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<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
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<title>zstd 1.3.8 Manual</title>
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<title>zstd 1.4.0 Manual</title>
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</head>
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<body>
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<h1>zstd 1.3.8 Manual</h1>
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<h1>zstd 1.4.0 Manual</h1>
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<hr>
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<a name="Contents"></a><h2>Contents</h2>
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<ol>
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<li><a href="#Chapter1">Introduction</a></li>
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<li><a href="#Chapter2">Version</a></li>
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<li><a href="#Chapter3">Default constant</a></li>
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<li><a href="#Chapter4">Simple API</a></li>
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<li><a href="#Chapter5">Explicit context</a></li>
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<li><a href="#Chapter6">Simple dictionary API</a></li>
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<li><a href="#Chapter7">Bulk processing dictionary API</a></li>
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<li><a href="#Chapter8">Streaming</a></li>
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<li><a href="#Chapter9">Streaming compression - HowTo</a></li>
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<li><a href="#Chapter10">Streaming decompression - HowTo</a></li>
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<li><a href="#Chapter11">ADVANCED AND EXPERIMENTAL FUNCTIONS</a></li>
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<li><a href="#Chapter12">Candidate API for promotion to stable status</a></li>
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<li><a href="#Chapter13">Advanced compression API</a></li>
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<li><a href="#Chapter14">experimental API (static linking only)</a></li>
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<li><a href="#Chapter15">Frame size functions</a></li>
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<li><a href="#Chapter16">Memory management</a></li>
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<li><a href="#Chapter17">Advanced compression functions</a></li>
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<li><a href="#Chapter18">Advanced decompression functions</a></li>
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<li><a href="#Chapter19">Advanced streaming functions</a></li>
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<li><a href="#Chapter20">Buffer-less and synchronous inner streaming functions</a></li>
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<li><a href="#Chapter21">Buffer-less streaming compression (synchronous mode)</a></li>
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<li><a href="#Chapter22">Buffer-less streaming decompression (synchronous mode)</a></li>
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<li><a href="#Chapter23">ZSTD_getFrameHeader() :</a></li>
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<li><a href="#Chapter24">Block level API</a></li>
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<li><a href="#Chapter4">Constants</a></li>
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<li><a href="#Chapter5">Simple API</a></li>
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<li><a href="#Chapter6">Explicit context</a></li>
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<li><a href="#Chapter7">Advanced compression API</a></li>
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<li><a href="#Chapter8">Advanced decompression API</a></li>
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<li><a href="#Chapter9">Streaming</a></li>
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<li><a href="#Chapter10">Streaming compression - HowTo</a></li>
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<li><a href="#Chapter11">This is a legacy streaming API, and can be replaced by ZSTD_CCtx_reset() and</a></li>
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<li><a href="#Chapter12">Equivalent to:</a></li>
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<li><a href="#Chapter13">Alternative for ZSTD_compressStream2(zcs, output, input, ZSTD_e_continue).</a></li>
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<li><a href="#Chapter14">Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_flush).</a></li>
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<li><a href="#Chapter15">Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_end).</a></li>
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<li><a href="#Chapter16">Streaming decompression - HowTo</a></li>
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<li><a href="#Chapter17">Simple dictionary API</a></li>
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<li><a href="#Chapter18">Bulk processing dictionary API</a></li>
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<li><a href="#Chapter19">Dictionary helper functions</a></li>
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<li><a href="#Chapter20">Advanced dictionary and prefix API</a></li>
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<li><a href="#Chapter21">ADVANCED AND EXPERIMENTAL FUNCTIONS</a></li>
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<li><a href="#Chapter22">experimental API (static linking only)</a></li>
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<li><a href="#Chapter23">Frame size functions</a></li>
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<li><a href="#Chapter24">ZSTD_decompressBound() :</a></li>
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<li><a href="#Chapter25">Memory management</a></li>
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<li><a href="#Chapter26">Advanced compression functions</a></li>
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<li><a href="#Chapter27">Advanced decompression functions</a></li>
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<li><a href="#Chapter28">Advanced streaming functions</a></li>
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<li><a href="#Chapter29">Buffer-less and synchronous inner streaming functions</a></li>
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<li><a href="#Chapter30">Buffer-less streaming compression (synchronous mode)</a></li>
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<li><a href="#Chapter31">Buffer-less streaming decompression (synchronous mode)</a></li>
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<li><a href="#Chapter32">ZSTD_getFrameHeader() :</a></li>
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<li><a href="#Chapter33">Block level API</a></li>
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</ol>
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<hr>
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<a name="Chapter1"></a><h2>Introduction</h2><pre>
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@@ -71,7 +80,9 @@
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</b></pre><BR>
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<a name="Chapter3"></a><h2>Default constant</h2><pre></pre>
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<a name="Chapter4"></a><h2>Simple API</h2><pre></pre>
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<a name="Chapter4"></a><h2>Constants</h2><pre></pre>
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<a name="Chapter5"></a><h2>Simple API</h2><pre></pre>
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<pre><b>size_t ZSTD_compress( void* dst, size_t dstCapacity,
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const void* src, size_t srcSize,
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@@ -126,13 +137,22 @@ unsigned long long ZSTD_getFrameContentSize(const void *src, size_t srcSize);
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@return : decompressed size of `src` frame content _if known and not empty_, 0 otherwise.
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</p></pre><BR>
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<pre><b>size_t ZSTD_findFrameCompressedSize(const void* src, size_t srcSize);
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</b><p> `src` should point to the start of a ZSTD frame or skippable frame.
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`srcSize` must be >= first frame size
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@return : the compressed size of the first frame starting at `src`,
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suitable to pass as `srcSize` to `ZSTD_decompress` or similar,
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or an error code if input is invalid
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</p></pre><BR>
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<h3>Helper functions</h3><pre></pre><b><pre>#define ZSTD_COMPRESSBOUND(srcSize) ((srcSize) + ((srcSize)>>8) + (((srcSize) < (128<<10)) ? (((128<<10) - (srcSize)) >> 11) </b>/* margin, from 64 to 0 */ : 0)) /* this formula ensures that bound(A) + bound(B) <= bound(A+B) as long as A and B >= 128 KB */<b>
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size_t ZSTD_compressBound(size_t srcSize); </b>/*!< maximum compressed size in worst case single-pass scenario */<b>
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unsigned ZSTD_isError(size_t code); </b>/*!< tells if a `size_t` function result is an error code */<b>
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const char* ZSTD_getErrorName(size_t code); </b>/*!< provides readable string from an error code */<b>
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int ZSTD_minCLevel(void); </b>/*!< minimum negative compression level allowed */<b>
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int ZSTD_maxCLevel(void); </b>/*!< maximum compression level available */<b>
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</pre></b><BR>
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<a name="Chapter5"></a><h2>Explicit context</h2><pre></pre>
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<a name="Chapter6"></a><h2>Explicit context</h2><pre></pre>
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<h3>Compression context</h3><pre> When compressing many times,
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it is recommended to allocate a context just once, and re-use it for each successive compression operation.
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@@ -169,228 +189,7 @@ size_t ZSTD_freeDCtx(ZSTD_DCtx* dctx);
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</p></pre><BR>
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<a name="Chapter6"></a><h2>Simple dictionary API</h2><pre></pre>
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<pre><b>size_t ZSTD_compress_usingDict(ZSTD_CCtx* ctx,
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void* dst, size_t dstCapacity,
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const void* src, size_t srcSize,
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const void* dict,size_t dictSize,
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int compressionLevel);
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</b><p> Compression at an explicit compression level using a Dictionary.
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A dictionary can be any arbitrary data segment (also called a prefix),
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or a buffer with specified information (see dictBuilder/zdict.h).
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Note : This function loads the dictionary, resulting in significant startup delay.
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It's intended for a dictionary used only once.
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Note 2 : When `dict == NULL || dictSize < 8` no dictionary is used.
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</p></pre><BR>
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<pre><b>size_t ZSTD_decompress_usingDict(ZSTD_DCtx* dctx,
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void* dst, size_t dstCapacity,
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const void* src, size_t srcSize,
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const void* dict,size_t dictSize);
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</b><p> Decompression using a known Dictionary.
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Dictionary must be identical to the one used during compression.
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Note : This function loads the dictionary, resulting in significant startup delay.
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It's intended for a dictionary used only once.
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Note : When `dict == NULL || dictSize < 8` no dictionary is used.
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</p></pre><BR>
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<a name="Chapter7"></a><h2>Bulk processing dictionary API</h2><pre></pre>
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<pre><b>ZSTD_CDict* ZSTD_createCDict(const void* dictBuffer, size_t dictSize,
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int compressionLevel);
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</b><p> When compressing multiple messages / blocks using the same dictionary, it's recommended to load it only once.
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ZSTD_createCDict() will create a digested dictionary, ready to start future compression operations without startup cost.
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ZSTD_CDict can be created once and shared by multiple threads concurrently, since its usage is read-only.
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`dictBuffer` can be released after ZSTD_CDict creation, because its content is copied within CDict.
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Consider experimental function `ZSTD_createCDict_byReference()` if you prefer to not duplicate `dictBuffer` content.
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Note : A ZSTD_CDict can be created from an empty dictBuffer, but it is inefficient when used to compress small data.
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</p></pre><BR>
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<pre><b>size_t ZSTD_freeCDict(ZSTD_CDict* CDict);
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</b><p> Function frees memory allocated by ZSTD_createCDict().
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</p></pre><BR>
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<pre><b>size_t ZSTD_compress_usingCDict(ZSTD_CCtx* cctx,
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void* dst, size_t dstCapacity,
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const void* src, size_t srcSize,
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const ZSTD_CDict* cdict);
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</b><p> Compression using a digested Dictionary.
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Recommended when same dictionary is used multiple times.
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Note : compression level is _decided at dictionary creation time_,
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and frame parameters are hardcoded (dictID=yes, contentSize=yes, checksum=no)
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</p></pre><BR>
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<pre><b>ZSTD_DDict* ZSTD_createDDict(const void* dictBuffer, size_t dictSize);
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</b><p> Create a digested dictionary, ready to start decompression operation without startup delay.
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dictBuffer can be released after DDict creation, as its content is copied inside DDict.
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</p></pre><BR>
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<pre><b>size_t ZSTD_freeDDict(ZSTD_DDict* ddict);
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</b><p> Function frees memory allocated with ZSTD_createDDict()
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</p></pre><BR>
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<pre><b>size_t ZSTD_decompress_usingDDict(ZSTD_DCtx* dctx,
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void* dst, size_t dstCapacity,
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const void* src, size_t srcSize,
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const ZSTD_DDict* ddict);
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</b><p> Decompression using a digested Dictionary.
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Recommended when same dictionary is used multiple times.
