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author | Dr. David Alan Gilbert <dgilbert@redhat.com> | 2014-12-12 11:13:38 +0000 |
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committer | Amit Shah <amit.shah@redhat.com> | 2014-12-16 17:47:36 +0530 |
commit | 60fe637bf0e4d7989e21e50f52526444765c63b4 (patch) | |
tree | b5dbcea1d25fe151e097cc1401cb19b64262401c /migration/xbzrle.c | |
parent | d6d69731f5295e4c3bb0196f57e8848af28b705e (diff) | |
download | qemu-60fe637bf0e4d7989e21e50f52526444765c63b4.zip qemu-60fe637bf0e4d7989e21e50f52526444765c63b4.tar.gz qemu-60fe637bf0e4d7989e21e50f52526444765c63b4.tar.bz2 |
Start migrating migration code into a migration directory
The migration code now occupies a fair chunk of the top level .c
files, it seems time to give it it's own directory.
I've not touched:
arch_init.c - that's mostly RAM migration but has a few random other
bits
savevm.c - because it's built target specific
This is purely a code move; no code has changed.
- it fails checkpatch because of old violations, it feels safer
to keep this as purely a move and fix those at some mythical future
date.
The xbzrle and vmstate tests are now only run for softmmu builds
since they require files in the migrate/ directory which is only built
for softmmu.
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Diffstat (limited to 'migration/xbzrle.c')
-rw-r--r-- | migration/xbzrle.c | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/migration/xbzrle.c b/migration/xbzrle.c new file mode 100644 index 0000000..8e220bf --- /dev/null +++ b/migration/xbzrle.c @@ -0,0 +1,175 @@ +/* + * 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; + 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 */ + unsigned long mask = (unsigned long)0x0101010101010101ULL; + while (i < slen) { + unsigned long xor; + xor = *(unsigned long *)(old_buf + i) + ^ *(unsigned 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; +} |