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dynamic bucket sizes

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This commit is contained in:
Yann Collet
2025-02-10 10:46:37 -08:00
committed by Yann Collet
parent 4609a40b89
commit f26cc54f37
1 changed files with 10 additions and 2 deletions
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lib/compress/zstd_ldm.c
+10 -2
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@@ -16,7 +16,7 @@
#include "zstd_double_fast.h" /* ZSTD_fillDoubleHashTable() */
#include "zstd_ldm_geartab.h"
#define LDM_BUCKET_SIZE_LOG 3
#define LDM_BUCKET_SIZE_LOG 4
#define LDM_MIN_MATCH_LENGTH 64
#define LDM_HASH_RLOG 7
@@ -138,7 +138,6 @@ void ZSTD_ldm_adjustParameters(ldmParams_t* params,
params->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->hashRateLog == 0) {
assert(1 <= (int)cParams->strategy && (int)cParams->strategy <= 9);
/* mapping: strat1 -> rate8 ... strat9 -> rate4*/
@@ -152,6 +151,15 @@ void ZSTD_ldm_adjustParameters(ldmParams_t* params,
params->minMatchLength = (params->hashRateLog < 6) ?
LDM_MIN_MATCH_LENGTH :
LDM_MIN_MATCH_LENGTH * 2;
if (cParams->strategy >= ZSTD_btultra2)
params->minMatchLength /= 2;
}
if (params->bucketSizeLog==0) {
params->bucketSizeLog = LDM_BUCKET_SIZE_LOG;
if (cParams->strategy > ZSTD_lazy) {
params->bucketSizeLog += (U32)cParams->strategy - (U32)ZSTD_lazy;
}
params->bucketSizeLog = MIN(params->bucketSizeLog, ZSTD_LDM_BUCKETSIZELOG_MAX);
}
params->bucketSizeLog = MIN(params->bucketSizeLog, params->hashLog);
}