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</p></pre><BR>
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<a name="Chapter8"></a><h2>Streaming</h2><pre></pre>
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<pre><b>typedef struct ZSTD_inBuffer_s {
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const void* src; </b>/**< start of input buffer */<b>
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size_t size; </b>/**< size of input buffer */<b>
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size_t pos; </b>/**< position where reading stopped. Will be updated. Necessarily 0 <= pos <= size */<b>
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} ZSTD_inBuffer;
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</b></pre><BR>
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<pre><b>typedef struct ZSTD_outBuffer_s {
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void* dst; </b>/**< start of output buffer */<b>
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size_t size; </b>/**< size of output buffer */<b>
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size_t pos; </b>/**< position where writing stopped. Will be updated. Necessarily 0 <= pos <= size */<b>
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} ZSTD_outBuffer;
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</b></pre><BR>
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<a name="Chapter9"></a><h2>Streaming compression - HowTo</h2><pre>
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A ZSTD_CStream object is required to track streaming operation.
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Use ZSTD_createCStream() and ZSTD_freeCStream() to create/release resources.
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ZSTD_CStream objects can be reused multiple times on consecutive compression operations.
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It is recommended to re-use ZSTD_CStream since it will play nicer with system's memory, by re-using already allocated memory.
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For parallel execution, use one separate ZSTD_CStream per thread.
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note : since v1.3.0, ZSTD_CStream and ZSTD_CCtx are the same thing.
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Parameters are sticky : when starting a new compression on the same context,
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it will re-use the same sticky parameters as previous compression session.
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When in doubt, it's recommended to fully initialize the context before usage.
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Use ZSTD_initCStream() to set the parameter to a selected compression level.
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Use advanced API (ZSTD_CCtx_setParameter(), etc.) to set more specific parameters.
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Use ZSTD_compressStream() as many times as necessary to consume input stream.
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The function will automatically update both `pos` fields within `input` and `output`.
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Note that the function may not consume the entire input,
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for example, because the output buffer is already full,
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in which case `input.pos < input.size`.
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The caller must check if input has been entirely consumed.
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If not, the caller must make some room to receive more compressed data,
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and then present again remaining input data.
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@return : a size hint, preferred nb of bytes to use as input for next function call
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or an error code, which can be tested using ZSTD_isError().
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Note 1 : it's just a hint, to help latency a little, any value will work fine.
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Note 2 : size hint is guaranteed to be <= ZSTD_CStreamInSize()
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At any moment, it's possible to flush whatever data might remain stuck within internal buffer,
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using ZSTD_flushStream(). `output->pos` will be updated.
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Note that, if `output->size` is too small, a single invocation of ZSTD_flushStream() might not be enough (return code > 0).
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In which case, make some room to receive more compressed data, and call again ZSTD_flushStream().
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@return : 0 if internal buffers are entirely flushed,
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>0 if some data still present within internal buffer (the value is minimal estimation of remaining size),
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or an error code, which can be tested using ZSTD_isError().
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ZSTD_endStream() instructs to finish a frame.
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It will perform a flush and write frame epilogue.
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The epilogue is required for decoders to consider a frame completed.
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flush() operation is the same, and follows same rules as ZSTD_flushStream().
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@return : 0 if frame fully completed and fully flushed,
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>0 if some data still present within internal buffer (the value is minimal estimation of remaining size),
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or an error code, which can be tested using ZSTD_isError().
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<BR></pre>
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<pre><b>typedef ZSTD_CCtx ZSTD_CStream; </b>/**< CCtx and CStream are now effectively same object (>= v1.3.0) */<b>
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</b></pre><BR>
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<h3>ZSTD_CStream management functions</h3><pre></pre><b><pre>ZSTD_CStream* ZSTD_createCStream(void);
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size_t ZSTD_freeCStream(ZSTD_CStream* zcs);
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</pre></b><BR>
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<h3>Streaming compression functions</h3><pre></pre><b><pre>size_t ZSTD_initCStream(ZSTD_CStream* zcs, int compressionLevel);
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size_t ZSTD_compressStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output, ZSTD_inBuffer* input);
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size_t ZSTD_flushStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output);
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size_t ZSTD_endStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output);
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</pre></b><BR>
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<pre><b>size_t ZSTD_CStreamInSize(void); </b>/**< recommended size for input buffer */<b>
|
|
|
|
|
</b></pre><BR>
|
|
|
|
|
<pre><b>size_t ZSTD_CStreamOutSize(void); </b>/**< recommended size for output buffer. Guarantee to successfully flush at least one complete compressed block in all circumstances. */<b>
|
|
|
|
|
</b></pre><BR>
|
|
|
|
|
<a name="Chapter10"></a><h2>Streaming decompression - HowTo</h2><pre>
|
|
|
|
|
A ZSTD_DStream object is required to track streaming operations.
|
|
|
|
|
Use ZSTD_createDStream() and ZSTD_freeDStream() to create/release resources.
|
|
|
|
|
ZSTD_DStream objects can be re-used multiple times.
|
|
|
|
|
|
|
|
|
|
Use ZSTD_initDStream() to start a new decompression operation.
|
|
|
|
|
@return : recommended first input size
|
|
|
|
|
Alternatively, use advanced API to set specific properties.
|
|
|
|
|
|
|
|
|
|
Use ZSTD_decompressStream() repetitively to consume your input.
|
|
|
|
|
The function will update both `pos` fields.
|
|
|
|
|
If `input.pos < input.size`, some input has not been consumed.
|
|
|
|
|
It's up to the caller to present again remaining data.
|
|
|
|
|
The function tries to flush all data decoded immediately, respecting output buffer size.
|
|
|
|
|
If `output.pos < output.size`, decoder has flushed everything it could.
|
|
|
|
|
But if `output.pos == output.size`, there might be some data left within internal buffers.,
|
|
|
|
|
In which case, call ZSTD_decompressStream() again to flush whatever remains in the buffer.
|
|
|
|
|
Note : with no additional input provided, amount of data flushed is necessarily <= ZSTD_BLOCKSIZE_MAX.
|
|
|
|
|
@return : 0 when a frame is completely decoded and fully flushed,
|
|
|
|
|
or an error code, which can be tested using ZSTD_isError(),
|
|
|
|
|
or any other value > 0, which means there is still some decoding or flushing to do to complete current frame :
|
|
|
|
|
the return value is a suggested next input size (just a hint for better latency)
|
|
|
|
|
that will never request more than the remaining frame size.
|
|
|
|
|
|
|
|
|
|
<BR></pre>
|
|
|
|
|
|
|
|
|
|
<pre><b>typedef ZSTD_DCtx ZSTD_DStream; </b>/**< DCtx and DStream are now effectively same object (>= v1.3.0) */<b>
|
|
|
|
|
</b></pre><BR>
|
|
|
|
|
<h3>ZSTD_DStream management functions</h3><pre></pre><b><pre>ZSTD_DStream* ZSTD_createDStream(void);
|
|
|
|
|
size_t ZSTD_freeDStream(ZSTD_DStream* zds);
|
|
|
|
|
</pre></b><BR>
|
|
|
|
|
<h3>Streaming decompression functions</h3><pre></pre><b><pre>size_t ZSTD_initDStream(ZSTD_DStream* zds);
|
|
|
|
|
size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inBuffer* input);
|
|
|
|
|
</pre></b><BR>
|
|
|
|
|
<pre><b>size_t ZSTD_DStreamInSize(void); </b>/*!< recommended size for input buffer */<b>
|
|
|
|
|
</b></pre><BR>
|
|
|
|
|
<pre><b>size_t ZSTD_DStreamOutSize(void); </b>/*!< recommended size for output buffer. Guarantee to successfully flush at least one complete block in all circumstances. */<b>
|
|
|
|
|
</b></pre><BR>
|
|
|
|
|
<a name="Chapter11"></a><h2>ADVANCED AND EXPERIMENTAL FUNCTIONS</h2><pre>
|
|
|
|
|
The definitions in the following section are considered experimental.
|
|
|
|
|
They are provided for advanced scenarios.
|
|
|
|
|
They should never be used with a dynamic library, as prototypes may change in the future.
|
|
|
|
|
Use them only in association with static linking.
|
|
|
|
|
|
|
|
|
|
<BR></pre>
|
|
|
|
|
|
|
|
|
|
<a name="Chapter12"></a><h2>Candidate API for promotion to stable status</h2><pre>
|
|
|
|
|
The following symbols and constants form the "staging area" :
|
|
|
|
|
they are considered to join "stable API" by v1.4.0.
|
|
|
|
|
The proposal is written so that it can be made stable "as is",
|
|
|
|
|
though it's still possible to suggest improvements.
|
|
|
|
|
Staging is in fact last chance for changes,
|
|
|
|
|
the API is locked once reaching "stable" status.
|
|
|
|
|
|
|
|
|
|
<BR></pre>
|
|
|
|
|
|
|
|
|
|
<pre><b>int ZSTD_minCLevel(void); </b>/*!< minimum negative compression level allowed */<b>
|
|
|
|
|
</b></pre><BR>
|
|
|
|
|
<pre><b>size_t ZSTD_findFrameCompressedSize(const void* src, size_t srcSize);
|
|
|
|
|
</b><p> `src` should point to the start of a ZSTD frame or skippable frame.
|
|
|
|
|
`srcSize` must be >= first frame size
|
|
|
|
|
@return : the compressed size of the first frame starting at `src`,
|
|
|
|
|
suitable to pass as `srcSize` to `ZSTD_decompress` or similar,
|
|
|
|
|
or an error code if input is invalid
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<pre><b>size_t ZSTD_sizeof_CCtx(const ZSTD_CCtx* cctx);
|
|
|
|
|
size_t ZSTD_sizeof_DCtx(const ZSTD_DCtx* dctx);
|
|
|
|
|
size_t ZSTD_sizeof_CStream(const ZSTD_CStream* zcs);
|
|
|
|
|
size_t ZSTD_sizeof_DStream(const ZSTD_DStream* zds);
|
|
|
|
|
size_t ZSTD_sizeof_CDict(const ZSTD_CDict* cdict);
|
|
|
|
|
size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
|
|
|
|
|
</b><p> These functions give the _current_ memory usage of selected object.
|
|
|
|
|
Note that object memory usage can evolve (increase or decrease) over time.
