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linux/lib/lz4/lz4hc_compress.c

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/*
* LZ4 HC - High Compression Mode of LZ4
* Copyright (C) 2011-2012, 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.
*
* You can contact the author at :
* - LZ4 homepage : http://fastcompression.blogspot.com/p/lz4.html
* - LZ4 source repository : http://code.google.com/p/lz4/
*
* Changed for kernel use by:
* Chanho Min <chanho.min@lge.com>
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/lz4.h>
#include <asm/unaligned.h>
#include "lz4defs.h"
struct lz4hc_data {
const u8 *base;
HTYPE hashtable[HASHTABLESIZE];
u16 chaintable[MAXD];
const u8 *nexttoupdate;
} __attribute__((__packed__));
static inline int lz4hc_init(struct lz4hc_data *hc4, const u8 *base)
{
memset((void *)hc4->hashtable, 0, sizeof(hc4->hashtable));
memset(hc4->chaintable, 0xFF, sizeof(hc4->chaintable));
#if LZ4_ARCH64
hc4->nexttoupdate = base + 1;
#else
hc4->nexttoupdate = base;
#endif
hc4->base = base;
return 1;
}
/* Update chains up to ip (excluded) */
static inline void lz4hc_insert(struct lz4hc_data *hc4, const u8 *ip)
{
u16 *chaintable = hc4->chaintable;
HTYPE *hashtable = hc4->hashtable;
#if LZ4_ARCH64
const BYTE * const base = hc4->base;
#else
const int base = 0;
#endif
while (hc4->nexttoupdate < ip) {
const u8 *p = hc4->nexttoupdate;
size_t delta = p - (hashtable[HASH_VALUE(p)] + base);
if (delta > MAX_DISTANCE)
delta = MAX_DISTANCE;
chaintable[(size_t)(p) & MAXD_MASK] = (u16)delta;
hashtable[HASH_VALUE(p)] = (p) - base;
hc4->nexttoupdate++;
}
}
static inline size_t lz4hc_commonlength(const u8 *p1, const u8 *p2,
const u8 *const matchlimit)
{
const u8 *p1t = p1;
while (p1t < matchlimit - (STEPSIZE - 1)) {
#if LZ4_ARCH64
u64 diff = A64(p2) ^ A64(p1t);
#else
u32 diff = A32(p2) ^ A32(p1t);
#endif
if (!diff) {
p1t += STEPSIZE;
p2 += STEPSIZE;
continue;
}
p1t += LZ4_NBCOMMONBYTES(diff);
return p1t - p1;
}
#if LZ4_ARCH64
if ((p1t < (matchlimit-3)) && (A32(p2) == A32(p1t))) {
p1t += 4;
p2 += 4;
}
#endif
if ((p1t < (matchlimit - 1)) && (A16(p2) == A16(p1t))) {
p1t += 2;
p2 += 2;
}
if ((p1t < matchlimit) && (*p2 == *p1t))
p1t++;
return p1t - p1;
}
static inline int lz4hc_insertandfindbestmatch(struct lz4hc_data *hc4,
const u8 *ip, const u8 *const matchlimit, const u8 **matchpos)
{
u16 *const chaintable = hc4->chaintable;
HTYPE *const hashtable = hc4->hashtable;
const u8 *ref;
#if LZ4_ARCH64
const BYTE * const base = hc4->base;
#else
const int base = 0;
#endif
int nbattempts = MAX_NB_ATTEMPTS;
size_t repl = 0, ml = 0;
u16 delta;
/* HC4 match finder */
lz4hc_insert(hc4, ip);
ref = hashtable[HASH_VALUE(ip)] + base;
/* potential repetition */
if (ref >= ip-4) {
/* confirmed */
if (A32(ref) == A32(ip)) {
delta = (u16)(ip-ref);
repl = ml = lz4hc_commonlength(ip + MINMATCH,
ref + MINMATCH, matchlimit) + MINMATCH;
*matchpos = ref;
}
ref -= (size_t)chaintable[(size_t)(ref) & MAXD_MASK];
}
while ((ref >= ip - MAX_DISTANCE) && nbattempts) {
nbattempts--;
if (*(ref + ml) == *(ip + ml)) {
if (A32(ref) == A32(ip)) {
size_t mlt =
lz4hc_commonlength(ip + MINMATCH,
ref + MINMATCH, matchlimit) + MINMATCH;
if (mlt > ml) {
ml = mlt;
*matchpos = ref;
}
}
}
ref -= (size_t)chaintable[(size_t)(ref) & MAXD_MASK];
}
/* Complete table */
if (repl) {
const BYTE *ptr = ip;
const BYTE *end;
end = ip + repl - (MINMATCH-1);
/* Pre-Load */
while (ptr < end - delta) {
chaintable[(size_t)(ptr) & MAXD_MASK] = delta;
