1*01826a49SYabin Cui<html> 2*01826a49SYabin Cui<head> 3*01826a49SYabin Cui<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> 4*01826a49SYabin Cui<title>zstd 1.5.6 Manual</title> 5*01826a49SYabin Cui</head> 6*01826a49SYabin Cui<body> 7*01826a49SYabin Cui<h1>zstd 1.5.6 Manual</h1> 8*01826a49SYabin Cui<hr> 9*01826a49SYabin Cui<a name="Contents"></a><h2>Contents</h2> 10*01826a49SYabin Cui<ol> 11*01826a49SYabin Cui<li><a href="#Chapter1">Introduction</a></li> 12*01826a49SYabin Cui<li><a href="#Chapter2">Version</a></li> 13*01826a49SYabin Cui<li><a href="#Chapter3">Simple API</a></li> 14*01826a49SYabin Cui<li><a href="#Chapter4">Explicit context</a></li> 15*01826a49SYabin Cui<li><a href="#Chapter5">Advanced compression API (Requires v1.4.0+)</a></li> 16*01826a49SYabin Cui<li><a href="#Chapter6">Advanced decompression API (Requires v1.4.0+)</a></li> 17*01826a49SYabin Cui<li><a href="#Chapter7">Streaming</a></li> 18*01826a49SYabin Cui<li><a href="#Chapter8">Streaming compression - HowTo</a></li> 19*01826a49SYabin Cui<li><a href="#Chapter9">Streaming decompression - HowTo</a></li> 20*01826a49SYabin Cui<li><a href="#Chapter10">Simple dictionary API</a></li> 21*01826a49SYabin Cui<li><a href="#Chapter11">Bulk processing dictionary API</a></li> 22*01826a49SYabin Cui<li><a href="#Chapter12">Dictionary helper functions</a></li> 23*01826a49SYabin Cui<li><a href="#Chapter13">Advanced dictionary and prefix API (Requires v1.4.0+)</a></li> 24*01826a49SYabin Cui<li><a href="#Chapter14">experimental API (static linking only)</a></li> 25*01826a49SYabin Cui<li><a href="#Chapter15">Frame header and size functions</a></li> 26*01826a49SYabin Cui<li><a href="#Chapter16">Memory management</a></li> 27*01826a49SYabin Cui<li><a href="#Chapter17">Advanced compression functions</a></li> 28*01826a49SYabin Cui<li><a href="#Chapter18">Advanced decompression functions</a></li> 29*01826a49SYabin Cui<li><a href="#Chapter19">Advanced streaming functions</a></li> 30*01826a49SYabin Cui<li><a href="#Chapter20">Buffer-less and synchronous inner streaming functions (DEPRECATED)</a></li> 31*01826a49SYabin Cui<li><a href="#Chapter21">Buffer-less streaming compression (synchronous mode)</a></li> 32*01826a49SYabin Cui<li><a href="#Chapter22">Buffer-less streaming decompression (synchronous mode)</a></li> 33*01826a49SYabin Cui<li><a href="#Chapter23">Block level API (DEPRECATED)</a></li> 34*01826a49SYabin Cui</ol> 35*01826a49SYabin Cui<hr> 36*01826a49SYabin Cui<a name="Chapter1"></a><h2>Introduction</h2><pre> 37*01826a49SYabin Cui zstd, short for Zstandard, is a fast lossless compression algorithm, targeting 38*01826a49SYabin Cui real-time compression scenarios at zlib-level and better compression ratios. 39*01826a49SYabin Cui The zstd compression library provides in-memory compression and decompression 40*01826a49SYabin Cui functions. 41*01826a49SYabin Cui 42*01826a49SYabin Cui The library supports regular compression levels from 1 up to ZSTD_maxCLevel(), 43*01826a49SYabin Cui which is currently 22. Levels >= 20, labeled `--ultra`, should be used with 44*01826a49SYabin Cui caution, as they require more memory. The library also offers negative 45*01826a49SYabin Cui compression levels, which extend the range of speed vs. ratio preferences. 46*01826a49SYabin Cui The lower the level, the faster the speed (at the cost of compression). 47*01826a49SYabin Cui 48*01826a49SYabin Cui Compression can be done in: 49*01826a49SYabin Cui - a single step (described as Simple API) 50*01826a49SYabin Cui - a single step, reusing a context (described as Explicit context) 51*01826a49SYabin Cui - unbounded multiple steps (described as Streaming compression) 52*01826a49SYabin Cui 53*01826a49SYabin Cui The compression ratio achievable on small data can be highly improved using 54*01826a49SYabin Cui a dictionary. Dictionary compression can be performed in: 55*01826a49SYabin Cui - a single step (described as Simple dictionary API) 56*01826a49SYabin Cui - a single step, reusing a dictionary (described as Bulk-processing 57*01826a49SYabin Cui dictionary API) 58*01826a49SYabin Cui 59*01826a49SYabin Cui Advanced experimental functions can be accessed using 60*01826a49SYabin Cui `#define ZSTD_STATIC_LINKING_ONLY` before including zstd.h. 61*01826a49SYabin Cui 62*01826a49SYabin Cui Advanced experimental APIs should never be used with a dynamically-linked 63*01826a49SYabin Cui library. They are not "stable"; their definitions or signatures may change in 64*01826a49SYabin Cui the future. Only static linking is allowed. 65*01826a49SYabin Cui<BR></pre> 66*01826a49SYabin Cui 67*01826a49SYabin Cui<a name="Chapter2"></a><h2>Version</h2><pre></pre> 68*01826a49SYabin Cui 69*01826a49SYabin Cui<pre><b>unsigned ZSTD_versionNumber(void); 70*01826a49SYabin Cui</b><p> Return runtime library version, the value is (MAJOR*100*100 + MINOR*100 + RELEASE). 71*01826a49SYabin Cui</p></pre><BR> 72*01826a49SYabin Cui 73*01826a49SYabin Cui<pre><b>const char* ZSTD_versionString(void); 74*01826a49SYabin Cui</b><p> Return runtime library version, like "1.4.5". Requires v1.3.0+. 