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<a name="Chapter13"></a><h2>Advanced compression API</h2><pre></pre>
|
|
|
|
|
<a name="Chapter7"></a><h2>Advanced compression API</h2><pre></pre>
|
|
|
|
|
|
|
|
|
|
<pre><b>typedef enum { ZSTD_fast=1,
|
|
|
|
|
ZSTD_dfast=2,
|
|
|
|
@@ -407,7 +206,10 @@ size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
|
|
|
|
|
</b></pre><BR>
|
|
|
|
|
<pre><b>typedef enum {
|
|
|
|
|
|
|
|
|
|
</b>/* compression parameters */<b>
|
|
|
|
|
</b>/* compression parameters<b>
|
|
|
|
|
* Note: When compressing with a ZSTD_CDict these parameters are superseded
|
|
|
|
|
* by the parameters used to construct the ZSTD_CDict. See ZSTD_CCtx_refCDict()
|
|
|
|
|
* for more info (superseded-by-cdict). */
|
|
|
|
|
ZSTD_c_compressionLevel=100, </b>/* Update all compression parameters according to pre-defined cLevel table<b>
|
|
|
|
|
* Default level is ZSTD_CLEVEL_DEFAULT==3.
|
|
|
|
|
* Special: value 0 means default, which is controlled by ZSTD_CLEVEL_DEFAULT.
|
|
|
|
@@ -529,6 +331,7 @@ size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
|
|
|
|
|
* ZSTD_c_format
|
|
|
|
|
* ZSTD_c_forceMaxWindow
|
|
|
|
|
* ZSTD_c_forceAttachDict
|
|
|
|
|
* ZSTD_c_literalCompressionMode
|
|
|
|
|
* Because they are not stable, it's necessary to define ZSTD_STATIC_LINKING_ONLY to access them.
|
|
|
|
|
* note : never ever use experimentalParam? names directly;
|
|
|
|
|
* also, the enums values themselves are unstable and can still change.
|
|
|
|
@@ -536,7 +339,8 @@ size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
|
|
|
|
|
ZSTD_c_experimentalParam1=500,
|
|
|
|
|
ZSTD_c_experimentalParam2=10,
|
|
|
|
|
ZSTD_c_experimentalParam3=1000,
|
|
|
|
|
ZSTD_c_experimentalParam4=1001
|
|
|
|
|
ZSTD_c_experimentalParam4=1001,
|
|
|
|
|
ZSTD_c_experimentalParam5=1002,
|
|
|
|
|
} ZSTD_cParameter;
|
|
|
|
|
</b></pre><BR>
|
|
|
|
|
<pre><b>typedef struct {
|
|
|
|
@@ -584,58 +388,6 @@ size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
|
|
|
|
|
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<pre><b>size_t ZSTD_CCtx_loadDictionary(ZSTD_CCtx* cctx, const void* dict, size_t dictSize);
|
|
|
|
|
</b><p> Create an internal CDict from `dict` buffer.
|
|
|
|
|
Decompression will have to use same dictionary.
|
|
|
|
|
@result : 0, or an error code (which can be tested with ZSTD_isError()).
|
|
|
|
|
Special: Loading a NULL (or 0-size) dictionary invalidates previous dictionary,
|
|
|
|
|
meaning "return to no-dictionary mode".
|
|
|
|
|
Note 1 : Dictionary is sticky, it will be used for all future compressed frames.
|
|
|
|
|
To return to "no-dictionary" situation, load a NULL dictionary (or reset parameters).
|
|
|
|
|
Note 2 : Loading a dictionary involves building tables.
|
|
|
|
|
It's also a CPU consuming operation, with non-negligible impact on latency.
|
|
|
|
|
Tables are dependent on compression parameters, and for this reason,
|
|
|
|
|
compression parameters can no longer be changed after loading a dictionary.
|
|
|
|
|
Note 3 :`dict` content will be copied internally.
|
|
|
|
|
Use experimental ZSTD_CCtx_loadDictionary_byReference() to reference content instead.
|
|
|
|
|
In such a case, dictionary buffer must outlive its users.
|
|
|
|
|
Note 4 : Use ZSTD_CCtx_loadDictionary_advanced()
|
|
|
|
|
to precisely select how dictionary content must be interpreted.
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<pre><b>size_t ZSTD_CCtx_refCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict);
|
|
|
|
|
</b><p> Reference a prepared dictionary, to be used for all next compressed frames.
|
|
|
|
|
Note that compression parameters are enforced from within CDict,
|
|
|
|
|
and supercede any compression parameter previously set within CCtx.
|
|
|
|
|
The dictionary will remain valid for future compressed frames using same CCtx.
|
|
|
|
|
@result : 0, or an error code (which can be tested with ZSTD_isError()).
|
|
|
|
|
Special : Referencing a NULL CDict means "return to no-dictionary mode".
|
|
|
|
|
Note 1 : Currently, only one dictionary can be managed.
|
|
|
|
|
Referencing a new dictionary effectively "discards" any previous one.
|
|
|
|
|
Note 2 : CDict is just referenced, its lifetime must outlive its usage within CCtx.
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<pre><b>size_t ZSTD_CCtx_refPrefix(ZSTD_CCtx* cctx,
|
|
|
|
|
const void* prefix, size_t prefixSize);
|
|
|
|
|
</b><p> Reference a prefix (single-usage dictionary) for next compressed frame.
|
|
|
|
|
A prefix is **only used once**. Tables are discarded at end of frame (ZSTD_e_end).
|
|
|
|
|
Decompression will need same prefix to properly regenerate data.
|
|
|
|
|
Compressing with a prefix is similar in outcome as performing a diff and compressing it,
|
|
|
|
|
but performs much faster, especially during decompression (compression speed is tunable with compression level).
|
|
|
|
|
@result : 0, or an error code (which can be tested with ZSTD_isError()).
|
|
|
|
|
Special: Adding any prefix (including NULL) invalidates any previous prefix or dictionary
|
|
|
|
|
Note 1 : Prefix buffer is referenced. It **must** outlive compression.
|
|
|
|
|
Its content must remain unmodified during compression.
|
|
|
|
|
Note 2 : If the intention is to diff some large src data blob with some prior version of itself,
|
|
|
|
|
ensure that the window size is large enough to contain the entire source.
|
|
|
|
|
See ZSTD_c_windowLog.
|
|
|
|
|
Note 3 : Referencing a prefix involves building tables, which are dependent on compression parameters.
|
|
|
|
|
It's a CPU consuming operation, with non-negligible impact on latency.
|
|
|
|
|
If there is a need to use the same prefix multiple times, consider loadDictionary instead.
|
|
|
|
|
Note 4 : By default, the prefix is interpreted as raw content (ZSTD_dm_rawContent).
|
|
|
|
|
Use experimental ZSTD_CCtx_refPrefix_advanced() to alter dictionary interpretation.
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<pre><b>typedef enum {
|
|
|
|
|
ZSTD_reset_session_only = 1,
|
|
|
|
|
ZSTD_reset_parameters = 2,
|
|
|
|
@@ -672,42 +424,7 @@ size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
|
|
|
|
|
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<pre><b>typedef enum {
|
|
|
|
|
ZSTD_e_continue=0, </b>/* collect more data, encoder decides when to output compressed result, for optimal compression ratio */<b>
|
|
|
|
|
ZSTD_e_flush=1, </b>/* flush any data provided so far,<b>
|
|
|
|
|
* it creates (at least) one new block, that can be decoded immediately on reception;
|
|
|
|
|
* frame will continue: any future data can still reference previously compressed data, improving compression. */
|
|
|
|
|
ZSTD_e_end=2 </b>/* flush any remaining data _and_ close current frame.<b>
|
|
|
|
|
* note that frame is only closed after compressed data is fully flushed (return value == 0).
|
|
|
|
|
* After that point, any additional data starts a new frame.
|
|
|
|
|
* note : each frame is independent (does not reference any content from previous frame). */
|
|
|
|
|
} ZSTD_EndDirective;
|
|
|
|
|
</b></pre><BR>
|
|
|
|
|
<pre><b>size_t ZSTD_compressStream2( ZSTD_CCtx* cctx,
|
|
|
|
|
ZSTD_outBuffer* output,
|
|
|
|
|
ZSTD_inBuffer* input,
|
|
|
|
|
ZSTD_EndDirective endOp);
|
|
|
|
|
</b><p> Behaves about the same as ZSTD_compressStream, with additional control on end directive.
|
|
|
|
|
- Compression parameters are pushed into CCtx before starting compression, using ZSTD_CCtx_set*()
|
|
|
|
|
- Compression parameters cannot be changed once compression is started (save a list of exceptions in multi-threading mode)
|
|
|
|
|
- outpot->pos must be <= dstCapacity, input->pos must be <= srcSize
|
|
|
|
|
- outpot->pos and input->pos will be updated. They are guaranteed to remain below their respective limit.
|
|
|
|
|
- When nbWorkers==0 (default), function is blocking : it completes its job before returning to caller.
|
|
|
|
|
- When nbWorkers>=1, function is non-blocking : it just acquires a copy of input, and distributes jobs to internal worker threads, flush whatever is available,
|
|
|
|
|
and then immediately returns, just indicating that there is some data remaining to be flushed.
|
|
|
|
|
The function nonetheless guarantees forward progress : it will return only after it reads or write at least 1+ byte.
|
|
|
|
|
- Exception : if the first call requests a ZSTD_e_end directive and provides enough dstCapacity, the function delegates to ZSTD_compress2() which is always blocking.
|
|
|
|
|
- @return provides a minimum amount of data remaining to be flushed from internal buffers
|
|
|
|
|
or an error code, which can be tested using ZSTD_isError().
|
|
|
|
|
if @return != 0, flush is not fully completed, there is still some data left within internal buffers.
|
|
|
|
|
This is useful for ZSTD_e_flush, since in this case more flushes are necessary to empty all buffers.
|
|
|
|
|
For ZSTD_e_end, @return == 0 when internal buffers are fully flushed and frame is completed.
|
|
|
|
|
- after a ZSTD_e_end directive, if internal buffer is not fully flushed (@return != 0),
|
|
|
|
|
only ZSTD_e_end or ZSTD_e_flush operations are allowed.
|
|
|
|
|
Before starting a new compression job, or changing compression parameters,
|
|
|
|
|
it is required to fully flush internal buffers.
|
|
|
|
|
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
<a name="Chapter8"></a><h2>Advanced decompression API</h2><pre></pre>
|
|
|
|
|
|
|
|
|
|
<pre><b>typedef enum {
|
|
|
|
|
|
|
|
|
@@ -715,7 +432,8 @@ size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
|
|
|
|
|
* the streaming API will refuse to allocate memory buffer
|
|
|
|
|
* in order to protect the host from unreasonable memory requirements.
|
|
|
|
|
* This parameter is only useful in streaming mode, since no internal buffer is allocated in single-pass mode.
|
|
|
|
|
* By default, a decompression context accepts window sizes <= (1 << ZSTD_WINDOWLOG_LIMIT_DEFAULT) */
|
|
|
|
|
* By default, a decompression context accepts window sizes <= (1 << ZSTD_WINDOWLOG_LIMIT_DEFAULT).
|
|
|
|
|
* Special: value 0 means "use default maximum windowLog". */
|
|
|
|
|
|
|
|
|
|
</b>/* note : additional experimental parameters are also available<b>
|
|
|
|
|
* within the experimental section of the API.
|
|
|
|
@@ -746,6 +464,352 @@ size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
|
|
|
|
|
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<pre><b>size_t ZSTD_DCtx_reset(ZSTD_DCtx* dctx, ZSTD_ResetDirective reset);
|
|
|
|
|
</b><p> Return a DCtx to clean state.
|
|
|
|
|
Session and parameters can be reset jointly or separately.
|
|
|
|
|
Parameters can only be reset when no active frame is being decompressed.
