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create command --fast[=#]

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access negative compression levels from command line
for both compression and benchmark modes.

also : ensure proper propagation of parameters
through ZSTD_compress_generic() interface.

added relevant cli tests.
This commit is contained in:
Yann Collet
2018-03-11 20:01:23 -07:00
parent a146ee04ae
commit 6a9b41b731
8 changed files with 111 additions and 52 deletions
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lib/zstd.h
+10 -2
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@@ -947,7 +947,9 @@ typedef enum {
/* compression parameters */
ZSTD_p_compressionLevel=100, /* Update all compression parameters according to pre-defined cLevel table
* Default level is ZSTD_CLEVEL_DEFAULT==3.
* Special: value 0 means "do not change cLevel". */
* 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_literalCompression. */
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".
@@ -1010,10 +1012,16 @@ typedef enum {
* 0 => no overlap, 6(default) => use 1/8th of windowSize, >=9 => use full windowSize */
/* advanced parameters - may not remain available after API update */
ZSTD_p_literalCompression=1000, /* control huffman compression of literals (enabled) by default.
* disabling it improves speed and decreases compression ratio by a large amount. */
* disabling it improves speed and decreases compression ratio by a large amount.
* note : this setting is updated when changing compression level.
* positive compression levels set literalCompression to 1.
* negative compression levels set literalCompression to 0. */
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.