75*01826a49SYabin Cui</p></pre><BR> 76*01826a49SYabin Cui 77*01826a49SYabin Cui<a name="Chapter3"></a><h2>Simple API</h2><pre></pre> 78*01826a49SYabin Cui 79*01826a49SYabin Cui<pre><b>size_t ZSTD_compress( void* dst, size_t dstCapacity, 80*01826a49SYabin Cui const void* src, size_t srcSize, 81*01826a49SYabin Cui int compressionLevel); 82*01826a49SYabin Cui</b><p> Compresses `src` content as a single zstd compressed frame into already allocated `dst`. 83*01826a49SYabin Cui NOTE: Providing `dstCapacity >= ZSTD_compressBound(srcSize)` guarantees that zstd will have 84*01826a49SYabin Cui enough space to successfully compress the data. 85*01826a49SYabin Cui @return : compressed size written into `dst` (<= `dstCapacity), 86*01826a49SYabin Cui or an error code if it fails (which can be tested using ZSTD_isError()). 87*01826a49SYabin Cui</p></pre><BR> 88*01826a49SYabin Cui 89*01826a49SYabin Cui<pre><b>size_t ZSTD_decompress( void* dst, size_t dstCapacity, 90*01826a49SYabin Cui const void* src, size_t compressedSize); 91*01826a49SYabin Cui</b><p> `compressedSize` : must be the _exact_ size of some number of compressed and/or skippable frames. 92*01826a49SYabin Cui `dstCapacity` is an upper bound of originalSize to regenerate. 93*01826a49SYabin Cui If user cannot imply a maximum upper bound, it's better to use streaming mode to decompress data. 94*01826a49SYabin Cui @return : the number of bytes decompressed into `dst` (<= `dstCapacity`), 95*01826a49SYabin Cui or an errorCode if it fails (which can be tested using ZSTD_isError()). 96*01826a49SYabin Cui</p></pre><BR> 97*01826a49SYabin Cui 98*01826a49SYabin Cui<pre><b>#define ZSTD_CONTENTSIZE_UNKNOWN (0ULL - 1) 99*01826a49SYabin Cui#define ZSTD_CONTENTSIZE_ERROR (0ULL - 2) 100*01826a49SYabin Cuiunsigned long long ZSTD_getFrameContentSize(const void *src, size_t srcSize); 101*01826a49SYabin Cui</b><p> `src` should point to the start of a ZSTD encoded frame. 102*01826a49SYabin Cui `srcSize` must be at least as large as the frame header. 103*01826a49SYabin Cui hint : any size >= `ZSTD_frameHeaderSize_max` is large enough. 104*01826a49SYabin Cui @return : - decompressed size of `src` frame content, if known 105*01826a49SYabin Cui - ZSTD_CONTENTSIZE_UNKNOWN if the size cannot be determined 106*01826a49SYabin Cui - ZSTD_CONTENTSIZE_ERROR if an error occurred (e.g. invalid magic number, srcSize too small) 107*01826a49SYabin Cui note 1 : a 0 return value means the frame is valid but "empty". 108*01826a49SYabin Cui note 2 : decompressed size is an optional field, it may not be present, typically in streaming mode. 109*01826a49SYabin Cui When `return==ZSTD_CONTENTSIZE_UNKNOWN`, data to decompress could be any size. 110*01826a49SYabin Cui In which case, it's necessary to use streaming mode to decompress data. 111*01826a49SYabin Cui Optionally, application can rely on some implicit limit, 112*01826a49SYabin Cui as ZSTD_decompress() only needs an upper bound of decompressed size. 113*01826a49SYabin Cui (For example, data could be necessarily cut into blocks <= 16 KB). 114*01826a49SYabin Cui note 3 : decompressed size is always present when compression is completed using single-pass functions, 115*01826a49SYabin Cui such as ZSTD_compress(), ZSTD_compressCCtx() ZSTD_compress_usingDict() or ZSTD_compress_usingCDict(). 116*01826a49SYabin Cui note 4 : decompressed size can be very large (64-bits value), 117*01826a49SYabin Cui potentially larger than what local system can handle as a single memory segment. 118*01826a49SYabin Cui In which case, it's necessary to use streaming mode to decompress data. 119*01826a49SYabin Cui note 5 : If source is untrusted, decompressed size could be wrong or intentionally modified. 120*01826a49SYabin Cui Always ensure return value fits within application's authorized limits. 121*01826a49SYabin Cui Each application can set its own limits. 122*01826a49SYabin Cui note 6 : This function replaces ZSTD_getDecompressedSize() 123*01826a49SYabin Cui</p></pre><BR> 124*01826a49SYabin Cui 125*01826a49SYabin Cui<pre><b>ZSTD_DEPRECATED("Replaced by ZSTD_getFrameContentSize") 126*01826a49SYabin CuiZSTDLIB_API 127*01826a49SYabin Cuiunsigned long long ZSTD_getDecompressedSize(const void* src, size_t srcSize); 128*01826a49SYabin Cui</b><p> NOTE: This function is now obsolete, in favor of ZSTD_getFrameContentSize(). 129*01826a49SYabin Cui Both functions work the same way, but ZSTD_getDecompressedSize() blends 130*01826a49SYabin Cui "empty", "unknown" and "error" results to the same return value (0), 131*01826a49SYabin Cui while ZSTD_getFrameContentSize() gives them separate return values. 132*01826a49SYabin Cui @return : decompressed size of `src` frame content _if known and not empty_, 0 otherwise. 133*01826a49SYabin Cui</p></pre><BR> 134*01826a49SYabin Cui 135*01826a49SYabin Cui<pre><b>size_t ZSTD_findFrameCompressedSize(const void* src, size_t srcSize); 136*01826a49SYabin Cui</b><p> `src` should point to the start of a ZSTD frame or skippable frame. 