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Move XBZRLE encoding code to a separate file to allow testing 

Signed-off-by: Orit Wasserman <owasserm@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
This commit is contained in:
Orit Wasserman 2013-01-31 09:12:15 +02:00 committed by Juan Quintela
parent 8a55ebf015
commit ba2e28e8a2
3 changed files with 174 additions and 160 deletions
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2
Makefile.objs
View File

@ -59,7 +59,7 @@ common-obj-$(CONFIG_LINUX) += fsdev/
common-obj-y += migration.o migration-tcp.o
common-obj-y += qemu-char.o #aio.o
common-obj-y += block-migration.o
common-obj-y += page_cache.o
common-obj-y += page_cache.o xbzrle.o
common-obj-$(CONFIG_POSIX) += migration-exec.o migration-unix.o migration-fd.o

159
savevm.c
View File

@ -2388,162 +2388,3 @@ void vmstate_register_ram_global(MemoryRegion *mr)
{
vmstate_register_ram(mr, NULL);
}
/*
page = zrun nzrun
| zrun nzrun page
zrun = length
nzrun = length byte...
length = uleb128 encoded integer
*/
int xbzrle_encode_buffer(uint8_t *old_buf, uint8_t *new_buf, int slen,
uint8_t *dst, int dlen)
{
uint32_t zrun_len = 0, nzrun_len = 0;
int d = 0, i = 0;
long res, xor;
uint8_t *nzrun_start = NULL;
g_assert(!(((uintptr_t)old_buf | (uintptr_t)new_buf | slen) %
sizeof(long)));
while (i < slen) {
/* overflow */
if (d + 2 > dlen) {
return -1;
}
/* not aligned to sizeof(long) */
res = (slen - i) % sizeof(long);
while (res && old_buf[i] == new_buf[i]) {
zrun_len++;
i++;
res--;
}
/* word at a time for speed */
if (!res) {
while (i < slen &&
(*(long *)(old_buf + i)) == (*(long *)(new_buf + i))) {
i += sizeof(long);
zrun_len += sizeof(long);
}
/* go over the rest */
while (i < slen && old_buf[i] == new_buf[i]) {
zrun_len++;
i++;
}
}
/* buffer unchanged */
if (zrun_len == slen) {
return 0;
}
/* skip last zero run */
if (i == slen) {
return d;
}
d += uleb128_encode_small(dst + d, zrun_len);
zrun_len = 0;
nzrun_start = new_buf + i;
/* overflow */
if (d + 2 > dlen) {
return -1;
}
/* not aligned to sizeof(long) */
res = (slen - i) % sizeof(long);
while (res && old_buf[i] != new_buf[i]) {
i++;
nzrun_len++;
res--;
}
/* word at a time for speed, use of 32-bit long okay */
if (!res) {
/* truncation to 32-bit long okay */
long mask = (long)0x0101010101010101ULL;
while (i < slen) {
xor = *(long *)(old_buf + i) ^ *(long *)(new_buf + i);
if ((xor - mask) & ~xor & (mask << 7)) {
/* found the end of an nzrun within the current long */
while (old_buf[i] != new_buf[i]) {
nzrun_len++;
i++;
}
break;
} else {
i += sizeof(long);
nzrun_len += sizeof(long);
}
}
}
d += uleb128_encode_small(dst + d, nzrun_len);
/* overflow */
if (d + nzrun_len > dlen) {
return -1;
}
memcpy(dst + d, nzrun_start, nzrun_len);
d += nzrun_len;
nzrun_len = 0;
}
return d;
}
int xbzrle_decode_buffer(uint8_t *src, int slen, uint8_t *dst, int dlen)
{
int i = 0, d = 0;
int ret;
uint32_t count = 0;
while (i < slen) {
/* zrun */
if ((slen - i) < 2) {
return -1;
}
ret = uleb128_decode_small(src + i, &count);
if (ret < 0 || (i && !count)) {
return -1;
}
i += ret;
d += count;
/* overflow */
if (d > dlen) {
return -1;
}
/* nzrun */
if ((slen - i) < 2) {
return -1;
}
ret = uleb128_decode_small(src + i, &count);
if (ret < 0 || !count) {
return -1;
}
i += ret;
/* overflow */
if (d + count > dlen || i + count > slen) {
return -1;
}
memcpy(dst + d, src + i, count);
d += count;
i += count;
}
return d;
}