|
|
|
|
|
@return : 0, or an error code, which can be tested with ZSTD_isError()
|
|
|
|
|
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<a name="Chapter9"></a><h2>Streaming</h2><pre></pre>
|
|
|
|
|
|
|
|
|
|
<pre><b>typedef struct ZSTD_inBuffer_s {
|
|
|
|
|
const void* src; </b>/**< start of input buffer */<b>
|
|
|
|
|
size_t size; </b>/**< size of input buffer */<b>
|
|
|
|
|
size_t pos; </b>/**< position where reading stopped. Will be updated. Necessarily 0 <= pos <= size */<b>
|
|
|
|
|
} ZSTD_inBuffer;
|
|
|
|
|
</b></pre><BR>
|
|
|
|
|
<pre><b>typedef struct ZSTD_outBuffer_s {
|
|
|
|
|
void* dst; </b>/**< start of output buffer */<b>
|
|
|
|
|
size_t size; </b>/**< size of output buffer */<b>
|
|
|
|
|
size_t pos; </b>/**< position where writing stopped. Will be updated. Necessarily 0 <= pos <= size */<b>
|
|
|
|
|
} ZSTD_outBuffer;
|
|
|
|
|
</b></pre><BR>
|
|
|
|
|
<a name="Chapter10"></a><h2>Streaming compression - HowTo</h2><pre>
|
|
|
|
|
A ZSTD_CStream object is required to track streaming operation.
|
|
|
|
|
Use ZSTD_createCStream() and ZSTD_freeCStream() to create/release resources.
|
|
|
|
|
ZSTD_CStream objects can be reused multiple times on consecutive compression operations.
|
|
|
|
|
It is recommended to re-use ZSTD_CStream since it will play nicer with system's memory, by re-using already allocated memory.
|
|
|
|
|
|
|
|
|
|
For parallel execution, use one separate ZSTD_CStream per thread.
|
|
|
|
|
|
|
|
|
|
note : since v1.3.0, ZSTD_CStream and ZSTD_CCtx are the same thing.
|
|
|
|
|
|
|
|
|
|
Parameters are sticky : when starting a new compression on the same context,
|
|
|
|
|
it will re-use the same sticky parameters as previous compression session.
|
|
|
|
|
When in doubt, it's recommended to fully initialize the context before usage.
|
|
|
|
|
Use ZSTD_CCtx_reset() to reset the context and ZSTD_CCtx_setParameter(),
|
|
|
|
|
ZSTD_CCtx_setPledgedSrcSize(), or ZSTD_CCtx_loadDictionary() and friends to
|
|
|
|
|
set more specific parameters, the pledged source size, or load a dictionary.
|
|
|
|
|
|
|
|
|
|
Use ZSTD_compressStream2() with ZSTD_e_continue as many times as necessary to
|
|
|
|
|
consume input stream. The function will automatically update both `pos`
|
|
|
|
|
fields within `input` and `output`.
|
|
|
|
|
Note that the function may not consume the entire input, for example, because
|
|
|
|
|
the output buffer is already full, in which case `input.pos < input.size`.
|
|
|
|
|
The caller must check if input has been entirely consumed.
|
|
|
|
|
If not, the caller must make some room to receive more compressed data,
|
|
|
|
|
and then present again remaining input data.
|
|
|
|
|
note: ZSTD_e_continue is guaranteed to make some forward progress when called,
|
|
|
|
|
but doesn't guarantee maximal forward progress. This is especially relevant
|
|
|
|
|
when compressing with multiple threads. The call won't block if it can
|
|
|
|
|
consume some input, but if it can't it will wait for some, but not all,
|
|
|
|
|
output to be flushed.
|
|
|
|
|
@return : provides a minimum amount of data remaining to be flushed from internal buffers
|
|
|
|
|
or an error code, which can be tested using ZSTD_isError().
|
|
|
|
|
|
|
|
|
|
At any moment, it's possible to flush whatever data might remain stuck within internal buffer,
|
|
|
|
|
using ZSTD_compressStream2() with ZSTD_e_flush. `output->pos` will be updated.
|
|
|
|
|
Note that, if `output->size` is too small, a single invocation with ZSTD_e_flush might not be enough (return code > 0).
|
|
|
|
|
In which case, make some room to receive more compressed data, and call again ZSTD_compressStream2() with ZSTD_e_flush.
|
|
|
|
|
You must continue calling ZSTD_compressStream2() with ZSTD_e_flush until it returns 0, at which point you can change the
|
|
|
|
|
operation.
|
|
|
|
|
note: ZSTD_e_flush will flush as much output as possible, meaning when compressing with multiple threads, it will
|
|
|
|
|
block until the flush is complete or the output buffer is full.
|
|
|
|
|
@return : 0 if internal buffers are entirely flushed,
|
|
|
|
|
>0 if some data still present within internal buffer (the value is minimal estimation of remaining size),
|
|
|
|
|
or an error code, which can be tested using ZSTD_isError().
|
|
|
|
|
|
|
|
|
|
Calling ZSTD_compressStream2() with ZSTD_e_end instructs to finish a frame.
|
|
|
|
|
It will perform a flush and write frame epilogue.
|
|
|
|
|
The epilogue is required for decoders to consider a frame completed.
|
|
|
|
|
flush operation is the same, and follows same rules as calling ZSTD_compressStream2() with ZSTD_e_flush.
|
|
|
|
|
You must continue calling ZSTD_compressStream2() with ZSTD_e_end until it returns 0, at which point you are free to
|
|
|
|
|
start a new frame.
|
|
|
|
|
note: ZSTD_e_end will flush as much output as possible, meaning when compressing with multiple threads, it will
|
|
|
|
|
block until the flush is complete or the output buffer is full.
|
|
|
|
|
@return : 0 if frame fully completed and fully flushed,
|
|
|
|
|
>0 if some data still present within internal buffer (the value is minimal estimation of remaining size),
|
|
|
|
|
or an error code, which can be tested using ZSTD_isError().
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<BR></pre>
|
|
|
|
|
|
|
|
|
|
<pre><b>typedef ZSTD_CCtx ZSTD_CStream; </b>/**< CCtx and CStream are now effectively same object (>= v1.3.0) */<b>
|
|
|
|
|
</b></pre><BR>
|
|
|
|
|
<h3>ZSTD_CStream management functions</h3><pre></pre><b><pre>ZSTD_CStream* ZSTD_createCStream(void);
|
|
|
|
|
size_t ZSTD_freeCStream(ZSTD_CStream* zcs);
|
|
|
|
|
</pre></b><BR>
|
|
|
|
|
<h3>Streaming compression functions</h3><pre></pre><b><pre>typedef enum {
|
|
|
|
|
ZSTD_e_continue=0, </b>/* collect more data, encoder decides when to output compressed result, for optimal compression ratio */<b>
|
|
|
|
|
ZSTD_e_flush=1, </b>/* flush any data provided so far,<b>
|
|
|
|
|
* it creates (at least) one new block, that can be decoded immediately on reception;
|
|
|
|
|
* frame will continue: any future data can still reference previously compressed data, improving compression.
|
|
|
|
|
* note : multithreaded compression will block to flush as much output as possible. */
|
|
|
|
|
ZSTD_e_end=2 </b>/* flush any remaining data _and_ close current frame.<b>
|
|
|
|
|
* note that frame is only closed after compressed data is fully flushed (return value == 0).
|
|
|
|
|
* After that point, any additional data starts a new frame.
|
|
|
|
|
* note : each frame is independent (does not reference any content from previous frame).
|
|
|
|
|
: note : multithreaded compression will block to flush as much output as possible. */
|
|
|
|
|
} ZSTD_EndDirective;
|
|
|
|
|
</pre></b><BR>
|
|
|
|
|
<pre><b>size_t ZSTD_compressStream2( ZSTD_CCtx* cctx,
|
|
|
|
|
ZSTD_outBuffer* output,
|
|
|
|
|
ZSTD_inBuffer* input,
|
|
|
|
|
ZSTD_EndDirective endOp);
|
|
|
|
|
</b><p> Behaves about the same as ZSTD_compressStream, with additional control on end directive.
|
|
|
|
|
- Compression parameters are pushed into CCtx before starting compression, using ZSTD_CCtx_set*()
|
|
|
|
|
- Compression parameters cannot be changed once compression is started (save a list of exceptions in multi-threading mode)
|
|
|
|
|
- outpot->pos must be <= dstCapacity, input->pos must be <= srcSize
|
|
|
|
|
- outpot->pos and input->pos will be updated. They are guaranteed to remain below their respective limit.
|
|
|
|
|
- When nbWorkers==0 (default), function is blocking : it completes its job before returning to caller.
|
|
|
|
|
- When nbWorkers>=1, function is non-blocking : it just acquires a copy of input, and distributes jobs to internal worker threads, flush whatever is available,
|
|
|
|
|
and then immediately returns, just indicating that there is some data remaining to be flushed.
|
|
|
|
|
The function nonetheless guarantees forward progress : it will return only after it reads or write at least 1+ byte.
|
|
|
|
|
- Exception : if the first call requests a ZSTD_e_end directive and provides enough dstCapacity, the function delegates to ZSTD_compress2() which is always blocking.
|
|
|
|
|
- @return provides a minimum amount of data remaining to be flushed from internal buffers
|
|
|
|
|
or an error code, which can be tested using ZSTD_isError().
|
|
|
|
|
if @return != 0, flush is not fully completed, there is still some data left within internal buffers.
|
|
|
|
|
This is useful for ZSTD_e_flush, since in this case more flushes are necessary to empty all buffers.
|
|
|
|
|
For ZSTD_e_end, @return == 0 when internal buffers are fully flushed and frame is completed.
|
|
|
|
|
- after a ZSTD_e_end directive, if internal buffer is not fully flushed (@return != 0),
|
|
|
|
|
only ZSTD_e_end or ZSTD_e_flush operations are allowed.
|
|
|
|
|
Before starting a new compression job, or changing compression parameters,
|
|
|
|
|
it is required to fully flush internal buffers.
|
|
|
|
|
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<pre><b>size_t ZSTD_CStreamInSize(void); </b>/**< recommended size for input buffer */<b>
|
|
|
|
|
</b></pre><BR>
|
|
|
|
|
<pre><b>size_t ZSTD_CStreamOutSize(void); </b>/**< recommended size for output buffer. Guarantee to successfully flush at least one complete compressed block in all circumstances. */<b>
|
|
|
|
|
</b></pre><BR>
|
|
|
|
|
<a name="Chapter11"></a><h2>This is a legacy streaming API, and can be replaced by ZSTD_CCtx_reset() and</h2><pre> ZSTD_compressStream2(). It is redundent, but is still fully supported.
|
|
|
|
|
Advanced parameters and dictionary compression can only be used through the
|
|
|
|
|
new API.