137*01826a49SYabin Cui `srcSize` must be >= first frame size 138*01826a49SYabin Cui @return : the compressed size of the first frame starting at `src`, 139*01826a49SYabin Cui suitable to pass as `srcSize` to `ZSTD_decompress` or similar, 140*01826a49SYabin Cui or an error code if input is invalid 141*01826a49SYabin Cui</p></pre><BR> 142*01826a49SYabin Cui 143*01826a49SYabin Cui<h3>Helper functions</h3><pre></pre><b><pre></b>/* ZSTD_compressBound() :<b> 144*01826a49SYabin Cui * maximum compressed size in worst case single-pass scenario. 145*01826a49SYabin Cui * When invoking `ZSTD_compress()` or any other one-pass compression function, 146*01826a49SYabin Cui * it's recommended to provide @dstCapacity >= ZSTD_compressBound(srcSize) 147*01826a49SYabin Cui * as it eliminates one potential failure scenario, 148*01826a49SYabin Cui * aka not enough room in dst buffer to write the compressed frame. 149*01826a49SYabin Cui * Note : ZSTD_compressBound() itself can fail, if @srcSize > ZSTD_MAX_INPUT_SIZE . 150*01826a49SYabin Cui * In which case, ZSTD_compressBound() will return an error code 151*01826a49SYabin Cui * which can be tested using ZSTD_isError(). 152*01826a49SYabin Cui * 153*01826a49SYabin Cui * ZSTD_COMPRESSBOUND() : 154*01826a49SYabin Cui * same as ZSTD_compressBound(), but as a macro. 155*01826a49SYabin Cui * It can be used to produce constants, which can be useful for static allocation, 156*01826a49SYabin Cui * for example to size a static array on stack. 157*01826a49SYabin Cui * Will produce constant value 0 if srcSize too large. 158*01826a49SYabin Cui */ 159*01826a49SYabin Cui#define ZSTD_MAX_INPUT_SIZE ((sizeof(size_t)==8) ? 0xFF00FF00FF00FF00ULL : 0xFF00FF00U) 160*01826a49SYabin Cui#define ZSTD_COMPRESSBOUND(srcSize) (((size_t)(srcSize) >= ZSTD_MAX_INPUT_SIZE) ? 0 : (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> 161*01826a49SYabin Cuisize_t ZSTD_compressBound(size_t srcSize); </b>/*!< maximum compressed size in worst case single-pass scenario */<b> 162*01826a49SYabin Cui</b>/* ZSTD_isError() :<b> 163*01826a49SYabin Cui * Most ZSTD_* functions returning a size_t value can be tested for error, 164*01826a49SYabin Cui * using ZSTD_isError(). 165*01826a49SYabin Cui * @return 1 if error, 0 otherwise 166*01826a49SYabin Cui */ 167*01826a49SYabin Cuiunsigned ZSTD_isError(size_t code); </b>/*!< tells if a `size_t` function result is an error code */<b> 168*01826a49SYabin Cuiconst char* ZSTD_getErrorName(size_t code); </b>/*!< provides readable string from an error code */<b> 169*01826a49SYabin Cuiint ZSTD_minCLevel(void); </b>/*!< minimum negative compression level allowed, requires v1.4.0+ */<b> 170*01826a49SYabin Cuiint ZSTD_maxCLevel(void); </b>/*!< maximum compression level available */<b> 171*01826a49SYabin Cuiint ZSTD_defaultCLevel(void); </b>/*!< default compression level, specified by ZSTD_CLEVEL_DEFAULT, requires v1.5.0+ */<b> 172*01826a49SYabin Cui</pre></b><BR> 173*01826a49SYabin Cui<a name="Chapter4"></a><h2>Explicit context</h2><pre></pre> 174*01826a49SYabin Cui 175*01826a49SYabin Cui<h3>Compression context</h3><pre> When compressing many times, 176*01826a49SYabin Cui it is recommended to allocate a context just once, 177*01826a49SYabin Cui and reuse it for each successive compression operation. 178*01826a49SYabin Cui This will make workload friendlier for system's memory. 179*01826a49SYabin Cui Note : re-using context is just a speed / resource optimization. 180*01826a49SYabin Cui It doesn't change the compression ratio, which remains identical. 181*01826a49SYabin Cui Note 2 : In multi-threaded environments, 182*01826a49SYabin Cui use one different context per thread for parallel execution. 183*01826a49SYabin Cui 184*01826a49SYabin Cui</pre><b><pre>typedef struct ZSTD_CCtx_s ZSTD_CCtx; 185*01826a49SYabin CuiZSTD_CCtx* ZSTD_createCCtx(void); 186*01826a49SYabin Cuisize_t ZSTD_freeCCtx(ZSTD_CCtx* cctx); </b>/* accept NULL pointer */<b> 187*01826a49SYabin Cui</pre></b><BR> 188*01826a49SYabin Cui<pre><b>size_t ZSTD_compressCCtx(ZSTD_CCtx* cctx, 189*01826a49SYabin Cui void* dst, size_t dstCapacity, 190*01826a49SYabin Cui const void* src, size_t srcSize, 191*01826a49SYabin Cui int compressionLevel); 192*01826a49SYabin Cui</b><p> Same as ZSTD_compress(), using an explicit ZSTD_CCtx. 193*01826a49SYabin Cui Important : in order to mirror `ZSTD_compress()` behavior, 194*01826a49SYabin Cui this function compresses at the requested compression level, 195*01826a49SYabin Cui __ignoring any other advanced parameter__ . 196*01826a49SYabin Cui If any advanced parameter was set using the advanced API, 197*01826a49SYabin Cui they will all be reset. Only `compressionLevel` remains. 198*01826a49SYabin Cui 199*01826a49SYabin Cui</p></pre><BR> 200*01826a49SYabin Cui 201*01826a49SYabin Cui<h3>Decompression context</h3><pre> When decompressing many times, 202*01826a49SYabin Cui it is recommended to allocate a context only once, 203*01826a49SYabin Cui and reuse it for each successive compression operation. 204*01826a49SYabin Cui This will make workload friendlier for system's memory. 205*01826a49SYabin Cui Use one context per thread for parallel execution. 