "use default tableLog value".
+If you are unsure of which tableLog value to use, you can ask FSE_optimalTableLog(),
+which will provide the optimal valid tableLog given sourceSize, maxSymbolValue, and a user-defined maximum (0 means "default").
+
+The result of FSE_normalizeCount() will be saved into a table,
+called 'normalizedCounter', which is a table of signed short.
+'normalizedCounter' must be already allocated, and have at least 'maxSymbolValue+1' cells.
+The return value is tableLog if everything proceeded as expected.
+It is 0 if there is a single symbol within distribution.
+If there is an error (ex: invalid tableLog value), the function will return an ErrorCode (which can be tested using FSE_isError()).
+
+'normalizedCounter' can be saved in a compact manner to a memory area using FSE_writeNCount().
+'buffer' must be already allocated.
+For guaranteed success, buffer size must be at least FSE_headerBound().
+The result of the function is the number of bytes written into 'buffer'.
+If there is an error, the function will return an ErrorCode (which can be tested using FSE_isError(); ex : buffer size too small).
+
+'normalizedCounter' can then be used to create the compression table 'CTable'.
+The space required by 'CTable' must be already allocated, using FSE_createCTable().
+You can then use FSE_buildCTable() to fill 'CTable'.
+If there is an error, both functions will return an ErrorCode (which can be tested using FSE_isError()).
+
+'CTable' can then be used to compress 'src', with FSE_compress_usingCTable().
+Similar to FSE_count(), the convention is that 'src' is assumed to be a table of char of size 'srcSize'
+The function returns the size of compressed data (without header), necessarily <= `dstCapacity`.
+If it returns '0', compressed data could not fit into 'dst'.
+If there is an error, the function will return an ErrorCode (which can be tested using FSE_isError()).
+*/
+
+/* *** DECOMPRESSION *** */
+
+/*! FSE_readNCount():
+	Read compactly saved 'normalizedCounter' from 'rBuffer'.
+	@return : size read from 'rBuffer',
+			  or an errorCode, which can be tested using FSE_isError().
+			  maxSymbolValuePtr[0] and tableLogPtr[0] will also be updated with their respective values */
+FSE_PUBLIC_API size_t FSE_readNCount(short *normalizedCounter, unsigned *maxSymbolValuePtr, unsigned *tableLogPtr, const void *rBuffer, size_t rBuffSize);
+
+/*! Constructor and Destructor of FSE_DTable.
+	Note that its size depends on 'tableLog' */
+typedef unsigned FSE_DTable; /* don't allocate that. It's just a way to be more restrictive than void* */
+
+/*! FSE_buildDTable():
+	Builds 'dt', which must be already allocated, using FSE_createDTable().
+	return : 0, or an errorCode, which can be tested using FSE_isError() */
+FSE_PUBLIC_API size_t FSE_buildDTable_wksp(FSE_DTable *dt, const short *normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void *workspace, size_t workspaceSize);
+
+/*! FSE_decompress_usingDTable():
+	Decompress compressed source `cSrc` of size `cSrcSize` using `dt`
+	into `dst` which must be already allocated.
+	@return : size of regenerated data (necessarily <= `dstCapacity`),
+			  or an errorCode, which can be tested using FSE_isError() */
+FSE_PUBLIC_API size_t FSE_decompress_usingDTable(void *dst, size_t dstCapacity, const void *cSrc, size_t cSrcSize, const FSE_DTable *dt);
+
+/*!
+Tutorial :
+----------
+(Note : these functions only decompress FSE-compressed blocks.
+ If block is uncompressed, use memcpy() instead
+ If block is a single repeated byte, use memset() instead )
+
+The first step is to obtain the normalized frequencies of symbols.
+This can be performed by FSE_readNCount() if it was saved using FSE_writeNCount().
+'normalizedCounter' must be already allocated, and have at least 'maxSymbolValuePtr[0]+1' cells of signed short.
+In practice, that means it's necessary to know 'maxSymbolValue' beforehand,
+or size the table to handle worst case situations (typically 256).
+FSE_readNCount() will provide 'tableLog' and 'maxSymbolValue'.
+The result of FSE_readNCount() is the number of bytes read from 'rBuffer'.
+Note that 'rBufferSize' must be at least 4 bytes, even if useful information is less than that.
+If there is an error, the function will return an error code, which can be tested using FSE_isError().
+
+The next step is to build the decompression tables 'FSE_DTable' from 'normalizedCounter'.
+This is performed by the function FSE_buildDTable().
+The space required by 'FSE_DTable' must be already allocated using FSE_createDTable().
+If there is an error, the function will return an error code, which can be tested using FSE_isError().
+
+`FSE_DTable` can then be used to decompress `cSrc`, with FSE_decompress_usingDTable().
+`cSrcSize` must be strictly correct, otherwise decompression will fail.
+FSE_decompress_usingDTable() result will tell how many bytes were regenerated (<=`dstCapacity`).
+If there is an error, the function will return an error code, which can be tested using FSE_isError(). (ex: dst buffer too small)
+*/
+
+/* *** Dependency *** */
+#include "bitstream.h"
+
+/* *****************************************
+*  Static allocation
+*******************************************/
+/* FSE buffer bounds */
+#define FSE_NCOUNTBOUND 512
+#define FSE_BLOCKBOUND(size) (size + (size >> 7))
+#define FSE_COMPRESSBOUND(size) (FSE_NCOUNTBOUND + FSE_BLOCKBOUND(size)) /* Macro version, useful for static allocation */
+
+/* It is possible to statically allocate FSE CTable/DTable as a table of FSE_CTable/FSE_DTable using below macros */
+#define FSE_CTABLE_SIZE_U32(maxTableLog, maxSymbolValue) (1 + (1 << (maxTableLog - 1)) + ((maxSymbolValue + 1) * 2))
+#define FSE_DTABLE_SIZE_U32(maxTableLog) (1 + (1 << maxTableLog))
+
+/* *****************************************
+*  FSE advanced API
+*******************************************/
+/* FSE_count_wksp() :
+ * Same as FSE_count(), but using an externally provided scratch buffer.
+ * `workSpace` size must be table of >= `1024` unsigned
+ */
+size_t FSE_count_wksp(unsigned *count, unsigned *maxSymbolValuePtr, const void *source, size_t sourceSize, unsigned *workSpace);
+
+/* FSE_countFast_wksp() :
+ * Same as FSE_countFast(), but using an externally provided scratch buffer.
+ * `workSpace` must be a table of minimum `1024` unsigned
+ */
+size_t FSE_countFast_wksp(unsigned *count, unsigned *maxSymbolValuePtr, const void *src, size_t srcSize, unsigned *workSpace);
+
+/*! FSE_count_simple
+ * Same as FSE_countFast(), but does not use any additional memory (not even on stack).
+ * This function is unsafe, and will segfault if any value within `src` is `> *maxSymbolValuePtr` (presuming it's also the size of `count`).
+*/
+size_t FSE_count_simple(unsigned *count, unsigned *maxSymbolValuePtr, const void *src, size_t srcSize);
+
+unsigned FSE_optimalTableLog_internal(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue, unsigned minus);
+/**< same as FSE_optimalTableLog(), which used `minus==2` */
+
+size_t FSE_buildCTable_raw(FSE_CTable *ct, unsigned nbBits);
+/**< build a fake FSE_CTable, designed for a flat distribution, where each symbol uses nbBits */
+
+size_t FSE_buildCTable_rle(FSE_CTable *ct, unsigned char symbolValue);
+/**< build a fake FSE_CTable, designed to compress always the same symbolValue */
+
+/* FSE_buildCTable_wksp() :
+ * Same as FSE_buildCTable(), but using an externally allocated scratch buffer (`workSpace`).
+ * `wkspSize` must be >= `(1<<tableLog)`.
+ */
+size_t FSE_buildCTable_wksp(FSE_CTable *ct, const short *normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void *workSpace, size_t wkspSize);
+
+size_t FSE_buildDTable_raw(FSE_DTable *dt, unsigned nbBits);
+/**< build a fake FSE_DTable, designed to read a flat distribution where each symbol uses nbBits */
+
+size_t FSE_buildDTable_rle(FSE_DTable *dt, unsigned char symbolValue);
+/**< build a fake FSE_DTable, designed to always generate the same symbolValue */
+
+size_t FSE_decompress_wksp(void *dst, size_t dstCapacity, const void *cSrc, size_t cSrcSize, unsigned maxLog, void *workspace, size_t workspaceSize);
+/**< same as FSE_decompress(), using an externally allocated `workSpace` produced with `FSE_DTABLE_SIZE_U32(maxLog)` */
+
+/* *****************************************
+*  FSE symbol compression API
+*******************************************/
+/*!
+   This API consists of small unitary functions, which highly benefit from being inlined.
+   Hence their body are included in next section.
+*/
+typedef struct {
+	ptrdiff_t value;
+	const void *stateTable;
+	const void *symbolTT;
+	unsigned stateLog;
+} FSE_CState_t;
+
+static void FSE_initCState(FSE_CState_t *CStatePtr, const FSE_CTable *ct);
+
+static void FSE_encodeSymbol(BIT_CStream_t *bitC, FSE_CState_t *CStatePtr, unsigned symbol);
+
+static void FSE_flushCState(BIT_CStream_t *bitC, const FSE_CState_t *CStatePtr);
+
+/**<
+These functions are inner components of FSE_compress_usingCTable().
+They allow the creation of custom streams, mixing multiple tables and bit sources.
+
+A key property to keep in mind is that encoding and decoding are done **in reverse direction**.
+So the first symbol you will encode is the last you will decode, like a LIFO stack.
+
+You will need a few variables to track your CStream. They are :
+
+FSE_CTable    ct;         // Provided by FSE_buildCTable()
+BIT_CStream_t bitStream;  // bitStream tracking structure
+FSE_CState_t  state;      // State tracking structure (can have several)
+
+
+The first thing to do is to init bitStream and state.
+	size_t errorCode = BIT_initCStream(&bitStream, dstBuffer, maxDstSize);
+	FSE_initCState(&state, ct);
+
+Note that BIT_initCStream() can produce an error code, so its result should be tested, using FSE_isError();
+You can then encode your input data, byte after byte.
+FSE_encodeSymbol() outputs a maximum of 'tableLog' bits at a time.
+Remember decoding will be done in reverse direction.
+	FSE_encodeByte(&bitStream, &state, symbol);
+
+At any time, you can also add any bit sequence.
+Note : maximum allowed nbBits is 25, for compatibility with 32-bits decoders
+	BIT_addBits(&bitStream, bitField, nbBits);
+
+The above methods don't commit data to memory, they just store it into local register, for speed.
+Local register size is 64-bits on 64-bits systems, 32-bits on 32-bits systems (size_t).
+Writing data to memory is a manual operation, performed by the flushBits function.
+	BIT_flushBits(&bitStream);
+
+Your last FSE encoding operation shall be to flush your last state value(s).
+	FSE_flushState(&bitStream, &state);
+
+Finally, you must close the bitStream.
+The function returns the size of CStream in bytes.
+If data couldn't fit into dstBuffer, it will return a 0 ( == not compressible)
+If there is an error, it returns an errorCode (which can be tested using FSE_isError()).
+	size_t size = BIT_closeCStream(&bitStream);
+*/
+
+/* *****************************************
+*  FSE symbol decompression API
+*******************************************/
+typedef struct {
+	size_t state;
+	const void *table; /* precise table may vary, depending on U16 */
+} FSE_DState_t;
+
+static void FSE_initDState(FSE_DState_t *DStatePtr, BIT_DStream_t *bitD, const FSE_DTable *dt);
+
+static unsigned char FSE_decodeSymbol(FSE_DState_t *DStatePtr, BIT_DStream_t *bitD);
+
+static unsigned FSE_endOfDState(const FSE_DState_t *DStatePtr);
+
+/**<
+Let's now decompose FSE_decompress_usingDTable() into its unitary components.
+You will decode FSE-encoded symbols from the bitStream,
+and also any other bitFields you put in, **in reverse order**.
+
+You will need a few variables to track your bitStream. They are :
+
+BIT_DStream_t DStream;    // Stream context
+FSE_DState_t  DState;     // State context. Multiple ones are possible
+FSE_DTable*   DTablePtr;  // Decoding table, provided by FSE_buildDTable()
+
+The first thing to do is to init the bitStream.
+	errorCode = BIT_initDStream(&DStream, srcBuffer, srcSize);
+
+You should then retrieve your initial state(s)
+(in reverse flushing order if you have several ones) :
+	errorCode = FSE_initDState(&DState, &DStream, DTablePtr);
+
+You can then decode your data, symbol after symbol.
+For information the maximum number of bits read by FSE_decodeSymbol() is 'tableLog'.
+Keep in mind that symbols are decoded in reverse order, like a LIFO stack (last in, first out).
+	unsigned char symbol = FSE_decodeSymbol(&DState, &DStream);
+
+You can retrieve any bitfield you eventually stored into the bitStream (in reverse order)
+Note : maximum allowed nbBits is 25, for 32-bits compatibility
+	size_t bitField = BIT_readBits(&DStream, nbBits);
+
+All above operations only read from local register (which size depends on size_t).
+Refueling the register from memory is manually performed by the reload method.
+	endSignal = FSE_reloadDStream(&DStream);
+
+BIT_reloadDStream() result tells if there is still some more data to read from DStream.
+BIT_DStream_unfinished : there is still some data left into the DStream.
+BIT_DStream_endOfBuffer : Dstream reached end of buffer. Its container may no longer be completely filled.
+BIT_DStream_completed : Dstream reached its exact end, corresponding in general to decompression completed.
+BIT_DStream_tooFar : Dstream went too far. Decompression result is corrupted.
+
+When reaching end of buffer (BIT_DStream_endOfBuffer), progress slowly, notably if you decode multiple symbols per loop,
+to properly detect the exact end of stream.
+After each decoded symbol, check if DStream is fully consumed using this simple test :
+	BIT_reloadDStream(&DStream) >= BIT_DStream_completed
+
+When it's done, verify decompression is fully completed, by checking both DStream and the relevant states.
+Checking if DStream has reached its end is performed by :
+	BIT_endOfDStream(&DStream);
+Check also the states. There might be some symbols left there, if some high probability ones (>50%) are possible.
+	FSE_endOfDState(&DState);
+*/
+
+/* *****************************************
+*  FSE unsafe API
+*******************************************/
+static unsigned char FSE_decodeSymbolFast(FSE_DState_t *DStatePtr, BIT_DStream_t *bitD);
+/* faster, but works only if nbBits is always >= 1 (otherwise, result will be corrupted) */
+
+/* *****************************************
+*  Implementation of inlined functions
+*******************************************/
+typedef struct {
+	int deltaFindState;
+	U32 deltaNbBits;
+} FSE_symbolCompressionTransform; /* total 8 bytes */
+
+ZSTD_STATIC void FSE_initCState(FSE_CState_t *statePtr, const FSE_CTable *ct)
+{
+	const void *ptr = ct;
+	const U16 *u16ptr = (const U16 *)ptr;
+	const U32 tableLog = ZSTD_read16(ptr);
+	statePtr->value = (ptrdiff_t)1 << tableLog;
+	statePtr->stateTable = u16ptr + 2;
+	statePtr->symbolTT = ((const U32 *)ct + 1 + (tableLog ? (1 << (tableLog - 1)) : 1));
+	statePtr->stateLog = tableLog;
+}
+
+/*! FSE_initCState2() :
+*   Same as FSE_initCState(), but the first symbol to include (which will be the last to be read)
+*   uses the smallest state value possible, saving the cost of this symbol */
+ZSTD_STATIC void FSE_initCState2(FSE_CState_t *statePtr, const FSE_CTable *ct, U32 symbol)
+{
+	FSE_initCState(statePtr, ct);
+	{
+		const FSE_symbolCompressionTransform symbolTT = ((const FSE_symbolCompressionTransform *)(statePtr->symbolTT))[symbol];
+		const U16 *stateTable = (const U16 *)(statePtr->stateTable);
+		U32 nbBitsOut = (U32)((symbolTT.deltaNbBits + (1 << 15)) >> 16);
+		statePtr->value = (nbBitsOut << 16) - symbolTT.deltaNbBits;
+		statePtr->value = stateTable[(statePtr->value >> nbBitsOut) + symbolTT.deltaFindState];
+	}
+}
+
+ZSTD_STATIC void FSE_encodeSymbol(BIT_CStream_t *bitC, FSE_CState_t *statePtr, U32 symbol)
+{
+	const FSE_symbolCompressionTransform symbolTT = ((const FSE_symbolCompressionTransform *)(statePtr->symbolTT))[symbol];
+	const U16 *const stateTable = (const U16 *)(statePtr->stateTable);
+	U32 nbBitsOut = (U32)((statePtr->value + symbolTT.deltaNbBits) >> 16);
+	BIT_addBits(bitC, statePtr->value, nbBitsOut);
+	statePtr->value = stateTable[(statePtr->value >> nbBitsOut) + symbolTT.deltaFindState];
+}
+
+ZSTD_STATIC void FSE_flushCState(BIT_CStream_t *bitC, const FSE_CState_t *statePtr)
+{
+	BIT_addBits(bitC, statePtr->value, statePtr->stateLog);
+	BIT_flushBits(bitC);
+}
+
+/* ======    Decompression    ====== */
+
+typedef struct {
+	U16 tableLog;
+	U16 fastMode;
+} FSE_DTableHeader; /* sizeof U32 */
+
+typedef struct {
+	unsigned short newState;
+	unsigned char symbol;
+	unsigned char nbBits;
+} FSE_decode_t; /* size == U32 */
+
+ZSTD_STATIC void FSE_initDState(FSE_DState_t *DStatePtr, BIT_DStream_t *bitD, const FSE_DTable *dt)
+{
+	const void *ptr = dt;
+	const FSE_DTableHeader *const DTableH = (const FSE_DTableHeader *)ptr;
+	DStatePtr->state = BIT_readBits(bitD, DTableH->tableLog);
+	BIT_reloadDStream(bitD);
+	DStatePtr->table = dt + 1;
+}
+
+ZSTD_STATIC BYTE FSE_peekSymbol(const FSE_DState_t *DStatePtr)
+{
+	FSE_decode_t const DInfo = ((const FSE_decode_t *)(DStatePtr->table))[DStatePtr->state];
+	return DInfo.symbol;
+}
+
+ZSTD_STATIC void FSE_updateState(FSE_DState_t *DStatePtr, BIT_DStream_t *bitD)
+{
+	FSE_decode_t const DInfo = ((const FSE_decode_t *)(DStatePtr->table))[DStatePtr->state];
+	U32 const nbBits = DInfo.nbBits;
+	size_t const lowBits = BIT_readBits(bitD, nbBits);
+	DStatePtr->state = DInfo.newState + lowBits;
+}
+
+ZSTD_STATIC BYTE FSE_decodeSymbol(FSE_DState_t *DStatePtr, BIT_DStream_t *bitD)
+{
+	FSE_decode_t const DInfo = ((const FSE_decode_t *)(DStatePtr->table))[DStatePtr->state];
+	U32 const nbBits = DInfo.nbBits;
+	BYTE const symbol = DInfo.symbol;
+	size_t const lowBits = BIT_readBits(bitD, nbBits);
+
+	DStatePtr->state = DInfo.newState + lowBits;
+	return symbol;
+}
+
+/*! FSE_decodeSymbolFast() :
+	unsafe, only works if no symbol has a probability > 50% */
+ZSTD_STATIC BYTE FSE_decodeSymbolFast(FSE_DState_t *DStatePtr, BIT_DStream_t *bitD)
+{
+	FSE_decode_t const DInfo = ((const FSE_decode_t *)(DStatePtr->table))[DStatePtr->state];
+	U32 const nbBits = DInfo.nbBits;
+	BYTE const symbol = DInfo.symbol;
+	size_t const lowBits = BIT_readBitsFast(bitD, nbBits);
+
+	DStatePtr->state = DInfo.newState + lowBits;
+	return symbol;
+}
+
+ZSTD_STATIC unsigned FSE_endOfDState(const FSE_DState_t *DStatePtr) { return DStatePtr->state == 0; }
+
+/* **************************************************************
+*  Tuning parameters
+****************************************************************/
+/*!MEMORY_USAGE :
+*  Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
+*  Increasing memory usage improves compression ratio
+*  Reduced memory usage can improve speed, due to cache effect
+*  Recommended max value is 14, for 16KB, which nicely fits into Intel x86 L1 cache */
+#ifndef FSE_MAX_MEMORY_USAGE
+#define FSE_MAX_MEMORY_USAGE 14
+#endif
+#ifndef FSE_DEFAULT_MEMORY_USAGE
+#define FSE_DEFAULT_MEMORY_USAGE 13
+#endif
+
+/*!FSE_MAX_SYMBOL_VALUE :
+*  Maximum symbol value authorized.
+*  Required for proper stack allocation */
+#ifndef FSE_MAX_SYMBOL_VALUE
+#define FSE_MAX_SYMBOL_VALUE 255
+#endif
+
+/* **************************************************************
+*  template functions type & suffix
+****************************************************************/
+#define FSE_FUNCTION_TYPE BYTE
+#define FSE_FUNCTION_EXTENSION
+#define FSE_DECODE_TYPE FSE_decode_t
+
+/* ***************************************************************
+*  Constants
+*****************************************************************/
+#define FSE_MAX_TABLELOG (FSE_MAX_MEMORY_USAGE - 2)
+#define FSE_MAX_TABLESIZE (1U << FSE_MAX_TABLELOG)
+#define FSE_MAXTABLESIZE_MASK (FSE_MAX_TABLESIZE - 1)
+#define FSE_DEFAULT_TABLELOG (FSE_DEFAULT_MEMORY_USAGE - 2)
+#define FSE_MIN_TABLELOG 5
+
+#define FSE_TABLELOG_ABSOLUTE_MAX 15
+#if FSE_MAX_TABLELOG > FSE_TABLELOG_ABSOLUTE_MAX
+#error "FSE_MAX_TABLELOG > FSE_TABLELOG_ABSOLUTE_MAX is not supported"
+#endif
+
+#define FSE_TABLESTEP(tableSize) ((tableSize >> 1) + (tableSize >> 3) + 3)
+
+#endif /* FSE_H */

