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Move XBZRLE encoding code to a separate file to allow testing
Signed-off-by: Orit Wasserman <[email protected]> Reviewed-by: Paolo Bonzini <[email protected]> Signed-off-by: Juan Quintela <[email protected]> Reviewed-by: Eric Blake <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,173 @@ | ||
| /* | ||
| * Xor Based Zero Run Length Encoding | ||
| * | ||
| * Copyright 2013 Red Hat, Inc. and/or its affiliates | ||
| * | ||
| * Authors: | ||
| * Orit Wasserman <[email protected]> | ||
| * | ||
| * 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; | ||
| } |