|
|
|
|
|
<BR></pre>
|
|
|
|
|
|
|
|
|
|
<a name="Chapter12"></a><h2>Equivalent to:</h2><pre>
|
|
|
|
|
ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
|
|
|
|
|
ZSTD_CCtx_refCDict(zcs, NULL); // clear the dictionary (if any)
|
|
|
|
|
ZSTD_CCtx_setParameter(zcs, ZSTD_c_compressionLevel, compressionLevel);
|
|
|
|
|
|
|
|
|
|
<BR></pre>
|
|
|
|
|
|
|
|
|
|
<a name="Chapter13"></a><h2>Alternative for ZSTD_compressStream2(zcs, output, input, ZSTD_e_continue).</h2><pre> NOTE: The return value is different. ZSTD_compressStream() returns a hint for
|
|
|
|
|
the next read size (if non-zero and not an error). ZSTD_compressStream2()
|
|
|
|
|
returns the number of bytes left to flush (if non-zero and not an error).
|
|
|
|
|
|
|
|
|
|
<BR></pre>
|
|
|
|
|
|
|
|
|
|
<a name="Chapter14"></a><h2>Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_flush).</h2><pre></pre>
|
|
|
|
|
|
|
|
|
|
<a name="Chapter15"></a><h2>Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_end).</h2><pre></pre>
|
|
|
|
|
|
|
|
|
|
<a name="Chapter16"></a><h2>Streaming decompression - HowTo</h2><pre>
|
|
|
|
|
A ZSTD_DStream object is required to track streaming operations.
|
|
|
|
|
Use ZSTD_createDStream() and ZSTD_freeDStream() to create/release resources.
|
|
|
|
|
ZSTD_DStream objects can be re-used multiple times.
|
|
|
|
|
|
|
|
|
|
Use ZSTD_initDStream() to start a new decompression operation.
|
|
|
|
|
@return : recommended first input size
|
|
|
|
|
Alternatively, use advanced API to set specific properties.
|
|
|
|
|
|
|
|
|
|
Use ZSTD_decompressStream() repetitively to consume your input.
|
|
|
|
|
The function will update both `pos` fields.
|
|
|
|
|
If `input.pos < input.size`, some input has not been consumed.
|
|
|
|
|
It's up to the caller to present again remaining data.
|
|
|
|
|
The function tries to flush all data decoded immediately, respecting output buffer size.
|
|
|
|
|
If `output.pos < output.size`, decoder has flushed everything it could.
|
|
|
|
|
But if `output.pos == output.size`, there might be some data left within internal buffers.,
|
|
|
|
|
In which case, call ZSTD_decompressStream() again to flush whatever remains in the buffer.
|
|
|
|
|
Note : with no additional input provided, amount of data flushed is necessarily <= ZSTD_BLOCKSIZE_MAX.
|
|
|
|
|
@return : 0 when a frame is completely decoded and fully flushed,
|
|
|
|
|
or an error code, which can be tested using ZSTD_isError(),
|
|
|
|
|
or any other value > 0, which means there is still some decoding or flushing to do to complete current frame :
|
|
|
|
|
the return value is a suggested next input size (just a hint for better latency)
|
|
|
|
|
that will never request more than the remaining frame size.
|
|
|
|
|
|
|
|
|
|
<BR></pre>
|
|
|
|
|
|
|
|
|
|
<pre><b>typedef ZSTD_DCtx ZSTD_DStream; </b>/**< DCtx and DStream are now effectively same object (>= v1.3.0) */<b>
|
|
|
|
|
</b></pre><BR>
|
|
|
|
|
<h3>ZSTD_DStream management functions</h3><pre></pre><b><pre>ZSTD_DStream* ZSTD_createDStream(void);
|
|
|
|
|
size_t ZSTD_freeDStream(ZSTD_DStream* zds);
|
|
|
|
|
</pre></b><BR>
|
|
|
|
|
<h3>Streaming decompression functions</h3><pre></pre><b><pre>size_t ZSTD_initDStream(ZSTD_DStream* zds);
|
|
|
|
|
size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inBuffer* input);
|
|
|
|
|
</pre></b><BR>
|
|
|
|
|
<pre><b>size_t ZSTD_DStreamInSize(void); </b>/*!< recommended size for input buffer */<b>
|
|
|
|
|
</b></pre><BR>
|
|
|
|
|
<pre><b>size_t ZSTD_DStreamOutSize(void); </b>/*!< recommended size for output buffer. Guarantee to successfully flush at least one complete block in all circumstances. */<b>
|
|
|
|
|
</b></pre><BR>
|
|
|
|
|
<a name="Chapter17"></a><h2>Simple dictionary API</h2><pre></pre>
|
|
|
|
|
|
|
|
|
|
<pre><b>size_t ZSTD_compress_usingDict(ZSTD_CCtx* ctx,
|
|
|
|
|
void* dst, size_t dstCapacity,
|
|
|
|
|
const void* src, size_t srcSize,
|
|
|
|
|
const void* dict,size_t dictSize,
|
|
|
|
|
int compressionLevel);
|
|
|
|
|
</b><p> Compression at an explicit compression level using a Dictionary.
|
|
|
|
|
A dictionary can be any arbitrary data segment (also called a prefix),
|
|
|
|
|
or a buffer with specified information (see dictBuilder/zdict.h).
|
|
|
|
|
Note : This function loads the dictionary, resulting in significant startup delay.
|
|
|
|
|
It's intended for a dictionary used only once.
|
|
|
|
|
Note 2 : When `dict == NULL || dictSize < 8` no dictionary is used.
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<pre><b>size_t ZSTD_decompress_usingDict(ZSTD_DCtx* dctx,
|
|
|
|
|
void* dst, size_t dstCapacity,
|
|
|
|
|
const void* src, size_t srcSize,
|
|
|
|
|
const void* dict,size_t dictSize);
|
|
|
|
|
</b><p> Decompression using a known Dictionary.
|
|
|
|
|
Dictionary must be identical to the one used during compression.
|
|
|
|
|
Note : This function loads the dictionary, resulting in significant startup delay.
|
|
|
|
|
It's intended for a dictionary used only once.
|
|
|
|
|
Note : When `dict == NULL || dictSize < 8` no dictionary is used.
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<a name="Chapter18"></a><h2>Bulk processing dictionary API</h2><pre></pre>
|
|
|
|
|
|
|
|
|
|
<pre><b>ZSTD_CDict* ZSTD_createCDict(const void* dictBuffer, size_t dictSize,
|
|
|
|
|
int compressionLevel);
|
|
|
|
|
</b><p> When compressing multiple messages / blocks using the same dictionary, it's recommended to load it only once.
|
|
|
|
|
ZSTD_createCDict() will create a digested dictionary, ready to start future compression operations without startup cost.
|
|
|
|
|
ZSTD_CDict can be created once and shared by multiple threads concurrently, since its usage is read-only.
|
|
|
|
|
`dictBuffer` can be released after ZSTD_CDict creation, because its content is copied within CDict.
|
|
|
|
|
Consider experimental function `ZSTD_createCDict_byReference()` if you prefer to not duplicate `dictBuffer` content.
|
|
|
|
|
Note : A ZSTD_CDict can be created from an empty dictBuffer, but it is inefficient when used to compress small data.
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<pre><b>size_t ZSTD_freeCDict(ZSTD_CDict* CDict);
|
|
|
|
|
</b><p> Function frees memory allocated by ZSTD_createCDict().
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<pre><b>size_t ZSTD_compress_usingCDict(ZSTD_CCtx* cctx,
|
|
|
|
|
void* dst, size_t dstCapacity,
|
|
|
|
|
const void* src, size_t srcSize,
|
|
|
|
|
const ZSTD_CDict* cdict);
|
|
|
|
|
</b><p> Compression using a digested Dictionary.
|
|
|
|
|
Recommended when same dictionary is used multiple times.
|
|
|
|
|
Note : compression level is _decided at dictionary creation time_,
|
|
|
|
|
and frame parameters are hardcoded (dictID=yes, contentSize=yes, checksum=no)
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<pre><b>ZSTD_DDict* ZSTD_createDDict(const void* dictBuffer, size_t dictSize);
|
|
|
|
|
</b><p> Create a digested dictionary, ready to start decompression operation without startup delay.
|
|
|
|
|
dictBuffer can be released after DDict creation, as its content is copied inside DDict.
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<pre><b>size_t ZSTD_freeDDict(ZSTD_DDict* ddict);
|
|
|
|
|
</b><p> Function frees memory allocated with ZSTD_createDDict()
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<pre><b>size_t ZSTD_decompress_usingDDict(ZSTD_DCtx* dctx,
|
|
|
|
|
void* dst, size_t dstCapacity,
|
|
|
|
|
const void* src, size_t srcSize,
|
|
|
|
|
const ZSTD_DDict* ddict);
|
|
|
|
|
</b><p> Decompression using a digested Dictionary.
|
|
|
|
|
Recommended when same dictionary is used multiple times.
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<a name="Chapter19"></a><h2>Dictionary helper functions</h2><pre></pre>
|
|
|
|
|
|
|
|
|
|
<pre><b>unsigned ZSTD_getDictID_fromDict(const void* dict, size_t dictSize);
|
|
|
|
|
</b><p> Provides the dictID stored within dictionary.
|
|
|
|
|
if @return == 0, the dictionary is not conformant with Zstandard specification.
|
|
|
|
|
It can still be loaded, but as a content-only dictionary.
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<pre><b>unsigned ZSTD_getDictID_fromDDict(const ZSTD_DDict* ddict);
|
|
|
|
|
</b><p> Provides the dictID of the dictionary loaded into `ddict`.
|
|
|
|
|
If @return == 0, the dictionary is not conformant to Zstandard specification, or empty.
|
|
|
|
|
Non-conformant dictionaries can still be loaded, but as content-only dictionaries.
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<pre><b>unsigned ZSTD_getDictID_fromFrame(const void* src, size_t srcSize);
|
|
|
|
|
</b><p> Provides the dictID required to decompressed the frame stored within `src`.
|
|
|
|
|
If @return == 0, the dictID could not be decoded.
|
|
|
|
|
This could for one of the following reasons :
|
|
|
|
|
- The frame does not require a dictionary to be decoded (most common case).
|
|
|
|
|
- The frame was built with dictID intentionally removed. Whatever dictionary is necessary is a hidden information.
|
|
|
|
|
Note : this use case also happens when using a non-conformant dictionary.
|
|
|
|
|
- `srcSize` is too small, and as a result, the frame header could not be decoded (only possible if `srcSize < ZSTD_FRAMEHEADERSIZE_MAX`).
|
|
|
|
|
- This is not a Zstandard frame.
|
|
|
|
|
When identifying the exact failure cause, it's possible to use ZSTD_getFrameHeader(), which will provide a more precise error code.