206*01826a49SYabin Cui</pre><b><pre>typedef struct ZSTD_DCtx_s ZSTD_DCtx; 207*01826a49SYabin CuiZSTD_DCtx* ZSTD_createDCtx(void); 208*01826a49SYabin Cuisize_t ZSTD_freeDCtx(ZSTD_DCtx* dctx); </b>/* accept NULL pointer */<b> 209*01826a49SYabin Cui</pre></b><BR> 210*01826a49SYabin Cui<pre><b>size_t ZSTD_decompressDCtx(ZSTD_DCtx* dctx, 211*01826a49SYabin Cui void* dst, size_t dstCapacity, 212*01826a49SYabin Cui const void* src, size_t srcSize); 213*01826a49SYabin Cui</b><p> Same as ZSTD_decompress(), 214*01826a49SYabin Cui requires an allocated ZSTD_DCtx. 215*01826a49SYabin Cui Compatible with sticky parameters (see below). 216*01826a49SYabin Cui 217*01826a49SYabin Cui</p></pre><BR> 218*01826a49SYabin Cui 219*01826a49SYabin Cui<a name="Chapter5"></a><h2>Advanced compression API (Requires v1.4.0+)</h2><pre></pre> 220*01826a49SYabin Cui 221*01826a49SYabin Cui<pre><b>typedef enum { ZSTD_fast=1, 222*01826a49SYabin Cui ZSTD_dfast=2, 223*01826a49SYabin Cui ZSTD_greedy=3, 224*01826a49SYabin Cui ZSTD_lazy=4, 225*01826a49SYabin Cui ZSTD_lazy2=5, 226*01826a49SYabin Cui ZSTD_btlazy2=6, 227*01826a49SYabin Cui ZSTD_btopt=7, 228*01826a49SYabin Cui ZSTD_btultra=8, 229*01826a49SYabin Cui ZSTD_btultra2=9 230*01826a49SYabin Cui </b>/* note : new strategies _might_ be added in the future.<b> 231*01826a49SYabin Cui Only the order (from fast to strong) is guaranteed */ 232*01826a49SYabin Cui} ZSTD_strategy; 233*01826a49SYabin Cui</b></pre><BR> 234*01826a49SYabin Cui<pre><b>typedef enum { 235*01826a49SYabin Cui 236*01826a49SYabin Cui </b>/* compression parameters<b> 237*01826a49SYabin Cui * Note: When compressing with a ZSTD_CDict these parameters are superseded 238*01826a49SYabin Cui * by the parameters used to construct the ZSTD_CDict. 239*01826a49SYabin Cui * See ZSTD_CCtx_refCDict() for more info (superseded-by-cdict). */ 240*01826a49SYabin Cui ZSTD_c_compressionLevel=100, </b>/* Set compression parameters according to pre-defined cLevel table.<b> 241*01826a49SYabin Cui * Note that exact compression parameters are dynamically determined, 242*01826a49SYabin Cui * depending on both compression level and srcSize (when known). 243*01826a49SYabin Cui * Default level is ZSTD_CLEVEL_DEFAULT==3. 244*01826a49SYabin Cui * Special: value 0 means default, which is controlled by ZSTD_CLEVEL_DEFAULT. 245*01826a49SYabin Cui * Note 1 : it's possible to pass a negative compression level. 246*01826a49SYabin Cui * Note 2 : setting a level does not automatically set all other compression parameters 247*01826a49SYabin Cui * to default. Setting this will however eventually dynamically impact the compression 248*01826a49SYabin Cui * parameters which have not been manually set. The manually set 249*01826a49SYabin Cui * ones will 'stick'. */ 250*01826a49SYabin Cui </b>/* Advanced compression parameters :<b> 251*01826a49SYabin Cui * It's possible to pin down compression parameters to some specific values. 252*01826a49SYabin Cui * In which case, these values are no longer dynamically selected by the compressor */ 253*01826a49SYabin Cui ZSTD_c_windowLog=101, </b>/* Maximum allowed back-reference distance, expressed as power of 2.<b> 254*01826a49SYabin Cui * This will set a memory budget for streaming decompression, 255*01826a49SYabin Cui * with larger values requiring more memory 256*01826a49SYabin Cui * and typically compressing more. 257*01826a49SYabin Cui * Must be clamped between ZSTD_WINDOWLOG_MIN and ZSTD_WINDOWLOG_MAX. 258*01826a49SYabin Cui * Special: value 0 means "use default windowLog". 259*01826a49SYabin Cui * Note: Using a windowLog greater than ZSTD_WINDOWLOG_LIMIT_DEFAULT 260*01826a49SYabin Cui * requires explicitly allowing such size at streaming decompression stage. */ 261*01826a49SYabin Cui ZSTD_c_hashLog=102, </b>/* Size of the initial probe table, as a power of 2.<b> 262*01826a49SYabin Cui * Resulting memory usage is (1 << (hashLog+2)). 263*01826a49SYabin Cui * Must be clamped between ZSTD_HASHLOG_MIN and ZSTD_HASHLOG_MAX. 264*01826a49SYabin Cui * Larger tables improve compression ratio of strategies <= dFast, 265*01826a49SYabin Cui * and improve speed of strategies > dFast. 266*01826a49SYabin Cui * Special: value 0 means "use default hashLog". */ 267*01826a49SYabin Cui ZSTD_c_chainLog=103, </b>/* Size of the multi-probe search table, as a power of 2.<b> 268*01826a49SYabin Cui * Resulting memory usage is (1 << (chainLog+2)). 269*01826a49SYabin Cui * Must be clamped between ZSTD_CHAINLOG_MIN and ZSTD_CHAINLOG_MAX. 270*01826a49SYabin Cui * Larger tables result in better and slower compression. 271*01826a49SYabin Cui * This parameter is useless for "fast" strategy. 272*01826a49SYabin Cui * It's still useful when using "dfast" strategy, 273*01826a49SYabin Cui * in which case it defines a secondary probe table. 274*01826a49SYabin Cui * Special: value 0 means "use default chainLog". */ 275*01826a49SYabin Cui ZSTD_c_searchLog=104, </b>/* Number of search attempts, as a power of 2.<b> 276*01826a49SYabin Cui * More attempts result in better and slower compression. 277*01826a49SYabin Cui * This parameter is useless for "fast" and "dFast" strategies. 278*01826a49SYabin Cui * Special: value 0 means "use default searchLog". */ 279*01826a49SYabin Cui ZSTD_c_minMatch=105, </b>/* Minimum size of searched matches.