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added ZSTD_estimateCCtxSize()

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This commit is contained in:
Yann Collet
2016-07-11 03:12:17 +02:00
parent 677ed26aa7
commit 3ae543ce75
4 changed files with 37 additions and 19 deletions
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35
lib/compress/zstd_compress.c
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@@ -175,6 +175,11 @@ size_t ZSTD_freeCCtx(ZSTD_CCtx* cctx)
return 0; /* reserved as a potential error code in the future */
}
size_t ZSTD_sizeofCCtx(const ZSTD_CCtx* cctx)
{
return sizeof(*cctx) + cctx->workSpaceSize;
}
const seqStore_t* ZSTD_getSeqStore(const ZSTD_CCtx* ctx) /* hidden interface */
{
return &(ctx->seqStore);
@@ -244,17 +249,27 @@ ZSTD_compressionParameters ZSTD_adjustCParams(ZSTD_compressionParameters cPar, u
}
size_t ZSTD_sizeofCCtx(ZSTD_compressionParameters cParams) /* hidden interface, for paramagrill */
size_t ZSTD_estimateCCtxSize(ZSTD_compressionParameters cParams, unsigned long long frameContentSize)
{
ZSTD_CCtx* const zc = ZSTD_createCCtx();
ZSTD_parameters params;
memset(&params, 0, sizeof(params));
params.cParams = cParams;
params.fParams.contentSizeFlag = 1;
ZSTD_compressBegin_advanced(zc, NULL, 0, params, 0);
{ size_t const ccsize = sizeof(*zc) + zc->workSpaceSize;
ZSTD_freeCCtx(zc);
return ccsize; }
const size_t blockSize = MIN(ZSTD_BLOCKSIZE_MAX, (size_t)1 << cParams.windowLog);
const U32 divider = (cParams.searchLength==3) ? 3 : 4;
const size_t maxNbSeq = blockSize / divider;
const size_t tokenSpace = blockSize + 11*maxNbSeq;
const size_t chainSize = (cParams.strategy == ZSTD_fast) ? 0 : (1 << cParams.chainLog);
const size_t hSize = ((size_t)1) << cParams.hashLog;
const U32 hashLog3 = (cParams.searchLength>3) ? 0 :
( (!frameContentSize || frameContentSize >= 8192) ? ZSTD_HASHLOG3_MAX :
((frameContentSize >= 2048) ? ZSTD_HASHLOG3_MIN + 1 : ZSTD_HASHLOG3_MIN) );
const size_t h3Size = ((size_t)1) << hashLog3;
const size_t tableSpace = (chainSize + hSize + h3Size) * sizeof(U32);
size_t const optSpace = ((MaxML+1) + (MaxLL+1) + (MaxOff+1) + (1<<Litbits))*sizeof(U32)
+ (ZSTD_OPT_NUM+1)*(sizeof(ZSTD_match_t) + sizeof(ZSTD_optimal_t));
size_t const neededSpace = tableSpace + (256*sizeof(U32)) /* huffTable */ + tokenSpace
+ ((cParams.strategy == ZSTD_btopt) ? optSpace : 0);
return sizeof(ZSTD_CCtx) + neededSpace;
}
/*! ZSTD_resetCCtx_advanced() :