173
xbzrle.c Normal file
View File

@ -0,0 +1,173 @@
/*
* Xor Based Zero Run Length Encoding
*
* Copyright 2013 Red Hat, Inc. and/or its affiliates
*
* Authors:
* Orit Wasserman <owasserm@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*
*/
#include "qemu-common.h"
#include "include/migration/migration.h"
/*
page = zrun nzrun
| zrun nzrun page
zrun = length
nzrun = length byte...
length = uleb128 encoded integer
*/
int xbzrle_encode_buffer(uint8_t *old_buf, uint8_t *new_buf, int slen,
uint8_t *dst, int dlen)
{
uint32_t zrun_len = 0, nzrun_len = 0;
int d = 0, i = 0;
long res, xor;
uint8_t *nzrun_start = NULL;
g_assert(!(((uintptr_t)old_buf | (uintptr_t)new_buf | slen) %
sizeof(long)));
while (i < slen) {
/* overflow */
if (d + 2 > dlen) {
return -1;
}
/* not aligned to sizeof(long) */
res = (slen - i) % sizeof(long);
while (res && old_buf[i] == new_buf[i]) {
zrun_len++;
i++;
res--;
}
/* word at a time for speed */
if (!res) {
while (i < slen &&
(*(long *)(old_buf + i)) == (*(long *)(new_buf + i))) {
i += sizeof(long);
zrun_len += sizeof(long);
}
/* go over the rest */
while (i < slen && old_buf[i] == new_buf[i]) {
zrun_len++;
i++;
}
}
/* buffer unchanged */
if (zrun_len == slen) {
return 0;
}
/* skip last zero run */
if (i == slen) {
return d;
}
d += uleb128_encode_small(dst + d, zrun_len);
zrun_len = 0;
nzrun_start = new_buf + i;
/* overflow */
if (d + 2 > dlen) {
return -1;
}
/* not aligned to sizeof(long) */
res = (slen - i) % sizeof(long);
while (res && old_buf[i] != new_buf[i]) {
i++;
nzrun_len++;
res--;
}
/* word at a time for speed, use of 32-bit long okay */
if (!res) {
/* truncation to 32-bit long okay */
long mask = (long)0x0101010101010101ULL;
while (i < slen) {
xor = *(long *)(old_buf + i) ^ *(long *)(new_buf + i);
if ((xor - mask) & ~xor & (mask << 7)) {
/* found the end of an nzrun within the current long */
while (old_buf[i] != new_buf[i]) {
nzrun_len++;
i++;
}
break;
} else {
i += sizeof(long);
nzrun_len += sizeof(long);
}
}
}
d += uleb128_encode_small(dst + d, nzrun_len);
/* overflow */
if (d + nzrun_len > dlen) {
return -1;
}
memcpy(dst + d, nzrun_start, nzrun_len);
d += nzrun_len;
nzrun_len = 0;
}
return d;
}
int xbzrle_decode_buffer(uint8_t *src, int slen, uint8_t *dst, int dlen)
{
int i = 0, d = 0;
int ret;
uint32_t count = 0;
while (i < slen) {
/* zrun */
if ((slen - i) < 2) {
return -1;
}
ret = uleb128_decode_small(src + i, &count);
if (ret < 0 || (i && !count)) {
return -1;
}
i += ret;
d += count;
/* overflow */
if (d > dlen) {
return -1;
}
/* nzrun */
if ((slen - i) < 2) {
return -1;
}
ret = uleb128_decode_small(src + i, &count);
if (ret < 0 || !count) {
return -1;
}
i += ret;
/* overflow */
if (d + count > dlen || i + count > slen) {
return -1;
}
memcpy(dst + d, src + i, count);
d += count;
i += count;
}
return d;
}