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<a name="Chapter20"></a><h2>Advanced dictionary and prefix API</h2><pre>
|
|
|
|
|
This API allows dictionaries to be used with ZSTD_compress2(),
|
|
|
|
|
ZSTD_compressStream2(), and ZSTD_decompress(). Dictionaries are sticky, and
|
|
|
|
|
only reset with the context is reset with ZSTD_reset_parameters or
|
|
|
|
|
ZSTD_reset_session_and_parameters. Prefixes are single-use.
|
|
|
|
|
<BR></pre>
|
|
|
|
|
|
|
|
|
|
<pre><b>size_t ZSTD_CCtx_loadDictionary(ZSTD_CCtx* cctx, const void* dict, size_t dictSize);
|
|
|
|
|
</b><p> Create an internal CDict from `dict` buffer.
|
|
|
|
|
Decompression will have to use same dictionary.
|
|
|
|
|
@result : 0, or an error code (which can be tested with ZSTD_isError()).
|
|
|
|
|
Special: Loading a NULL (or 0-size) dictionary invalidates previous dictionary,
|
|
|
|
|
meaning "return to no-dictionary mode".
|
|
|
|
|
Note 1 : Dictionary is sticky, it will be used for all future compressed frames.
|
|
|
|
|
To return to "no-dictionary" situation, load a NULL dictionary (or reset parameters).
|
|
|
|
|
Note 2 : Loading a dictionary involves building tables.
|
|
|
|
|
It's also a CPU consuming operation, with non-negligible impact on latency.
|
|
|
|
|
Tables are dependent on compression parameters, and for this reason,
|
|
|
|
|
compression parameters can no longer be changed after loading a dictionary.
|
|
|
|
|
Note 3 :`dict` content will be copied internally.
|
|
|
|
|
Use experimental ZSTD_CCtx_loadDictionary_byReference() to reference content instead.
|
|
|
|
|
In such a case, dictionary buffer must outlive its users.
|
|
|
|
|
Note 4 : Use ZSTD_CCtx_loadDictionary_advanced()
|
|
|
|
|
to precisely select how dictionary content must be interpreted.
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<pre><b>size_t ZSTD_CCtx_refCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict);
|
|
|
|
|
</b><p> Reference a prepared dictionary, to be used for all next compressed frames.
|
|
|
|
|
Note that compression parameters are enforced from within CDict,
|
|
|
|
|
and supersede any compression parameter previously set within CCtx.
|
|
|
|
|
The parameters ignored are labled as "superseded-by-cdict" in the ZSTD_cParameter enum docs.
|
|
|
|
|
The ignored parameters will be used again if the CCtx is returned to no-dictionary mode.
|
|
|
|
|
The dictionary will remain valid for future compressed frames using same CCtx.
|
|
|
|
|
@result : 0, or an error code (which can be tested with ZSTD_isError()).
|
|
|
|
|
Special : Referencing a NULL CDict means "return to no-dictionary mode".
|
|
|
|
|
Note 1 : Currently, only one dictionary can be managed.
|
|
|
|
|
Referencing a new dictionary effectively "discards" any previous one.
|
|
|
|
|
Note 2 : CDict is just referenced, its lifetime must outlive its usage within CCtx.
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<pre><b>size_t ZSTD_CCtx_refPrefix(ZSTD_CCtx* cctx,
|
|
|
|
|
const void* prefix, size_t prefixSize);
|
|
|
|
|
</b><p> Reference a prefix (single-usage dictionary) for next compressed frame.
|
|
|
|
|
A prefix is **only used once**. Tables are discarded at end of frame (ZSTD_e_end).
|
|
|
|
|
Decompression will need same prefix to properly regenerate data.
|
|
|
|
|
Compressing with a prefix is similar in outcome as performing a diff and compressing it,
|
|
|
|
|
but performs much faster, especially during decompression (compression speed is tunable with compression level).
|
|
|
|
|
@result : 0, or an error code (which can be tested with ZSTD_isError()).
|
|
|
|
|
Special: Adding any prefix (including NULL) invalidates any previous prefix or dictionary
|
|
|
|
|
Note 1 : Prefix buffer is referenced. It **must** outlive compression.
|
|
|
|
|
Its content must remain unmodified during compression.
|
|
|
|
|
Note 2 : If the intention is to diff some large src data blob with some prior version of itself,
|
|
|
|
|
ensure that the window size is large enough to contain the entire source.
|
|
|
|
|
See ZSTD_c_windowLog.
|
|
|
|
|
Note 3 : Referencing a prefix involves building tables, which are dependent on compression parameters.
|
|
|
|
|
It's a CPU consuming operation, with non-negligible impact on latency.
|
|
|
|
|
If there is a need to use the same prefix multiple times, consider loadDictionary instead.
|
|
|
|
|
Note 4 : By default, the prefix is interpreted as raw content (ZSTD_dm_rawContent).
|
|
|
|
|
Use experimental ZSTD_CCtx_refPrefix_advanced() to alter dictionary interpretation.
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<pre><b>size_t ZSTD_DCtx_loadDictionary(ZSTD_DCtx* dctx, const void* dict, size_t dictSize);
|
|
|
|
|
</b><p> Create an internal DDict from dict buffer,
|
|
|
|
|
to be used to decompress next frames.
|
|
|
|
@@ -793,15 +857,25 @@ size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
|
|
|
|
|
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<pre><b>size_t ZSTD_DCtx_reset(ZSTD_DCtx* dctx, ZSTD_ResetDirective reset);
|
|
|
|
|
</b><p> Return a DCtx to clean state.
|
|
|
|
|
Session and parameters can be reset jointly or separately.
|
|
|
|
|
Parameters can only be reset when no active frame is being decompressed.
|
|
|
|
|
@return : 0, or an error code, which can be tested with ZSTD_isError()
|
|
|
|
|
|
|
|
|
|
<pre><b>size_t ZSTD_sizeof_CCtx(const ZSTD_CCtx* cctx);
|
|
|
|
|
size_t ZSTD_sizeof_DCtx(const ZSTD_DCtx* dctx);
|
|
|
|
|
size_t ZSTD_sizeof_CStream(const ZSTD_CStream* zcs);
|
|
|
|
|
size_t ZSTD_sizeof_DStream(const ZSTD_DStream* zds);
|
|
|
|
|
size_t ZSTD_sizeof_CDict(const ZSTD_CDict* cdict);
|
|
|
|
|
size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
|
|
|
|
|
</b><p> These functions give the _current_ memory usage of selected object.
|
|
|
|
|
Note that object memory usage can evolve (increase or decrease) over time.
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<a name="Chapter14"></a><h2>experimental API (static linking only)</h2><pre>
|
|
|
|
|
<a name="Chapter21"></a><h2>ADVANCED AND EXPERIMENTAL FUNCTIONS</h2><pre>
|
|
|
|
|
The definitions in the following section are considered experimental.
|
|
|
|
|
They are provided for advanced scenarios.
|
|
|
|
|
They should never be used with a dynamic library, as prototypes may change in the future.
|
|
|
|
|
Use them only in association with static linking.
|
|
|
|
|
|
|
|
|
|
<BR></pre>
|
|
|
|
|
|
|
|
|
|
<a name="Chapter22"></a><h2>experimental API (static linking only)</h2><pre>
|
|
|
|
|
The following symbols and constants
|
|
|
|
|
are not planned to join "stable API" status in the near future.
|
|
|
|
|
They can still change in future versions.
|
|
|
|
@@ -890,12 +964,21 @@ size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
|
|
|
|
|
ZSTD_dictForceCopy = 2, </b>/* Always copy the dictionary. */<b>
|
|
|
|
|
} ZSTD_dictAttachPref_e;
|
|
|
|
|
</b></pre><BR>
|
|
|
|
|
<a name="Chapter15"></a><h2>Frame size functions</h2><pre></pre>
|
|
|
|
|
<pre><b>typedef enum {
|
|
|
|
|
ZSTD_lcm_auto = 0, </b>/**< Automatically determine the compression mode based on the compression level.<b>
|
|
|
|
|
* Negative compression levels will be uncompressed, and positive compression
|
|
|
|
|
* levels will be compressed. */
|
|
|
|
|
ZSTD_lcm_huffman = 1, </b>/**< Always attempt Huffman compression. Uncompressed literals will still be<b>
|
|
|
|
|
* emitted if Huffman compression is not profitable. */
|
|
|
|
|
ZSTD_lcm_uncompressed = 2, </b>/**< Always emit uncompressed literals. */<b>
|
|
|
|
|
} ZSTD_literalCompressionMode_e;
|
|
|
|
|
</b></pre><BR>
|
|
|
|
|
<a name="Chapter23"></a><h2>Frame size functions</h2><pre></pre>
|
|
|
|
|
|
|
|
|
|
<pre><b>unsigned long long ZSTD_findDecompressedSize(const void* src, size_t srcSize);
|
|
|
|
|
</b><p> `src` should point the start of a series of ZSTD encoded and/or skippable frames
|
|
|
|
|
</b><p> `src` should point to the start of a series of ZSTD encoded and/or skippable frames
|
|
|
|
|
`srcSize` must be the _exact_ size of this series
|
|
|
|
|
(i.e. there should be a frame boundary exactly at `srcSize` bytes after `src`)
|
|
|
|
|
(i.e. there should be a frame boundary at `src + srcSize`)
|
|
|
|
|
@return : - decompressed size of all data in all successive frames
|
|
|
|
|
- if the decompressed size cannot be determined: ZSTD_CONTENTSIZE_UNKNOWN
|
|
|
|
|
- if an error occurred: ZSTD_CONTENTSIZE_ERROR
|
|
|
|
@@ -915,13 +998,27 @@ size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
|
|
|
|
|
however it does mean that all frame data must be present and valid.
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<a name="Chapter24"></a><h2>ZSTD_decompressBound() :</h2><pre> `src` should point to the start of a series of ZSTD encoded and/or skippable frames
|
|
|
|
|
`srcSize` must be the _exact_ size of this series
|
|
|
|
|
(i.e. there should be a frame boundary at `src + srcSize`)
|
|
|
|
|
@return : - upper-bound for the decompressed size of all data in all successive frames
|
|
|
|
|
- if an error occured: ZSTD_CONTENTSIZE_ERROR
|
|
|
|
|
|
|
|
|
|
note 1 : an error can occur if `src` contains an invalid or incorrectly formatted frame.
|
|
|
|
|
note 2 : the upper-bound is exact when the decompressed size field is available in every ZSTD encoded frame of `src`.
|
|
|
|
|
in this case, `ZSTD_findDecompressedSize` and `ZSTD_decompressBound` return the same value.
|
|
|
|
|
note 3 : when the decompressed size field isn't available, the upper-bound for that frame is calculated by:
|
|
|
|
|
upper-bound = # blocks * min(128 KB, Window_Size)
|
|
|
|
|
|
|
|
|
|
<BR></pre>
|
|
|
|
|
|
|
|
|
|
<pre><b>size_t ZSTD_frameHeaderSize(const void* src, size_t srcSize);
|
|
|
|
|
</b><p> srcSize must be >= ZSTD_FRAMEHEADERSIZE_PREFIX.
|
|
|
|
|
@return : size of the Frame Header,
|
|
|
|
|
or an error code (if srcSize is too small)
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<a name="Chapter16"></a><h2>Memory management</h2><pre></pre>
|
|
|
|
|
<a name="Chapter25"></a><h2>Memory management</h2><pre></pre>
|
|
|
|
|
|
|
|
|
|
<pre><b>size_t ZSTD_estimateCCtxSize(int compressionLevel);
|
|
|
|
|
size_t ZSTD_estimateCCtxSize_usingCParams(ZSTD_compressionParameters cParams);
|
|
|
|
@@ -933,7 +1030,7 @@ size_t ZSTD_estimateDCtxSize(void);
|
|
|
|
|
It will also consider src size to be arbitrarily "large", which is worst case.
|
|
|
|
|
If srcSize is known to always be small, ZSTD_estimateCCtxSize_usingCParams() can provide a tighter estimation.
|
|
|
|
|
ZSTD_estimateCCtxSize_usingCParams() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel.
|
|
|
|
|
ZSTD_estimateCCtxSize_usingCCtxParams() can be used in tandem with ZSTD_CCtxParam_setParameter(). Only single-threaded compression is supported. This function will return an error code if ZSTD_c_nbWorkers is >= 1.
|
|
|
|
|
ZSTD_estimateCCtxSize_usingCCtxParams() can be used in tandem with ZSTD_CCtxParams_setParameter(). Only single-threaded compression is supported. This function will return an error code if ZSTD_c_nbWorkers is >= 1.
|
|
|
|
|
Note : CCtx size estimation is only correct for single-threaded compression.
