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[Qemu-devel] [PATCH v15 6/9] Add xbzrle_encode_buffer and xbzrle_decode_
From: |
Orit Wasserman |
Subject: |
[Qemu-devel] [PATCH v15 6/9] Add xbzrle_encode_buffer and xbzrle_decode_buffer functions |
Date: |
Thu, 5 Jul 2012 15:51:46 +0300 |
Signed-off-by: Benoit Hudzia <address@hidden>
Signed-off-by: Petter Svard <address@hidden>
Signed-off-by: Aidan Shribman <address@hidden>
Signed-off-by: Orit Wasserman <address@hidden>
---
migration.h | 4 ++
savevm.c | 157 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 161 insertions(+), 0 deletions(-)
diff --git a/migration.h b/migration.h
index acc0b94..c46af82 100644
--- a/migration.h
+++ b/migration.h
@@ -100,4 +100,8 @@ void migrate_add_blocker(Error *reason);
*/
void migrate_del_blocker(Error *reason);
+int xbzrle_encode_buffer(uint8_t *old_buf, uint8_t *new_buf, int slen,
+ uint8_t *dst, int dlen);
+int xbzrle_decode_buffer(uint8_t *src, int slen, uint8_t *dst, int dlen);
+
#endif
diff --git a/savevm.c b/savevm.c
index a15c163..1534cbd 100644
--- a/savevm.c
+++ b/savevm.c
@@ -2385,3 +2385,160 @@ 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--;
+ }
+
+ 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--;
+ }
+
+ if (!res) {
+ /* truncation to 32-bit long okay */
+ long mask = 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;
+}
--
1.7.7.6
- [Qemu-devel] [PATCH v15 0/9] XBZRLE delta for live migration of large memory app, Orit Wasserman, 2012/07/05
- [Qemu-devel] [PATCH v15 1/9] Add migration capabilities, Orit Wasserman, 2012/07/05
- [Qemu-devel] [PATCH v15 4/9] Add uleb encoding/decoding functions, Orit Wasserman, 2012/07/05
- [Qemu-devel] [PATCH v15 5/9] Change ram_save_block to return -1 if there are no more changes, Orit Wasserman, 2012/07/05
- [Qemu-devel] [PATCH v15 6/9] Add xbzrle_encode_buffer and xbzrle_decode_buffer functions,
Orit Wasserman <=
- [Qemu-devel] [PATCH v15 3/9] Add cache handling functions, Orit Wasserman, 2012/07/05
- [Qemu-devel] [PATCH v15 2/9] Add XBZRLE documentation, Orit Wasserman, 2012/07/05
- [Qemu-devel] [PATCH v15 7/9] Add XBZRLE to ram_save_block and ram_save_live, Orit Wasserman, 2012/07/05
- [Qemu-devel] [PATCH v15 8/9] Add set_cachesize command, Orit Wasserman, 2012/07/05