typedef enum {
- /* Question : should we have a format ZSTD_f_auto ?
- * For the time being, it would mean exactly the same as ZSTD_f_zstd1.
- * But, in the future, should several formats be supported,
+ /* Opened question : should we have a format ZSTD_f_auto ?
+ * Today, it would mean exactly the same as ZSTD_f_zstd1.
+ * But, in the future, should several formats become supported,
* on the compression side, it would mean "default format".
- * On the decompression side, it would mean "multi format",
- * and ZSTD_f_zstd1 could be reserved to mean "accept *only* zstd frames".
+ * On the decompression side, it would mean "automatic format detection",
+ * so that ZSTD_f_zstd1 would mean "accept *only* zstd frames".
* Since meaning is a little different, another option could be to define different enums for compression and decompression.
* This question could be kept for later, when there are actually multiple formats to support,
* but there is also the question of pinning enum values, and pinning value `0` is especially important */
@@ -755,33 +755,34 @@ size_t ZSTD_decodingBufferSize_min(unsigned long long windowSize, unsigned long
* Default level is ZSTD_CLEVEL_DEFAULT==3.
* Special: value 0 means "do not change cLevel".
* Note 1 : it's possible to pass a negative compression level by casting it to unsigned type.
- * Note 2 : setting compressionLevel automatically updates ZSTD_p_compressLiterals. */
+ * Note 2 : setting a level sets all default values of other compression parameters.
+ * Note 3 : setting compressionLevel automatically updates ZSTD_p_compressLiterals. */
ZSTD_p_windowLog, /* Maximum allowed back-reference distance, expressed as power of 2.
* Must be clamped between ZSTD_WINDOWLOG_MIN and ZSTD_WINDOWLOG_MAX.
- * Special: value 0 means "do not change windowLog".
+ * Special: value 0 means "use default windowLog".
* Note: Using a window size greater than ZSTD_MAXWINDOWSIZE_DEFAULT (default: 2^27)
- * requires setting the maximum window size at least as large during decompression. */
+ * requires explicitly allowing such window size during decompression stage. */
ZSTD_p_hashLog, /* Size of the probe table, as a power of 2.
* Resulting table size is (1 << (hashLog+2)).
* Must be clamped between ZSTD_HASHLOG_MIN and ZSTD_HASHLOG_MAX.
* Larger tables improve compression ratio of strategies <= dFast,
* and improve speed of strategies > dFast.
- * Special: value 0 means "do not change hashLog". */
+ * Special: value 0 means "use default hashLog". */
ZSTD_p_chainLog, /* Size of the full-search table, as a power of 2.
* Resulting table size is (1 << (chainLog+2)).
* Larger tables result in better and slower compression.
* This parameter is useless when using "fast" strategy.
- * Special: value 0 means "do not change chainLog". */
+ * Special: value 0 means "use default chainLog". */
ZSTD_p_searchLog, /* Number of search attempts, as a power of 2.
* More attempts result in better and slower compression.
* This parameter is useless when using "fast" and "dFast" strategies.
- * Special: value 0 means "do not change searchLog". */
+ * Special: value 0 means "use default searchLog". */
ZSTD_p_minMatch, /* Minimum size of searched matches (note : repCode matches can be smaller).
* Larger values make faster compression and decompression, but decrease ratio.
* Must be clamped between ZSTD_SEARCHLENGTH_MIN and ZSTD_SEARCHLENGTH_MAX.
* Note that currently, for all strategies < btopt, effective minimum is 4.
- * Note that currently, for all strategies > fast, effective maximum is 6.
- * Special: value 0 means "do not change minMatchLength". */
+ * , for all strategies > fast, effective maximum is 6.
+ * Special: value 0 means "use default minMatchLength". */
ZSTD_p_targetLength, /* Impact of this field depends on strategy.
* For strategies btopt & btultra:
* Length of Match considered "good enough" to stop search.
@@ -789,12 +790,39 @@ size_t ZSTD_decodingBufferSize_min(unsigned long long windowSize, unsigned long
* For strategy fast:
* Distance between match sampling.
* Larger values make compression faster, and weaker.
- * Special: value 0 means "do not change targetLength". */
+ * Special: value 0 means "use default targetLength". */
ZSTD_p_compressionStrategy, /* See ZSTD_strategy enum definition.
* Cast selected strategy as unsigned for ZSTD_CCtx_setParameter() compatibility.
* The higher the value of selected strategy, the more complex it is,
* resulting in stronger and slower compression.
- * Special: value 0 means "do not change strategy". */
+ * Special: value 0 means "use default strategy". */
+
+ ZSTD_p_enableLongDistanceMatching=160, /* Enable long distance matching.
+ * This parameter is designed to improve compression ratio
+ * for large inputs, by finding large matches at long distance.