<b> 280*01826a49SYabin Cui * Note that Zstandard can still find matches of smaller size, 281*01826a49SYabin Cui * it just tweaks its search algorithm to look for this size and larger. 282*01826a49SYabin Cui * Larger values increase compression and decompression speed, but decrease ratio. 283*01826a49SYabin Cui * Must be clamped between ZSTD_MINMATCH_MIN and ZSTD_MINMATCH_MAX. 284*01826a49SYabin Cui * Note that currently, for all strategies < btopt, effective minimum is 4. 285*01826a49SYabin Cui * , for all strategies > fast, effective maximum is 6. 286*01826a49SYabin Cui * Special: value 0 means "use default minMatchLength". */ 287*01826a49SYabin Cui ZSTD_c_targetLength=106, </b>/* Impact of this field depends on strategy.<b> 288*01826a49SYabin Cui * For strategies btopt, btultra & btultra2: 289*01826a49SYabin Cui * Length of Match considered "good enough" to stop search. 290*01826a49SYabin Cui * Larger values make compression stronger, and slower. 291*01826a49SYabin Cui * For strategy fast: 292*01826a49SYabin Cui * Distance between match sampling. 293*01826a49SYabin Cui * Larger values make compression faster, and weaker. 294*01826a49SYabin Cui * Special: value 0 means "use default targetLength". */ 295*01826a49SYabin Cui ZSTD_c_strategy=107, </b>/* See ZSTD_strategy enum definition.<b> 296*01826a49SYabin Cui * The higher the value of selected strategy, the more complex it is, 297*01826a49SYabin Cui * resulting in stronger and slower compression. 298*01826a49SYabin Cui * Special: value 0 means "use default strategy". */ 299*01826a49SYabin Cui 300*01826a49SYabin Cui ZSTD_c_targetCBlockSize=130, </b>/* v1.5.6+<b> 301*01826a49SYabin Cui * Attempts to fit compressed block size into approximatively targetCBlockSize. 302*01826a49SYabin Cui * Bound by ZSTD_TARGETCBLOCKSIZE_MIN and ZSTD_TARGETCBLOCKSIZE_MAX. 303*01826a49SYabin Cui * Note that it's not a guarantee, just a convergence target (default:0). 304*01826a49SYabin Cui * No target when targetCBlockSize == 0. 305*01826a49SYabin Cui * This is helpful in low bandwidth streaming environments to improve end-to-end latency, 306*01826a49SYabin Cui * when a client can make use of partial documents (a prominent example being Chrome). 307*01826a49SYabin Cui * Note: this parameter is stable since v1.5.6. 308*01826a49SYabin Cui * It was present as an experimental parameter in earlier versions, 309*01826a49SYabin Cui * but it's not recommended using it with earlier library versions 310*01826a49SYabin Cui * due to massive performance regressions. 311*01826a49SYabin Cui */ 312*01826a49SYabin Cui </b>/* LDM mode parameters */<b> 313*01826a49SYabin Cui ZSTD_c_enableLongDistanceMatching=160, </b>/* Enable long distance matching.<b> 314*01826a49SYabin Cui * This parameter is designed to improve compression ratio 315*01826a49SYabin Cui * for large inputs, by finding large matches at long distance. 316*01826a49SYabin Cui * It increases memory usage and window size. 317*01826a49SYabin Cui * Note: enabling this parameter increases default ZSTD_c_windowLog to 128 MB 318*01826a49SYabin Cui * except when expressly set to a different value. 319*01826a49SYabin Cui * Note: will be enabled by default if ZSTD_c_windowLog >= 128 MB and 320*01826a49SYabin Cui * compression strategy >= ZSTD_btopt (== compression level 16+) */ 321*01826a49SYabin Cui ZSTD_c_ldmHashLog=161, </b>/* Size of the table for long distance matching, as a power of 2.<b> 322*01826a49SYabin Cui * Larger values increase memory usage and compression ratio, 323*01826a49SYabin Cui * but decrease compression speed. 324*01826a49SYabin Cui * Must be clamped between ZSTD_HASHLOG_MIN and ZSTD_HASHLOG_MAX 325*01826a49SYabin Cui * default: windowlog - 7. 326*01826a49SYabin Cui * Special: value 0 means "automatically determine hashlog". */ 327*01826a49SYabin Cui ZSTD_c_ldmMinMatch=162, </b>/* Minimum match size for long distance matcher.<b> 328*01826a49SYabin Cui * Larger/too small values usually decrease compression ratio. 329*01826a49SYabin Cui * Must be clamped between ZSTD_LDM_MINMATCH_MIN and ZSTD_LDM_MINMATCH_MAX. 330*01826a49SYabin Cui * Special: value 0 means "use default value" (default: 64). */ 331*01826a49SYabin Cui ZSTD_c_ldmBucketSizeLog=163, </b>/* Log size of each bucket in the LDM hash table for collision resolution.<b> 332*01826a49SYabin Cui * Larger values improve collision resolution but decrease compression speed. 333*01826a49SYabin Cui * The maximum value is ZSTD_LDM_BUCKETSIZELOG_MAX. 334*01826a49SYabin Cui * Special: value 0 means "use default value" (default: 3). */ 335*01826a49SYabin Cui ZSTD_c_ldmHashRateLog=164, </b>/* Frequency of inserting/looking up entries into the LDM hash table.<b> 336*01826a49SYabin Cui * Must be clamped between 0 and (ZSTD_WINDOWLOG_MAX - ZSTD_HASHLOG_MIN). 337*01826a49SYabin Cui * Default is MAX(0, (windowLog - ldmHashLog)), optimizing hash table usage. 338*01826a49SYabin Cui * Larger values improve compression speed. 339*01826a49SYabin Cui * Deviating far from default value will likely result in a compression ratio decrease. 