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Merge pull request #1057 from facebook/lrmSettings

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LRM parameters
This commit is contained in:
Yann Collet
2018-03-21 05:59:39 -07:00
committed by GitHub
parent 1292a738d8 878728dc26
commit 87b0cf05bd
8 changed files with 184 additions and 191 deletions
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lib/compress/zstd_ldm.c
+6 -12
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@@ -17,21 +17,14 @@
#define LDM_HASH_RLOG 7
#define LDM_HASH_CHAR_OFFSET 10
size_t ZSTD_ldm_initializeParameters(ldmParams_t* params, U32 enableLdm)
{
ZSTD_STATIC_ASSERT(LDM_BUCKET_SIZE_LOG <= ZSTD_LDM_BUCKETSIZELOG_MAX);
params->enableLdm = enableLdm>0;
params->hashLog = 0;
params->bucketSizeLog = LDM_BUCKET_SIZE_LOG;
params->minMatchLength = LDM_MIN_MATCH_LENGTH;
params->hashEveryLog = ZSTD_LDM_HASHEVERYLOG_NOTSET;
return 0;
}
void ZSTD_ldm_adjustParameters(ldmParams_t* params,
ZSTD_compressionParameters const* cParams)
{
U32 const windowLog = cParams->windowLog;
ZSTD_STATIC_ASSERT(LDM_BUCKET_SIZE_LOG <= ZSTD_LDM_BUCKETSIZELOG_MAX);
DEBUGLOG(4, "ZSTD_ldm_adjustParameters");
if (!params->bucketSizeLog) params->bucketSizeLog = LDM_BUCKET_SIZE_LOG;
if (!params->minMatchLength) params->minMatchLength = LDM_MIN_MATCH_LENGTH;
if (cParams->strategy >= ZSTD_btopt) {
/* Get out of the way of the optimal parser */
U32 const minMatch = MAX(cParams->targetLength, params->minMatchLength);
@@ -43,7 +36,7 @@ void ZSTD_ldm_adjustParameters(ldmParams_t* params,
params->hashLog = MAX(ZSTD_HASHLOG_MIN, windowLog - LDM_HASH_RLOG);
assert(params->hashLog <= ZSTD_HASHLOG_MAX);
}
if (params->hashEveryLog == ZSTD_LDM_HASHEVERYLOG_NOTSET) {
if (params->hashEveryLog == 0) {
params->hashEveryLog =
windowLog < params->hashLog ? 0 : windowLog - params->hashLog;
}
@@ -183,6 +176,7 @@ static U64 ZSTD_ldm_ipow(U64 base, U64 exp)
}
U64 ZSTD_ldm_getHashPower(U32 minMatchLength) {
DEBUGLOG(4, "ZSTD_ldm_getHashPower: mml=%u", minMatchLength);
assert(minMatchLength >= ZSTD_LDM_MINMATCH_MIN);
return ZSTD_ldm_ipow(prime8bytes, minMatchLength - 1);
}