size_t ZSTD_frameHeaderSize(const void* src, size_t srcSize); +`src` should point to the start of a ZSTD frame + `srcSize` must be >= ZSTD_frameHeaderSize_prefix. + @return : size of the Frame Header +
size_t ZSTD_sizeof_CCtx(const ZSTD_CCtx* cctx); @@ -401,12 +407,15 @@ size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict); Object memory usage can evolve if it's re-used multiple times.
size_t ZSTD_estimateCCtxSize(ZSTD_compressionParameters cParams); +size_t ZSTD_estimateCCtxSize(int compressionLevel); +size_t ZSTD_estimateCCtxSize_advanced(ZSTD_compressionParameters cParams); size_t ZSTD_estimateDCtxSize(void);These functions make it possible to estimate memory usage - of a future target object, before its allocation, - given a set of parameters, which vary depending on target object. + of a future {D,C}Ctx, before its creation. The objective is to guide decision before allocation. + ZSTD_estimateCCtxSize() will consider src size to be arbitrarily "large". + If srcSize is known to be small, ZSTD_estimateCCtxSize_advanced() will provide a better (smaller) estimation. + ZSTD_estimateCCtxSize_advanced() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel. Note : CCtx estimation is only correct for single-threaded compression
diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c index e5349609..1bf67692 100644 --- a/lib/compress/zstd_compress.c +++ b/lib/compress/zstd_compress.c @@ -532,7 +532,7 @@ ZSTD_compressionParameters ZSTD_adjustCParams(ZSTD_compressionParameters cPar, u } -size_t ZSTD_estimateCCtxSize(ZSTD_compressionParameters cParams) +size_t ZSTD_estimateCCtxSize_advanced(ZSTD_compressionParameters cParams) { size_t const blockSize = MIN(ZSTD_BLOCKSIZE_MAX, (size_t)1 << cParams.windowLog); U32 const divider = (cParams.searchLength==3) ? 3 : 4; @@ -558,9 +558,15 @@ size_t ZSTD_estimateCCtxSize(ZSTD_compressionParameters cParams) return sizeof(ZSTD_CCtx) + neededSpace; } +size_t ZSTD_estimateCCtxSize(int compressionLevel) +{ + ZSTD_compressionParameters const cParams = ZSTD_getCParams(compressionLevel, 0, 0); + return ZSTD_estimateCCtxSize_advanced(cParams); +} + size_t ZSTD_estimateCStreamSize(ZSTD_compressionParameters cParams) { - size_t const CCtxSize = ZSTD_estimateCCtxSize(cParams); + size_t const CCtxSize = ZSTD_estimateCCtxSize_advanced(cParams); size_t const blockSize = MIN(ZSTD_BLOCKSIZE_MAX, (size_t)1 << cParams.windowLog); size_t const inBuffSize = ((size_t)1 << cParams.windowLog) + blockSize; size_t const outBuffSize = ZSTD_compressBound(blockSize) + 1; @@ -3355,8 +3361,8 @@ size_t ZSTD_compress(void* dst, size_t dstCapacity, const void* src, size_t srcS size_t ZSTD_estimateCDictSize(ZSTD_compressionParameters cParams, size_t dictSize, unsigned byReference) { DEBUGLOG(5, "sizeof(ZSTD_CDict) : %u", (U32)sizeof(ZSTD_CDict)); - DEBUGLOG(5, "CCtx estimate : %u", (U32)ZSTD_estimateCCtxSize(cParams)); - return sizeof(ZSTD_CDict) + ZSTD_estimateCCtxSize(cParams) + DEBUGLOG(5, "CCtx estimate : %u", (U32)ZSTD_estimateCCtxSize_advanced(cParams)); + return sizeof(ZSTD_CDict) + ZSTD_estimateCCtxSize_advanced(cParams) + (byReference ? 0 : dictSize); } @@ -3482,7 +3488,7 @@ ZSTD_CDict* ZSTD_initStaticCDict(void* workspace, size_t workspaceSize, unsigned byReference, ZSTD_dictMode_e dictMode, ZSTD_compressionParameters cParams) { - size_t const cctxSize = ZSTD_estimateCCtxSize(cParams); + size_t const cctxSize = ZSTD_estimateCCtxSize_advanced(cParams); size_t const neededSize = sizeof(ZSTD_CDict) + (byReference ? 0 : dictSize) + cctxSize; ZSTD_CDict* const cdict = (ZSTD_CDict*) workspace; diff --git a/lib/zstd.h b/lib/zstd.h index 8cf9ba75..65932088 100644 --- a/lib/zstd.h +++ b/lib/zstd.h @@ -495,11 +495,14 @@ ZSTDLIB_API size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict); /*! ZSTD_estimate*() : * These functions make it possible to estimate memory usage - * of a future target object, before its allocation, - * given a set of parameters, which vary depending on target object. + * of a future {D,C}Ctx, before its creation. * The objective is to guide decision before allocation. + * ZSTD_estimateCCtxSize() will consider src size to be arbitrarily "large". + * If srcSize is known to be small, ZSTD_estimateCCtxSize_advanced() will provide a better (smaller) estimation. + * ZSTD_estimateCCtxSize_advanced() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel. * Note : CCtx estimation is only correct for single-threaded compression */ -ZSTDLIB_API size_t ZSTD_estimateCCtxSize(ZSTD_compressionParameters cParams); +ZSTDLIB_API size_t ZSTD_estimateCCtxSize(int compressionLevel); +ZSTDLIB_API size_t ZSTD_estimateCCtxSize_advanced(ZSTD_compressionParameters cParams); ZSTDLIB_API size_t ZSTD_estimateDCtxSize(void); /*! ZSTD_estimate?StreamSize() : diff --git a/tests/paramgrill.c b/tests/paramgrill.c index 1185c664..da06ccb5 100644 --- a/tests/paramgrill.c +++ b/tests/paramgrill.c @@ -390,8 +390,8 @@ static int BMK_seed(winnerInfo_t* winners, const ZSTD_compressionParameters para double W_DMemUsed_note = W_ratioNote * ( 40 + 9*cLevel) - log((double)W_DMemUsed); double O_DMemUsed_note = O_ratioNote * ( 40 + 9*cLevel) - log((double)O_DMemUsed); - size_t W_CMemUsed = (1 << params.windowLog) + ZSTD_estimateCCtxSize(params); - size_t O_CMemUsed = (1 << winners[cLevel].params.windowLog) + ZSTD_estimateCCtxSize(winners[cLevel].params); + size_t W_CMemUsed = (1 << params.windowLog) + ZSTD_estimateCCtxSize_advanced(params); + size_t O_CMemUsed = (1 << winners[cLevel].params.windowLog) + ZSTD_estimateCCtxSize_advanced(winners[cLevel].params); double W_CMemUsed_note = W_ratioNote * ( 50 + 13*cLevel) - log((double)W_CMemUsed); double O_CMemUsed_note = O_ratioNote * ( 50 + 13*cLevel) - log((double)O_CMemUsed);