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
@@ -946,7 +1043,7 @@ size_t ZSTD_estimateDStreamSize_fromFrame(const void* src, size_t srcSize);
|
|
|
|
|
It will also consider src size to be arbitrarily "large", which is worst case.
|
|
|
|
|
If srcSize is known to always be small, ZSTD_estimateCStreamSize_usingCParams() can provide a tighter estimation.
|
|
|
|
|
ZSTD_estimateCStreamSize_usingCParams() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel.
|
|
|
|
|
ZSTD_estimateCStreamSize_usingCCtxParams() can be used in tandem with ZSTD_CCtxParam_setParameter(). Only single-threaded compression is supported. This function will return an error code if ZSTD_c_nbWorkers is >= 1.
|
|
|
|
|
ZSTD_estimateCStreamSize_usingCCtxParams() can be used in tandem with ZSTD_CCtxParams_setParameter(). Only single-threaded compression is supported. This function will return an error code if ZSTD_c_nbWorkers is >= 1.
|
|
|
|
|
Note : CStream size estimation is only correct for single-threaded compression.
|
|
|
|
|
ZSTD_DStream memory budget depends on window Size.
|
|
|
|
|
This information can be passed manually, using ZSTD_estimateDStreamSize,
|
|
|
|
@@ -1001,7 +1098,7 @@ static ZSTD_customMem const ZSTD_defaultCMem = { NULL, NULL, NULL }; </b>/**< t
|
|
|
|
|
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<a name="Chapter17"></a><h2>Advanced compression functions</h2><pre></pre>
|
|
|
|
|
<a name="Chapter26"></a><h2>Advanced compression functions</h2><pre></pre>
|
|
|
|
|
|
|
|
|
|
<pre><b>ZSTD_CDict* ZSTD_createCDict_byReference(const void* dictBuffer, size_t dictSize, int compressionLevel);
|
|
|
|
|
</b><p> Create a digested dictionary for compression
|
|
|
|
@@ -1076,10 +1173,10 @@ static ZSTD_customMem const ZSTD_defaultCMem = { NULL, NULL, NULL }; </b>/**< t
|
|
|
|
|
size_t ZSTD_freeCCtxParams(ZSTD_CCtx_params* params);
|
|
|
|
|
</b><p> Quick howto :
|
|
|
|
|
- ZSTD_createCCtxParams() : Create a ZSTD_CCtx_params structure
|
|
|
|
|
- ZSTD_CCtxParam_setParameter() : Push parameters one by one into
|
|
|
|
|
an existing ZSTD_CCtx_params structure.
|
|
|
|
|
This is similar to
|
|
|
|
|
ZSTD_CCtx_setParameter().
|
|
|
|
|
- ZSTD_CCtxParams_setParameter() : Push parameters one by one into
|
|
|
|
|
an existing ZSTD_CCtx_params structure.
|
|
|
|
|
This is similar to
|
|
|
|
|
ZSTD_CCtx_setParameter().
|
|
|
|
|
- ZSTD_CCtx_setParametersUsingCCtxParams() : Apply parameters to
|
|
|
|
|
an existing CCtx.
|
|
|
|
|
These parameters will be applied to
|
|
|
|
@@ -1109,7 +1206,7 @@ size_t ZSTD_freeCCtxParams(ZSTD_CCtx_params* params);
|
|
|
|
|
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<pre><b>size_t ZSTD_CCtxParam_setParameter(ZSTD_CCtx_params* params, ZSTD_cParameter param, int value);
|
|
|
|
|
<pre><b>size_t ZSTD_CCtxParams_setParameter(ZSTD_CCtx_params* params, ZSTD_cParameter param, int value);
|
|
|
|
|
</b><p> Similar to ZSTD_CCtx_setParameter.
|
|
|
|
|
Set one compression parameter, selected by enum ZSTD_cParameter.
|
|
|
|
|
Parameters must be applied to a ZSTD_CCtx using ZSTD_CCtx_setParametersUsingCCtxParams().
|
|
|
|
@@ -1117,7 +1214,7 @@ size_t ZSTD_freeCCtxParams(ZSTD_CCtx_params* params);
|
|
|
|
|
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<pre><b>size_t ZSTD_CCtxParam_getParameter(ZSTD_CCtx_params* params, ZSTD_cParameter param, int* value);
|
|
|
|
|
<pre><b>size_t ZSTD_CCtxParams_getParameter(ZSTD_CCtx_params* params, ZSTD_cParameter param, int* value);
|
|
|
|
|
</b><p> Similar to ZSTD_CCtx_getParameter.
|
|
|
|
|
Get the requested value of one compression parameter, selected by enum ZSTD_cParameter.
|
|
|
|
|
@result : 0, or an error code (which can be tested with ZSTD_isError()).
|
|
|
|
@@ -1146,7 +1243,7 @@ size_t ZSTD_freeCCtxParams(ZSTD_CCtx_params* params);
|
|
|
|
|
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<a name="Chapter18"></a><h2>Advanced decompression functions</h2><pre></pre>
|
|
|
|
|
<a name="Chapter27"></a><h2>Advanced decompression functions</h2><pre></pre>
|
|
|
|
|
|
|
|
|
|
<pre><b>unsigned ZSTD_isFrame(const void* buffer, size_t size);
|
|
|
|
|
</b><p> Tells if the content of `buffer` starts with a valid Frame Identifier.
|
|
|
|
@@ -1162,30 +1259,6 @@ size_t ZSTD_freeCCtxParams(ZSTD_CCtx_params* params);
|
|
|
|
|
it must remain read accessible throughout the lifetime of DDict
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<pre><b>unsigned ZSTD_getDictID_fromDict(const void* dict, size_t dictSize);
|
|
|
|
|
</b><p> Provides the dictID stored within dictionary.
|
|
|
|
|
if @return == 0, the dictionary is not conformant with Zstandard specification.
|
|
|
|
|
It can still be loaded, but as a content-only dictionary.
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<pre><b>unsigned ZSTD_getDictID_fromDDict(const ZSTD_DDict* ddict);
|
|
|
|
|
</b><p> Provides the dictID of the dictionary loaded into `ddict`.
|
|
|
|
|
If @return == 0, the dictionary is not conformant to Zstandard specification, or empty.
|
|
|
|
|
Non-conformant dictionaries can still be loaded, but as content-only dictionaries.
|
|
|
|
|
</p></pre><BR>
|
|
|
|
|
|
|
|
|
|
<pre><b>unsigned ZSTD_getDictID_fromFrame(const void* src, size_t srcSize);
|
|
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</b><p> Provides the dictID required to decompressed the frame stored within `src`.
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If @return == 0, the dictID could not be decoded.
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This could for one of the following reasons :
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- The frame does not require a dictionary to be decoded (most common case).
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- The frame was built with dictID intentionally removed. Whatever dictionary is necessary is a hidden information.
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Note : this use case also happens when using a non-conformant dictionary.
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- `srcSize` is too small, and as a result, the frame header could not be decoded (only possible if `srcSize < ZSTD_FRAMEHEADERSIZE_MAX`).
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- This is not a Zstandard frame.
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When identifying the exact failure cause, it's possible to use ZSTD_getFrameHeader(), which will provide a more precise error code.
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</p></pre><BR>
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<pre><b>size_t ZSTD_DCtx_loadDictionary_byReference(ZSTD_DCtx* dctx, const void* dict, size_t dictSize);
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</b><p> Same as ZSTD_DCtx_loadDictionary(),
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but references `dict` content instead of copying it into `dctx`.
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@@ -1232,20 +1305,74 @@ size_t ZSTD_freeCCtxParams(ZSTD_CCtx_params* params);
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</p></pre><BR>
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<a name="Chapter19"></a><h2>Advanced streaming functions</h2><pre> Warning : most of these functions are now redundant with the Advanced API.
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<a name="Chapter28"></a><h2>Advanced streaming functions</h2><pre> Warning : most of these functions are now redundant with the Advanced API.
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Once Advanced API reaches "stable" status,
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redundant functions will be deprecated, and then at some point removed.
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<BR></pre>
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<h3>Advanced Streaming compression functions</h3><pre></pre><b><pre>size_t ZSTD_initCStream_srcSize(ZSTD_CStream* zcs, int compressionLevel, unsigned long long pledgedSrcSize); </b>/**< pledgedSrcSize must be correct. If it is not known at init time, use ZSTD_CONTENTSIZE_UNKNOWN. Note that, for compatibility with older programs, "0" also disables frame content size field. It may be enabled in the future. */<b>
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|
size_t ZSTD_initCStream_usingDict(ZSTD_CStream* zcs, const void* dict, size_t dictSize, int compressionLevel); </b>/**< creates of an internal CDict (incompatible with static CCtx), except if dict == NULL or dictSize < 8, in which case no dict is used. Note: dict is loaded with ZSTD_dm_auto (treated as a full zstd dictionary if it begins with ZSTD_MAGIC_DICTIONARY, else as raw content) and ZSTD_dlm_byCopy.*/<b>
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<h3>Advanced Streaming compression functions</h3><pre></pre><b><pre></b>/**! ZSTD_initCStream_srcSize() :<b>
|
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* This function is deprecated, and equivalent to:
|
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|
|
* ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
|
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|
|
* ZSTD_CCtx_refCDict(zcs, NULL); // clear the dictionary (if any)
|
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|
|
* ZSTD_CCtx_setParameter(zcs, ZSTD_c_compressionLevel, compressionLevel);
|
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|
|
* ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize);
|
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|
|
*
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|
|
* pledgedSrcSize must be correct. If it is not known at init time, use
|
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|
|
* ZSTD_CONTENTSIZE_UNKNOWN. Note that, for compatibility with older programs,
|
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|
|
|
* "0" also disables frame content size field. It may be enabled in the future.