+ * It increases memory usage and window size.
+ * Note: enabling this parameter increases ZSTD_p_windowLog to 128 MB
+ * except when expressly set to a different value. */
+ ZSTD_p_ldmHashLog, /* Size of the table for long distance matching, as a power of 2.
+ * Larger values increase memory usage and compression ratio,
+ * but decrease compression speed.
+ * Must be clamped between ZSTD_HASHLOG_MIN and ZSTD_HASHLOG_MAX
+ * default: windowlog - 7.
+ * Special: value 0 means "automatically determine hashlog". */
+ ZSTD_p_ldmMinMatch, /* Minimum match size for long distance matcher.
+ * Larger/too small values usually decrease compression ratio.
+ * Must be clamped between ZSTD_LDM_MINMATCH_MIN and ZSTD_LDM_MINMATCH_MAX.
+ * Special: value 0 means "use default value" (default: 64). */
+ ZSTD_p_ldmBucketSizeLog, /* Log size of each bucket in the LDM hash table for collision resolution.
+ * Larger values improve collision resolution but decrease compression speed.
+ * The maximum value is ZSTD_LDM_BUCKETSIZELOG_MAX .
+ * Special: value 0 means "use default value" (default: 3). */
+ ZSTD_p_ldmHashEveryLog, /* Frequency of inserting/looking up entries in the LDM hash table.
+ * Must be clamped between 0 and (ZSTD_WINDOWLOG_MAX - ZSTD_HASHLOG_MIN).
+ * Default is MAX(0, (windowLog - ldmHashLog)), optimizing hash table usage.
+ * Larger values improve compression speed.
+ * Deviating far from default value will likely result in a compression ratio decrease.
+ * Special: value 0 means "automatically determine hashEveryLog". */
/* frame parameters */
ZSTD_p_contentSizeFlag=200, /* Content size will be written into frame header _whenever known_ (default:1)
@@ -821,7 +849,9 @@ size_t ZSTD_decodingBufferSize_min(unsigned long long windowSize, unsigned long
ZSTD_p_overlapSizeLog, /* Size of previous input reloaded at the beginning of each job.
* 0 => no overlap, 6(default) => use 1/8th of windowSize, >=9 => use full windowSize */
- /* advanced parameters - may not remain available after API update */
+ /* =================================================================== */
+ /* experimental parameters - no stability guaranteed */
+ /* =================================================================== */
ZSTD_p_compressLiterals=1000, /* control huffman compression of literals (enabled) by default.
* disabling it improves speed and decreases compression ratio by a large amount.
@@ -832,40 +862,6 @@ size_t ZSTD_decodingBufferSize_min(unsigned long long windowSize, unsigned long
ZSTD_p_forceMaxWindow=1100, /* Force back-reference distances to remain < windowSize,
* even when referencing into Dictionary content (default:0) */
- ZSTD_p_enableLongDistanceMatching=1200, /* Enable long distance matching.
- * This parameter is designed to improve the compression
- * ratio for large inputs with long distance matches.
- * This increases the memory usage as well as window size.
- * Note: setting this parameter sets all the LDM parameters
- * as well as ZSTD_p_windowLog. It should be set after
- * ZSTD_p_compressionLevel and before ZSTD_p_windowLog and
- * other LDM parameters. Setting the compression level
- * after this parameter overrides the window log, though LDM
- * will remain enabled until explicitly disabled. */
- ZSTD_p_ldmHashLog, /* Size of the table for long distance matching, as a power of 2.
- * Larger values increase memory usage and compression ratio, but decrease
- * compression speed.
- * Must be clamped between ZSTD_HASHLOG_MIN and ZSTD_HASHLOG_MAX
- * (default: windowlog - 7).
- * Special: value 0 means "do not change ldmHashLog". */
- ZSTD_p_ldmMinMatch, /* Minimum size of searched matches for long distance matcher.
- * Larger/too small values usually decrease compression ratio.
- * Must be clamped between ZSTD_LDM_MINMATCH_MIN
- * and ZSTD_LDM_MINMATCH_MAX (default: 64).
- * Special: value 0 means "do not change ldmMinMatch". */
- ZSTD_p_ldmBucketSizeLog, /* Log size of each bucket in the LDM hash table for collision resolution.
- * Larger values usually improve collision resolution but may decrease
- * compression speed.
- * The maximum value is ZSTD_LDM_BUCKETSIZELOG_MAX (default: 3).
- * note : 0 is a valid value */
- ZSTD_p_ldmHashEveryLog, /* Frequency of inserting/looking up entries in the LDM hash table.
- * The default is MAX(0, (windowLog - ldmHashLog)) to
- * optimize hash table usage.
- * Larger values improve compression speed. Deviating far from the
- * default value will likely result in a decrease in compression ratio.