ptr++;
}
do {
chaintable[(size_t)(ptr) & MAXD_MASK] = delta;
/* Head of chain */
hashtable[HASH_VALUE(ptr)] = (ptr) - base;
ptr++;
} while (ptr < end);
hc4->nexttoupdate = end;
}
return (int)ml;
}
static inline int lz4hc_insertandgetwidermatch(struct lz4hc_data *hc4,
const u8 *ip, const u8 *startlimit, const u8 *matchlimit, int longest,
const u8 **matchpos, const u8 **startpos)
{
u16 *const chaintable = hc4->chaintable;
HTYPE *const hashtable = hc4->hashtable;
#if LZ4_ARCH64
const BYTE * const base = hc4->base;
#else
const int base = 0;
#endif
const u8 *ref;
int nbattempts = MAX_NB_ATTEMPTS;
int delta = (int)(ip - startlimit);
/* First Match */
lz4hc_insert(hc4, ip);
ref = hashtable[HASH_VALUE(ip)] + base;
while ((ref >= ip - MAX_DISTANCE) && (ref >= hc4->base)
&& (nbattempts)) {
nbattempts--;
if (*(startlimit + longest) == *(ref - delta + longest)) {
if (A32(ref) == A32(ip)) {
const u8 *reft = ref + MINMATCH;
const u8 *ipt = ip + MINMATCH;
const u8 *startt = ip;
while (ipt < matchlimit-(STEPSIZE - 1)) {
#if LZ4_ARCH64
u64 diff = A64(reft) ^ A64(ipt);
#else
u32 diff = A32(reft) ^ A32(ipt);
#endif
if (!diff) {
ipt += STEPSIZE;
reft += STEPSIZE;
continue;
}
ipt += LZ4_NBCOMMONBYTES(diff);
goto _endcount;
}
#if LZ4_ARCH64
if ((ipt < (matchlimit - 3))
&& (A32(reft) == A32(ipt))) {
ipt += 4;
reft += 4;
}
ipt += 2;
#endif
if ((ipt < (matchlimit - 1))
&& (A16(reft) == A16(ipt))) {
reft += 2;
}
if ((ipt < matchlimit) && (*reft == *ipt))
ipt++;
_endcount:
reft = ref;
while ((startt > startlimit)
&& (reft > hc4->base)
&& (startt[-1] == reft[-1])) {
startt--;
reft--;
}
if ((ipt - startt) > longest) {
longest = (int)(ipt - startt);
*matchpos = reft;
*startpos = startt;
}
}
}
ref -= (size_t)chaintable[(size_t)(ref) & MAXD_MASK];
}
return longest;
}
static inline int lz4_encodesequence(const u8 **ip, u8 **op, const u8 **anchor,
int ml, const u8 *ref)
{
int length, len;
u8 *token;
/* Encode Literal length */
length = (int)(*ip - *anchor);
token = (*op)++;
if (length >= (int)RUN_MASK) {
*token = (RUN_MASK << ML_BITS);
len = length - RUN_MASK;
for (; len > 254 ; len -= 255)
*(*op)++ = 255;
*(*op)++ = (u8)len;
} else
*token = (length << ML_BITS);
/* Copy Literals */
LZ4_BLINDCOPY(*anchor, *op, length);
/* Encode Offset */
LZ4_WRITE_LITTLEENDIAN_16(*op, (u16)(*ip - ref));
/* Encode MatchLength */
len = (int)(ml - MINMATCH);
if (len >= (int)ML_MASK) {
*token += ML_MASK;
len -= ML_MASK;
for (; len > 509 ; len -= 510) {
*(*op)++ = 255;
*(*op)++ = 255;
}
if (len > 254) {
len -= 255;
*(*op)++ = 255;
}
*(*op)++ = (u8)len;
} else
*token += len;
/* Prepare next loop */
*ip += ml;
*anchor = *ip;
return 0;
}
static int lz4_compresshcctx(struct lz4hc_data *ctx,
const char *source,
char *dest,
int isize)
{
const u8 *ip = (const u8 *)source;
const u8 *anchor = ip;
const u8 *const iend = ip + isize;
const u8 *const mflimit = iend - MFLIMIT;
const u8 *const matchlimit = (iend - LASTLITERALS);
u8 *op = (u8 *)dest;
int ml, ml2, ml3, ml0;
const u8 *ref = NULL;
const u8 *start2 = NULL;
const u8 *ref2 = NULL;
const u8 *start3 = NULL;
const u8 *ref3 = NULL;
const u8 *start0;
const u8 *ref0;
int lastrun;
ip++;
/* Main Loop */
while (ip < mflimit) {
ml = lz4hc_insertandfindbestmatch(ctx, ip, matchlimit, (&ref));
if (!ml) {
ip++;
continue;
}
/* saved, in case we would skip too much */
start0 = ip;
ref0 = ref;
ml0 = ml;
_search2:
if (ip+ml < mflimit)
ml2 = lz4hc_insertandgetwidermatch(ctx, ip + ml - 2,