lib/zstd/fse_compress.c

@@ -0,0 +1,795 @@
+/*
+ * FSE : Finite State Entropy encoder
+ * Copyright (C) 2013-2015, Yann Collet.
+ *
+ * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *   * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License version 2 as published by the
+ * Free Software Foundation. This program is dual-licensed; you may select
+ * either version 2 of the GNU General Public License ("GPL") or BSD license
+ * ("BSD").
+ *
+ * You can contact the author at :
+ * - Source repository : https://github.com/Cyan4973/FiniteStateEntropy
+ */
+
+/* **************************************************************
+*  Compiler specifics
+****************************************************************/
+#define FORCE_INLINE static __always_inline
+
+/* **************************************************************
+*  Includes
+****************************************************************/
+#include "bitstream.h"
+#include "fse.h"
+#include <linux/compiler.h>
+#include <linux/kernel.h>
+#include <linux/math64.h>
+#include <linux/string.h> /* memcpy, memset */
+
+/* **************************************************************
+*  Error Management
+****************************************************************/
+#define FSE_STATIC_ASSERT(c)                                   \
+	{                                                      \
+		enum { FSE_static_assert = 1 / (int)(!!(c)) }; \
+	} /* use only *after* variable declarations */
+
+/* **************************************************************
+*  Templates
+****************************************************************/
+/*
+  designed to be included
+  for type-specific functions (template emulation in C)
+  Objective is to write these functions only once, for improved maintenance
+*/
+
+/* safety checks */
+#ifndef FSE_FUNCTION_EXTENSION
+#error "FSE_FUNCTION_EXTENSION must be defined"
+#endif
+#ifndef FSE_FUNCTION_TYPE
+#error "FSE_FUNCTION_TYPE must be defined"
+#endif
+
+/* Function names */
+#define FSE_CAT(X, Y) X##Y
+#define FSE_FUNCTION_NAME(X, Y) FSE_CAT(X, Y)
+#define FSE_TYPE_NAME(X, Y) FSE_CAT(X, Y)
+
+/* Function templates */
+
+/* FSE_buildCTable_wksp() :
+ * Same as FSE_buildCTable(), but using an externally allocated scratch buffer (`workSpace`).
+ * wkspSize should be sized to handle worst case situation, which is `1<<max_tableLog * sizeof(FSE_FUNCTION_TYPE)`
+ * workSpace must also be properly aligned with FSE_FUNCTION_TYPE requirements
+ */
+size_t FSE_buildCTable_wksp(FSE_CTable *ct, const short *normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void *workspace, size_t workspaceSize)
+{
+	U32 const tableSize = 1 << tableLog;
+	U32 const tableMask = tableSize - 1;
+	void *const ptr = ct;
+	U16 *const tableU16 = ((U16 *)ptr) + 2;
+	void *const FSCT = ((U32 *)ptr) + 1 /* header */ + (tableLog ? tableSize >> 1 : 1);
+	FSE_symbolCompressionTransform *const symbolTT = (FSE_symbolCompressionTransform *)(FSCT);
+	U32 const step = FSE_TABLESTEP(tableSize);
+	U32 highThreshold = tableSize - 1;
+
+	U32 *cumul;
+	FSE_FUNCTION_TYPE *tableSymbol;
+	size_t spaceUsed32 = 0;
+
+	cumul = (U32 *)workspace + spaceUsed32;
+	spaceUsed32 += FSE_MAX_SYMBOL_VALUE + 2;
+	tableSymbol = (FSE_FUNCTION_TYPE *)((U32 *)workspace + spaceUsed32);
+	spaceUsed32 += ALIGN(sizeof(FSE_FUNCTION_TYPE) * ((size_t)1 << tableLog), sizeof(U32)) >> 2;
+
+	if ((spaceUsed32 << 2) > workspaceSize)
+		return ERROR(tableLog_tooLarge);
+	workspace = (U32 *)workspace + spaceUsed32;
+	workspaceSize -= (spaceUsed32 << 2);
+
+	/* CTable header */
+	tableU16[-2] = (U16)tableLog;
+	tableU16[-1] = (U16)maxSymbolValue;
+
+	/* For explanations on how to distribute symbol values over the table :
+	*  http://fastcompression.blogspot.fr/2014/02/fse-distributing-symbol-values.html */
+
+	/* symbol start positions */
+	{
+		U32 u;
+		cumul[0] = 0;
+		for (u = 1; u <= maxSymbolValue + 1; u++) {
+			if (normalizedCounter[u - 1] == -1) { /* Low proba symbol */
+				cumul[u] = cumul[u - 1] + 1;
+				tableSymbol[highThreshold--] = (FSE_FUNCTION_TYPE)(u - 1);
+			} else {
+				cumul[u] = cumul[u - 1] + normalizedCounter[u - 1];
+			}
+		}
+		cumul[maxSymbolValue + 1] = tableSize + 1;
+	}
+
+	/* Spread symbols */
+	{
+		U32 position = 0;
+		U32 symbol;
+		for (symbol = 0; symbol <= maxSymbolValue; symbol++) {
+			int nbOccurences;
+			for (nbOccurences = 0; nbOccurences < normalizedCounter[symbol]; nbOccurences++) {
+				tableSymbol[position] = (FSE_FUNCTION_TYPE)symbol;
+				position = (position + step) & tableMask;
+				while (position > highThreshold)
+					position = (position + step) & tableMask; /* Low proba area */
+			}
+		}
+
+		if (position != 0)
+			return ERROR(GENERIC); /* Must have gone through all positions */
+	}
+
+	/* Build table */
+	{
+		U32 u;
+		for (u = 0; u < tableSize; u++) {
+			FSE_FUNCTION_TYPE s = tableSymbol[u];	/* note : static analyzer may not understand tableSymbol is properly initialized */
+			tableU16[cumul[s]++] = (U16)(tableSize + u); /* TableU16 : sorted by symbol order; gives next state value */
+		}
+	}
+
+	/* Build Symbol Transformation Table */
+	{
+		unsigned total = 0;
+		unsigned s;
+		for (s = 0; s <= maxSymbolValue; s++) {
+			switch (normalizedCounter[s]) {
+			case 0: break;
+
+			case -1:
+			case 1:
+				symbolTT[s].deltaNbBits = (tableLog << 16) - (1 << tableLog);
+				symbolTT[s].deltaFindState = total - 1;
+				total++;
+				break;
+			default: {
+				U32 const maxBitsOut = tableLog - BIT_highbit32(normalizedCounter[s] - 1);
+				U32 const minStatePlus = normalizedCounter[s] << maxBitsOut;
+				symbolTT[s].deltaNbBits = (maxBitsOut << 16) - minStatePlus;
+				symbolTT[s].deltaFindState = total - normalizedCounter[s];
+				total += normalizedCounter[s];
+			}
+			}
+		}
+	}
+
+	return 0;
+}
+
+/*-**************************************************************
+*  FSE NCount encoding-decoding
+****************************************************************/
+size_t FSE_NCountWriteBound(unsigned maxSymbolValue, unsigned tableLog)
+{
+	size_t const maxHeaderSize = (((maxSymbolValue + 1) * tableLog) >> 3) + 3;
+	return maxSymbolValue ? maxHeaderSize : FSE_NCOUNTBOUND; /* maxSymbolValue==0 ? use default */
+}
+
+static size_t FSE_writeNCount_generic(void *header, size_t headerBufferSize, const short *normalizedCounter, unsigned maxSymbolValue, unsigned tableLog,
+				      unsigned writeIsSafe)
+{
+	BYTE *const ostart = (BYTE *)header;
+	BYTE *out = ostart;
+	BYTE *const oend = ostart + headerBufferSize;
+	int nbBits;
+	const int tableSize = 1 << tableLog;
+	int remaining;
+	int threshold;
+	U32 bitStream;
+	int bitCount;
+	unsigned charnum = 0;
+	int previous0 = 0;
+
+	bitStream = 0;
+	bitCount = 0;
+	/* Table Size */
+	bitStream += (tableLog - FSE_MIN_TABLELOG) << bitCount;
+	bitCount += 4;
+
+	/* Init */
+	remaining = tableSize + 1; /* +1 for extra accuracy */
+	threshold = tableSize;
+	nbBits = tableLog + 1;
+
+	while (remaining > 1) { /* stops at 1 */
+		if (previous0) {
+			unsigned start = charnum;
+			while (!normalizedCounter[charnum])
+				charnum++;
+			while (charnum >= start + 24) {
+				start += 24;
+				bitStream += 0xFFFFU << bitCount;
+				if ((!writeIsSafe) && (out > oend - 2))
+					return ERROR(dstSize_tooSmall); /* Buffer overflow */
+				out[0] = (BYTE)bitStream;
+				out[1] = (BYTE)(bitStream >> 8);
+				out += 2;
+				bitStream >>= 16;
+			}
+			while (charnum >= start + 3) {
+				start += 3;
+				bitStream += 3 << bitCount;
+				bitCount += 2;
+			}
+			bitStream += (charnum - start) << bitCount;
+			bitCount += 2;
+			if (bitCount > 16) {
+				if ((!writeIsSafe) && (out > oend - 2))
+					return ERROR(dstSize_tooSmall); /* Buffer overflow */
+				out[0] = (BYTE)bitStream;
+				out[1] = (BYTE)(bitStream >> 8);
+				out += 2;
+				bitStream >>= 16;
+				bitCount -= 16;
+			}
+		}
+		{
+			int count = normalizedCounter[charnum++];
+			int const max = (2 * threshold - 1) - remaining;
+			remaining -= count < 0 ? -count : count;
+			count++; /* +1 for extra accuracy */
+			if (count >= threshold)
+				count += max; /* [0..max[ [max..threshold[ (...) [threshold+max 2*threshold[ */
+			bitStream += count << bitCount;
+			bitCount += nbBits;
+			bitCount -= (count < max);
+			previous0 = (count == 1);
+			if (remaining < 1)
+				return ERROR(GENERIC);
+			while (remaining < threshold)
+				nbBits--, threshold >>= 1;
+		}
+		if (bitCount > 16) {
+			if ((!writeIsSafe) && (out > oend - 2))
+				return ERROR(dstSize_tooSmall); /* Buffer overflow */
+			out[0] = (BYTE)bitStream;
+			out[1] = (BYTE)(bitStream >> 8);
+			out += 2;
+			bitStream >>= 16;
+			bitCount -= 16;
+		}
+	}
+
+	/* flush remaining bitStream */
+	if ((!writeIsSafe) && (out > oend - 2))
+		return ERROR(dstSize_tooSmall); /* Buffer overflow */
+	out[0] = (BYTE)bitStream;
+	out[1] = (BYTE)(bitStream >> 8);
+	out += (bitCount + 7) / 8;
+
+	if (charnum > maxSymbolValue + 1)
+		return ERROR(GENERIC);
+
+	return (out - ostart);
+}
+
+size_t FSE_writeNCount(void *buffer, size_t bufferSize, const short *normalizedCounter, unsigned maxSymbolValue, unsigned tableLog)
+{
+	if (tableLog > FSE_MAX_TABLELOG)
+		return ERROR(tableLog_tooLarge); /* Unsupported */
+	if (tableLog < FSE_MIN_TABLELOG)
+		return ERROR(GENERIC); /* Unsupported */
+
+	if (bufferSize < FSE_NCountWriteBound(maxSymbolValue, tableLog))
+		return FSE_writeNCount_generic(buffer, bufferSize, normalizedCounter, maxSymbolValue, tableLog, 0);
+
+	return FSE_writeNCount_generic(buffer, bufferSize, normalizedCounter, maxSymbolValue, tableLog, 1);
+}
+
+/*-**************************************************************
+*  Counting histogram
+****************************************************************/
+/*! FSE_count_simple
+	This function counts byte values within `src`, and store the histogram into table `count`.
+	It doesn't use any additional memory.
+	But this function is unsafe : it doesn't check that all values within `src` can fit into `count`.
+	For this reason, prefer using a table `count` with 256 elements.
+	@return : count of most numerous element
+*/
+size_t FSE_count_simple(unsigned *count, unsigned *maxSymbolValuePtr, const void *src, size_t srcSize)
+{
+	const BYTE *ip = (const BYTE *)src;
+	const BYTE *const end = ip + srcSize;
+	unsigned maxSymbolValue = *maxSymbolValuePtr;
+	unsigned max = 0;
+
+	memset(count, 0, (maxSymbolValue + 1) * sizeof(*count));
+	if (srcSize == 0) {
+		*maxSymbolValuePtr = 0;
+		return 0;
+	}
+
+	while (ip < end)
+		count[*ip++]++;
+
+	while (!count[maxSymbolValue])
+		maxSymbolValue--;
+	*maxSymbolValuePtr = maxSymbolValue;
+
+	{
+		U32 s;
+		for (s = 0; s <= maxSymbolValue; s++)
+			if (count[s] > max)
+				max = count[s];
+	}
+
+	return (size_t)max;
+}
+
+/* FSE_count_parallel_wksp() :
+ * Same as FSE_count_parallel(), but using an externally provided scratch buffer.
+ * `workSpace` size must be a minimum of `1024 * sizeof(unsigned)`` */
+static size_t FSE_count_parallel_wksp(unsigned *count, unsigned *maxSymbolValuePtr, const void *source, size_t sourceSize, unsigned checkMax,
+				      unsigned *const workSpace)
+{
+	const BYTE *ip = (const BYTE *)source;
+	const BYTE *const iend = ip + sourceSize;
+	unsigned maxSymbolValue = *maxSymbolValuePtr;
+	unsigned max = 0;
+	U32 *const Counting1 = workSpace;
+	U32 *const Counting2 = Counting1 + 256;
+	U32 *const Counting3 = Counting2 + 256;
+	U32 *const Counting4 = Counting3 + 256;
+
+	memset(Counting1, 0, 4 * 256 * sizeof(unsigned));
+
+	/* safety checks */
+	if (!sourceSize) {
+		memset(count, 0, maxSymbolValue + 1);
+		*maxSymbolValuePtr = 0;
+		return 0;
+	}
+	if (!maxSymbolValue)
+		maxSymbolValue = 255; /* 0 == default */
+
+	/* by stripes of 16 bytes */
+	{
+		U32 cached = ZSTD_read32(ip);
+		ip += 4;
+		while (ip < iend - 15) {
+			U32 c = cached;
+			cached = ZSTD_read32(ip);
+			ip += 4;
+			Counting1[(BYTE)c]++;
+			Counting2[(BYTE)(c >> 8)]++;
+			Counting3[(BYTE)(c >> 16)]++;
+			Counting4[c >> 24]++;
+			c = cached;
+			cached = ZSTD_read32(ip);
+			ip += 4;
+			Counting1[(BYTE)c]++;
+			Counting2[(BYTE)(c >> 8)]++;
+			Counting3[(BYTE)(c >> 16)]++;
+			Counting4[c >> 24]++;
+			c = cached;
+			cached = ZSTD_read32(ip);
+			ip += 4;
+			Counting1[(BYTE)c]++;
+			Counting2[(BYTE)(c >> 8)]++;
+			Counting3[(BYTE)(c >> 16)]++;
+			Counting4[c >> 24]++;
+			c = cached;
+			cached = ZSTD_read32(ip);
+			ip += 4;
+			Counting1[(BYTE)c]++;
+			Counting2[(BYTE)(c >> 8)]++;
+			Counting3[(BYTE)(c >> 16)]++;
+			Counting4[c >> 24]++;
+		}
+		ip -= 4;
+	}
+
+	/* finish last symbols */
+	while (ip < iend)
+		Counting1[*ip++]++;
+
+	if (checkMax) { /* verify stats will fit into destination table */
+		U32 s;
+		for (s = 255; s > maxSymbolValue; s--) {
+			Counting1[s] += Counting2[s] + Counting3[s] + Counting4[s];
+			if (Counting1[s])
+				return ERROR(maxSymbolValue_tooSmall);
+		}
+	}
+
+	{
+		U32 s;
+		for (s = 0; s <= maxSymbolValue; s++) {
+			count[s] = Counting1[s] + Counting2[s] + Counting3[s] + Counting4[s];
+			if (count[s] > max)
+				max = count[s];
+		}
+	}
+
+	while (!count[maxSymbolValue])
+		maxSymbolValue--;
+	*maxSymbolValuePtr = maxSymbolValue;
+	return (size_t)max;
+}
+
+/* FSE_countFast_wksp() :
+ * Same as FSE_countFast(), but using an externally provided scratch buffer.
+ * `workSpace` size must be table of >= `1024` unsigned */
+size_t FSE_countFast_wksp(unsigned *count, unsigned *maxSymbolValuePtr, const void *source, size_t sourceSize, unsigned *workSpace)
+{
+	if (sourceSize < 1500)
+		return FSE_count_simple(count, maxSymbolValuePtr, source, sourceSize);
+	return FSE_count_parallel_wksp(count, maxSymbolValuePtr, source, sourceSize, 0, workSpace);
+}
+
+/* FSE_count_wksp() :
+ * Same as FSE_count(), but using an externally provided scratch buffer.
+ * `workSpace` size must be table of >= `1024` unsigned */
+size_t FSE_count_wksp(unsigned *count, unsigned *maxSymbolValuePtr, const void *source, size_t sourceSize, unsigned *workSpace)
+{
+	if (*maxSymbolValuePtr < 255)
+		return FSE_count_parallel_wksp(count, maxSymbolValuePtr, source, sourceSize, 1, workSpace);
+	*maxSymbolValuePtr = 255;
+	return FSE_countFast_wksp(count, maxSymbolValuePtr, source, sourceSize, workSpace);
+}
+
+/*-**************************************************************
+*  FSE Compression Code
+****************************************************************/
+/*! FSE_sizeof_CTable() :
+	FSE_CTable is a variable size structure which contains :
+	`U16 tableLog;`
+	`U16 maxSymbolValue;`
+	`U16 nextStateNumber[1 << tableLog];`                         // This size is variable
+	`FSE_symbolCompressionTransform symbolTT[maxSymbolValue+1];`  // This size is variable
+Allocation is manual (C standard does not support variable-size structures).
+*/
+size_t FSE_sizeof_CTable(unsigned maxSymbolValue, unsigned tableLog)
+{
+	if (tableLog > FSE_MAX_TABLELOG)
+		return ERROR(tableLog_tooLarge);
+	return FSE_CTABLE_SIZE_U32(tableLog, maxSymbolValue) * sizeof(U32);
+}
+
+/* provides the minimum logSize to safely represent a distribution */
+static unsigned FSE_minTableLog(size_t srcSize, unsigned maxSymbolValue)
+{
+	U32 minBitsSrc = BIT_highbit32((U32)(srcSize - 1)) + 1;
+	U32 minBitsSymbols = BIT_highbit32(maxSymbolValue) + 2;
+	U32 minBits = minBitsSrc < minBitsSymbols ? minBitsSrc : minBitsSymbols;
+	return minBits;
+}
+
+unsigned FSE_optimalTableLog_internal(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue, unsigned minus)
+{
+	U32 maxBitsSrc = BIT_highbit32((U32)(srcSize - 1)) - minus;
+	U32 tableLog = maxTableLog;
+	U32 minBits = FSE_minTableLog(srcSize, maxSymbolValue);
+	if (tableLog == 0)
+		tableLog = FSE_DEFAULT_TABLELOG;
+	if (maxBitsSrc < tableLog)
+		tableLog = maxBitsSrc; /* Accuracy can be reduced */
+	if (minBits > tableLog)
+		tableLog = minBits; /* Need a minimum to safely represent all symbol values */
+	if (tableLog < FSE_MIN_TABLELOG)
+		tableLog = FSE_MIN_TABLELOG;
+	if (tableLog > FSE_MAX_TABLELOG)
+		tableLog = FSE_MAX_TABLELOG;
+	return tableLog;
+}
+
+unsigned FSE_optimalTableLog(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue)
+{
+	return FSE_optimalTableLog_internal(maxTableLog, srcSize, maxSymbolValue, 2);
+}
+
+/* Secondary normalization method.
+   To be used when primary method fails. */
+
+static size_t FSE_normalizeM2(short *norm, U32 tableLog, const unsigned *count, size_t total, U32 maxSymbolValue)
+{
+	short const NOT_YET_ASSIGNED = -2;
+	U32 s;
+	U32 distributed = 0;
+	U32 ToDistribute;
+
+	/* Init */
+	U32 const lowThreshold = (U32)(total >> tableLog);
+	U32 lowOne = (U32)((total * 3) >> (tableLog + 1));
+
+	for (s = 0; s <= maxSymbolValue; s++) {
+		if (count[s] == 0) {
+			norm[s] = 0;
+			continue;
+		}
+		if (count[s] <= lowThreshold) {
+			norm[s] = -1;
+			distributed++;
+			total -= count[s];
+			continue;
+		}
+		if (count[s] <= lowOne) {
+			norm[s] = 1;
+			distributed++;
+			total -= count[s];
+			continue;
+		}
+
+		norm[s] = NOT_YET_ASSIGNED;
+	}
+	ToDistribute = (1 << tableLog) - distributed;
+
+	if ((total / ToDistribute) > lowOne) {
+		/* risk of rounding to zero */
+		lowOne = (U32)((total * 3) / (ToDistribute * 2));
+		for (s = 0; s <= maxSymbolValue; s++) {
+			if ((norm[s] == NOT_YET_ASSIGNED) && (count[s] <= lowOne)) {
+				norm[s] = 1;
+				distributed++;
+				total -= count[s];
+				continue;
+			}
+		}
+		ToDistribute = (1 << tableLog) - distributed;
+	}
+
+	if (distributed == maxSymbolValue + 1) {
+		/* all values are pretty poor;
+		   probably incompressible data (should have already been detected);
+		   find max, then give all remaining points to max */
+		U32 maxV = 0, maxC = 0;
+		for (s = 0; s <= maxSymbolValue; s++)
+			if (count[s] > maxC)
+				maxV = s, maxC = count[s];
+		norm[maxV] += (short)ToDistribute;
+		return 0;
+	}
+
+	if (total == 0) {
+		/* all of the symbols were low enough for the lowOne or lowThreshold */
+		for (s = 0; ToDistribute > 0; s = (s + 1) % (maxSymbolValue + 1))
+			if (norm[s] > 0)
+				ToDistribute--, norm[s]++;
+		return 0;
+	}
+
+	{
+		U64 const vStepLog = 62 - tableLog;
+		U64 const mid = (1ULL << (vStepLog - 1)) - 1;
+		U64 const rStep = div_u64((((U64)1 << vStepLog) * ToDistribute) + mid, (U32)total); /* scale on remaining */
+		U64 tmpTotal = mid;
+		for (s = 0; s <= maxSymbolValue; s++) {
+			if (norm[s] == NOT_YET_ASSIGNED) {
+				U64 const end = tmpTotal + (count[s] * rStep);
+				U32 const sStart = (U32)(tmpTotal >> vStepLog);
+				U32 const sEnd = (U32)(end >> vStepLog);
+				U32 const weight = sEnd - sStart;
+				if (weight < 1)
+					return ERROR(GENERIC);
+				norm[s] = (short)weight;
+				tmpTotal = end;
+			}
+		}
+	}
+
+	return 0;
+}
+
+size_t FSE_normalizeCount(short *normalizedCounter, unsigned tableLog, const unsigned *count, size_t total, unsigned maxSymbolValue)
+{
+	/* Sanity checks */
+	if (tableLog == 0)
+		tableLog = FSE_DEFAULT_TABLELOG;
+	if (tableLog < FSE_MIN_TABLELOG)
+		return ERROR(GENERIC); /* Unsupported size */
+	if (tableLog > FSE_MAX_TABLELOG)
+		return ERROR(tableLog_tooLarge); /* Unsupported size */
+	if (tableLog < FSE_minTableLog(total, maxSymbolValue))
+		return ERROR(GENERIC); /* Too small tableLog, compression potentially impossible */
+
+	{
+		U32 const rtbTable[] = {0, 473195, 504333, 520860, 550000, 700000, 750000, 830000};
+		U64 const scale = 62 - tableLog;
+		U64 const step = div_u64((U64)1 << 62, (U32)total); /* <== here, one division ! */
+		U64 const vStep = 1ULL << (scale - 20);
+		int stillToDistribute = 1 << tableLog;
+		unsigned s;
+		unsigned largest = 0;
+		short largestP = 0;
+		U32 lowThreshold = (U32)(total >> tableLog);
+
+		for (s = 0; s <= maxSymbolValue; s++) {
+			if (count[s] == total)
+				return 0; /* rle special case */
+			if (count[s] == 0) {
+				normalizedCounter[s] = 0;
+				continue;
+			}
+			if (count[s] <= lowThreshold) {
+				normalizedCounter[s] = -1;
+				stillToDistribute--;
+			} else {
+				short proba = (short)((count[s] * step) >> scale);
+				if (proba < 8) {
+					U64 restToBeat = vStep * rtbTable[proba];
+					proba += (count[s] * step) - ((U64)proba << scale) > restToBeat;
+				}
+				if (proba > largestP)
+					largestP = proba, largest = s;
+				normalizedCounter[s] = proba;
+				stillToDistribute -= proba;
+			}
+		}
+		if (-stillToDistribute >= (normalizedCounter[largest] >> 1)) {
+			/* corner case, need another normalization method */
+			size_t const errorCode = FSE_normalizeM2(normalizedCounter, tableLog, count, total, maxSymbolValue);
+			if (FSE_isError(errorCode))
+				return errorCode;
+		} else
+			normalizedCounter[largest] += (short)stillToDistribute;
+	}
+
+	return tableLog;
+}
+
+/* fake FSE_CTable, for raw (uncompressed) input */
+size_t FSE_buildCTable_raw(FSE_CTable *ct, unsigned nbBits)
+{
+	const unsigned tableSize = 1 << nbBits;
+	const unsigned tableMask = tableSize - 1;
+	const unsigned maxSymbolValue = tableMask;
+	void *const ptr = ct;
+	U16 *const tableU16 = ((U16 *)ptr) + 2;
+	void *const FSCT = ((U32 *)ptr) + 1 /* header */ + (tableSize >> 1); /* assumption : tableLog >= 1 */
+	FSE_symbolCompressionTransform *const symbolTT = (FSE_symbolCompressionTransform *)(FSCT);
+	unsigned s;
+
+	/* Sanity checks */
+	if (nbBits < 1)
+		return ERROR(GENERIC); /* min size */
+
+	/* header */
+	tableU16[-2] = (U16)nbBits;
+	tableU16[-1] = (U16)maxSymbolValue;
+
+	/* Build table */
+	for (s = 0; s < tableSize; s++)
+		tableU16[s] = (U16)(tableSize + s);
+
+	/* Build Symbol Transformation Table */
+	{
+		const U32 deltaNbBits = (nbBits << 16) - (1 << nbBits);
+		for (s = 0; s <= maxSymbolValue; s++) {
+			symbolTT[s].deltaNbBits = deltaNbBits;
+			symbolTT[s].deltaFindState = s - 1;
+		}
+	}
+
+	return 0;
+}
+
+/* fake FSE_CTable, for rle input (always same symbol) */
+size_t FSE_buildCTable_rle(FSE_CTable *ct, BYTE symbolValue)
+{
+	void *ptr = ct;
+	U16 *tableU16 = ((U16 *)ptr) + 2;
+	void *FSCTptr = (U32 *)ptr + 2;
+	FSE_symbolCompressionTransform *symbolTT = (FSE_symbolCompressionTransform *)FSCTptr;
+
+	/* header */
+	tableU16[-2] = (U16)0;
+	tableU16[-1] = (U16)symbolValue;
+
+	/* Build table */
+	tableU16[0] = 0;
+	tableU16[1] = 0; /* just in case */
+
+	/* Build Symbol Transformation Table */
+	symbolTT[symbolValue].deltaNbBits = 0;
+	symbolTT[symbolValue].deltaFindState = 0;
+
+	return 0;
+}
+
+static size_t FSE_compress_usingCTable_generic(void *dst, size_t dstSize, const void *src, size_t srcSize, const FSE_CTable *ct, const unsigned fast)
+{
+	const BYTE *const istart = (const BYTE *)src;
+	const BYTE *const iend = istart + srcSize;
+	const BYTE *ip = iend;
+
+	BIT_CStream_t bitC;
+	FSE_CState_t CState1, CState2;
+
+	/* init */
+	if (srcSize <= 2)
+		return 0;
+	{
+		size_t const initError = BIT_initCStream(&bitC, dst, dstSize);
+		if (FSE_isError(initError))
+			return 0; /* not enough space available to write a bitstream */
+	}
+
+#define FSE_FLUSHBITS(s) (fast ? BIT_flushBitsFast(s) : BIT_flushBits(s))
+
+	if (srcSize & 1) {
+		FSE_initCState2(&CState1, ct, *--ip);
+		FSE_initCState2(&CState2, ct, *--ip);
+		FSE_encodeSymbol(&bitC, &CState1, *--ip);
+		FSE_FLUSHBITS(&bitC);
+	} else {
+		FSE_initCState2(&CState2, ct, *--ip);
+		FSE_initCState2(&CState1, ct, *--ip);
+	}
+
+	/* join to mod 4 */
+	srcSize -= 2;
+	if ((sizeof(bitC.bitContainer) * 8 > FSE_MAX_TABLELOG * 4 + 7) && (srcSize & 2)) { /* test bit 2 */
+		FSE_encodeSymbol(&bitC, &CState2, *--ip);
+		FSE_encodeSymbol(&bitC, &CState1, *--ip);
+		FSE_FLUSHBITS(&bitC);
+	}
+
+	/* 2 or 4 encoding per loop */
+	while (ip > istart) {
+
+		FSE_encodeSymbol(&bitC, &CState2, *--ip);
+
+		if (sizeof(bitC.bitContainer) * 8 < FSE_MAX_TABLELOG * 2 + 7) /* this test must be static */
+			FSE_FLUSHBITS(&bitC);
+
+		FSE_encodeSymbol(&bitC, &CState1, *--ip);
+
+		if (sizeof(bitC.bitContainer) * 8 > FSE_MAX_TABLELOG * 4 + 7) { /* this test must be static */
+			FSE_encodeSymbol(&bitC, &CState2, *--ip);
+			FSE_encodeSymbol(&bitC, &CState1, *--ip);
+		}
+
+		FSE_FLUSHBITS(&bitC);
+	}
+
+	FSE_flushCState(&bitC, &CState2);
+	FSE_flushCState(&bitC, &CState1);
+	return BIT_closeCStream(&bitC);
+}
+
+size_t FSE_compress_usingCTable(void *dst, size_t dstSize, const void *src, size_t srcSize, const FSE_CTable *ct)
+{
+	unsigned const fast = (dstSize >= FSE_BLOCKBOUND(srcSize));
+
+	if (fast)
+		return FSE_compress_usingCTable_generic(dst, dstSize, src, srcSize, ct, 1);
+	else
+		return FSE_compress_usingCTable_generic(dst, dstSize, src, srcSize, ct, 0);
+}
+
+size_t FSE_compressBound(size_t size) { return FSE_COMPRESSBOUND(size); }

