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Try beginning and end of match

dev
Sen Huang 2021-09-23 07:08:56 -07:00
parent b8fd6bf30c
commit ccdcbf4621
1 changed files with 18 additions and 3 deletions
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21
lib/compress/zstd_lazy.c
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@ -1025,14 +1025,29 @@ FORCE_INLINE_TEMPLATE void ZSTD_row_update_internal(ZSTD_matchState_t* ms, const
U32 idx = ms->nextToUpdate;
const BYTE* const base = ms->window.base;
const U32 target = (U32)(ip - base);
const U32 kMaxPositionsToUpdate = 256;
const U32 kMaxPositionsToUpdate = 128;
assert(target >= idx);
if (useCache) {
/* Only skip positions when using hash cache, i.e.
if we are loading a dict, don't skip anything */
* if we are loading a dict, don't skip anything.
*/
if (UNLIKELY(target - idx > kMaxPositionsToUpdate)) {
idx = target - kMaxPositionsToUpdate;
U32 const bound = idx + 3*kMaxPositionsToUpdate/4;
for (; idx < bound; ++idx) {
U32 const hash = useCache ? ZSTD_row_nextCachedHash(ms->hashCache, hashTable, tagTable, base, idx, hashLog, rowLog, mls)
: (U32)ZSTD_hashPtr(base + idx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls);
U32 const relRow = (hash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog;
U32* const row = hashTable + relRow;
BYTE* tagRow = (BYTE*)(tagTable + relRow); /* Though tagTable is laid out as a table of U16, each tag is only 1 byte.
Explicit cast allows us to get exact desired position within each row */
U32 const pos = ZSTD_row_nextIndex(tagRow, rowMask);
assert(hash == ZSTD_hashPtr(base + idx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls));
tagRow[pos + ZSTD_ROW_HASH_TAG_OFFSET] = hash & ZSTD_ROW_HASH_TAG_MASK;
row[pos] = idx;
}
idx = target - kMaxPositionsToUpdate/4;
ZSTD_row_fillHashCache(ms, base, rowLog, mls, idx, ip+1);
}
}