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[Qemu-devel] [PATCH v14 10/13] Add xbzrle_encode_buffer and xbzrle_decod
From: |
Orit Wasserman |
Subject: |
[Qemu-devel] [PATCH v14 10/13] Add xbzrle_encode_buffer and xbzrle_decode_buffer functions |
Date: |
Tue, 3 Jul 2012 16:52:51 +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 | 172 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 176 insertions(+), 0 deletions(-)
diff --git a/migration.h b/migration.h
index 1ae99f1..7582ecb 100644
--- a/migration.h
+++ b/migration.h
@@ -99,4 +99,8 @@ 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 d1d9020..2ab0986 100644
--- a/savevm.c
+++ b/savevm.c
@@ -2374,3 +2374,175 @@ 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, start;
+ long res, xor;
+ uint8_t *nzrun_start = NULL;
+
+ g_assert(!((uintptr_t)old_buf & (sizeof(long) - 1)) &&
+ !((uintptr_t)new_buf & (sizeof(long) - 1)) &&
+ !(slen & (sizeof(long) - 1)));
+
+ while (i < slen) {
+ /* overflow */
+ if (d + 2 > dlen) {
+ return -1;
+ }
+
+ /* not aligned to sizeof(long) */
+ res = (slen - i) % sizeof(long);
+ if (res) {
+ start = i;
+ while (!(old_buf[i] ^ new_buf[i]) && (i - start) <= res) {
+ zrun_len++;
+ i++;
+ }
+ }
+
+ if (zrun_len == res) {
+ while (i <= (slen - sizeof(long)) &&
+ (*(long *)(old_buf + i)) == (*(long *)(new_buf + i))) {
+ i += sizeof(long);
+ zrun_len += sizeof(long);
+ }
+
+ /* go over the rest */
+ while (old_buf[i] == new_buf[i] && ++i <= slen) {
+ zrun_len++;
+ }
+ }
+
+ /* buffer unchanged */
+ if (zrun_len == slen) {
+ return 0;
+ }
+
+ /* skip last zero run */
+ if (i == slen + 1) {
+ return d;
+ }
+
+ d += uleb128_encode_small(dst + d, zrun_len);
+
+ /* no nzrun */
+ if (i == slen) {
+ return d;
+ }
+
+ zrun_len = 0;
+ nzrun_start = new_buf + i;
+
+ /* not aligned to sizeof(long) */
+ res = (slen - i) % sizeof(long);
+ if (res) {
+ start = i;
+ while (old_buf[i] != new_buf[i] && i - start < res) {
+ i++;
+ nzrun_len++;
+ }
+ }
+
+ if (nzrun_len == res) {
+ /* truncation to 32-bit long okay */
+ long mask = 0x0101010101010101ULL;
+ xor = *(long *)(old_buf + i) ^ *(long *)(new_buf + i);
+ printf("cont\n");
+ while (i <= (slen - sizeof(long))) {
+ if ((xor - mask) & ~xor & (mask << 7)) {
+ /* found the end of an nzrun within the current long */
+ while (old_buf[i] != new_buf[i] && ++i <= slen) {
+ nzrun_len++;
+ }
+ break;
+ } else {
+ i += sizeof(long);
+ nzrun_len += sizeof(long);
+ xor = *(long *)(old_buf + i) ^ *(long *)(new_buf + i);
+ }
+ }
+
+ while (old_buf[i] != new_buf[i] && ++i <= slen) {
+ nzrun_len++;
+ }
+ }
+
+ /* overflow */
+ if (d + nzrun_len + 2 > dlen) {
+ return -1;
+ }
+
+ d += uleb128_encode_small(dst + d, nzrun_len);
+ 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 && *(src + i) & 0x80) {
+ return -1;
+ }
+
+ ret = uleb128_decode_small(src + i, &count);
+ if (ret < 0) {
+ return -1;
+ }
+ i += ret;
+ d += count;
+
+ /* overflow */
+ if (d > dlen) {
+ return -1;
+ }
+
+ /* completed decoding */
+ if (i == slen - 1) {
+ return d;
+ }
+
+ /* nzrun */
+ if ((slen - i) < 2 && *(src + i) & 0x80) {
+ return -1;
+ }
+ ret = uleb128_decode_small(src + i, &count);
+ if (ret < 0) {
+ return -1;
+ }
+ i += ret;
+
+ /* overflow */
+ if (d + count > dlen) {
+ return -1;
+ }
+
+ memcpy(dst + d , src + i, count);
+ d += count;
+ i += count;
+ }
+
+ return d;
+}
--
1.7.7.6
- Re: [Qemu-devel] [PATCH v14 07/13] Add debugging infrastructure, (continued)
- [Qemu-devel] [PATCH v14 06/13] Add save_block_hdr function, Orit Wasserman, 2012/07/03
- [Qemu-devel] [PATCH v14 01/13] Add MigrationParams structure, Orit Wasserman, 2012/07/03
- [Qemu-devel] [PATCH v14 08/13] Change ram_save_block to return -1 if there are no more changes, Orit Wasserman, 2012/07/03
- [Qemu-devel] [PATCH v14 04/13] Add cache handling functions, Orit Wasserman, 2012/07/03
- Re: [Qemu-devel] [PATCH v14 04/13] Add cache handling functions, Eric Blake, 2012/07/03
- [Qemu-devel] [PATCH v14 10/13] Add xbzrle_encode_buffer and xbzrle_decode_buffer functions,
Orit Wasserman <=
- Re: [Qemu-devel] [PATCH v14 10/13] Add xbzrle_encode_buffer and xbzrle_decode_buffer functions, Orit Wasserman, 2012/07/04
- Re: [Qemu-devel] [PATCH v14 10/13] Add xbzrle_encode_buffer and xbzrle_decode_buffer functions, Eric Blake, 2012/07/04
[Qemu-devel] [PATCH v14 05/13] Add uleb encoding/decoding functions, Orit Wasserman, 2012/07/03
[Qemu-devel] [PATCH v14 11/13] Add XBZRLE to ram_save_block and ram_save_live, Orit Wasserman, 2012/07/03
[Qemu-devel] [PATCH v14 02/13] Add migration capabilities, Orit Wasserman, 2012/07/03