lib/zstd/fse_decompress.c

@@ -0,0 +1,332 @@
+/*
+ * FSE : Finite State Entropy decoder
+ * Copyright (C) 2013-2015, Yann Collet.
+ *
+ * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *   * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License version 2 as published by the
+ * Free Software Foundation. This program is dual-licensed; you may select
+ * either version 2 of the GNU General Public License ("GPL") or BSD license
+ * ("BSD").
+ *
+ * You can contact the author at :
+ * - Source repository : https://github.com/Cyan4973/FiniteStateEntropy
+ */
+
+/* **************************************************************
+*  Compiler specifics
+****************************************************************/
+#define FORCE_INLINE static __always_inline
+
+/* **************************************************************
+*  Includes
+****************************************************************/
+#include "bitstream.h"
+#include "fse.h"
+#include <linux/compiler.h>
+#include <linux/kernel.h>
+#include <linux/string.h> /* memcpy, memset */
+
+/* **************************************************************
+*  Error Management
+****************************************************************/
+#define FSE_isError ERR_isError
+#define FSE_STATIC_ASSERT(c)                                   \
+	{                                                      \
+		enum { FSE_static_assert = 1 / (int)(!!(c)) }; \
+	} /* use only *after* variable declarations */
+
+/* check and forward error code */
+#define CHECK_F(f)                  \
+	{                           \
+		size_t const e = f; \
+		if (FSE_isError(e)) \
+			return e;   \
+	}
+
+/* **************************************************************
+*  Templates
+****************************************************************/
+/*
+  designed to be included
+  for type-specific functions (template emulation in C)
+  Objective is to write these functions only once, for improved maintenance
+*/
+
+/* safety checks */
+#ifndef FSE_FUNCTION_EXTENSION
+#error "FSE_FUNCTION_EXTENSION must be defined"
+#endif
+#ifndef FSE_FUNCTION_TYPE
+#error "FSE_FUNCTION_TYPE must be defined"
+#endif
+
+/* Function names */
+#define FSE_CAT(X, Y) X##Y
+#define FSE_FUNCTION_NAME(X, Y) FSE_CAT(X, Y)
+#define FSE_TYPE_NAME(X, Y) FSE_CAT(X, Y)
+
+/* Function templates */
+
+size_t FSE_buildDTable_wksp(FSE_DTable *dt, const short *normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void *workspace, size_t workspaceSize)
+{
+	void *const tdPtr = dt + 1; /* because *dt is unsigned, 32-bits aligned on 32-bits */
+	FSE_DECODE_TYPE *const tableDecode = (FSE_DECODE_TYPE *)(tdPtr);
+	U16 *symbolNext = (U16 *)workspace;
+
+	U32 const maxSV1 = maxSymbolValue + 1;
+	U32 const tableSize = 1 << tableLog;
+	U32 highThreshold = tableSize - 1;
+
+	/* Sanity Checks */
+	if (workspaceSize < sizeof(U16) * (FSE_MAX_SYMBOL_VALUE + 1))
+		return ERROR(tableLog_tooLarge);
+	if (maxSymbolValue > FSE_MAX_SYMBOL_VALUE)
+		return ERROR(maxSymbolValue_tooLarge);
+	if (tableLog > FSE_MAX_TABLELOG)
+		return ERROR(tableLog_tooLarge);
+
+	/* Init, lay down lowprob symbols */
+	{
+		FSE_DTableHeader DTableH;
+		DTableH.tableLog = (U16)tableLog;
+		DTableH.fastMode = 1;
+		{
+			S16 const largeLimit = (S16)(1 << (tableLog - 1));
+			U32 s;
+			for (s = 0; s < maxSV1; s++) {
+				if (normalizedCounter[s] == -1) {
+					tableDecode[highThreshold--].symbol = (FSE_FUNCTION_TYPE)s;
+					symbolNext[s] = 1;
+				} else {
+					if (normalizedCounter[s] >= largeLimit)
+						DTableH.fastMode = 0;
+					symbolNext[s] = normalizedCounter[s];
+				}
+			}
+		}
+		memcpy(dt, &DTableH, sizeof(DTableH));
+	}
+
+	/* Spread symbols */
+	{
+		U32 const tableMask = tableSize - 1;
+		U32 const step = FSE_TABLESTEP(tableSize);
+		U32 s, position = 0;
+		for (s = 0; s < maxSV1; s++) {
+			int i;
+			for (i = 0; i < normalizedCounter[s]; i++) {
+				tableDecode[position].symbol = (FSE_FUNCTION_TYPE)s;
+				position = (position + step) & tableMask;
+				while (position > highThreshold)
+					position = (position + step) & tableMask; /* lowprob area */
+			}
+		}
+		if (position != 0)
+			return ERROR(GENERIC); /* position must reach all cells once, otherwise normalizedCounter is incorrect */
+	}
+
+	/* Build Decoding table */
+	{
+		U32 u;
+		for (u = 0; u < tableSize; u++) {
+			FSE_FUNCTION_TYPE const symbol = (FSE_FUNCTION_TYPE)(tableDecode[u].symbol);
+			U16 nextState = symbolNext[symbol]++;
+			tableDecode[u].nbBits = (BYTE)(tableLog - BIT_highbit32((U32)nextState));
+			tableDecode[u].newState = (U16)((nextState << tableDecode[u].nbBits) - tableSize);
+		}
+	}
+
+	return 0;
+}
+
+/*-*******************************************************
+*  Decompression (Byte symbols)
+*********************************************************/
+size_t FSE_buildDTable_rle(FSE_DTable *dt, BYTE symbolValue)
+{
+	void *ptr = dt;
+	FSE_DTableHeader *const DTableH = (FSE_DTableHeader *)ptr;
+	void *dPtr = dt + 1;
+	FSE_decode_t *const cell = (FSE_decode_t *)dPtr;
+
+	DTableH->tableLog = 0;
+	DTableH->fastMode = 0;
+
+	cell->newState = 0;
+	cell->symbol = symbolValue;
+	cell->nbBits = 0;
+
+	return 0;
+}
+
+size_t FSE_buildDTable_raw(FSE_DTable *dt, unsigned nbBits)
+{
+	void *ptr = dt;
+	FSE_DTableHeader *const DTableH = (FSE_DTableHeader *)ptr;
+	void *dPtr = dt + 1;
+	FSE_decode_t *const dinfo = (FSE_decode_t *)dPtr;
+	const unsigned tableSize = 1 << nbBits;
+	const unsigned tableMask = tableSize - 1;
+	const unsigned maxSV1 = tableMask + 1;
+	unsigned s;
+
+	/* Sanity checks */
+	if (nbBits < 1)
+		return ERROR(GENERIC); /* min size */
+
+	/* Build Decoding Table */
+	DTableH->tableLog = (U16)nbBits;
+	DTableH->fastMode = 1;
+	for (s = 0; s < maxSV1; s++) {
+		dinfo[s].newState = 0;
+		dinfo[s].symbol = (BYTE)s;
+		dinfo[s].nbBits = (BYTE)nbBits;
+	}
+
+	return 0;
+}
+
+FORCE_INLINE size_t FSE_decompress_usingDTable_generic(void *dst, size_t maxDstSize, const void *cSrc, size_t cSrcSize, const FSE_DTable *dt,
+						       const unsigned fast)
+{
+	BYTE *const ostart = (BYTE *)dst;
+	BYTE *op = ostart;
+	BYTE *const omax = op + maxDstSize;
+	BYTE *const olimit = omax - 3;
+
+	BIT_DStream_t bitD;
+	FSE_DState_t state1;
+	FSE_DState_t state2;
+
+	/* Init */
+	CHECK_F(BIT_initDStream(&bitD, cSrc, cSrcSize));
+
+	FSE_initDState(&state1, &bitD, dt);
+	FSE_initDState(&state2, &bitD, dt);
+
+#define FSE_GETSYMBOL(statePtr) fast ? FSE_decodeSymbolFast(statePtr, &bitD) : FSE_decodeSymbol(statePtr, &bitD)
+
+	/* 4 symbols per loop */
+	for (; (BIT_reloadDStream(&bitD) == BIT_DStream_unfinished) & (op < olimit); op += 4) {
+		op[0] = FSE_GETSYMBOL(&state1);
+
+		if (FSE_MAX_TABLELOG * 2 + 7 > sizeof(bitD.bitContainer) * 8) /* This test must be static */
+			BIT_reloadDStream(&bitD);
+
+		op[1] = FSE_GETSYMBOL(&state2);
+
+		if (FSE_MAX_TABLELOG * 4 + 7 > sizeof(bitD.bitContainer) * 8) /* This test must be static */
+		{
+			if (BIT_reloadDStream(&bitD) > BIT_DStream_unfinished) {
+				op += 2;
+				break;
+			}
+		}
+
+		op[2] = FSE_GETSYMBOL(&state1);
+
+		if (FSE_MAX_TABLELOG * 2 + 7 > sizeof(bitD.bitContainer) * 8) /* This test must be static */
+			BIT_reloadDStream(&bitD);
+
+		op[3] = FSE_GETSYMBOL(&state2);
+	}
+
+	/* tail */
+	/* note : BIT_reloadDStream(&bitD) >= FSE_DStream_partiallyFilled; Ends at exactly BIT_DStream_completed */
+	while (1) {
+		if (op > (omax - 2))
+			return ERROR(dstSize_tooSmall);
+		*op++ = FSE_GETSYMBOL(&state1);
+		if (BIT_reloadDStream(&bitD) == BIT_DStream_overflow) {
+			*op++ = FSE_GETSYMBOL(&state2);
+			break;
+		}
+
+		if (op > (omax - 2))
+			return ERROR(dstSize_tooSmall);
+		*op++ = FSE_GETSYMBOL(&state2);
+		if (BIT_reloadDStream(&bitD) == BIT_DStream_overflow) {
+			*op++ = FSE_GETSYMBOL(&state1);
+			break;
+		}
+	}
+
+	return op - ostart;
+}
+
+size_t FSE_decompress_usingDTable(void *dst, size_t originalSize, const void *cSrc, size_t cSrcSize, const FSE_DTable *dt)
+{
+	const void *ptr = dt;
+	const FSE_DTableHeader *DTableH = (const FSE_DTableHeader *)ptr;
+	const U32 fastMode = DTableH->fastMode;
+
+	/* select fast mode (static) */
+	if (fastMode)
+		return FSE_decompress_usingDTable_generic(dst, originalSize, cSrc, cSrcSize, dt, 1);
+	return FSE_decompress_usingDTable_generic(dst, originalSize, cSrc, cSrcSize, dt, 0);
+}
+
+size_t FSE_decompress_wksp(void *dst, size_t dstCapacity, const void *cSrc, size_t cSrcSize, unsigned maxLog, void *workspace, size_t workspaceSize)
+{
+	const BYTE *const istart = (const BYTE *)cSrc;
+	const BYTE *ip = istart;
+	unsigned tableLog;
+	unsigned maxSymbolValue = FSE_MAX_SYMBOL_VALUE;
+	size_t NCountLength;
+
+	FSE_DTable *dt;
+	short *counting;
+	size_t spaceUsed32 = 0;
+
+	FSE_STATIC_ASSERT(sizeof(FSE_DTable) == sizeof(U32));
+
+	dt = (FSE_DTable *)((U32 *)workspace + spaceUsed32);
+	spaceUsed32 += FSE_DTABLE_SIZE_U32(maxLog);
+	counting = (short *)((U32 *)workspace + spaceUsed32);
+	spaceUsed32 += ALIGN(sizeof(short) * (FSE_MAX_SYMBOL_VALUE + 1), sizeof(U32)) >> 2;
+
+	if ((spaceUsed32 << 2) > workspaceSize)
+		return ERROR(tableLog_tooLarge);
+	workspace = (U32 *)workspace + spaceUsed32;
+	workspaceSize -= (spaceUsed32 << 2);
+
+	/* normal FSE decoding mode */
+	NCountLength = FSE_readNCount(counting, &maxSymbolValue, &tableLog, istart, cSrcSize);
+	if (FSE_isError(NCountLength))
+		return NCountLength;
+	// if (NCountLength >= cSrcSize) return ERROR(srcSize_wrong);   /* too small input size; supposed to be already checked in NCountLength, only remaining
+	// case : NCountLength==cSrcSize */
+	if (tableLog > maxLog)
+		return ERROR(tableLog_tooLarge);
+	ip += NCountLength;
+	cSrcSize -= NCountLength;
+
+	CHECK_F(FSE_buildDTable_wksp(dt, counting, maxSymbolValue, tableLog, workspace, workspaceSize));
+
+	return FSE_decompress_usingDTable(dst, dstCapacity, ip, cSrcSize, dt); /* always return, even if it is an error code */
+}