340*01826a49SYabin Cui * Special: value 0 means "automatically determine hashRateLog". */ 341*01826a49SYabin Cui 342*01826a49SYabin Cui </b>/* frame parameters */<b> 343*01826a49SYabin Cui ZSTD_c_contentSizeFlag=200, </b>/* Content size will be written into frame header _whenever known_ (default:1)<b> 344*01826a49SYabin Cui * Content size must be known at the beginning of compression. 345*01826a49SYabin Cui * This is automatically the case when using ZSTD_compress2(), 346*01826a49SYabin Cui * For streaming scenarios, content size must be provided with ZSTD_CCtx_setPledgedSrcSize() */ 347*01826a49SYabin Cui ZSTD_c_checksumFlag=201, </b>/* A 32-bits checksum of content is written at end of frame (default:0) */<b> 348*01826a49SYabin Cui ZSTD_c_dictIDFlag=202, </b>/* When applicable, dictionary's ID is written into frame header (default:1) */<b> 349*01826a49SYabin Cui 350*01826a49SYabin Cui </b>/* multi-threading parameters */<b> 351*01826a49SYabin Cui </b>/* These parameters are only active if multi-threading is enabled (compiled with build macro ZSTD_MULTITHREAD).<b> 352*01826a49SYabin Cui * Otherwise, trying to set any other value than default (0) will be a no-op and return an error. 353*01826a49SYabin Cui * In a situation where it's unknown if the linked library supports multi-threading or not, 354*01826a49SYabin Cui * setting ZSTD_c_nbWorkers to any value >= 1 and consulting the return value provides a quick way to check this property. 355*01826a49SYabin Cui */ 356*01826a49SYabin Cui ZSTD_c_nbWorkers=400, </b>/* Select how many threads will be spawned to compress in parallel.<b> 357*01826a49SYabin Cui * When nbWorkers >= 1, triggers asynchronous mode when invoking ZSTD_compressStream*() : 358*01826a49SYabin Cui * ZSTD_compressStream*() consumes input and flush output if possible, but immediately gives back control to caller, 359*01826a49SYabin Cui * while compression is performed in parallel, within worker thread(s). 360*01826a49SYabin Cui * (note : a strong exception to this rule is when first invocation of ZSTD_compressStream2() sets ZSTD_e_end : 361*01826a49SYabin Cui * in which case, ZSTD_compressStream2() delegates to ZSTD_compress2(), which is always a blocking call). 362*01826a49SYabin Cui * More workers improve speed, but also increase memory usage. 363*01826a49SYabin Cui * Default value is `0`, aka "single-threaded mode" : no worker is spawned, 364*01826a49SYabin Cui * compression is performed inside Caller's thread, and all invocations are blocking */ 365*01826a49SYabin Cui ZSTD_c_jobSize=401, </b>/* Size of a compression job. This value is enforced only when nbWorkers >= 1.<b> 366*01826a49SYabin Cui * Each compression job is completed in parallel, so this value can indirectly impact the nb of active threads. 367*01826a49SYabin Cui * 0 means default, which is dynamically determined based on compression parameters. 368*01826a49SYabin Cui * Job size must be a minimum of overlap size, or ZSTDMT_JOBSIZE_MIN (= 512 KB), whichever is largest. 369*01826a49SYabin Cui * The minimum size is automatically and transparently enforced. */ 370*01826a49SYabin Cui ZSTD_c_overlapLog=402, </b>/* Control the overlap size, as a fraction of window size.<b> 371*01826a49SYabin Cui * The overlap size is an amount of data reloaded from previous job at the beginning of a new job. 372*01826a49SYabin Cui * It helps preserve compression ratio, while each job is compressed in parallel. 373*01826a49SYabin Cui * This value is enforced only when nbWorkers >= 1. 374*01826a49SYabin Cui * Larger values increase compression ratio, but decrease speed. 375*01826a49SYabin Cui * Possible values range from 0 to 9 : 376*01826a49SYabin Cui * - 0 means "default" : value will be determined by the library, depending on strategy 377*01826a49SYabin Cui * - 1 means "no overlap" 378*01826a49SYabin Cui * - 9 means "full overlap", using a full window size. 379*01826a49SYabin Cui * Each intermediate rank increases/decreases load size by a factor 2 : 380*01826a49SYabin Cui * 9: full window; 8: w/2; 7: w/4; 6: w/8; 5:w/16; 4: w/32; 3:w/64; 2:w/128; 1:no overlap; 0:default 381*01826a49SYabin Cui * default value varies between 6 and 9, depending on strategy */ 382*01826a49SYabin Cui 383*01826a49SYabin Cui </b>/* note : additional experimental parameters are also available<b> 384*01826a49SYabin Cui * within the experimental section of the API. 385*01826a49SYabin Cui * At the time of this writing, they include : 386*01826a49SYabin Cui * ZSTD_c_rsyncable 387*01826a49SYabin Cui * ZSTD_c_format 388*01826a49SYabin Cui * ZSTD_c_forceMaxWindow 389*01826a49SYabin Cui * ZSTD_c_forceAttachDict 390*01826a49SYabin Cui * ZSTD_c_literalCompressionMode 391*01826a49SYabin Cui * ZSTD_c_srcSizeHint 392*01826a49SYabin Cui * ZSTD_c_enableDedicatedDictSearch 393*01826a49SYabin Cui * ZSTD_c_stableInBuffer 394*01826a49SYabin Cui * ZSTD_c_stableOutBuffer 395*01826a49SYabin Cui * ZSTD_c_blockDelimiters 396*01826a49SYabin Cui * ZSTD_c_validateSequences 397*01826a49SYabin Cui * ZSTD_c_useBlockSplitter 398*01826a49SYabin Cui * ZSTD_c_useRowMatchFinder 399*01826a49SYabin Cui * ZSTD_c_prefetchCDictTables 400*01826a49SYabin Cui * ZSTD_c_enableSeqProducerFallback 401*01826a49SYabin Cui * ZSTD_c_maxBlockSize 402*01826a49SYabin Cui * Because they are not stable, it's necessary to define ZSTD_STATIC_LINKING_ONLY to access them. 403*01826a49SYabin Cui * note : never ever use experimentalParam? names directly; 404*01826a49SYabin Cui * also, the enums values themselves are unstable and can still change. 