|
|
|
|
|
*/
|
|
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|
|
size_t ZSTD_initCStream_srcSize(ZSTD_CStream* zcs, int compressionLevel, unsigned long long pledgedSrcSize);
|
|
|
|
|
</b>/**! ZSTD_initCStream_usingDict() :<b>
|
|
|
|
|
* This function is deprecated, and is equivalent to:
|
|
|
|
|
* ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
|
|
|
|
|
* ZSTD_CCtx_setParameter(zcs, ZSTD_c_compressionLevel, compressionLevel);
|
|
|
|
|
* ZSTD_CCtx_loadDictionary(zcs, dict, dictSize);
|
|
|
|
|
*
|
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|
|
|
* Creates of an internal CDict (incompatible with static CCtx), except if
|
|
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|
|
* dict == NULL or dictSize < 8, in which case no dict is used.
|
|
|
|
|
* Note: dict is loaded with ZSTD_dm_auto (treated as a full zstd dictionary if
|
|
|
|
|
* it begins with ZSTD_MAGIC_DICTIONARY, else as raw content) and ZSTD_dlm_byCopy.
|
|
|
|
|
*/
|
|
|
|
|
size_t ZSTD_initCStream_usingDict(ZSTD_CStream* zcs, const void* dict, size_t dictSize, int compressionLevel);
|
|
|
|
|
</b>/**! ZSTD_initCStream_advanced() :<b>
|
|
|
|
|
* This function is deprecated, and is approximately equivalent to:
|
|
|
|
|
* ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
|
|
|
|
|
* ZSTD_CCtx_setZstdParams(zcs, params); // Set the zstd params and leave the rest as-is
|
|
|
|
|
* ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize);
|
|
|
|
|
* ZSTD_CCtx_loadDictionary(zcs, dict, dictSize);
|
|
|
|
|
*
|
|
|
|
|
* pledgedSrcSize must be correct. If srcSize is not known at init time, use
|
|
|
|
|
* value ZSTD_CONTENTSIZE_UNKNOWN. dict is loaded with ZSTD_dm_auto and ZSTD_dlm_byCopy.
|
|
|
|
|
*/
|
|
|
|
|
size_t ZSTD_initCStream_advanced(ZSTD_CStream* zcs, const void* dict, size_t dictSize,
|
|
|
|
|
ZSTD_parameters params, unsigned long long pledgedSrcSize); </b>/**< pledgedSrcSize must be correct. If srcSize is not known at init time, use value ZSTD_CONTENTSIZE_UNKNOWN. dict is loaded with ZSTD_dm_auto and ZSTD_dlm_byCopy. */<b>
|
|
|
|
|
size_t ZSTD_initCStream_usingCDict(ZSTD_CStream* zcs, const ZSTD_CDict* cdict); </b>/**< note : cdict will just be referenced, and must outlive compression session */<b>
|
|
|
|
|
size_t ZSTD_initCStream_usingCDict_advanced(ZSTD_CStream* zcs, const ZSTD_CDict* cdict, ZSTD_frameParameters fParams, unsigned long long pledgedSrcSize); </b>/**< same as ZSTD_initCStream_usingCDict(), with control over frame parameters. pledgedSrcSize must be correct. If srcSize is not known at init time, use value ZSTD_CONTENTSIZE_UNKNOWN. */<b>
|
|
|
|
|
ZSTD_parameters params, unsigned long long pledgedSrcSize);
|
|
|
|
|
</b>/**! ZSTD_initCStream_usingCDict() :<b>
|
|
|
|
|
* This function is deprecated, and equivalent to:
|
|
|
|
|
* ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
|
|
|
|
|
* ZSTD_CCtx_refCDict(zcs, cdict);
|
|
|
|
|
*
|
|
|
|
|
* note : cdict will just be referenced, and must outlive compression session
|
|
|
|
|
*/
|
|
|
|
|
size_t ZSTD_initCStream_usingCDict(ZSTD_CStream* zcs, const ZSTD_CDict* cdict);
|
|
|
|
|
</b>/**! ZSTD_initCStream_usingCDict_advanced() :<b>
|
|
|
|
|
* This function is deprecated, and is approximately equivalent to:
|
|
|
|
|
* ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
|
|
|
|
|
* ZSTD_CCtx_setZstdFrameParams(zcs, fParams); // Set the zstd frame params and leave the rest as-is
|
|
|
|
|
* ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize);
|
|
|
|
|
* ZSTD_CCtx_refCDict(zcs, cdict);
|
|
|
|
|
*
|
|
|
|
|
* same as ZSTD_initCStream_usingCDict(), with control over frame parameters.
|
|
|
|
|
* pledgedSrcSize must be correct. If srcSize is not known at init time, use
|
|
|
|
|
* value ZSTD_CONTENTSIZE_UNKNOWN.
|
|
|
|
|
*/
|
|
|
|
|
size_t ZSTD_initCStream_usingCDict_advanced(ZSTD_CStream* zcs, const ZSTD_CDict* cdict, ZSTD_frameParameters fParams, unsigned long long pledgedSrcSize);
|
|
|
|
|
</pre></b><BR>
|
|
|
|
|
<pre><b>size_t ZSTD_resetCStream(ZSTD_CStream* zcs, unsigned long long pledgedSrcSize);
|
|
|
|
|
</b><p> start a new frame, using same parameters from previous frame.
|
|
|
|
|
</b><p> This function is deprecated, and is equivalent to:
|
|
|
|
|
ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only);
|
|
|
|
|
ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize);
|
|
|
|
|
|
|
|
|
|
start a new frame, using same parameters from previous frame.
|
|
|
|
|
This is typically useful to skip dictionary loading stage, since it will re-use it in-place.
|
|
|
|
|
Note that zcs must be init at least once before using ZSTD_resetCStream().
|
|
|
|
|
If pledgedSrcSize is not known at reset time, use macro ZSTD_CONTENTSIZE_UNKNOWN.
|
|
|
|
@@ -1284,14 +1411,14 @@ size_t ZSTD_initCStream_usingCDict_advanced(ZSTD_CStream* zcs, const ZSTD_CDict*
|
|
|
|
|
size_t ZSTD_initDStream_usingDDict(ZSTD_DStream* zds, const ZSTD_DDict* ddict); </b>/**< note : ddict is referenced, it must outlive decompression session */<b>
|
|
|
|
|
size_t ZSTD_resetDStream(ZSTD_DStream* zds); </b>/**< re-use decompression parameters from previous init; saves dictionary loading */<b>
|
|
|
|
|
</pre></b><BR>
|
|
|
|
|
<a name="Chapter20"></a><h2>Buffer-less and synchronous inner streaming functions</h2><pre>
|
|
|
|
|
<a name="Chapter29"></a><h2>Buffer-less and synchronous inner streaming functions</h2><pre>
|
|
|
|
|
This is an advanced API, giving full control over buffer management, for users which need direct control over memory.
|
|
|
|
|
But it's also a complex one, with several restrictions, documented below.
|
|
|
|
|
Prefer normal streaming API for an easier experience.
|
|
|
|
|
|
|
|
|
|
<BR></pre>
|
|
|
|
|
|
|
|
|
|
<a name="Chapter21"></a><h2>Buffer-less streaming compression (synchronous mode)</h2><pre>
|
|
|
|
|
<a name="Chapter30"></a><h2>Buffer-less streaming compression (synchronous mode)</h2><pre>
|
|
|
|
|
A ZSTD_CCtx object is required to track streaming operations.
|
|
|
|
|
Use ZSTD_createCCtx() / ZSTD_freeCCtx() to manage resource.
|
|
|
|
|
ZSTD_CCtx object can be re-used multiple times within successive compression operations.
|
|
|
|
@@ -1327,7 +1454,7 @@ size_t ZSTD_compressBegin_usingCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict);
|
|
|
|
|
size_t ZSTD_compressBegin_usingCDict_advanced(ZSTD_CCtx* const cctx, const ZSTD_CDict* const cdict, ZSTD_frameParameters const fParams, unsigned long long const pledgedSrcSize); </b>/* compression parameters are already set within cdict. pledgedSrcSize must be correct. If srcSize is not known, use macro ZSTD_CONTENTSIZE_UNKNOWN */<b>
|
|
|
|
|
size_t ZSTD_copyCCtx(ZSTD_CCtx* cctx, const ZSTD_CCtx* preparedCCtx, unsigned long long pledgedSrcSize); </b>/**< note: if pledgedSrcSize is not known, use ZSTD_CONTENTSIZE_UNKNOWN */<b>
|
|
|
|
|
</pre></b><BR>
|
|
|
|
|
<a name="Chapter22"></a><h2>Buffer-less streaming decompression (synchronous mode)</h2><pre>
|
|
|
|
|
<a name="Chapter31"></a><h2>Buffer-less streaming decompression (synchronous mode)</h2><pre>
|
|
|
|
|
A ZSTD_DCtx object is required to track streaming operations.
|
|
|
|
|
Use ZSTD_createDCtx() / ZSTD_freeDCtx() to manage it.
|
|
|
|
|
A ZSTD_DCtx object can be re-used multiple times.
|
|
|
|
@@ -1409,7 +1536,7 @@ typedef struct {
|
|
|
|
|
unsigned checksumFlag;
|
|
|
|
|
} ZSTD_frameHeader;
|
|
|
|
|
</pre></b><BR>
|
|
|
|
|
<a name="Chapter23"></a><h2>ZSTD_getFrameHeader() :</h2><pre> decode Frame Header, or requires larger `srcSize`.
|
|
|
|
|
<a name="Chapter32"></a><h2>ZSTD_getFrameHeader() :</h2><pre> decode Frame Header, or requires larger `srcSize`.
|
|
|
|
|
@return : 0, `zfhPtr` is correctly filled,
|
|
|
|
|
>0, `srcSize` is too small, value is wanted `srcSize` amount,
|
|
|
|
|
or an error code, which can be tested using ZSTD_isError()
|
|
|
|
@@ -1425,7 +1552,7 @@ size_t ZSTD_decodingBufferSize_min(unsigned long long windowSize, unsigned long
|
|
|
|
|
|
|
|
|
|
<pre><b>typedef enum { ZSTDnit_frameHeader, ZSTDnit_blockHeader, ZSTDnit_block, ZSTDnit_lastBlock, ZSTDnit_checksum, ZSTDnit_skippableFrame } ZSTD_nextInputType_e;
|
|
|
|
|
</b></pre><BR>
|
|
|
|
|
<a name="Chapter24"></a><h2>Block level API</h2><pre></pre>
|
|
|
|
|
<a name="Chapter33"></a><h2>Block level API</h2><pre></pre>
|
|
|
|
|
|
|
|
|
|
<pre><b></b><p> Frame metadata cost is typically ~18 bytes, which can be non-negligible for very small blocks (< 100 bytes).
|
|
|
|
|
User will have to take in charge required information to regenerate data, such as compressed and content sizes.
|
|
|
|
|