lib/zstd/huf.h

@@ -0,0 +1,212 @@
+/*
+ * Huffman coder, part of New Generation Entropy library
+ * header file
+ * Copyright (C) 2013-2016, Yann Collet.
+ *
+ * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *   * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License version 2 as published by the
+ * Free Software Foundation. This program is dual-licensed; you may select
+ * either version 2 of the GNU General Public License ("GPL") or BSD license
+ * ("BSD").
+ *
+ * You can contact the author at :
+ * - Source repository : https://github.com/Cyan4973/FiniteStateEntropy
+ */
+#ifndef HUF_H_298734234
+#define HUF_H_298734234
+
+/* *** Dependencies *** */
+#include <linux/types.h> /* size_t */
+
+/* ***   Tool functions *** */
+#define HUF_BLOCKSIZE_MAX (128 * 1024) /**< maximum input size for a single block compressed with HUF_compress */
+size_t HUF_compressBound(size_t size); /**< maximum compressed size (worst case) */
+
+/* Error Management */
+unsigned HUF_isError(size_t code); /**< tells if a return value is an error code */
+
+/* ***   Advanced function   *** */
+
+/** HUF_compress4X_wksp() :
+*   Same as HUF_compress2(), but uses externally allocated `workSpace`, which must be a table of >= 1024 unsigned */
+size_t HUF_compress4X_wksp(void *dst, size_t dstSize, const void *src, size_t srcSize, unsigned maxSymbolValue, unsigned tableLog, void *workSpace,
+			   size_t wkspSize); /**< `workSpace` must be a table of at least HUF_COMPRESS_WORKSPACE_SIZE_U32 unsigned */
+
+/* *** Dependencies *** */
+#include "mem.h" /* U32 */
+
+/* *** Constants *** */
+#define HUF_TABLELOG_MAX 12     /* max configured tableLog (for static allocation); can be modified up to HUF_ABSOLUTEMAX_TABLELOG */
+#define HUF_TABLELOG_DEFAULT 11 /* tableLog by default, when not specified */
+#define HUF_SYMBOLVALUE_MAX 255
+
+#define HUF_TABLELOG_ABSOLUTEMAX 15 /* absolute limit of HUF_MAX_TABLELOG. Beyond that value, code does not work */
+#if (HUF_TABLELOG_MAX > HUF_TABLELOG_ABSOLUTEMAX)
+#error "HUF_TABLELOG_MAX is too large !"
+#endif
+
+/* ****************************************
+*  Static allocation
+******************************************/
+/* HUF buffer bounds */
+#define HUF_CTABLEBOUND 129
+#define HUF_BLOCKBOUND(size) (size + (size >> 8) + 8)			 /* only true if incompressible pre-filtered with fast heuristic */
+#define HUF_COMPRESSBOUND(size) (HUF_CTABLEBOUND + HUF_BLOCKBOUND(size)) /* Macro version, useful for static allocation */
+
+/* static allocation of HUF's Compression Table */
+#define HUF_CREATE_STATIC_CTABLE(name, maxSymbolValue) \
+	U32 name##hb[maxSymbolValue + 1];              \
+	void *name##hv = &(name##hb);                  \
+	HUF_CElt *name = (HUF_CElt *)(name##hv) /* no final ; */
+
+/* static allocation of HUF's DTable */
+typedef U32 HUF_DTable;
+#define HUF_DTABLE_SIZE(maxTableLog) (1 + (1 << (maxTableLog)))
+#define HUF_CREATE_STATIC_DTABLEX2(DTable, maxTableLog) HUF_DTable DTable[HUF_DTABLE_SIZE((maxTableLog)-1)] = {((U32)((maxTableLog)-1) * 0x01000001)}
+#define HUF_CREATE_STATIC_DTABLEX4(DTable, maxTableLog) HUF_DTable DTable[HUF_DTABLE_SIZE(maxTableLog)] = {((U32)(maxTableLog)*0x01000001)}
+
+/* The workspace must have alignment at least 4 and be at least this large */
+#define HUF_COMPRESS_WORKSPACE_SIZE (6 << 10)
+#define HUF_COMPRESS_WORKSPACE_SIZE_U32 (HUF_COMPRESS_WORKSPACE_SIZE / sizeof(U32))
+
+/* The workspace must have alignment at least 4 and be at least this large */
+#define HUF_DECOMPRESS_WORKSPACE_SIZE (3 << 10)
+#define HUF_DECOMPRESS_WORKSPACE_SIZE_U32 (HUF_DECOMPRESS_WORKSPACE_SIZE / sizeof(U32))
+
+/* ****************************************
+*  Advanced decompression functions
+******************************************/
+size_t HUF_decompress4X_DCtx_wksp(HUF_DTable *dctx, void *dst, size_t dstSize, const void *cSrc, size_t cSrcSize, void *workspace, size_t workspaceSize); /**< decodes RLE and uncompressed */
+size_t HUF_decompress4X_hufOnly_wksp(HUF_DTable *dctx, void *dst, size_t dstSize, const void *cSrc, size_t cSrcSize, void *workspace,
+				size_t workspaceSize);							       /**< considers RLE and uncompressed as errors */
+size_t HUF_decompress4X2_DCtx_wksp(HUF_DTable *dctx, void *dst, size_t dstSize, const void *cSrc, size_t cSrcSize, void *workspace,
+				   size_t workspaceSize); /**< single-symbol decoder */
+size_t HUF_decompress4X4_DCtx_wksp(HUF_DTable *dctx, void *dst, size_t dstSize, const void *cSrc, size_t cSrcSize, void *workspace,
+				   size_t workspaceSize); /**< double-symbols decoder */
+
+/* ****************************************
+*  HUF detailed API
+******************************************/
+/*!
+HUF_compress() does the following:
+1. count symbol occurrence from source[] into table count[] using FSE_count()
+2. (optional) refine tableLog using HUF_optimalTableLog()
+3. build Huffman table from count using HUF_buildCTable()
+4. save Huffman table to memory buffer using HUF_writeCTable_wksp()
+5. encode the data stream using HUF_compress4X_usingCTable()
+
+The following API allows targeting specific sub-functions for advanced tasks.
+For example, it's possible to compress several blocks using the same 'CTable',
+or to save and regenerate 'CTable' using external methods.
+*/
+/* FSE_count() : find it within "fse.h" */
+unsigned HUF_optimalTableLog(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue);
+typedef struct HUF_CElt_s HUF_CElt; /* incomplete type */
+size_t HUF_writeCTable_wksp(void *dst, size_t maxDstSize, const HUF_CElt *CTable, unsigned maxSymbolValue, unsigned huffLog, void *workspace, size_t workspaceSize);
+size_t HUF_compress4X_usingCTable(void *dst, size_t dstSize, const void *src, size_t srcSize, const HUF_CElt *CTable);
+
+typedef enum {
+	HUF_repeat_none,  /**< Cannot use the previous table */
+	HUF_repeat_check, /**< Can use the previous table but it must be checked. Note : The previous table must have been constructed by HUF_compress{1,
+			     4}X_repeat */
+	HUF_repeat_valid  /**< Can use the previous table and it is asumed to be valid */
+} HUF_repeat;
+/** HUF_compress4X_repeat() :
+*   Same as HUF_compress4X_wksp(), but considers using hufTable if *repeat != HUF_repeat_none.
+*   If it uses hufTable it does not modify hufTable or repeat.
+*   If it doesn't, it sets *repeat = HUF_repeat_none, and it sets hufTable to the table used.
+*   If preferRepeat then the old table will always be used if valid. */
+size_t HUF_compress4X_repeat(void *dst, size_t dstSize, const void *src, size_t srcSize, unsigned maxSymbolValue, unsigned tableLog, void *workSpace,
+			     size_t wkspSize, HUF_CElt *hufTable, HUF_repeat *repeat,
+			     int preferRepeat); /**< `workSpace` must be a table of at least HUF_COMPRESS_WORKSPACE_SIZE_U32 unsigned */
+
+/** HUF_buildCTable_wksp() :
+ *  Same as HUF_buildCTable(), but using externally allocated scratch buffer.
+ *  `workSpace` must be aligned on 4-bytes boundaries, and be at least as large as a table of 1024 unsigned.
+ */
+size_t HUF_buildCTable_wksp(HUF_CElt *tree, const U32 *count, U32 maxSymbolValue, U32 maxNbBits, void *workSpace, size_t wkspSize);
+
+/*! HUF_readStats() :
+	Read compact Huffman tree, saved by HUF_writeCTable().
+	`huffWeight` is destination buffer.
+	@return : size read from `src` , or an error Code .
+	Note : Needed by HUF_readCTable() and HUF_readDTableXn() . */
+size_t HUF_readStats_wksp(BYTE *huffWeight, size_t hwSize, U32 *rankStats, U32 *nbSymbolsPtr, U32 *tableLogPtr, const void *src, size_t srcSize,
+			  void *workspace, size_t workspaceSize);
+
+/** HUF_readCTable() :
+*   Loading a CTable saved with HUF_writeCTable() */
+size_t HUF_readCTable_wksp(HUF_CElt *CTable, unsigned maxSymbolValue, const void *src, size_t srcSize, void *workspace, size_t workspaceSize);
+
+/*
+HUF_decompress() does the following:
+1. select the decompression algorithm (X2, X4) based on pre-computed heuristics
+2. build Huffman table from save, using HUF_readDTableXn()
+3. decode 1 or 4 segments in parallel using HUF_decompressSXn_usingDTable
+*/
+
+/** HUF_selectDecoder() :
+*   Tells which decoder is likely to decode faster,
+*   based on a set of pre-determined metrics.
+*   @return : 0==HUF_decompress4X2, 1==HUF_decompress4X4 .
+*   Assumption : 0 < cSrcSize < dstSize <= 128 KB */
+U32 HUF_selectDecoder(size_t dstSize, size_t cSrcSize);
+
+size_t HUF_readDTableX2_wksp(HUF_DTable *DTable, const void *src, size_t srcSize, void *workspace, size_t workspaceSize);
+size_t HUF_readDTableX4_wksp(HUF_DTable *DTable, const void *src, size_t srcSize, void *workspace, size_t workspaceSize);
+
+size_t HUF_decompress4X_usingDTable(void *dst, size_t maxDstSize, const void *cSrc, size_t cSrcSize, const HUF_DTable *DTable);
+size_t HUF_decompress4X2_usingDTable(void *dst, size_t maxDstSize, const void *cSrc, size_t cSrcSize, const HUF_DTable *DTable);
+size_t HUF_decompress4X4_usingDTable(void *dst, size_t maxDstSize, const void *cSrc, size_t cSrcSize, const HUF_DTable *DTable);
+
+/* single stream variants */
+
+size_t HUF_compress1X_wksp(void *dst, size_t dstSize, const void *src, size_t srcSize, unsigned maxSymbolValue, unsigned tableLog, void *workSpace,
+			   size_t wkspSize); /**< `workSpace` must be a table of at least HUF_COMPRESS_WORKSPACE_SIZE_U32 unsigned */
+size_t HUF_compress1X_usingCTable(void *dst, size_t dstSize, const void *src, size_t srcSize, const HUF_CElt *CTable);
+/** HUF_compress1X_repeat() :
+*   Same as HUF_compress1X_wksp(), but considers using hufTable if *repeat != HUF_repeat_none.
+*   If it uses hufTable it does not modify hufTable or repeat.
+*   If it doesn't, it sets *repeat = HUF_repeat_none, and it sets hufTable to the table used.
+*   If preferRepeat then the old table will always be used if valid. */
+size_t HUF_compress1X_repeat(void *dst, size_t dstSize, const void *src, size_t srcSize, unsigned maxSymbolValue, unsigned tableLog, void *workSpace,
+			     size_t wkspSize, HUF_CElt *hufTable, HUF_repeat *repeat,
+			     int preferRepeat); /**< `workSpace` must be a table of at least HUF_COMPRESS_WORKSPACE_SIZE_U32 unsigned */
+
+size_t HUF_decompress1X_DCtx_wksp(HUF_DTable *dctx, void *dst, size_t dstSize, const void *cSrc, size_t cSrcSize, void *workspace, size_t workspaceSize);
+size_t HUF_decompress1X2_DCtx_wksp(HUF_DTable *dctx, void *dst, size_t dstSize, const void *cSrc, size_t cSrcSize, void *workspace,
+				   size_t workspaceSize); /**< single-symbol decoder */
+size_t HUF_decompress1X4_DCtx_wksp(HUF_DTable *dctx, void *dst, size_t dstSize, const void *cSrc, size_t cSrcSize, void *workspace,
+				   size_t workspaceSize); /**< double-symbols decoder */
+
+size_t HUF_decompress1X_usingDTable(void *dst, size_t maxDstSize, const void *cSrc, size_t cSrcSize,
+				    const HUF_DTable *DTable); /**< automatic selection of sing or double symbol decoder, based on DTable */
+size_t HUF_decompress1X2_usingDTable(void *dst, size_t maxDstSize, const void *cSrc, size_t cSrcSize, const HUF_DTable *DTable);
+size_t HUF_decompress1X4_usingDTable(void *dst, size_t maxDstSize, const void *cSrc, size_t cSrcSize, const HUF_DTable *DTable);
+
+#endif /* HUF_H_298734234 */