405*01826a49SYabin Cui */ 406*01826a49SYabin Cui ZSTD_c_experimentalParam1=500, 407*01826a49SYabin Cui ZSTD_c_experimentalParam2=10, 408*01826a49SYabin Cui ZSTD_c_experimentalParam3=1000, 409*01826a49SYabin Cui ZSTD_c_experimentalParam4=1001, 410*01826a49SYabin Cui ZSTD_c_experimentalParam5=1002, 411*01826a49SYabin Cui </b>/* was ZSTD_c_experimentalParam6=1003; is now ZSTD_c_targetCBlockSize */<b> 412*01826a49SYabin Cui ZSTD_c_experimentalParam7=1004, 413*01826a49SYabin Cui ZSTD_c_experimentalParam8=1005, 414*01826a49SYabin Cui ZSTD_c_experimentalParam9=1006, 415*01826a49SYabin Cui ZSTD_c_experimentalParam10=1007, 416*01826a49SYabin Cui ZSTD_c_experimentalParam11=1008, 417*01826a49SYabin Cui ZSTD_c_experimentalParam12=1009, 418*01826a49SYabin Cui ZSTD_c_experimentalParam13=1010, 419*01826a49SYabin Cui ZSTD_c_experimentalParam14=1011, 420*01826a49SYabin Cui ZSTD_c_experimentalParam15=1012, 421*01826a49SYabin Cui ZSTD_c_experimentalParam16=1013, 422*01826a49SYabin Cui ZSTD_c_experimentalParam17=1014, 423*01826a49SYabin Cui ZSTD_c_experimentalParam18=1015, 424*01826a49SYabin Cui ZSTD_c_experimentalParam19=1016 425*01826a49SYabin Cui} ZSTD_cParameter; 426*01826a49SYabin Cui</b></pre><BR> 427*01826a49SYabin Cui<pre><b>typedef struct { 428*01826a49SYabin Cui size_t error; 429*01826a49SYabin Cui int lowerBound; 430*01826a49SYabin Cui int upperBound; 431*01826a49SYabin Cui} ZSTD_bounds; 432*01826a49SYabin Cui</b></pre><BR> 433*01826a49SYabin Cui<pre><b>ZSTD_bounds ZSTD_cParam_getBounds(ZSTD_cParameter cParam); 434*01826a49SYabin Cui</b><p> All parameters must belong to an interval with lower and upper bounds, 435*01826a49SYabin Cui otherwise they will either trigger an error or be automatically clamped. 436*01826a49SYabin Cui @return : a structure, ZSTD_bounds, which contains 437*01826a49SYabin Cui - an error status field, which must be tested using ZSTD_isError() 438*01826a49SYabin Cui - lower and upper bounds, both inclusive 439*01826a49SYabin Cui 440*01826a49SYabin Cui</p></pre><BR> 441*01826a49SYabin Cui 442*01826a49SYabin Cui<pre><b>size_t ZSTD_CCtx_setParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, int value); 443*01826a49SYabin Cui</b><p> Set one compression parameter, selected by enum ZSTD_cParameter. 444*01826a49SYabin Cui All parameters have valid bounds. Bounds can be queried using ZSTD_cParam_getBounds(). 445*01826a49SYabin Cui Providing a value beyond bound will either clamp it, or trigger an error (depending on parameter). 446*01826a49SYabin Cui Setting a parameter is generally only possible during frame initialization (before starting compression). 447*01826a49SYabin Cui Exception : when using multi-threading mode (nbWorkers >= 1), 448*01826a49SYabin Cui the following parameters can be updated _during_ compression (within same frame): 449*01826a49SYabin Cui => compressionLevel, hashLog, chainLog, searchLog, minMatch, targetLength and strategy. 450*01826a49SYabin Cui new parameters will be active for next job only (after a flush()). 451*01826a49SYabin Cui @return : an error code (which can be tested using ZSTD_isError()). 452*01826a49SYabin Cui 453*01826a49SYabin Cui</p></pre><BR> 454*01826a49SYabin Cui 455*01826a49SYabin Cui<pre><b>size_t ZSTD_CCtx_setPledgedSrcSize(ZSTD_CCtx* cctx, unsigned long long pledgedSrcSize); 456*01826a49SYabin Cui</b><p> Total input data size to be compressed as a single frame. 457*01826a49SYabin Cui Value will be written in frame header, unless if explicitly forbidden using ZSTD_c_contentSizeFlag. 458*01826a49SYabin Cui This value will also be controlled at end of frame, and trigger an error if not respected. 459*01826a49SYabin Cui @result : 0, or an error code (which can be tested with ZSTD_isError()). 460*01826a49SYabin Cui Note 1 : pledgedSrcSize==0 actually means zero, aka an empty frame. 461*01826a49SYabin Cui In order to mean "unknown content size", pass constant ZSTD_CONTENTSIZE_UNKNOWN. 462*01826a49SYabin Cui ZSTD_CONTENTSIZE_UNKNOWN is default value for any new frame. 463*01826a49SYabin Cui Note 2 : pledgedSrcSize is only valid once, for the next frame. 464*01826a49SYabin Cui It's discarded at the end of the frame, and replaced by ZSTD_CONTENTSIZE_UNKNOWN. 465*01826a49SYabin Cui Note 3 : Whenever all input data is provided and consumed in a single round, 466*01826a49SYabin Cui for example with ZSTD_compress2(), 467*01826a49SYabin Cui or invoking immediately ZSTD_compressStream2(,,,ZSTD_e_end), 468*01826a49SYabin Cui this value is automatically overridden by srcSize instead. 