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Fix ZSTD_adjustCParams_internal() to handle dictionary logic

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Pass in the `ZSTD_cParamMode_e` to select how we define our cparams.
Based on the mode we either take the `dictSize` into account or we set
it to `0`. See the documentation for `ZSTD_cParamMode_e`.

Some of the modes currently share the same behavior. But they have
distinct modes because they are drastically different cases. E.g.
compression + reprocessing the dictionary and creating a cdict.

Additionally, when downsizing the hashLog and chainLog take the
(adjusted) dictionary size into account, since the size of the
dictionary gets added onto the window size.

Adds a simple test to ensure that we aren't downsizing too far.
This commit is contained in:
Nick Terrell
2020-10-12 12:50:04 -07:00
parent fadaab8c7c
commit d5c688e8ae
4 changed files with 155 additions and 41 deletions
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lib/compress/zstd_compress_internal.h
+20 -1
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@@ -302,6 +302,25 @@ typedef enum {
ZSTD_dedicatedDictSearch = 3
} ZSTD_dictMode_e;
typedef enum {
ZSTD_cpm_noAttachDict = 0, /* Compression with ZSTD_noDict or ZSTD_extDict.
* In this mode we use both the srcSize and the dictSize
* when selecting and adjusting parameters.
*/
ZSTD_cpm_attachDict = 1, /* Compression with ZSTD_dictMatchState or ZSTD_dedicatedDictSearch.
* In this mode we only take the srcSize into account when selecting
* and adjusting parameters.
*/
ZSTD_cpm_createCDict = 2, /* Creating a CDict.
* In this mode we take both the source size and the dictionary size
* into account when selecting and adjusting the parameters.
*/
ZSTD_cpm_unknown = 3, /* ZSTD_getCParams, ZSTD_getParams, ZSTD_adjustParams.
* We don't know what these parameters are for. We default to the legacy
* behavior of taking both the source size and the dict size into account
* when selecting and adjusting parameters.
*/
} ZSTD_cParamMode_e;
typedef size_t (*ZSTD_blockCompressor) (
ZSTD_matchState_t* bs, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
@@ -1090,7 +1109,7 @@ void ZSTD_reset_compressedBlockState(ZSTD_compressedBlockState_t* bs);
* Note: srcSizeHint == 0 means 0!
*/
ZSTD_compressionParameters ZSTD_getCParamsFromCCtxParams(
const ZSTD_CCtx_params* CCtxParams, U64 srcSizeHint, size_t dictSize);
const ZSTD_CCtx_params* CCtxParams, U64 srcSizeHint, size_t dictSize, ZSTD_cParamMode_e mode);
/*! ZSTD_initCStream_internal() :
* Private use only. Init streaming operation.