lib/zstd/huf_compress.c

@@ -0,0 +1,770 @@
+/*
+ * Huffman encoder, part of New Generation Entropy library
+ * Copyright (C) 2013-2016, Yann Collet.
+ *
+ * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *   * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License version 2 as published by the
+ * Free Software Foundation. This program is dual-licensed; you may select
+ * either version 2 of the GNU General Public License ("GPL") or BSD license
+ * ("BSD").
+ *
+ * You can contact the author at :
+ * - Source repository : https://github.com/Cyan4973/FiniteStateEntropy
+ */
+
+/* **************************************************************
+*  Includes
+****************************************************************/
+#include "bitstream.h"
+#include "fse.h" /* header compression */
+#include "huf.h"
+#include <linux/kernel.h>
+#include <linux/string.h> /* memcpy, memset */
+
+/* **************************************************************
+*  Error Management
+****************************************************************/
+#define HUF_STATIC_ASSERT(c)                                   \
+	{                                                      \
+		enum { HUF_static_assert = 1 / (int)(!!(c)) }; \
+	} /* use only *after* variable declarations */
+#define CHECK_V_F(e, f)     \
+	size_t const e = f; \
+	if (ERR_isError(e)) \
+	return f
+#define CHECK_F(f)                        \
+	{                                 \
+		CHECK_V_F(_var_err__, f); \
+	}
+
+/* **************************************************************
+*  Utils
+****************************************************************/
+unsigned HUF_optimalTableLog(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue)
+{
+	return FSE_optimalTableLog_internal(maxTableLog, srcSize, maxSymbolValue, 1);
+}
+
+/* *******************************************************
+*  HUF : Huffman block compression
+*********************************************************/
+/* HUF_compressWeights() :
+ * Same as FSE_compress(), but dedicated to huff0's weights compression.
+ * The use case needs much less stack memory.
+ * Note : all elements within weightTable are supposed to be <= HUF_TABLELOG_MAX.
+ */
+#define MAX_FSE_TABLELOG_FOR_HUFF_HEADER 6
+size_t HUF_compressWeights_wksp(void *dst, size_t dstSize, const void *weightTable, size_t wtSize, void *workspace, size_t workspaceSize)
+{
+	BYTE *const ostart = (BYTE *)dst;
+	BYTE *op = ostart;
+	BYTE *const oend = ostart + dstSize;
+
+	U32 maxSymbolValue = HUF_TABLELOG_MAX;
+	U32 tableLog = MAX_FSE_TABLELOG_FOR_HUFF_HEADER;
+
+	FSE_CTable *CTable;
+	U32 *count;
+	S16 *norm;
+	size_t spaceUsed32 = 0;
+
+	HUF_STATIC_ASSERT(sizeof(FSE_CTable) == sizeof(U32));
+
+	CTable = (FSE_CTable *)((U32 *)workspace + spaceUsed32);
+	spaceUsed32 += FSE_CTABLE_SIZE_U32(MAX_FSE_TABLELOG_FOR_HUFF_HEADER, HUF_TABLELOG_MAX);
+	count = (U32 *)workspace + spaceUsed32;
+	spaceUsed32 += HUF_TABLELOG_MAX + 1;
+	norm = (S16 *)((U32 *)workspace + spaceUsed32);
+	spaceUsed32 += ALIGN(sizeof(S16) * (HUF_TABLELOG_MAX + 1), sizeof(U32)) >> 2;
+
+	if ((spaceUsed32 << 2) > workspaceSize)
+		return ERROR(tableLog_tooLarge);
+	workspace = (U32 *)workspace + spaceUsed32;
+	workspaceSize -= (spaceUsed32 << 2);
+
+	/* init conditions */
+	if (wtSize <= 1)
+		return 0; /* Not compressible */
+
+	/* Scan input and build symbol stats */
+	{
+		CHECK_V_F(maxCount, FSE_count_simple(count, &maxSymbolValue, weightTable, wtSize));
+		if (maxCount == wtSize)
+			return 1; /* only a single symbol in src : rle */
+		if (maxCount == 1)
+			return 0; /* each symbol present maximum once => not compressible */
+	}
+
+	tableLog = FSE_optimalTableLog(tableLog, wtSize, maxSymbolValue);
+	CHECK_F(FSE_normalizeCount(norm, tableLog, count, wtSize, maxSymbolValue));
+
+	/* Write table description header */
+	{
+		CHECK_V_F(hSize, FSE_writeNCount(op, oend - op, norm, maxSymbolValue, tableLog));
+		op += hSize;
+	}
+
+	/* Compress */
+	CHECK_F(FSE_buildCTable_wksp(CTable, norm, maxSymbolValue, tableLog, workspace, workspaceSize));
+	{
+		CHECK_V_F(cSize, FSE_compress_usingCTable(op, oend - op, weightTable, wtSize, CTable));
+		if (cSize == 0)
+			return 0; /* not enough space for compressed data */
+		op += cSize;
+	}
+
+	return op - ostart;
+}
+
+struct HUF_CElt_s {
+	U16 val;
+	BYTE nbBits;
+}; /* typedef'd to HUF_CElt within "huf.h" */
+
+/*! HUF_writeCTable_wksp() :
+	`CTable` : Huffman tree to save, using huf representation.
+	@return : size of saved CTable */
+size_t HUF_writeCTable_wksp(void *dst, size_t maxDstSize, const HUF_CElt *CTable, U32 maxSymbolValue, U32 huffLog, void *workspace, size_t workspaceSize)
+{
+	BYTE *op = (BYTE *)dst;
+	U32 n;
+
+	BYTE *bitsToWeight;
+	BYTE *huffWeight;
+	size_t spaceUsed32 = 0;
+
+	bitsToWeight = (BYTE *)((U32 *)workspace + spaceUsed32);
+	spaceUsed32 += ALIGN(HUF_TABLELOG_MAX + 1, sizeof(U32)) >> 2;
+	huffWeight = (BYTE *)((U32 *)workspace + spaceUsed32);
+	spaceUsed32 += ALIGN(HUF_SYMBOLVALUE_MAX, sizeof(U32)) >> 2;
+
+	if ((spaceUsed32 << 2) > workspaceSize)
+		return ERROR(tableLog_tooLarge);
+	workspace = (U32 *)workspace + spaceUsed32;
+	workspaceSize -= (spaceUsed32 << 2);
+
+	/* check conditions */
+	if (maxSymbolValue > HUF_SYMBOLVALUE_MAX)
+		return ERROR(maxSymbolValue_tooLarge);
+
+	/* convert to weight */
+	bitsToWeight[0] = 0;
+	for (n = 1; n < huffLog + 1; n++)
+		bitsToWeight[n] = (BYTE)(huffLog + 1 - n);
+	for (n = 0; n < maxSymbolValue; n++)
+		huffWeight[n] = bitsToWeight[CTable[n].nbBits];
+
+	/* attempt weights compression by FSE */
+	{
+		CHECK_V_F(hSize, HUF_compressWeights_wksp(op + 1, maxDstSize - 1, huffWeight, maxSymbolValue, workspace, workspaceSize));
+		if ((hSize > 1) & (hSize < maxSymbolValue / 2)) { /* FSE compressed */
+			op[0] = (BYTE)hSize;
+			return hSize + 1;
+		}
+	}
+
+	/* write raw values as 4-bits (max : 15) */
+	if (maxSymbolValue > (256 - 128))
+		return ERROR(GENERIC); /* should not happen : likely means source cannot be compressed */
+	if (((maxSymbolValue + 1) / 2) + 1 > maxDstSize)
+		return ERROR(dstSize_tooSmall); /* not enough space within dst buffer */
+	op[0] = (BYTE)(128 /*special case*/ + (maxSymbolValue - 1));
+	huffWeight[maxSymbolValue] = 0; /* to be sure it doesn't cause msan issue in final combination */
+	for (n = 0; n < maxSymbolValue; n += 2)
+		op[(n / 2) + 1] = (BYTE)((huffWeight[n] << 4) + huffWeight[n + 1]);
+	return ((maxSymbolValue + 1) / 2) + 1;
+}
+
+size_t HUF_readCTable_wksp(HUF_CElt *CTable, U32 maxSymbolValue, const void *src, size_t srcSize, void *workspace, size_t workspaceSize)
+{
+	U32 *rankVal;
+	BYTE *huffWeight;
+	U32 tableLog = 0;
+	U32 nbSymbols = 0;
+	size_t readSize;
+	size_t spaceUsed32 = 0;
+
+	rankVal = (U32 *)workspace + spaceUsed32;
+	spaceUsed32 += HUF_TABLELOG_ABSOLUTEMAX + 1;
+	huffWeight = (BYTE *)((U32 *)workspace + spaceUsed32);
+	spaceUsed32 += ALIGN(HUF_SYMBOLVALUE_MAX + 1, sizeof(U32)) >> 2;
+
+	if ((spaceUsed32 << 2) > workspaceSize)
+		return ERROR(tableLog_tooLarge);
+	workspace = (U32 *)workspace + spaceUsed32;
+	workspaceSize -= (spaceUsed32 << 2);
+
+	/* get symbol weights */
+	readSize = HUF_readStats_wksp(huffWeight, HUF_SYMBOLVALUE_MAX + 1, rankVal, &nbSymbols, &tableLog, src, srcSize, workspace, workspaceSize);
+	if (ERR_isError(readSize))
+		return readSize;
+
+	/* check result */
+	if (tableLog > HUF_TABLELOG_MAX)
+		return ERROR(tableLog_tooLarge);
+	if (nbSymbols > maxSymbolValue + 1)
+		return ERROR(maxSymbolValue_tooSmall);
+
+	/* Prepare base value per rank */
+	{
+		U32 n, nextRankStart = 0;
+		for (n = 1; n <= tableLog; n++) {
+			U32 curr = nextRankStart;
+			nextRankStart += (rankVal[n] << (n - 1));
+			rankVal[n] = curr;
+		}
+	}
+
+	/* fill nbBits */
+	{
+		U32 n;
+		for (n = 0; n < nbSymbols; n++) {
+			const U32 w = huffWeight[n];
+			CTable[n].nbBits = (BYTE)(tableLog + 1 - w);
+		}
+	}
+
+	/* fill val */
+	{
+		U16 nbPerRank[HUF_TABLELOG_MAX + 2] = {0}; /* support w=0=>n=tableLog+1 */
+		U16 valPerRank[HUF_TABLELOG_MAX + 2] = {0};
+		{
+			U32 n;
+			for (n = 0; n < nbSymbols; n++)
+				nbPerRank[CTable[n].nbBits]++;
+		}
+		/* determine stating value per rank */
+		valPerRank[tableLog + 1] = 0; /* for w==0 */
+		{
+			U16 min = 0;
+			U32 n;
+			for (n = tableLog; n > 0; n--) { /* start at n=tablelog <-> w=1 */
+				valPerRank[n] = min;     /* get starting value within each rank */
+				min += nbPerRank[n];
+				min >>= 1;
+			}
+		}
+		/* assign value within rank, symbol order */
+		{
+			U32 n;
+			for (n = 0; n <= maxSymbolValue; n++)
+				CTable[n].val = valPerRank[CTable[n].nbBits]++;
+		}
+	}
+
+	return readSize;
+}
+
+typedef struct nodeElt_s {
+	U32 count;
+	U16 parent;
+	BYTE byte;
+	BYTE nbBits;
+} nodeElt;
+
+static U32 HUF_setMaxHeight(nodeElt *huffNode, U32 lastNonNull, U32 maxNbBits)
+{
+	const U32 largestBits = huffNode[lastNonNull].nbBits;
+	if (largestBits <= maxNbBits)
+		return largestBits; /* early exit : no elt > maxNbBits */
+
+	/* there are several too large elements (at least >= 2) */
+	{
+		int totalCost = 0;
+		const U32 baseCost = 1 << (largestBits - maxNbBits);
+		U32 n = lastNonNull;
+
+		while (huffNode[n].nbBits > maxNbBits) {
+			totalCost += baseCost - (1 << (largestBits - huffNode[n].nbBits));
+			huffNode[n].nbBits = (BYTE)maxNbBits;
+			n--;
+		} /* n stops at huffNode[n].nbBits <= maxNbBits */
+		while (huffNode[n].nbBits == maxNbBits)
+			n--; /* n end at index of smallest symbol using < maxNbBits */
+
+		/* renorm totalCost */
+		totalCost >>= (largestBits - maxNbBits); /* note : totalCost is necessarily a multiple of baseCost */
+
+		/* repay normalized cost */
+		{
+			U32 const noSymbol = 0xF0F0F0F0;
+			U32 rankLast[HUF_TABLELOG_MAX + 2];
+			int pos;
+
+			/* Get pos of last (smallest) symbol per rank */
+			memset(rankLast, 0xF0, sizeof(rankLast));
+			{
+				U32 currNbBits = maxNbBits;
+				for (pos = n; pos >= 0; pos--) {
+					if (huffNode[pos].nbBits >= currNbBits)
+						continue;
+					currNbBits = huffNode[pos].nbBits; /* < maxNbBits */
+					rankLast[maxNbBits - currNbBits] = pos;
+				}
+			}
+
+			while (totalCost > 0) {
+				U32 nBitsToDecrease = BIT_highbit32(totalCost) + 1;
+				for (; nBitsToDecrease > 1; nBitsToDecrease--) {
+					U32 highPos = rankLast[nBitsToDecrease];
+					U32 lowPos = rankLast[nBitsToDecrease - 1];
+					if (highPos == noSymbol)
+						continue;
+					if (lowPos == noSymbol)
+						break;
+					{
+						U32 const highTotal = huffNode[highPos].count;
+						U32 const lowTotal = 2 * huffNode[lowPos].count;
+						if (highTotal <= lowTotal)
+							break;
+					}
+				}
+				/* only triggered when no more rank 1 symbol left => find closest one (note : there is necessarily at least one !) */
+				/* HUF_MAX_TABLELOG test just to please gcc 5+; but it should not be necessary */
+				while ((nBitsToDecrease <= HUF_TABLELOG_MAX) && (rankLast[nBitsToDecrease] == noSymbol))
+					nBitsToDecrease++;
+				totalCost -= 1 << (nBitsToDecrease - 1);
+				if (rankLast[nBitsToDecrease - 1] == noSymbol)
+					rankLast[nBitsToDecrease - 1] = rankLast[nBitsToDecrease]; /* this rank is no longer empty */
+				huffNode[rankLast[nBitsToDecrease]].nbBits++;
+				if (rankLast[nBitsToDecrease] == 0) /* special case, reached largest symbol */
+					rankLast[nBitsToDecrease] = noSymbol;
+				else {
+					rankLast[nBitsToDecrease]--;
+					if (huffNode[rankLast[nBitsToDecrease]].nbBits != maxNbBits - nBitsToDecrease)
+						rankLast[nBitsToDecrease] = noSymbol; /* this rank is now empty */
+				}
+			} /* while (totalCost > 0) */
+
+			while (totalCost < 0) {		       /* Sometimes, cost correction overshoot */
+				if (rankLast[1] == noSymbol) { /* special case : no rank 1 symbol (using maxNbBits-1); let's create one from largest rank 0
+								  (using maxNbBits) */
+					while (huffNode[n].nbBits == maxNbBits)
+						n--;
+					huffNode[n + 1].nbBits--;
+					rankLast[1] = n + 1;
+					totalCost++;
+					continue;
+				}
+				huffNode[rankLast[1] + 1].nbBits--;
+				rankLast[1]++;
+				totalCost++;
+			}
+		}
+	} /* there are several too large elements (at least >= 2) */
+
+	return maxNbBits;
+}
+
+typedef struct {
+	U32 base;
+	U32 curr;
+} rankPos;
+
+static void HUF_sort(nodeElt *huffNode, const U32 *count, U32 maxSymbolValue)
+{
+	rankPos rank[32];
+	U32 n;
+
+	memset(rank, 0, sizeof(rank));
+	for (n = 0; n <= maxSymbolValue; n++) {
+		U32 r = BIT_highbit32(count[n] + 1);
+		rank[r].base++;
+	}
+	for (n = 30; n > 0; n--)
+		rank[n - 1].base += rank[n].base;
+	for (n = 0; n < 32; n++)
+		rank[n].curr = rank[n].base;
+	for (n = 0; n <= maxSymbolValue; n++) {
+		U32 const c = count[n];
+		U32 const r = BIT_highbit32(c + 1) + 1;
+		U32 pos = rank[r].curr++;
+		while ((pos > rank[r].base) && (c > huffNode[pos - 1].count))
+			huffNode[pos] = huffNode[pos - 1], pos--;
+		huffNode[pos].count = c;
+		huffNode[pos].byte = (BYTE)n;
+	}
+}
+
+/** HUF_buildCTable_wksp() :
+ *  Same as HUF_buildCTable(), but using externally allocated scratch buffer.
+ *  `workSpace` must be aligned on 4-bytes boundaries, and be at least as large as a table of 1024 unsigned.
+ */
+#define STARTNODE (HUF_SYMBOLVALUE_MAX + 1)
+typedef nodeElt huffNodeTable[2 * HUF_SYMBOLVALUE_MAX + 1 + 1];
+size_t HUF_buildCTable_wksp(HUF_CElt *tree, const U32 *count, U32 maxSymbolValue, U32 maxNbBits, void *workSpace, size_t wkspSize)
+{
+	nodeElt *const huffNode0 = (nodeElt *)workSpace;
+	nodeElt *const huffNode = huffNode0 + 1;
+	U32 n, nonNullRank;
+	int lowS, lowN;
+	U16 nodeNb = STARTNODE;
+	U32 nodeRoot;
+
+	/* safety checks */
+	if (wkspSize < sizeof(huffNodeTable))
+		return ERROR(GENERIC); /* workSpace is not large enough */
+	if (maxNbBits == 0)
+		maxNbBits = HUF_TABLELOG_DEFAULT;
+	if (maxSymbolValue > HUF_SYMBOLVALUE_MAX)
+		return ERROR(GENERIC);
+	memset(huffNode0, 0, sizeof(huffNodeTable));
+
+	/* sort, decreasing order */
+	HUF_sort(huffNode, count, maxSymbolValue);
+
+	/* init for parents */
+	nonNullRank = maxSymbolValue;
+	while (huffNode[nonNullRank].count == 0)
+		nonNullRank--;
+	lowS = nonNullRank;
+	nodeRoot = nodeNb + lowS - 1;
+	lowN = nodeNb;
+	huffNode[nodeNb].count = huffNode[lowS].count + huffNode[lowS - 1].count;
+	huffNode[lowS].parent = huffNode[lowS - 1].parent = nodeNb;
+	nodeNb++;
+	lowS -= 2;
+	for (n = nodeNb; n <= nodeRoot; n++)
+		huffNode[n].count = (U32)(1U << 30);
+	huffNode0[0].count = (U32)(1U << 31); /* fake entry, strong barrier */
+
+	/* create parents */
+	while (nodeNb <= nodeRoot) {
+		U32 n1 = (huffNode[lowS].count < huffNode[lowN].count) ? lowS-- : lowN++;
+		U32 n2 = (huffNode[lowS].count < huffNode[lowN].count) ? lowS-- : lowN++;
+		huffNode[nodeNb].count = huffNode[n1].count + huffNode[n2].count;
+		huffNode[n1].parent = huffNode[n2].parent = nodeNb;
+		nodeNb++;
+	}
+
+	/* distribute weights (unlimited tree height) */
+	huffNode[nodeRoot].nbBits = 0;
+	for (n = nodeRoot - 1; n >= STARTNODE; n--)
+		huffNode[n].nbBits = huffNode[huffNode[n].parent].nbBits + 1;
+	for (n = 0; n <= nonNullRank; n++)
+		huffNode[n].nbBits = huffNode[huffNode[n].parent].nbBits + 1;
+
+	/* enforce maxTableLog */
+	maxNbBits = HUF_setMaxHeight(huffNode, nonNullRank, maxNbBits);
+
+	/* fill result into tree (val, nbBits) */
+	{
+		U16 nbPerRank[HUF_TABLELOG_MAX + 1] = {0};
+		U16 valPerRank[HUF_TABLELOG_MAX + 1] = {0};
+		if (maxNbBits > HUF_TABLELOG_MAX)
+			return ERROR(GENERIC); /* check fit into table */
+		for (n = 0; n <= nonNullRank; n++)
+			nbPerRank[huffNode[n].nbBits]++;
+		/* determine stating value per rank */
+		{
+			U16 min = 0;
+			for (n = maxNbBits; n > 0; n--) {
+				valPerRank[n] = min; /* get starting value within each rank */
+				min += nbPerRank[n];
+				min >>= 1;
+			}
+		}
+		for (n = 0; n <= maxSymbolValue; n++)
+			tree[huffNode[n].byte].nbBits = huffNode[n].nbBits; /* push nbBits per symbol, symbol order */
+		for (n = 0; n <= maxSymbolValue; n++)
+			tree[n].val = valPerRank[tree[n].nbBits]++; /* assign value within rank, symbol order */
+	}
+
+	return maxNbBits;
+}
+
+static size_t HUF_estimateCompressedSize(HUF_CElt *CTable, const unsigned *count, unsigned maxSymbolValue)
+{
+	size_t nbBits = 0;
+	int s;
+	for (s = 0; s <= (int)maxSymbolValue; ++s) {
+		nbBits += CTable[s].nbBits * count[s];
+	}
+	return nbBits >> 3;
+}
+
+static int HUF_validateCTable(const HUF_CElt *CTable, const unsigned *count, unsigned maxSymbolValue)
+{
+	int bad = 0;
+	int s;
+	for (s = 0; s <= (int)maxSymbolValue; ++s) {
+		bad |= (count[s] != 0) & (CTable[s].nbBits == 0);
+	}
+	return !bad;
+}
+
+static void HUF_encodeSymbol(BIT_CStream_t *bitCPtr, U32 symbol, const HUF_CElt *CTable)
+{
+	BIT_addBitsFast(bitCPtr, CTable[symbol].val, CTable[symbol].nbBits);
+}
+
+size_t HUF_compressBound(size_t size) { return HUF_COMPRESSBOUND(size); }
+
+#define HUF_FLUSHBITS(s)  BIT_flushBits(s)
+
+#define HUF_FLUSHBITS_1(stream)                                            \
+	if (sizeof((stream)->bitContainer) * 8 < HUF_TABLELOG_MAX * 2 + 7) \
+	HUF_FLUSHBITS(stream)
+
+#define HUF_FLUSHBITS_2(stream)                                            \
+	if (sizeof((stream)->bitContainer) * 8 < HUF_TABLELOG_MAX * 4 + 7) \
+	HUF_FLUSHBITS(stream)
+
+size_t HUF_compress1X_usingCTable(void *dst, size_t dstSize, const void *src, size_t srcSize, const HUF_CElt *CTable)
+{
+	const BYTE *ip = (const BYTE *)src;
+	BYTE *const ostart = (BYTE *)dst;
+	BYTE *const oend = ostart + dstSize;
+	BYTE *op = ostart;
+	size_t n;
+	BIT_CStream_t bitC;
+
+	/* init */
+	if (dstSize < 8)
+		return 0; /* not enough space to compress */
+	{
+		size_t const initErr = BIT_initCStream(&bitC, op, oend - op);
+		if (HUF_isError(initErr))
+			return 0;
+	}
+
+	n = srcSize & ~3; /* join to mod 4 */
+	switch (srcSize & 3) {
+	case 3: HUF_encodeSymbol(&bitC, ip[n + 2], CTable); HUF_FLUSHBITS_2(&bitC);
+	case 2: HUF_encodeSymbol(&bitC, ip[n + 1], CTable); HUF_FLUSHBITS_1(&bitC);
+	case 1: HUF_encodeSymbol(&bitC, ip[n + 0], CTable); HUF_FLUSHBITS(&bitC);
+	case 0:
+	default:;
+	}
+
+	for (; n > 0; n -= 4) { /* note : n&3==0 at this stage */
+		HUF_encodeSymbol(&bitC, ip[n - 1], CTable);
+		HUF_FLUSHBITS_1(&bitC);
+		HUF_encodeSymbol(&bitC, ip[n - 2], CTable);
+		HUF_FLUSHBITS_2(&bitC);
+		HUF_encodeSymbol(&bitC, ip[n - 3], CTable);
+		HUF_FLUSHBITS_1(&bitC);
+		HUF_encodeSymbol(&bitC, ip[n - 4], CTable);
+		HUF_FLUSHBITS(&bitC);
+	}
+
+	return BIT_closeCStream(&bitC);
+}
+
+size_t HUF_compress4X_usingCTable(void *dst, size_t dstSize, const void *src, size_t srcSize, const HUF_CElt *CTable)
+{
+	size_t const segmentSize = (srcSize + 3) / 4; /* first 3 segments */
+	const BYTE *ip = (const BYTE *)src;
+	const BYTE *const iend = ip + srcSize;
+	BYTE *const ostart = (BYTE *)dst;
+	BYTE *const oend = ostart + dstSize;
+	BYTE *op = ostart;
+
+	if (dstSize < 6 + 1 + 1 + 1 + 8)
+		return 0; /* minimum space to compress successfully */
+	if (srcSize < 12)
+		return 0; /* no saving possible : too small input */
+	op += 6;	  /* jumpTable */
+
+	{
+		CHECK_V_F(cSize, HUF_compress1X_usingCTable(op, oend - op, ip, segmentSize, CTable));
+		if (cSize == 0)
+			return 0;
+		ZSTD_writeLE16(ostart, (U16)cSize);
+		op += cSize;
+	}
+
+	ip += segmentSize;
+	{
+		CHECK_V_F(cSize, HUF_compress1X_usingCTable(op, oend - op, ip, segmentSize, CTable));
+		if (cSize == 0)
+			return 0;
+		ZSTD_writeLE16(ostart + 2, (U16)cSize);
+		op += cSize;
+	}
+
+	ip += segmentSize;
+	{
+		CHECK_V_F(cSize, HUF_compress1X_usingCTable(op, oend - op, ip, segmentSize, CTable));
+		if (cSize == 0)
+			return 0;
+		ZSTD_writeLE16(ostart + 4, (U16)cSize);
+		op += cSize;
+	}
+
+	ip += segmentSize;
+	{
+		CHECK_V_F(cSize, HUF_compress1X_usingCTable(op, oend - op, ip, iend - ip, CTable));
+		if (cSize == 0)
+			return 0;
+		op += cSize;
+	}
+
+	return op - ostart;
+}
+
+static size_t HUF_compressCTable_internal(BYTE *const ostart, BYTE *op, BYTE *const oend, const void *src, size_t srcSize, unsigned singleStream,
+					  const HUF_CElt *CTable)
+{
+	size_t const cSize =
+	    singleStream ? HUF_compress1X_usingCTable(op, oend - op, src, srcSize, CTable) : HUF_compress4X_usingCTable(op, oend - op, src, srcSize, CTable);
+	if (HUF_isError(cSize)) {
+		return cSize;
+	}
+	if (cSize == 0) {
+		return 0;
+	} /* uncompressible */
+	op += cSize;
+	/* check compressibility */
+	if ((size_t)(op - ostart) >= srcSize - 1) {
+		return 0;
+	}
+	return op - ostart;
+}
+
+/* `workSpace` must a table of at least 1024 unsigned */
+static size_t HUF_compress_internal(void *dst, size_t dstSize, const void *src, size_t srcSize, unsigned maxSymbolValue, unsigned huffLog,
+				    unsigned singleStream, void *workSpace, size_t wkspSize, HUF_CElt *oldHufTable, HUF_repeat *repeat, int preferRepeat)
+{
+	BYTE *const ostart = (BYTE *)dst;
+	BYTE *const oend = ostart + dstSize;
+	BYTE *op = ostart;
+
+	U32 *count;
+	size_t const countSize = sizeof(U32) * (HUF_SYMBOLVALUE_MAX + 1);
+	HUF_CElt *CTable;
+	size_t const CTableSize = sizeof(HUF_CElt) * (HUF_SYMBOLVALUE_MAX + 1);
+
+	/* checks & inits */
+	if (wkspSize < sizeof(huffNodeTable) + countSize + CTableSize)
+		return ERROR(GENERIC);
+	if (!srcSize)
+		return 0; /* Uncompressed (note : 1 means rle, so first byte must be correct) */
+	if (!dstSize)
+		return 0; /* cannot fit within dst budget */
+	if (srcSize > HUF_BLOCKSIZE_MAX)
+		return ERROR(srcSize_wrong); /* curr block size limit */
+	if (huffLog > HUF_TABLELOG_MAX)
+		return ERROR(tableLog_tooLarge);
+	if (!maxSymbolValue)
+		maxSymbolValue = HUF_SYMBOLVALUE_MAX;
+	if (!huffLog)
+		huffLog = HUF_TABLELOG_DEFAULT;
+
+	count = (U32 *)workSpace;
+	workSpace = (BYTE *)workSpace + countSize;
+	wkspSize -= countSize;
+	CTable = (HUF_CElt *)workSpace;
+	workSpace = (BYTE *)workSpace + CTableSize;
+	wkspSize -= CTableSize;
+
+	/* Heuristic : If we don't need to check the validity of the old table use the old table for small inputs */
+	if (preferRepeat && repeat && *repeat == HUF_repeat_valid) {
+		return HUF_compressCTable_internal(ostart, op, oend, src, srcSize, singleStream, oldHufTable);
+	}
+
+	/* Scan input and build symbol stats */
+	{
+		CHECK_V_F(largest, FSE_count_wksp(count, &maxSymbolValue, (const BYTE *)src, srcSize, (U32 *)workSpace));
+		if (largest == srcSize) {
+			*ostart = ((const BYTE *)src)[0];
+			return 1;
+		} /* single symbol, rle */
+		if (largest <= (srcSize >> 7) + 1)
+			return 0; /* Fast heuristic : not compressible enough */
+	}
+
+	/* Check validity of previous table */
+	if (repeat && *repeat == HUF_repeat_check && !HUF_validateCTable(oldHufTable, count, maxSymbolValue)) {
+		*repeat = HUF_repeat_none;
+	}
+	/* Heuristic : use existing table for small inputs */
+	if (preferRepeat && repeat && *repeat != HUF_repeat_none) {
+		return HUF_compressCTable_internal(ostart, op, oend, src, srcSize, singleStream, oldHufTable);
+	}
+
+	/* Build Huffman Tree */
+	huffLog = HUF_optimalTableLog(huffLog, srcSize, maxSymbolValue);
+	{
+		CHECK_V_F(maxBits, HUF_buildCTable_wksp(CTable, count, maxSymbolValue, huffLog, workSpace, wkspSize));
+		huffLog = (U32)maxBits;
+		/* Zero the unused symbols so we can check it for validity */
+		memset(CTable + maxSymbolValue + 1, 0, CTableSize - (maxSymbolValue + 1) * sizeof(HUF_CElt));
+	}
+
+	/* Write table description header */
+	{
+		CHECK_V_F(hSize, HUF_writeCTable_wksp(op, dstSize, CTable, maxSymbolValue, huffLog, workSpace, wkspSize));
+		/* Check if using the previous table will be beneficial */
+		if (repeat && *repeat != HUF_repeat_none) {
+			size_t const oldSize = HUF_estimateCompressedSize(oldHufTable, count, maxSymbolValue);
+			size_t const newSize = HUF_estimateCompressedSize(CTable, count, maxSymbolValue);
+			if (oldSize <= hSize + newSize || hSize + 12 >= srcSize) {
+				return HUF_compressCTable_internal(ostart, op, oend, src, srcSize, singleStream, oldHufTable);
+			}
+		}
+		/* Use the new table */
+		if (hSize + 12ul >= srcSize) {
+			return 0;
+		}
+		op += hSize;
+		if (repeat) {
+			*repeat = HUF_repeat_none;
+		}
+		if (oldHufTable) {
+			memcpy(oldHufTable, CTable, CTableSize);
+		} /* Save the new table */
+	}
+	return HUF_compressCTable_internal(ostart, op, oend, src, srcSize, singleStream, CTable);
+}
+
+size_t HUF_compress1X_wksp(void *dst, size_t dstSize, const void *src, size_t srcSize, unsigned maxSymbolValue, unsigned huffLog, void *workSpace,
+			   size_t wkspSize)
+{
+	return HUF_compress_internal(dst, dstSize, src, srcSize, maxSymbolValue, huffLog, 1 /* single stream */, workSpace, wkspSize, NULL, NULL, 0);
+}
+
+size_t HUF_compress1X_repeat(void *dst, size_t dstSize, const void *src, size_t srcSize, unsigned maxSymbolValue, unsigned huffLog, void *workSpace,
+			     size_t wkspSize, HUF_CElt *hufTable, HUF_repeat *repeat, int preferRepeat)
+{
+	return HUF_compress_internal(dst, dstSize, src, srcSize, maxSymbolValue, huffLog, 1 /* single stream */, workSpace, wkspSize, hufTable, repeat,
+				     preferRepeat);
+}
+
+size_t HUF_compress4X_wksp(void *dst, size_t dstSize, const void *src, size_t srcSize, unsigned maxSymbolValue, unsigned huffLog, void *workSpace,
+			   size_t wkspSize)
+{
+	return HUF_compress_internal(dst, dstSize, src, srcSize, maxSymbolValue, huffLog, 0 /* 4 streams */, workSpace, wkspSize, NULL, NULL, 0);
+}
+
+size_t HUF_compress4X_repeat(void *dst, size_t dstSize, const void *src, size_t srcSize, unsigned maxSymbolValue, unsigned huffLog, void *workSpace,
+			     size_t wkspSize, HUF_CElt *hufTable, HUF_repeat *repeat, int preferRepeat)
+{
+	return HUF_compress_internal(dst, dstSize, src, srcSize, maxSymbolValue, huffLog, 0 /* 4 streams */, workSpace, wkspSize, hufTable, repeat,
+				     preferRepeat);
+}