- * Must be clamped between 0 and ZSTD_WINDOWLOG_MAX - ZSTD_HASHLOG_MIN.
- * note : 0 is a valid value */
-
} ZSTD_cParameter;
size_t ZSTD_CCtx_setParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, unsigned value); @@ -1067,7 +1063,7 @@ size_t ZSTD_DCtx_loadDictionary_advanced(ZSTD_DCtx* dctx, const void* dict, size
size_t ZSTD_DCtx_refDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict); /* not implemented */ +size_t ZSTD_DCtx_refDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict);Reference a prepared dictionary, to be used to decompress next frames. The dictionary remains active for decompression of future frames using same DCtx. @result : 0, or an error code (which can be tested with ZSTD_isError()). @@ -1078,8 +1074,8 @@ size_t ZSTD_DCtx_loadDictionary_advanced(ZSTD_DCtx* dctx, const void* dict, size
-size_t ZSTD_DCtx_refPrefix(ZSTD_DCtx* dctx, const void* prefix, size_t prefixSize); /* not implemented */ -size_t ZSTD_DCtx_refPrefix_advanced(ZSTD_DCtx* dctx, const void* prefix, size_t prefixSize, ZSTD_dictContentType_e dictContentType); /* not implemented */ +size_t ZSTD_DCtx_refPrefix(ZSTD_DCtx* dctx, const void* prefix, size_t prefixSize); +size_t ZSTD_DCtx_refPrefix_advanced(ZSTD_DCtx* dctx, const void* prefix, size_t prefixSize, ZSTD_dictContentType_e dictContentType);Reference a prefix (single-usage dictionary) for next compression job. Prefix is **only used once**. It must be explicitly referenced before each frame. If there is a need to use same prefix multiple times, consider embedding it into a ZSTD_DDict instead. diff --git a/tests/paramgrill.c b/tests/paramgrill.c index ae14aa074..13b102b2d 100644 --- a/tests/paramgrill.c +++ b/tests/paramgrill.c @@ -547,12 +547,12 @@ static ZSTD_compressionParameters randomParams(void) U32 validated = 0; while (!validated) { /* totally random entry */ - p.chainLog = FUZ_rand(&g_rand) % (ZSTD_CHAINLOG_MAX+1 - ZSTD_CHAINLOG_MIN) + ZSTD_CHAINLOG_MIN; - p.hashLog = FUZ_rand(&g_rand) % (ZSTD_HASHLOG_MAX+1 - ZSTD_HASHLOG_MIN) + ZSTD_HASHLOG_MIN; - p.searchLog = FUZ_rand(&g_rand) % (ZSTD_SEARCHLOG_MAX+1 - ZSTD_SEARCHLOG_MIN) + ZSTD_SEARCHLOG_MIN; - p.windowLog = FUZ_rand(&g_rand) % (ZSTD_WINDOWLOG_MAX+1 - ZSTD_WINDOWLOG_MIN) + ZSTD_WINDOWLOG_MIN; - p.searchLength=FUZ_rand(&g_rand) % (ZSTD_SEARCHLENGTH_MAX+1 - ZSTD_SEARCHLENGTH_MIN) + ZSTD_SEARCHLENGTH_MIN; - p.targetLength=FUZ_rand(&g_rand) % (ZSTD_TARGETLENGTH_MAX+1 - ZSTD_TARGETLENGTH_MIN) + ZSTD_TARGETLENGTH_MIN; + p.chainLog = (FUZ_rand(&g_rand) % (ZSTD_CHAINLOG_MAX+1 - ZSTD_CHAINLOG_MIN)) + ZSTD_CHAINLOG_MIN; + p.hashLog = (FUZ_rand(&g_rand) % (ZSTD_HASHLOG_MAX+1 - ZSTD_HASHLOG_MIN)) + ZSTD_HASHLOG_MIN; + p.searchLog = (FUZ_rand(&g_rand) % (ZSTD_SEARCHLOG_MAX+1 - ZSTD_SEARCHLOG_MIN)) + ZSTD_SEARCHLOG_MIN; + p.windowLog = (FUZ_rand(&g_rand) % (ZSTD_WINDOWLOG_MAX+1 - ZSTD_WINDOWLOG_MIN)) + ZSTD_WINDOWLOG_MIN; + p.searchLength=(FUZ_rand(&g_rand) % (ZSTD_SEARCHLENGTH_MAX+1 - ZSTD_SEARCHLENGTH_MIN)) + ZSTD_SEARCHLENGTH_MIN; + p.targetLength=(FUZ_rand(&g_rand) % (512)) + ZSTD_TARGETLENGTH_MIN; p.strategy = (ZSTD_strategy) (FUZ_rand(&g_rand) % (ZSTD_btultra +1)); validated = !ZSTD_isError(ZSTD_checkCParams(p)); }