ip + 1, matchlimit, ml, &ref2, &start2);
else
ml2 = ml;
/* No better match */
if (ml2 == ml) {
lz4_encodesequence(&ip, &op, &anchor, ml, ref);
continue;
}
if (start0 < ip) {
/* empirical */
if (start2 < ip + ml0) {
ip = start0;
ref = ref0;
ml = ml0;
}
}
/*
* Here, start0==ip
* First Match too small : removed
*/
if ((start2 - ip) < 3) {
ml = ml2;
ip = start2;
ref = ref2;
goto _search2;
}
_search3:
/*
* Currently we have :
* ml2 > ml1, and
* ip1+3 <= ip2 (usually < ip1+ml1)
*/
if ((start2 - ip) < OPTIMAL_ML) {
int correction;
int new_ml = ml;
if (new_ml > OPTIMAL_ML)
new_ml = OPTIMAL_ML;
if (ip + new_ml > start2 + ml2 - MINMATCH)
new_ml = (int)(start2 - ip) + ml2 - MINMATCH;
correction = new_ml - (int)(start2 - ip);
if (correction > 0) {
start2 += correction;
ref2 += correction;
ml2 -= correction;
}
}
/*
* Now, we have start2 = ip+new_ml,
* with new_ml=min(ml, OPTIMAL_ML=18)
*/
if (start2 + ml2 < mflimit)
ml3 = lz4hc_insertandgetwidermatch(ctx,
start2 + ml2 - 3, start2, matchlimit,
ml2, &ref3, &start3);
else
ml3 = ml2;
/* No better match : 2 sequences to encode */
if (ml3 == ml2) {
/* ip & ref are known; Now for ml */
if (start2 < ip+ml)
ml = (int)(start2 - ip);
/* Now, encode 2 sequences */
lz4_encodesequence(&ip, &op, &anchor, ml, ref);
ip = start2;
lz4_encodesequence(&ip, &op, &anchor, ml2, ref2);
continue;
}
/* Not enough space for match 2 : remove it */
if (start3 < ip + ml + 3) {
/*
* can write Seq1 immediately ==> Seq2 is removed,
* so Seq3 becomes Seq1
*/
if (start3 >= (ip + ml)) {
if (start2 < ip + ml) {
int correction =
(int)(ip + ml - start2);
start2 += correction;
ref2 += correction;
ml2 -= correction;
if (ml2 < MINMATCH) {
start2 = start3;
ref2 = ref3;
ml2 = ml3;
}
}
lz4_encodesequence(&ip, &op, &anchor, ml, ref);
ip = start3;
ref = ref3;
ml = ml3;
start0 = start2;
ref0 = ref2;
ml0 = ml2;
goto _search2;
}
start2 = start3;
ref2 = ref3;
ml2 = ml3;
goto _search3;
}
/*
* OK, now we have 3 ascending matches; let's write at least
* the first one ip & ref are known; Now for ml
*/
if (start2 < ip + ml) {
if ((start2 - ip) < (int)ML_MASK) {
int correction;
if (ml > OPTIMAL_ML)
ml = OPTIMAL_ML;
if (ip + ml > start2 + ml2 - MINMATCH)
ml = (int)(start2 - ip) + ml2
- MINMATCH;
correction = ml - (int)(start2 - ip);
if (correction > 0) {
start2 += correction;
ref2 += correction;
ml2 -= correction;
}
} else
ml = (int)(start2 - ip);
}
lz4_encodesequence(&ip, &op, &anchor, ml, ref);
ip = start2;
ref = ref2;
ml = ml2;
start2 = start3;
ref2 = ref3;
ml2 = ml3;
goto _search3;
}
/* Encode Last Literals */
lastrun = (int)(iend - anchor);
if (lastrun >= (int)RUN_MASK) {
*op++ = (RUN_MASK << ML_BITS);
lastrun -= RUN_MASK;
for (; lastrun > 254 ; lastrun -= 255)
*op++ = 255;
*op++ = (u8) lastrun;
} else
*op++ = (lastrun << ML_BITS);
memcpy(op, anchor, iend - anchor);
op += iend - anchor;
/* End */
return (int) (((char *)op) - dest);
}
int lz4hc_compress(const unsigned char *src, size_t src_len,
unsigned char *dst, size_t *dst_len, void *wrkmem)
{
int ret = -1;
int out_len = 0;
struct lz4hc_data *hc4 = (struct lz4hc_data *)wrkmem;
lz4hc_init(hc4, (const u8 *)src);
out_len = lz4_compresshcctx((struct lz4hc_data *)hc4, (const u8 *)src,
(char *)dst, (int)src_len);
if (out_len < 0)
goto exit;
*dst_len = out_len;
return 0;
exit:
return ret;
}
EXPORT_SYMBOL(lz4hc_compress);
MODULE_LICENSE("Dual BSD/GPL");
MODULE_DESCRIPTION("LZ4HC compressor");
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