lib/zstd/huf_decompress.c

@@ -0,0 +1,960 @@
+/*
+ * Huffman decoder, part of New Generation Entropy library
+ * Copyright (C) 2013-2016, Yann Collet.
+ *
+ * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *   * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License version 2 as published by the
+ * Free Software Foundation. This program is dual-licensed; you may select
+ * either version 2 of the GNU General Public License ("GPL") or BSD license
+ * ("BSD").
+ *
+ * You can contact the author at :
+ * - Source repository : https://github.com/Cyan4973/FiniteStateEntropy
+ */
+
+/* **************************************************************
+*  Compiler specifics
+****************************************************************/
+#define FORCE_INLINE static __always_inline
+
+/* **************************************************************
+*  Dependencies
+****************************************************************/
+#include "bitstream.h" /* BIT_* */
+#include "fse.h"       /* header compression */
+#include "huf.h"
+#include <linux/compiler.h>
+#include <linux/kernel.h>
+#include <linux/string.h> /* memcpy, memset */
+
+/* **************************************************************
+*  Error Management
+****************************************************************/
+#define HUF_STATIC_ASSERT(c)                                   \
+	{                                                      \
+		enum { HUF_static_assert = 1 / (int)(!!(c)) }; \
+	} /* use only *after* variable declarations */
+
+/*-***************************/
+/*  generic DTableDesc       */
+/*-***************************/
+
+typedef struct {
+	BYTE maxTableLog;
+	BYTE tableType;
+	BYTE tableLog;
+	BYTE reserved;
+} DTableDesc;
+
+static DTableDesc HUF_getDTableDesc(const HUF_DTable *table)
+{
+	DTableDesc dtd;
+	memcpy(&dtd, table, sizeof(dtd));
+	return dtd;
+}
+
+/*-***************************/
+/*  single-symbol decoding   */
+/*-***************************/
+
+typedef struct {
+	BYTE byte;
+	BYTE nbBits;
+} HUF_DEltX2; /* single-symbol decoding */
+
+size_t HUF_readDTableX2_wksp(HUF_DTable *DTable, const void *src, size_t srcSize, void *workspace, size_t workspaceSize)
+{
+	U32 tableLog = 0;
+	U32 nbSymbols = 0;
+	size_t iSize;
+	void *const dtPtr = DTable + 1;
+	HUF_DEltX2 *const dt = (HUF_DEltX2 *)dtPtr;
+
+	U32 *rankVal;
+	BYTE *huffWeight;
+	size_t spaceUsed32 = 0;
+
+	rankVal = (U32 *)workspace + spaceUsed32;
+	spaceUsed32 += HUF_TABLELOG_ABSOLUTEMAX + 1;
+	huffWeight = (BYTE *)((U32 *)workspace + spaceUsed32);
+	spaceUsed32 += ALIGN(HUF_SYMBOLVALUE_MAX + 1, sizeof(U32)) >> 2;
+
+	if ((spaceUsed32 << 2) > workspaceSize)
+		return ERROR(tableLog_tooLarge);
+	workspace = (U32 *)workspace + spaceUsed32;
+	workspaceSize -= (spaceUsed32 << 2);
+
+	HUF_STATIC_ASSERT(sizeof(DTableDesc) == sizeof(HUF_DTable));
+	/* memset(huffWeight, 0, sizeof(huffWeight)); */ /* is not necessary, even though some analyzer complain ... */
+
+	iSize = HUF_readStats_wksp(huffWeight, HUF_SYMBOLVALUE_MAX + 1, rankVal, &nbSymbols, &tableLog, src, srcSize, workspace, workspaceSize);
+	if (HUF_isError(iSize))
+		return iSize;
+
+	/* Table header */
+	{
+		DTableDesc dtd = HUF_getDTableDesc(DTable);
+		if (tableLog > (U32)(dtd.maxTableLog + 1))
+			return ERROR(tableLog_tooLarge); /* DTable too small, Huffman tree cannot fit in */
+		dtd.tableType = 0;
+		dtd.tableLog = (BYTE)tableLog;
+		memcpy(DTable, &dtd, sizeof(dtd));
+	}
+
+	/* Calculate starting value for each rank */
+	{
+		U32 n, nextRankStart = 0;
+		for (n = 1; n < tableLog + 1; n++) {
+			U32 const curr = nextRankStart;
+			nextRankStart += (rankVal[n] << (n - 1));
+			rankVal[n] = curr;
+		}
+	}
+
+	/* fill DTable */
+	{
+		U32 n;
+		for (n = 0; n < nbSymbols; n++) {
+			U32 const w = huffWeight[n];
+			U32 const length = (1 << w) >> 1;
+			U32 u;
+			HUF_DEltX2 D;
+			D.byte = (BYTE)n;
+			D.nbBits = (BYTE)(tableLog + 1 - w);
+			for (u = rankVal[w]; u < rankVal[w] + length; u++)
+				dt[u] = D;
+			rankVal[w] += length;
+		}
+	}
+
+	return iSize;
+}
+
+static BYTE HUF_decodeSymbolX2(BIT_DStream_t *Dstream, const HUF_DEltX2 *dt, const U32 dtLog)
+{
+	size_t const val = BIT_lookBitsFast(Dstream, dtLog); /* note : dtLog >= 1 */
+	BYTE const c = dt[val].byte;
+	BIT_skipBits(Dstream, dt[val].nbBits);
+	return c;
+}
+
+#define HUF_DECODE_SYMBOLX2_0(ptr, DStreamPtr) *ptr++ = HUF_decodeSymbolX2(DStreamPtr, dt, dtLog)
+
+#define HUF_DECODE_SYMBOLX2_1(ptr, DStreamPtr)         \
+	if (ZSTD_64bits() || (HUF_TABLELOG_MAX <= 12)) \
+	HUF_DECODE_SYMBOLX2_0(ptr, DStreamPtr)
+
+#define HUF_DECODE_SYMBOLX2_2(ptr, DStreamPtr) \
+	if (ZSTD_64bits())                     \
+	HUF_DECODE_SYMBOLX2_0(ptr, DStreamPtr)
+
+FORCE_INLINE size_t HUF_decodeStreamX2(BYTE *p, BIT_DStream_t *const bitDPtr, BYTE *const pEnd, const HUF_DEltX2 *const dt, const U32 dtLog)
+{
+	BYTE *const pStart = p;
+
+	/* up to 4 symbols at a time */
+	while ((BIT_reloadDStream(bitDPtr) == BIT_DStream_unfinished) && (p <= pEnd - 4)) {
+		HUF_DECODE_SYMBOLX2_2(p, bitDPtr);
+		HUF_DECODE_SYMBOLX2_1(p, bitDPtr);
+		HUF_DECODE_SYMBOLX2_2(p, bitDPtr);
+		HUF_DECODE_SYMBOLX2_0(p, bitDPtr);
+	}
+
+	/* closer to the end */
+	while ((BIT_reloadDStream(bitDPtr) == BIT_DStream_unfinished) && (p < pEnd))
+		HUF_DECODE_SYMBOLX2_0(p, bitDPtr);
+
+	/* no more data to retrieve from bitstream, hence no need to reload */
+	while (p < pEnd)
+		HUF_DECODE_SYMBOLX2_0(p, bitDPtr);
+
+	return pEnd - pStart;
+}
+
+static size_t HUF_decompress1X2_usingDTable_internal(void *dst, size_t dstSize, const void *cSrc, size_t cSrcSize, const HUF_DTable *DTable)
+{
+	BYTE *op = (BYTE *)dst;
+	BYTE *const oend = op + dstSize;
+	const void *dtPtr = DTable + 1;
+	const HUF_DEltX2 *const dt = (const HUF_DEltX2 *)dtPtr;
+	BIT_DStream_t bitD;
+	DTableDesc const dtd = HUF_getDTableDesc(DTable);
+	U32 const dtLog = dtd.tableLog;
+
+	{
+		size_t const errorCode = BIT_initDStream(&bitD, cSrc, cSrcSize);
+		if (HUF_isError(errorCode))
+			return errorCode;
+	}
+
+	HUF_decodeStreamX2(op, &bitD, oend, dt, dtLog);
+
+	/* check */
+	if (!BIT_endOfDStream(&bitD))
+		return ERROR(corruption_detected);
+
+	return dstSize;
+}
+
+size_t HUF_decompress1X2_usingDTable(void *dst, size_t dstSize, const void *cSrc, size_t cSrcSize, const HUF_DTable *DTable)
+{
+	DTableDesc dtd = HUF_getDTableDesc(DTable);
+	if (dtd.tableType != 0)
+		return ERROR(GENERIC);
+	return HUF_decompress1X2_usingDTable_internal(dst, dstSize, cSrc, cSrcSize, DTable);
+}
+
+size_t HUF_decompress1X2_DCtx_wksp(HUF_DTable *DCtx, void *dst, size_t dstSize, const void *cSrc, size_t cSrcSize, void *workspace, size_t workspaceSize)
+{
+	const BYTE *ip = (const BYTE *)cSrc;
+
+	size_t const hSize = HUF_readDTableX2_wksp(DCtx, cSrc, cSrcSize, workspace, workspaceSize);
+	if (HUF_isError(hSize))
+		return hSize;
+	if (hSize >= cSrcSize)
+		return ERROR(srcSize_wrong);
+	ip += hSize;
+	cSrcSize -= hSize;
+
+	return HUF_decompress1X2_usingDTable_internal(dst, dstSize, ip, cSrcSize, DCtx);
+}
+
+static size_t HUF_decompress4X2_usingDTable_internal(void *dst, size_t dstSize, const void *cSrc, size_t cSrcSize, const HUF_DTable *DTable)
+{
+	/* Check */
+	if (cSrcSize < 10)
+		return ERROR(corruption_detected); /* strict minimum : jump table + 1 byte per stream */
+
+	{
+		const BYTE *const istart = (const BYTE *)cSrc;
+		BYTE *const ostart = (BYTE *)dst;
+		BYTE *const oend = ostart + dstSize;
+		const void *const dtPtr = DTable + 1;
+		const HUF_DEltX2 *const dt = (const HUF_DEltX2 *)dtPtr;
+
+		/* Init */
+		BIT_DStream_t bitD1;
+		BIT_DStream_t bitD2;
+		BIT_DStream_t bitD3;
+		BIT_DStream_t bitD4;
+		size_t const length1 = ZSTD_readLE16(istart);
+		size_t const length2 = ZSTD_readLE16(istart + 2);
+		size_t const length3 = ZSTD_readLE16(istart + 4);
+		size_t const length4 = cSrcSize - (length1 + length2 + length3 + 6);
+		const BYTE *const istart1 = istart + 6; /* jumpTable */
+		const BYTE *const istart2 = istart1 + length1;
+		const BYTE *const istart3 = istart2 + length2;
+		const BYTE *const istart4 = istart3 + length3;
+		const size_t segmentSize = (dstSize + 3) / 4;
+		BYTE *const opStart2 = ostart + segmentSize;
+		BYTE *const opStart3 = opStart2 + segmentSize;
+		BYTE *const opStart4 = opStart3 + segmentSize;
+		BYTE *op1 = ostart;
+		BYTE *op2 = opStart2;
+		BYTE *op3 = opStart3;
+		BYTE *op4 = opStart4;
+		U32 endSignal;
+		DTableDesc const dtd = HUF_getDTableDesc(DTable);
+		U32 const dtLog = dtd.tableLog;
+
+		if (length4 > cSrcSize)
+			return ERROR(corruption_detected); /* overflow */
+		{
+			size_t const errorCode = BIT_initDStream(&bitD1, istart1, length1);
+			if (HUF_isError(errorCode))
+				return errorCode;
+		}
+		{
+			size_t const errorCode = BIT_initDStream(&bitD2, istart2, length2);
+			if (HUF_isError(errorCode))
+				return errorCode;
+		}
+		{
+			size_t const errorCode = BIT_initDStream(&bitD3, istart3, length3);
+			if (HUF_isError(errorCode))
+				return errorCode;
+		}
+		{
+			size_t const errorCode = BIT_initDStream(&bitD4, istart4, length4);
+			if (HUF_isError(errorCode))
+				return errorCode;
+		}
+
+		/* 16-32 symbols per loop (4-8 symbols per stream) */
+		endSignal = BIT_reloadDStream(&bitD1) | BIT_reloadDStream(&bitD2) | BIT_reloadDStream(&bitD3) | BIT_reloadDStream(&bitD4);
+		for (; (endSignal == BIT_DStream_unfinished) && (op4 < (oend - 7));) {
+			HUF_DECODE_SYMBOLX2_2(op1, &bitD1);
+			HUF_DECODE_SYMBOLX2_2(op2, &bitD2);
+			HUF_DECODE_SYMBOLX2_2(op3, &bitD3);
+			HUF_DECODE_SYMBOLX2_2(op4, &bitD4);
+			HUF_DECODE_SYMBOLX2_1(op1, &bitD1);
+			HUF_DECODE_SYMBOLX2_1(op2, &bitD2);
+			HUF_DECODE_SYMBOLX2_1(op3, &bitD3);
+			HUF_DECODE_SYMBOLX2_1(op4, &bitD4);
+			HUF_DECODE_SYMBOLX2_2(op1, &bitD1);
+			HUF_DECODE_SYMBOLX2_2(op2, &bitD2);
+			HUF_DECODE_SYMBOLX2_2(op3, &bitD3);
+			HUF_DECODE_SYMBOLX2_2(op4, &bitD4);
+			HUF_DECODE_SYMBOLX2_0(op1, &bitD1);
+			HUF_DECODE_SYMBOLX2_0(op2, &bitD2);
+			HUF_DECODE_SYMBOLX2_0(op3, &bitD3);
+			HUF_DECODE_SYMBOLX2_0(op4, &bitD4);
+			endSignal = BIT_reloadDStream(&bitD1) | BIT_reloadDStream(&bitD2) | BIT_reloadDStream(&bitD3) | BIT_reloadDStream(&bitD4);
+		}
+
+		/* check corruption */
+		if (op1 > opStart2)
+			return ERROR(corruption_detected);
+		if (op2 > opStart3)
+			return ERROR(corruption_detected);
+		if (op3 > opStart4)
+			return ERROR(corruption_detected);
+		/* note : op4 supposed already verified within main loop */
+
+		/* finish bitStreams one by one */
+		HUF_decodeStreamX2(op1, &bitD1, opStart2, dt, dtLog);
+		HUF_decodeStreamX2(op2, &bitD2, opStart3, dt, dtLog);
+		HUF_decodeStreamX2(op3, &bitD3, opStart4, dt, dtLog);
+		HUF_decodeStreamX2(op4, &bitD4, oend, dt, dtLog);
+
+		/* check */
+		endSignal = BIT_endOfDStream(&bitD1) & BIT_endOfDStream(&bitD2) & BIT_endOfDStream(&bitD3) & BIT_endOfDStream(&bitD4);
+		if (!endSignal)
+			return ERROR(corruption_detected);
+
+		/* decoded size */
+		return dstSize;
+	}
+}
+
+size_t HUF_decompress4X2_usingDTable(void *dst, size_t dstSize, const void *cSrc, size_t cSrcSize, const HUF_DTable *DTable)
+{
+	DTableDesc dtd = HUF_getDTableDesc(DTable);
+	if (dtd.tableType != 0)
+		return ERROR(GENERIC);
+	return HUF_decompress4X2_usingDTable_internal(dst, dstSize, cSrc, cSrcSize, DTable);
+}
+
+size_t HUF_decompress4X2_DCtx_wksp(HUF_DTable *dctx, void *dst, size_t dstSize, const void *cSrc, size_t cSrcSize, void *workspace, size_t workspaceSize)
+{
+	const BYTE *ip = (const BYTE *)cSrc;
+
+	size_t const hSize = HUF_readDTableX2_wksp(dctx, cSrc, cSrcSize, workspace, workspaceSize);
+	if (HUF_isError(hSize))
+		return hSize;
+	if (hSize >= cSrcSize)
+		return ERROR(srcSize_wrong);
+	ip += hSize;
+	cSrcSize -= hSize;
+
+	return HUF_decompress4X2_usingDTable_internal(dst, dstSize, ip, cSrcSize, dctx);
+}
+
+/* *************************/
+/* double-symbols decoding */
+/* *************************/
+typedef struct {
+	U16 sequence;
+	BYTE nbBits;
+	BYTE length;
+} HUF_DEltX4; /* double-symbols decoding */
+
+typedef struct {
+	BYTE symbol;
+	BYTE weight;
+} sortedSymbol_t;
+
+/* HUF_fillDTableX4Level2() :
+ * `rankValOrigin` must be a table of at least (HUF_TABLELOG_MAX + 1) U32 */
+static void HUF_fillDTableX4Level2(HUF_DEltX4 *DTable, U32 sizeLog, const U32 consumed, const U32 *rankValOrigin, const int minWeight,
+				   const sortedSymbol_t *sortedSymbols, const U32 sortedListSize, U32 nbBitsBaseline, U16 baseSeq)
+{
+	HUF_DEltX4 DElt;
+	U32 rankVal[HUF_TABLELOG_MAX + 1];
+
+	/* get pre-calculated rankVal */
+	memcpy(rankVal, rankValOrigin, sizeof(rankVal));
+
+	/* fill skipped values */
+	if (minWeight > 1) {
+		U32 i, skipSize = rankVal[minWeight];
+		ZSTD_writeLE16(&(DElt.sequence), baseSeq);
+		DElt.nbBits = (BYTE)(consumed);
+		DElt.length = 1;
+		for (i = 0; i < skipSize; i++)
+			DTable[i] = DElt;
+	}
+
+	/* fill DTable */
+	{
+		U32 s;
+		for (s = 0; s < sortedListSize; s++) { /* note : sortedSymbols already skipped */
+			const U32 symbol = sortedSymbols[s].symbol;
+			const U32 weight = sortedSymbols[s].weight;
+			const U32 nbBits = nbBitsBaseline - weight;
+			const U32 length = 1 << (sizeLog - nbBits);
+			const U32 start = rankVal[weight];
+			U32 i = start;
+			const U32 end = start + length;
+
+			ZSTD_writeLE16(&(DElt.sequence), (U16)(baseSeq + (symbol << 8)));
+			DElt.nbBits = (BYTE)(nbBits + consumed);
+			DElt.length = 2;
+			do {
+				DTable[i++] = DElt;
+			} while (i < end); /* since length >= 1 */
+
+			rankVal[weight] += length;
+		}
+	}
+}
+
+typedef U32 rankVal_t[HUF_TABLELOG_MAX][HUF_TABLELOG_MAX + 1];
+typedef U32 rankValCol_t[HUF_TABLELOG_MAX + 1];
+
+static void HUF_fillDTableX4(HUF_DEltX4 *DTable, const U32 targetLog, const sortedSymbol_t *sortedList, const U32 sortedListSize, const U32 *rankStart,
+			     rankVal_t rankValOrigin, const U32 maxWeight, const U32 nbBitsBaseline)
+{
+	U32 rankVal[HUF_TABLELOG_MAX + 1];
+	const int scaleLog = nbBitsBaseline - targetLog; /* note : targetLog >= srcLog, hence scaleLog <= 1 */
+	const U32 minBits = nbBitsBaseline - maxWeight;
+	U32 s;
+
+	memcpy(rankVal, rankValOrigin, sizeof(rankVal));
+
+	/* fill DTable */
+	for (s = 0; s < sortedListSize; s++) {
+		const U16 symbol = sortedList[s].symbol;
+		const U32 weight = sortedList[s].weight;
+		const U32 nbBits = nbBitsBaseline - weight;
+		const U32 start = rankVal[weight];
+		const U32 length = 1 << (targetLog - nbBits);
+
+		if (targetLog - nbBits >= minBits) { /* enough room for a second symbol */
+			U32 sortedRank;
+			int minWeight = nbBits + scaleLog;
+			if (minWeight < 1)
+				minWeight = 1;
+			sortedRank = rankStart[minWeight];
+			HUF_fillDTableX4Level2(DTable + start, targetLog - nbBits, nbBits, rankValOrigin[nbBits], minWeight, sortedList + sortedRank,
+					       sortedListSize - sortedRank, nbBitsBaseline, symbol);
+		} else {
+			HUF_DEltX4 DElt;
+			ZSTD_writeLE16(&(DElt.sequence), symbol);
+			DElt.nbBits = (BYTE)(nbBits);
+			DElt.length = 1;
+			{
+				U32 const end = start + length;
+				U32 u;
+				for (u = start; u < end; u++)
+					DTable[u] = DElt;
+			}
+		}
+		rankVal[weight] += length;
+	}
+}
+
+size_t HUF_readDTableX4_wksp(HUF_DTable *DTable, const void *src, size_t srcSize, void *workspace, size_t workspaceSize)
+{
+	U32 tableLog, maxW, sizeOfSort, nbSymbols;
+	DTableDesc dtd = HUF_getDTableDesc(DTable);
+	U32 const maxTableLog = dtd.maxTableLog;
+	size_t iSize;
+	void *dtPtr = DTable + 1; /* force compiler to avoid strict-aliasing */
+	HUF_DEltX4 *const dt = (HUF_DEltX4 *)dtPtr;
+	U32 *rankStart;
+
+	rankValCol_t *rankVal;
+	U32 *rankStats;
+	U32 *rankStart0;
+	sortedSymbol_t *sortedSymbol;
+	BYTE *weightList;
+	size_t spaceUsed32 = 0;
+
+	HUF_STATIC_ASSERT((sizeof(rankValCol_t) & 3) == 0);
+
+	rankVal = (rankValCol_t *)((U32 *)workspace + spaceUsed32);
+	spaceUsed32 += (sizeof(rankValCol_t) * HUF_TABLELOG_MAX) >> 2;
+	rankStats = (U32 *)workspace + spaceUsed32;
+	spaceUsed32 += HUF_TABLELOG_MAX + 1;
+	rankStart0 = (U32 *)workspace + spaceUsed32;
+	spaceUsed32 += HUF_TABLELOG_MAX + 2;
+	sortedSymbol = (sortedSymbol_t *)((U32 *)workspace + spaceUsed32);
+	spaceUsed32 += ALIGN(sizeof(sortedSymbol_t) * (HUF_SYMBOLVALUE_MAX + 1), sizeof(U32)) >> 2;
+	weightList = (BYTE *)((U32 *)workspace + spaceUsed32);
+	spaceUsed32 += ALIGN(HUF_SYMBOLVALUE_MAX + 1, sizeof(U32)) >> 2;
+
+	if ((spaceUsed32 << 2) > workspaceSize)
+		return ERROR(tableLog_tooLarge);
+	workspace = (U32 *)workspace + spaceUsed32;
+	workspaceSize -= (spaceUsed32 << 2);
+
+	rankStart = rankStart0 + 1;
+	memset(rankStats, 0, sizeof(U32) * (2 * HUF_TABLELOG_MAX + 2 + 1));
+
+	HUF_STATIC_ASSERT(sizeof(HUF_DEltX4) == sizeof(HUF_DTable)); /* if compiler fails here, assertion is wrong */
+	if (maxTableLog > HUF_TABLELOG_MAX)
+		return ERROR(tableLog_tooLarge);
+	/* memset(weightList, 0, sizeof(weightList)); */ /* is not necessary, even though some analyzer complain ... */
+
+	iSize = HUF_readStats_wksp(weightList, HUF_SYMBOLVALUE_MAX + 1, rankStats, &nbSymbols, &tableLog, src, srcSize, workspace, workspaceSize);
+	if (HUF_isError(iSize))
+		return iSize;
+
+	/* check result */
+	if (tableLog > maxTableLog)
+		return ERROR(tableLog_tooLarge); /* DTable can't fit code depth */
+
+	/* find maxWeight */
+	for (maxW = tableLog; rankStats[maxW] == 0; maxW--) {
+	} /* necessarily finds a solution before 0 */
+
+	/* Get start index of each weight */
+	{
+		U32 w, nextRankStart = 0;
+		for (w = 1; w < maxW + 1; w++) {
+			U32 curr = nextRankStart;
+			nextRankStart += rankStats[w];
+			rankStart[w] = curr;
+		}
+		rankStart[0] = nextRankStart; /* put all 0w symbols at the end of sorted list*/
+		sizeOfSort = nextRankStart;
+	}
+
+	/* sort symbols by weight */
+	{
+		U32 s;
+		for (s = 0; s < nbSymbols; s++) {
+			U32 const w = weightList[s];
+			U32 const r = rankStart[w]++;
+			sortedSymbol[r].symbol = (BYTE)s;
+			sortedSymbol[r].weight = (BYTE)w;
+		}
+		rankStart[0] = 0; /* forget 0w symbols; this is beginning of weight(1) */
+	}
+
+	/* Build rankVal */
+	{
+		U32 *const rankVal0 = rankVal[0];
+		{
+			int const rescale = (maxTableLog - tableLog) - 1; /* tableLog <= maxTableLog */
+			U32 nextRankVal = 0;
+			U32 w;
+			for (w = 1; w < maxW + 1; w++) {
+				U32 curr = nextRankVal;
+				nextRankVal += rankStats[w] << (w + rescale);
+				rankVal0[w] = curr;
+			}
+		}
+		{
+			U32 const minBits = tableLog + 1 - maxW;
+			U32 consumed;
+			for (consumed = minBits; consumed < maxTableLog - minBits + 1; consumed++) {
+				U32 *const rankValPtr = rankVal[consumed];
+				U32 w;
+				for (w = 1; w < maxW + 1; w++) {
+					rankValPtr[w] = rankVal0[w] >> consumed;
+				}
+			}
+		}
+	}
+
+	HUF_fillDTableX4(dt, maxTableLog, sortedSymbol, sizeOfSort, rankStart0, rankVal, maxW, tableLog + 1);
+
+	dtd.tableLog = (BYTE)maxTableLog;
+	dtd.tableType = 1;
+	memcpy(DTable, &dtd, sizeof(dtd));
+	return iSize;
+}
+
+static U32 HUF_decodeSymbolX4(void *op, BIT_DStream_t *DStream, const HUF_DEltX4 *dt, const U32 dtLog)
+{
+	size_t const val = BIT_lookBitsFast(DStream, dtLog); /* note : dtLog >= 1 */
+	memcpy(op, dt + val, 2);
+	BIT_skipBits(DStream, dt[val].nbBits);
+	return dt[val].length;
+}
+
+static U32 HUF_decodeLastSymbolX4(void *op, BIT_DStream_t *DStream, const HUF_DEltX4 *dt, const U32 dtLog)
+{
+	size_t const val = BIT_lookBitsFast(DStream, dtLog); /* note : dtLog >= 1 */
+	memcpy(op, dt + val, 1);
+	if (dt[val].length == 1)
+		BIT_skipBits(DStream, dt[val].nbBits);
+	else {
+		if (DStream->bitsConsumed < (sizeof(DStream->bitContainer) * 8)) {
+			BIT_skipBits(DStream, dt[val].nbBits);
+			if (DStream->bitsConsumed > (sizeof(DStream->bitContainer) * 8))
+				/* ugly hack; works only because it's the last symbol. Note : can't easily extract nbBits from just this symbol */
+				DStream->bitsConsumed = (sizeof(DStream->bitContainer) * 8);
+		}
+	}
+	return 1;
+}
+
+#define HUF_DECODE_SYMBOLX4_0(ptr, DStreamPtr) ptr += HUF_decodeSymbolX4(ptr, DStreamPtr, dt, dtLog)
+
+#define HUF_DECODE_SYMBOLX4_1(ptr, DStreamPtr)         \
+	if (ZSTD_64bits() || (HUF_TABLELOG_MAX <= 12)) \
+	ptr += HUF_decodeSymbolX4(ptr, DStreamPtr, dt, dtLog)
+
+#define HUF_DECODE_SYMBOLX4_2(ptr, DStreamPtr) \
+	if (ZSTD_64bits())                     \
+	ptr += HUF_decodeSymbolX4(ptr, DStreamPtr, dt, dtLog)
+
+FORCE_INLINE size_t HUF_decodeStreamX4(BYTE *p, BIT_DStream_t *bitDPtr, BYTE *const pEnd, const HUF_DEltX4 *const dt, const U32 dtLog)
+{
+	BYTE *const pStart = p;
+
+	/* up to 8 symbols at a time */
+	while ((BIT_reloadDStream(bitDPtr) == BIT_DStream_unfinished) & (p < pEnd - (sizeof(bitDPtr->bitContainer) - 1))) {
+		HUF_DECODE_SYMBOLX4_2(p, bitDPtr);
+		HUF_DECODE_SYMBOLX4_1(p, bitDPtr);
+		HUF_DECODE_SYMBOLX4_2(p, bitDPtr);
+		HUF_DECODE_SYMBOLX4_0(p, bitDPtr);
+	}
+
+	/* closer to end : up to 2 symbols at a time */
+	while ((BIT_reloadDStream(bitDPtr) == BIT_DStream_unfinished) & (p <= pEnd - 2))
+		HUF_DECODE_SYMBOLX4_0(p, bitDPtr);
+
+	while (p <= pEnd - 2)
+		HUF_DECODE_SYMBOLX4_0(p, bitDPtr); /* no need to reload : reached the end of DStream */
+
+	if (p < pEnd)
+		p += HUF_decodeLastSymbolX4(p, bitDPtr, dt, dtLog);
+
+	return p - pStart;
+}
+
+static size_t HUF_decompress1X4_usingDTable_internal(void *dst, size_t dstSize, const void *cSrc, size_t cSrcSize, const HUF_DTable *DTable)
+{
+	BIT_DStream_t bitD;
+
+	/* Init */
+	{
+		size_t const errorCode = BIT_initDStream(&bitD, cSrc, cSrcSize);
+		if (HUF_isError(errorCode))
+			return errorCode;
+	}
+
+	/* decode */
+	{
+		BYTE *const ostart = (BYTE *)dst;
+		BYTE *const oend = ostart + dstSize;
+		const void *const dtPtr = DTable + 1; /* force compiler to not use strict-aliasing */
+		const HUF_DEltX4 *const dt = (const HUF_DEltX4 *)dtPtr;
+		DTableDesc const dtd = HUF_getDTableDesc(DTable);
+		HUF_decodeStreamX4(ostart, &bitD, oend, dt, dtd.tableLog);
+	}
+
+	/* check */
+	if (!BIT_endOfDStream(&bitD))
+		return ERROR(corruption_detected);
+
+	/* decoded size */
+	return dstSize;
+}
+
+size_t HUF_decompress1X4_usingDTable(void *dst, size_t dstSize, const void *cSrc, size_t cSrcSize, const HUF_DTable *DTable)
+{
+	DTableDesc dtd = HUF_getDTableDesc(DTable);
+	if (dtd.tableType != 1)
+		return ERROR(GENERIC);
+	return HUF_decompress1X4_usingDTable_internal(dst, dstSize, cSrc, cSrcSize, DTable);
+}
+
+size_t HUF_decompress1X4_DCtx_wksp(HUF_DTable *DCtx, void *dst, size_t dstSize, const void *cSrc, size_t cSrcSize, void *workspace, size_t workspaceSize)
+{
+	const BYTE *ip = (const BYTE *)cSrc;
+
+	size_t const hSize = HUF_readDTableX4_wksp(DCtx, cSrc, cSrcSize, workspace, workspaceSize);
+	if (HUF_isError(hSize))
+		return hSize;
+	if (hSize >= cSrcSize)
+		return ERROR(srcSize_wrong);
+	ip += hSize;
+	cSrcSize -= hSize;
+
+	return HUF_decompress1X4_usingDTable_internal(dst, dstSize, ip, cSrcSize, DCtx);
+}
+
+static size_t HUF_decompress4X4_usingDTable_internal(void *dst, size_t dstSize, const void *cSrc, size_t cSrcSize, const HUF_DTable *DTable)
+{
+	if (cSrcSize < 10)
+		return ERROR(corruption_detected); /* strict minimum : jump table + 1 byte per stream */
+
+	{
+		const BYTE *const istart = (const BYTE *)cSrc;
+		BYTE *const ostart = (BYTE *)dst;
+		BYTE *const oend = ostart + dstSize;
+		const void *const dtPtr = DTable + 1;
+		const HUF_DEltX4 *const dt = (const HUF_DEltX4 *)dtPtr;
+
+		/* Init */
+		BIT_DStream_t bitD1;
+		BIT_DStream_t bitD2;
+		BIT_DStream_t bitD3;
+		BIT_DStream_t bitD4;
+		size_t const length1 = ZSTD_readLE16(istart);
+		size_t const length2 = ZSTD_readLE16(istart + 2);
+		size_t const length3 = ZSTD_readLE16(istart + 4);
+		size_t const length4 = cSrcSize - (length1 + length2 + length3 + 6);
+		const BYTE *const istart1 = istart + 6; /* jumpTable */
+		const BYTE *const istart2 = istart1 + length1;
+		const BYTE *const istart3 = istart2 + length2;
+		const BYTE *const istart4 = istart3 + length3;
+		size_t const segmentSize = (dstSize + 3) / 4;
+		BYTE *const opStart2 = ostart + segmentSize;
+		BYTE *const opStart3 = opStart2 + segmentSize;
+		BYTE *const opStart4 = opStart3 + segmentSize;
+		BYTE *op1 = ostart;
+		BYTE *op2 = opStart2;
+		BYTE *op3 = opStart3;
+		BYTE *op4 = opStart4;
+		U32 endSignal;
+		DTableDesc const dtd = HUF_getDTableDesc(DTable);
+		U32 const dtLog = dtd.tableLog;
+
+		if (length4 > cSrcSize)
+			return ERROR(corruption_detected); /* overflow */
+		{
+			size_t const errorCode = BIT_initDStream(&bitD1, istart1, length1);
+			if (HUF_isError(errorCode))
+				return errorCode;
+		}
+		{
+			size_t const errorCode = BIT_initDStream(&bitD2, istart2, length2);
+			if (HUF_isError(errorCode))
+				return errorCode;
+		}
+		{
+			size_t const errorCode = BIT_initDStream(&bitD3, istart3, length3);
+			if (HUF_isError(errorCode))
+				return errorCode;
+		}
+		{
+			size_t const errorCode = BIT_initDStream(&bitD4, istart4, length4);
+			if (HUF_isError(errorCode))
+				return errorCode;
+		}
+
+		/* 16-32 symbols per loop (4-8 symbols per stream) */
+		endSignal = BIT_reloadDStream(&bitD1) | BIT_reloadDStream(&bitD2) | BIT_reloadDStream(&bitD3) | BIT_reloadDStream(&bitD4);
+		for (; (endSignal == BIT_DStream_unfinished) & (op4 < (oend - (sizeof(bitD4.bitContainer) - 1)));) {
+			HUF_DECODE_SYMBOLX4_2(op1, &bitD1);
+			HUF_DECODE_SYMBOLX4_2(op2, &bitD2);
+			HUF_DECODE_SYMBOLX4_2(op3, &bitD3);
+			HUF_DECODE_SYMBOLX4_2(op4, &bitD4);
+			HUF_DECODE_SYMBOLX4_1(op1, &bitD1);
+			HUF_DECODE_SYMBOLX4_1(op2, &bitD2);
+			HUF_DECODE_SYMBOLX4_1(op3, &bitD3);
+			HUF_DECODE_SYMBOLX4_1(op4, &bitD4);
+			HUF_DECODE_SYMBOLX4_2(op1, &bitD1);
+			HUF_DECODE_SYMBOLX4_2(op2, &bitD2);
+			HUF_DECODE_SYMBOLX4_2(op3, &bitD3);
+			HUF_DECODE_SYMBOLX4_2(op4, &bitD4);
+			HUF_DECODE_SYMBOLX4_0(op1, &bitD1);
+			HUF_DECODE_SYMBOLX4_0(op2, &bitD2);
+			HUF_DECODE_SYMBOLX4_0(op3, &bitD3);
+			HUF_DECODE_SYMBOLX4_0(op4, &bitD4);
+
+			endSignal = BIT_reloadDStream(&bitD1) | BIT_reloadDStream(&bitD2) | BIT_reloadDStream(&bitD3) | BIT_reloadDStream(&bitD4);
+		}
+
+		/* check corruption */
+		if (op1 > opStart2)
+			return ERROR(corruption_detected);
+		if (op2 > opStart3)
+			return ERROR(corruption_detected);
+		if (op3 > opStart4)
+			return ERROR(corruption_detected);
+		/* note : op4 already verified within main loop */
+
+		/* finish bitStreams one by one */
+		HUF_decodeStreamX4(op1, &bitD1, opStart2, dt, dtLog);
+		HUF_decodeStreamX4(op2, &bitD2, opStart3, dt, dtLog);
+		HUF_decodeStreamX4(op3, &bitD3, opStart4, dt, dtLog);
+		HUF_decodeStreamX4(op4, &bitD4, oend, dt, dtLog);
+
+		/* check */
+		{
+			U32 const endCheck = BIT_endOfDStream(&bitD1) & BIT_endOfDStream(&bitD2) & BIT_endOfDStream(&bitD3) & BIT_endOfDStream(&bitD4);
+			if (!endCheck)
+				return ERROR(corruption_detected);
+		}
+
+		/* decoded size */
+		return dstSize;
+	}
+}
+
+size_t HUF_decompress4X4_usingDTable(void *dst, size_t dstSize, const void *cSrc, size_t cSrcSize, const HUF_DTable *DTable)
+{
+	DTableDesc dtd = HUF_getDTableDesc(DTable);
+	if (dtd.tableType != 1)
+		return ERROR(GENERIC);
+	return HUF_decompress4X4_usingDTable_internal(dst, dstSize, cSrc, cSrcSize, DTable);
+}
+
+size_t HUF_decompress4X4_DCtx_wksp(HUF_DTable *dctx, void *dst, size_t dstSize, const void *cSrc, size_t cSrcSize, void *workspace, size_t workspaceSize)
+{
+	const BYTE *ip = (const BYTE *)cSrc;
+
+	size_t hSize = HUF_readDTableX4_wksp(dctx, cSrc, cSrcSize, workspace, workspaceSize);
+	if (HUF_isError(hSize))
+		return hSize;
+	if (hSize >= cSrcSize)
+		return ERROR(srcSize_wrong);
+	ip += hSize;
+	cSrcSize -= hSize;
+
+	return HUF_decompress4X4_usingDTable_internal(dst, dstSize, ip, cSrcSize, dctx);
+}
+
+/* ********************************/
+/* Generic decompression selector */
+/* ********************************/
+
+size_t HUF_decompress1X_usingDTable(void *dst, size_t maxDstSize, const void *cSrc, size_t cSrcSize, const HUF_DTable *DTable)
+{
+	DTableDesc const dtd = HUF_getDTableDesc(DTable);
+	return dtd.tableType ? HUF_decompress1X4_usingDTable_internal(dst, maxDstSize, cSrc, cSrcSize, DTable)
+			     : HUF_decompress1X2_usingDTable_internal(dst, maxDstSize, cSrc, cSrcSize, DTable);
+}
+
+size_t HUF_decompress4X_usingDTable(void *dst, size_t maxDstSize, const void *cSrc, size_t cSrcSize, const HUF_DTable *DTable)
+{
+	DTableDesc const dtd = HUF_getDTableDesc(DTable);
+	return dtd.tableType ? HUF_decompress4X4_usingDTable_internal(dst, maxDstSize, cSrc, cSrcSize, DTable)
+			     : HUF_decompress4X2_usingDTable_internal(dst, maxDstSize, cSrc, cSrcSize, DTable);
+}
+
+typedef struct {
+	U32 tableTime;
+	U32 decode256Time;
+} algo_time_t;
+static const algo_time_t algoTime[16 /* Quantization */][3 /* single, double, quad */] = {
+    /* single, double, quad */
+    {{0, 0}, {1, 1}, {2, 2}},		     /* Q==0 : impossible */
+    {{0, 0}, {1, 1}, {2, 2}},		     /* Q==1 : impossible */
+    {{38, 130}, {1313, 74}, {2151, 38}},     /* Q == 2 : 12-18% */
+    {{448, 128}, {1353, 74}, {2238, 41}},    /* Q == 3 : 18-25% */
+    {{556, 128}, {1353, 74}, {2238, 47}},    /* Q == 4 : 25-32% */
+    {{714, 128}, {1418, 74}, {2436, 53}},    /* Q == 5 : 32-38% */
+    {{883, 128}, {1437, 74}, {2464, 61}},    /* Q == 6 : 38-44% */
+    {{897, 128}, {1515, 75}, {2622, 68}},    /* Q == 7 : 44-50% */
+    {{926, 128}, {1613, 75}, {2730, 75}},    /* Q == 8 : 50-56% */
+    {{947, 128}, {1729, 77}, {3359, 77}},    /* Q == 9 : 56-62% */
+    {{1107, 128}, {2083, 81}, {4006, 84}},   /* Q ==10 : 62-69% */
+    {{1177, 128}, {2379, 87}, {4785, 88}},   /* Q ==11 : 69-75% */
+    {{1242, 128}, {2415, 93}, {5155, 84}},   /* Q ==12 : 75-81% */
+    {{1349, 128}, {2644, 106}, {5260, 106}}, /* Q ==13 : 81-87% */
+    {{1455, 128}, {2422, 124}, {4174, 124}}, /* Q ==14 : 87-93% */
+    {{722, 128}, {1891, 145}, {1936, 146}},  /* Q ==15 : 93-99% */
+};
+
+/** HUF_selectDecoder() :
+*   Tells which decoder is likely to decode faster,
+*   based on a set of pre-determined metrics.
+*   @return : 0==HUF_decompress4X2, 1==HUF_decompress4X4 .
+*   Assumption : 0 < cSrcSize < dstSize <= 128 KB */
+U32 HUF_selectDecoder(size_t dstSize, size_t cSrcSize)
+{
+	/* decoder timing evaluation */
+	U32 const Q = (U32)(cSrcSize * 16 / dstSize); /* Q < 16 since dstSize > cSrcSize */
+	U32 const D256 = (U32)(dstSize >> 8);
+	U32 const DTime0 = algoTime[Q][0].tableTime + (algoTime[Q][0].decode256Time * D256);
+	U32 DTime1 = algoTime[Q][1].tableTime + (algoTime[Q][1].decode256Time * D256);
+	DTime1 += DTime1 >> 3; /* advantage to algorithm using less memory, for cache eviction */
+
+	return DTime1 < DTime0;
+}
+
+typedef size_t (*decompressionAlgo)(void *dst, size_t dstSize, const void *cSrc, size_t cSrcSize);
+
+size_t HUF_decompress4X_DCtx_wksp(HUF_DTable *dctx, void *dst, size_t dstSize, const void *cSrc, size_t cSrcSize, void *workspace, size_t workspaceSize)
+{
+	/* validation checks */
+	if (dstSize == 0)
+		return ERROR(dstSize_tooSmall);
+	if (cSrcSize > dstSize)
+		return ERROR(corruption_detected); /* invalid */
+	if (cSrcSize == dstSize) {
+		memcpy(dst, cSrc, dstSize);
+		return dstSize;
+	} /* not compressed */
+	if (cSrcSize == 1) {
+		memset(dst, *(const BYTE *)cSrc, dstSize);
+		return dstSize;
+	} /* RLE */
+
+	{
+		U32 const algoNb = HUF_selectDecoder(dstSize, cSrcSize);
+		return algoNb ? HUF_decompress4X4_DCtx_wksp(dctx, dst, dstSize, cSrc, cSrcSize, workspace, workspaceSize)
+			      : HUF_decompress4X2_DCtx_wksp(dctx, dst, dstSize, cSrc, cSrcSize, workspace, workspaceSize);
+	}
+}
+
+size_t HUF_decompress4X_hufOnly_wksp(HUF_DTable *dctx, void *dst, size_t dstSize, const void *cSrc, size_t cSrcSize, void *workspace, size_t workspaceSize)
+{
+	/* validation checks */
+	if (dstSize == 0)
+		return ERROR(dstSize_tooSmall);
+	if ((cSrcSize >= dstSize) || (cSrcSize <= 1))
+		return ERROR(corruption_detected); /* invalid */
+
+	{
+		U32 const algoNb = HUF_selectDecoder(dstSize, cSrcSize);
+		return algoNb ? HUF_decompress4X4_DCtx_wksp(dctx, dst, dstSize, cSrc, cSrcSize, workspace, workspaceSize)
+			      : HUF_decompress4X2_DCtx_wksp(dctx, dst, dstSize, cSrc, cSrcSize, workspace, workspaceSize);
+	}
+}
+
+size_t HUF_decompress1X_DCtx_wksp(HUF_DTable *dctx, void *dst, size_t dstSize, const void *cSrc, size_t cSrcSize, void *workspace, size_t workspaceSize)
+{
+	/* validation checks */
+	if (dstSize == 0)
+		return ERROR(dstSize_tooSmall);
+	if (cSrcSize > dstSize)
+		return ERROR(corruption_detected); /* invalid */
+	if (cSrcSize == dstSize) {
+		memcpy(dst, cSrc, dstSize);
+		return dstSize;
+	} /* not compressed */
+	if (cSrcSize == 1) {
+		memset(dst, *(const BYTE *)cSrc, dstSize);
+		return dstSize;
+	} /* RLE */
+
+	{
+		U32 const algoNb = HUF_selectDecoder(dstSize, cSrcSize);
+		return algoNb ? HUF_decompress1X4_DCtx_wksp(dctx, dst, dstSize, cSrc, cSrcSize, workspace, workspaceSize)
+			      : HUF_decompress1X2_DCtx_wksp(dctx, dst, dstSize, cSrc, cSrcSize, workspace, workspaceSize);
+	}
+}

lib/zstd/mem.h

@@ -0,0 +1,151 @@
+/**
+ * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of https://github.com/facebook/zstd.
+ * An additional grant of patent rights can be found in the PATENTS file in the
+ * same directory.
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License version 2 as published by the
+ * Free Software Foundation. This program is dual-licensed; you may select
+ * either version 2 of the GNU General Public License ("GPL") or BSD license
+ * ("BSD").
+ */
+
+#ifndef MEM_H_MODULE
+#define MEM_H_MODULE
+
+/*-****************************************
+*  Dependencies
+******************************************/
+#include <asm/unaligned.h>
+#include <linux/string.h> /* memcpy */
+#include <linux/types.h>  /* size_t, ptrdiff_t */
+
+/*-****************************************
+*  Compiler specifics
+******************************************/
+#define ZSTD_STATIC static __inline __attribute__((unused))
+
+/*-**************************************************************
+*  Basic Types
+*****************************************************************/
+typedef uint8_t BYTE;
+typedef uint16_t U16;
+typedef int16_t S16;
+typedef uint32_t U32;
+typedef int32_t S32;
+typedef uint64_t U64;
+typedef int64_t S64;
+typedef ptrdiff_t iPtrDiff;
+typedef uintptr_t uPtrDiff;
+
+/*-**************************************************************
+*  Memory I/O
+*****************************************************************/
+ZSTD_STATIC unsigned ZSTD_32bits(void) { return sizeof(size_t) == 4; }
+ZSTD_STATIC unsigned ZSTD_64bits(void) { return sizeof(size_t) == 8; }
+
+#if defined(__LITTLE_ENDIAN)
+#define ZSTD_LITTLE_ENDIAN 1
+#else
+#define ZSTD_LITTLE_ENDIAN 0
+#endif
+
+ZSTD_STATIC unsigned ZSTD_isLittleEndian(void) { return ZSTD_LITTLE_ENDIAN; }
+
+ZSTD_STATIC U16 ZSTD_read16(const void *memPtr) { return get_unaligned((const U16 *)memPtr); }
+
+ZSTD_STATIC U32 ZSTD_read32(const void *memPtr) { return get_unaligned((const U32 *)memPtr); }
+
+ZSTD_STATIC U64 ZSTD_read64(const void *memPtr) { return get_unaligned((const U64 *)memPtr); }
+
+ZSTD_STATIC size_t ZSTD_readST(const void *memPtr) { return get_unaligned((const size_t *)memPtr); }
+
+ZSTD_STATIC void ZSTD_write16(void *memPtr, U16 value) { put_unaligned(value, (U16 *)memPtr); }
+
+ZSTD_STATIC void ZSTD_write32(void *memPtr, U32 value) { put_unaligned(value, (U32 *)memPtr); }
+
+ZSTD_STATIC void ZSTD_write64(void *memPtr, U64 value) { put_unaligned(value, (U64 *)memPtr); }
+
+/*=== Little endian r/w ===*/
+
+ZSTD_STATIC U16 ZSTD_readLE16(const void *memPtr) { return get_unaligned_le16(memPtr); }
+
+ZSTD_STATIC void ZSTD_writeLE16(void *memPtr, U16 val) { put_unaligned_le16(val, memPtr); }
+
+ZSTD_STATIC U32 ZSTD_readLE24(const void *memPtr) { return ZSTD_readLE16(memPtr) + (((const BYTE *)memPtr)[2] << 16); }
+
+ZSTD_STATIC void ZSTD_writeLE24(void *memPtr, U32 val)
+{
+	ZSTD_writeLE16(memPtr, (U16)val);
+	((BYTE *)memPtr)[2] = (BYTE)(val >> 16);
+}
+
+ZSTD_STATIC U32 ZSTD_readLE32(const void *memPtr) { return get_unaligned_le32(memPtr); }
+
+ZSTD_STATIC void ZSTD_writeLE32(void *memPtr, U32 val32) { put_unaligned_le32(val32, memPtr); }
+
+ZSTD_STATIC U64 ZSTD_readLE64(const void *memPtr) { return get_unaligned_le64(memPtr); }
+
+ZSTD_STATIC void ZSTD_writeLE64(void *memPtr, U64 val64) { put_unaligned_le64(val64, memPtr); }
+
+ZSTD_STATIC size_t ZSTD_readLEST(const void *memPtr)
+{
+	if (ZSTD_32bits())
+		return (size_t)ZSTD_readLE32(memPtr);
+	else
+		return (size_t)ZSTD_readLE64(memPtr);
+}
+
+ZSTD_STATIC void ZSTD_writeLEST(void *memPtr, size_t val)
+{
+	if (ZSTD_32bits())
+		ZSTD_writeLE32(memPtr, (U32)val);
+	else
+		ZSTD_writeLE64(memPtr, (U64)val);
+}
+
+/*=== Big endian r/w ===*/
+
+ZSTD_STATIC U32 ZSTD_readBE32(const void *memPtr) { return get_unaligned_be32(memPtr); }
+
+ZSTD_STATIC void ZSTD_writeBE32(void *memPtr, U32 val32) { put_unaligned_be32(val32, memPtr); }
+
+ZSTD_STATIC U64 ZSTD_readBE64(const void *memPtr) { return get_unaligned_be64(memPtr); }
+
+ZSTD_STATIC void ZSTD_writeBE64(void *memPtr, U64 val64) { put_unaligned_be64(val64, memPtr); }
+
+ZSTD_STATIC size_t ZSTD_readBEST(const void *memPtr)
+{
+	if (ZSTD_32bits())
+		return (size_t)ZSTD_readBE32(memPtr);
+	else
+		return (size_t)ZSTD_readBE64(memPtr);
+}
+
+ZSTD_STATIC void ZSTD_writeBEST(void *memPtr, size_t val)
+{
+	if (ZSTD_32bits())
+		ZSTD_writeBE32(memPtr, (U32)val);
+	else
+		ZSTD_writeBE64(memPtr, (U64)val);
+}
+
+/* function safe only for comparisons */
+ZSTD_STATIC U32 ZSTD_readMINMATCH(const void *memPtr, U32 length)
+{
+	switch (length) {
+	default:
+	case 4: return ZSTD_read32(memPtr);
+	case 3:
+		if (ZSTD_isLittleEndian())
+			return ZSTD_read32(memPtr) << 8;
+		else
+			return ZSTD_read32(memPtr) >> 8;
+	}
+}
+
+#endif /* MEM_H_MODULE */

lib/zstd/zstd_common.c

@@ -0,0 +1,75 @@
+/**
+ * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of https://github.com/facebook/zstd.
+ * An additional grant of patent rights can be found in the PATENTS file in the
+ * same directory.
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License version 2 as published by the
+ * Free Software Foundation. This program is dual-licensed; you may select
+ * either version 2 of the GNU General Public License ("GPL") or BSD license
+ * ("BSD").
+ */
+
+/*-*************************************
+*  Dependencies
+***************************************/
+#include "error_private.h"
+#include "zstd_internal.h" /* declaration of ZSTD_isError, ZSTD_getErrorName, ZSTD_getErrorCode, ZSTD_getErrorString, ZSTD_versionNumber */
+#include <linux/kernel.h>
+
+/*=**************************************************************
+*  Custom allocator
+****************************************************************/
+
+#define stack_push(stack, size)                                 \
+	({                                                      \
+		void *const ptr = ZSTD_PTR_ALIGN((stack)->ptr); \
+		(stack)->ptr = (char *)ptr + (size);            \
+		(stack)->ptr <= (stack)->end ? ptr : NULL;      \
+	})
+
+ZSTD_customMem ZSTD_initStack(void *workspace, size_t workspaceSize)
+{
+	ZSTD_customMem stackMem = {ZSTD_stackAlloc, ZSTD_stackFree, workspace};
+	ZSTD_stack *stack = (ZSTD_stack *)workspace;
+	/* Verify preconditions */
+	if (!workspace || workspaceSize < sizeof(ZSTD_stack) || workspace != ZSTD_PTR_ALIGN(workspace)) {
+		ZSTD_customMem error = {NULL, NULL, NULL};
+		return error;
+	}
+	/* Initialize the stack */
+	stack->ptr = workspace;
+	stack->end = (char *)workspace + workspaceSize;
+	stack_push(stack, sizeof(ZSTD_stack));
+	return stackMem;
+}
+
+void *ZSTD_stackAllocAll(void *opaque, size_t *size)
+{
+	ZSTD_stack *stack = (ZSTD_stack *)opaque;
+	*size = (BYTE const *)stack->end - (BYTE *)ZSTD_PTR_ALIGN(stack->ptr);
+	return stack_push(stack, *size);
+}
+
+void *ZSTD_stackAlloc(void *opaque, size_t size)
+{
+	ZSTD_stack *stack = (ZSTD_stack *)opaque;
+	return stack_push(stack, size);
+}
+void ZSTD_stackFree(void *opaque, void *address)
+{
+	(void)opaque;
+	(void)address;
+}
+
+void *ZSTD_malloc(size_t size, ZSTD_customMem customMem) { return customMem.customAlloc(customMem.opaque, size); }
+
+void ZSTD_free(void *ptr, ZSTD_customMem customMem)
+{
+	if (ptr != NULL)
+		customMem.customFree(customMem.opaque, ptr);
+}

lib/zstd/zstd_internal.h

@@ -0,0 +1,263 @@
+/**
+ * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of https://github.com/facebook/zstd.
+ * An additional grant of patent rights can be found in the PATENTS file in the
+ * same directory.
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License version 2 as published by the
+ * Free Software Foundation. This program is dual-licensed; you may select
+ * either version 2 of the GNU General Public License ("GPL") or BSD license
+ * ("BSD").
+ */
+
+#ifndef ZSTD_CCOMMON_H_MODULE
+#define ZSTD_CCOMMON_H_MODULE
+
+/*-*******************************************************
+*  Compiler specifics
+*********************************************************/
+#define FORCE_INLINE static __always_inline
+#define FORCE_NOINLINE static noinline
+
+/*-*************************************
+*  Dependencies
+***************************************/
+#include "error_private.h"
+#include "mem.h"
+#include <linux/compiler.h>
+#include <linux/kernel.h>
+#include <linux/xxhash.h>
+#include <linux/zstd.h>
+
+/*-*************************************
+*  shared macros
+***************************************/
+#define MIN(a, b) ((a) < (b) ? (a) : (b))
+#define MAX(a, b) ((a) > (b) ? (a) : (b))
+#define CHECK_F(f)                       \
+	{                                \
+		size_t const errcod = f; \
+		if (ERR_isError(errcod)) \
+			return errcod;   \
+	} /* check and Forward error code */
+#define CHECK_E(f, e)                    \
+	{                                \
+		size_t const errcod = f; \
+		if (ERR_isError(errcod)) \
+			return ERROR(e); \
+	} /* check and send Error code */
+#define ZSTD_STATIC_ASSERT(c)                                   \
+	{                                                       \
+		enum { ZSTD_static_assert = 1 / (int)(!!(c)) }; \
+	}
+
+/*-*************************************
+*  Common constants
+***************************************/
+#define ZSTD_OPT_NUM (1 << 12)
+#define ZSTD_DICT_MAGIC 0xEC30A437 /* v0.7+ */
+
+#define ZSTD_REP_NUM 3		      /* number of repcodes */
+#define ZSTD_REP_CHECK (ZSTD_REP_NUM) /* number of repcodes to check by the optimal parser */
+#define ZSTD_REP_MOVE (ZSTD_REP_NUM - 1)
+#define ZSTD_REP_MOVE_OPT (ZSTD_REP_NUM)
+static const U32 repStartValue[ZSTD_REP_NUM] = {1, 4, 8};
+
+#define KB *(1 << 10)
+#define MB *(1 << 20)
+#define GB *(1U << 30)
+
+#define BIT7 128
+#define BIT6 64
+#define BIT5 32
+#define BIT4 16
+#define BIT1 2
+#define BIT0 1
+
+#define ZSTD_WINDOWLOG_ABSOLUTEMIN 10
+static const size_t ZSTD_fcs_fieldSize[4] = {0, 2, 4, 8};
+static const size_t ZSTD_did_fieldSize[4] = {0, 1, 2, 4};
+
+#define ZSTD_BLOCKHEADERSIZE 3 /* C standard doesn't allow `static const` variable to be init using another `static const` variable */
+static const size_t ZSTD_blockHeaderSize = ZSTD_BLOCKHEADERSIZE;
+typedef enum { bt_raw, bt_rle, bt_compressed, bt_reserved } blockType_e;
+
+#define MIN_SEQUENCES_SIZE 1									  /* nbSeq==0 */
+#define MIN_CBLOCK_SIZE (1 /*litCSize*/ + 1 /* RLE or RAW */ + MIN_SEQUENCES_SIZE /* nbSeq==0 */) /* for a non-null block */
+
+#define HufLog 12
+typedef enum { set_basic, set_rle, set_compressed, set_repeat } symbolEncodingType_e;
+
+#define LONGNBSEQ 0x7F00
+
+#define MINMATCH 3
+#define EQUAL_READ32 4
+
+#define Litbits 8
+#define MaxLit ((1 << Litbits) - 1)
+#define MaxML 52
+#define MaxLL 35
+#define MaxOff 28
+#define MaxSeq MAX(MaxLL, MaxML) /* Assumption : MaxOff < MaxLL,MaxML */
+#define MLFSELog 9
+#define LLFSELog 9
+#define OffFSELog 8
+
+static const U32 LL_bits[MaxLL + 1] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 3, 3, 4, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16};
+static const S16 LL_defaultNorm[MaxLL + 1] = {4, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 1, 1, 1, 1, 1, -1, -1, -1, -1};
+#define LL_DEFAULTNORMLOG 6 /* for static allocation */
+static const U32 LL_defaultNormLog = LL_DEFAULTNORMLOG;
+
+static const U32 ML_bits[MaxML + 1] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  0,  0,  0,  0,  0,  0, 0,
+				       0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 3, 3, 4, 4, 5, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16};
+static const S16 ML_defaultNorm[MaxML + 1] = {1, 4, 3, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  1,  1,  1,  1,  1,  1, 1,
+					      1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1};
+#define ML_DEFAULTNORMLOG 6 /* for static allocation */
+static const U32 ML_defaultNormLog = ML_DEFAULTNORMLOG;
+
+static const S16 OF_defaultNorm[MaxOff + 1] = {1, 1, 1, 1, 1, 1, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1};
+#define OF_DEFAULTNORMLOG 5 /* for static allocation */
+static const U32 OF_defaultNormLog = OF_DEFAULTNORMLOG;
+
+/*-*******************************************
+*  Shared functions to include for inlining
+*********************************************/
+ZSTD_STATIC void ZSTD_copy8(void *dst, const void *src) {
+	memcpy(dst, src, 8);
+}
+/*! ZSTD_wildcopy() :
+*   custom version of memcpy(), can copy up to 7 bytes too many (8 bytes if length==0) */
+#define WILDCOPY_OVERLENGTH 8
+ZSTD_STATIC void ZSTD_wildcopy(void *dst, const void *src, ptrdiff_t length)
+{
+	const BYTE* ip = (const BYTE*)src;
+	BYTE* op = (BYTE*)dst;
+	BYTE* const oend = op + length;
+	/* Work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81388.
+	 * Avoid the bad case where the loop only runs once by handling the
+	 * special case separately. This doesn't trigger the bug because it
+	 * doesn't involve pointer/integer overflow.
+	 */
+	if (length <= 8)
+		return ZSTD_copy8(dst, src);
+	do {
+		ZSTD_copy8(op, ip);
+		op += 8;
+		ip += 8;
+	} while (op < oend);
+}
+
+/*-*******************************************
+*  Private interfaces
+*********************************************/
+typedef struct ZSTD_stats_s ZSTD_stats_t;
+
+typedef struct {
+	U32 off;
+	U32 len;
+} ZSTD_match_t;
+
+typedef struct {
+	U32 price;
+	U32 off;
+	U32 mlen;
+	U32 litlen;
+	U32 rep[ZSTD_REP_NUM];
+} ZSTD_optimal_t;
+
+typedef struct seqDef_s {
+	U32 offset;
+	U16 litLength;
+	U16 matchLength;
+} seqDef;
+
+typedef struct {
+	seqDef *sequencesStart;
+	seqDef *sequences;
+	BYTE *litStart;
+	BYTE *lit;
+	BYTE *llCode;
+	BYTE *mlCode;
+	BYTE *ofCode;
+	U32 longLengthID; /* 0 == no longLength; 1 == Lit.longLength; 2 == Match.longLength; */
+	U32 longLengthPos;
+	/* opt */
+	ZSTD_optimal_t *priceTable;
+	ZSTD_match_t *matchTable;
+	U32 *matchLengthFreq;
+	U32 *litLengthFreq;
+	U32 *litFreq;
+	U32 *offCodeFreq;
+	U32 matchLengthSum;
+	U32 matchSum;
+	U32 litLengthSum;
+	U32 litSum;
+	U32 offCodeSum;
+	U32 log2matchLengthSum;
+	U32 log2matchSum;
+	U32 log2litLengthSum;
+	U32 log2litSum;
+	U32 log2offCodeSum;
+	U32 factor;
+	U32 staticPrices;
+	U32 cachedPrice;
+	U32 cachedLitLength;
+	const BYTE *cachedLiterals;
+} seqStore_t;
+
+const seqStore_t *ZSTD_getSeqStore(const ZSTD_CCtx *ctx);
+void ZSTD_seqToCodes(const seqStore_t *seqStorePtr);
+int ZSTD_isSkipFrame(ZSTD_DCtx *dctx);
+
+/*= Custom memory allocation functions */
+typedef void *(*ZSTD_allocFunction)(void *opaque, size_t size);
+typedef void (*ZSTD_freeFunction)(void *opaque, void *address);
+typedef struct {
+	ZSTD_allocFunction customAlloc;
+	ZSTD_freeFunction customFree;
+	void *opaque;
+} ZSTD_customMem;
+
+void *ZSTD_malloc(size_t size, ZSTD_customMem customMem);
+void ZSTD_free(void *ptr, ZSTD_customMem customMem);
+
+/*====== stack allocation  ======*/
+
+typedef struct {
+	void *ptr;
+	const void *end;
+} ZSTD_stack;
+
+#define ZSTD_ALIGN(x) ALIGN(x, sizeof(size_t))
+#define ZSTD_PTR_ALIGN(p) PTR_ALIGN(p, sizeof(size_t))
+
+ZSTD_customMem ZSTD_initStack(void *workspace, size_t workspaceSize);
+
+void *ZSTD_stackAllocAll(void *opaque, size_t *size);
+void *ZSTD_stackAlloc(void *opaque, size_t size);
+void ZSTD_stackFree(void *opaque, void *address);
+
+/*======  common function  ======*/
+
+ZSTD_STATIC U32 ZSTD_highbit32(U32 val) { return 31 - __builtin_clz(val); }
+
+/* hidden functions */
+
+/* ZSTD_invalidateRepCodes() :
+ * ensures next compression will not use repcodes from previous block.
+ * Note : only works with regular variant;
+ *        do not use with extDict variant ! */
+void ZSTD_invalidateRepCodes(ZSTD_CCtx *cctx);
+
+size_t ZSTD_freeCCtx(ZSTD_CCtx *cctx);
+size_t ZSTD_freeDCtx(ZSTD_DCtx *dctx);
+size_t ZSTD_freeCDict(ZSTD_CDict *cdict);
+size_t ZSTD_freeDDict(ZSTD_DDict *cdict);
+size_t ZSTD_freeCStream(ZSTD_CStream *zcs);
+size_t ZSTD_freeDStream(ZSTD_DStream *zds);
+
+#endif /* ZSTD_CCOMMON_H_MODULE */