469*01826a49SYabin Cui 470*01826a49SYabin Cui</p></pre><BR> 471*01826a49SYabin Cui 472*01826a49SYabin Cui<pre><b>typedef enum { 473*01826a49SYabin Cui ZSTD_reset_session_only = 1, 474*01826a49SYabin Cui ZSTD_reset_parameters = 2, 475*01826a49SYabin Cui ZSTD_reset_session_and_parameters = 3 476*01826a49SYabin Cui} ZSTD_ResetDirective; 477*01826a49SYabin Cui</b></pre><BR> 478*01826a49SYabin Cui<pre><b>size_t ZSTD_CCtx_reset(ZSTD_CCtx* cctx, ZSTD_ResetDirective reset); 479*01826a49SYabin Cui</b><p> There are 2 different things that can be reset, independently or jointly : 480*01826a49SYabin Cui - The session : will stop compressing current frame, and make CCtx ready to start a new one. 481*01826a49SYabin Cui Useful after an error, or to interrupt any ongoing compression. 482*01826a49SYabin Cui Any internal data not yet flushed is cancelled. 483*01826a49SYabin Cui Compression parameters and dictionary remain unchanged. 484*01826a49SYabin Cui They will be used to compress next frame. 485*01826a49SYabin Cui Resetting session never fails. 486*01826a49SYabin Cui - The parameters : changes all parameters back to "default". 487*01826a49SYabin Cui This also removes any reference to any dictionary or external sequence producer. 488*01826a49SYabin Cui Parameters can only be changed between 2 sessions (i.e. no compression is currently ongoing) 489*01826a49SYabin Cui otherwise the reset fails, and function returns an error value (which can be tested using ZSTD_isError()) 490*01826a49SYabin Cui - Both : similar to resetting the session, followed by resetting parameters. 491*01826a49SYabin Cui 492*01826a49SYabin Cui</p></pre><BR> 493*01826a49SYabin Cui 494*01826a49SYabin Cui<pre><b>size_t ZSTD_compress2( ZSTD_CCtx* cctx, 495*01826a49SYabin Cui void* dst, size_t dstCapacity, 496*01826a49SYabin Cui const void* src, size_t srcSize); 497*01826a49SYabin Cui</b><p> Behave the same as ZSTD_compressCCtx(), but compression parameters are set using the advanced API. 498*01826a49SYabin Cui (note that this entry point doesn't even expose a compression level parameter). 499*01826a49SYabin Cui ZSTD_compress2() always starts a new frame. 500*01826a49SYabin Cui Should cctx hold data from a previously unfinished frame, everything about it is forgotten. 501*01826a49SYabin Cui - Compression parameters are pushed into CCtx before starting compression, using ZSTD_CCtx_set*() 502*01826a49SYabin Cui - The function is always blocking, returns when compression is completed. 503*01826a49SYabin Cui NOTE: Providing `dstCapacity >= ZSTD_compressBound(srcSize)` guarantees that zstd will have 504*01826a49SYabin Cui enough space to successfully compress the data, though it is possible it fails for other reasons. 505*01826a49SYabin Cui @return : compressed size written into `dst` (<= `dstCapacity), 506*01826a49SYabin Cui or an error code if it fails (which can be tested using ZSTD_isError()). 507*01826a49SYabin Cui 508*01826a49SYabin Cui</p></pre><BR> 509*01826a49SYabin Cui 510*01826a49SYabin Cui<a name="Chapter6"></a><h2>Advanced decompression API (Requires v1.4.0+)</h2><pre></pre> 511*01826a49SYabin Cui 512*01826a49SYabin Cui<pre><b>typedef enum { 513*01826a49SYabin Cui 514*01826a49SYabin Cui ZSTD_d_windowLogMax=100, </b>/* Select a size limit (in power of 2) beyond which<b> 515*01826a49SYabin Cui * the streaming API will refuse to allocate memory buffer 516*01826a49SYabin Cui * in order to protect the host from unreasonable memory requirements. 517*01826a49SYabin Cui * This parameter is only useful in streaming mode, since no internal buffer is allocated in single-pass mode. 518*01826a49SYabin Cui * By default, a decompression context accepts window sizes <= (1 << ZSTD_WINDOWLOG_LIMIT_DEFAULT). 519*01826a49SYabin Cui * Special: value 0 means "use default maximum windowLog". */ 520*01826a49SYabin Cui 521*01826a49SYabin Cui </b>/* note : additional experimental parameters are also available<b> 522*01826a49SYabin Cui * within the experimental section of the API. 523*01826a49SYabin Cui * At the time of this writing, they include : 524*01826a49SYabin Cui * ZSTD_d_format 525*01826a49SYabin Cui * ZSTD_d_stableOutBuffer 526*01826a49SYabin Cui * ZSTD_d_forceIgnoreChecksum 527*01826a49SYabin Cui * ZSTD_d_refMultipleDDicts 528*01826a49SYabin Cui * ZSTD_d_disableHuffmanAssembly 529*01826a49SYabin Cui * ZSTD_d_maxBlockSize 530*01826a49SYabin Cui * Because they are not stable, it's necessary to define ZSTD_STATIC_LINKING_ONLY to access them. 531*01826a49SYabin Cui * note : never ever use experimentalParam? names directly 532*01826a49SYabin Cui */ 533*01826a49SYabin Cui ZSTD_d_experimentalParam1=1000, 534*01826a49SYabin Cui ZSTD_d_experimentalParam2=1001, 535*01826a49SYabin Cui ZSTD_d_experimentalParam3=1002, 536*01826a49SYabin Cui ZSTD_d_experimentalParam4=1003, 537*01826a49SYabin Cui ZSTD_d_experimentalParam5=1004, 538*01826a49SYabin Cui ZSTD_d_experimentalParam6=1005 539*01826a49SYabin Cui 540*01826a49SYabin Cui} ZSTD_dParameter; 541*01826a49SYabin Cui</b></pre><BR> 542*01826a49SYabin Cui<pre><b>ZSTD_bounds ZSTD_dParam_getBounds(ZSTD_dParameter dParam); 543*01826a49SYabin Cui</b><p> All parameters must belong to an interval with lower and upper bounds, 544*01826a49SYabin Cui otherwise they will either trigger an error or be automatically clamped. 545*01826a49SYabin Cui @return : a structure, ZSTD_bounds, which contains 546*01826a49SYabin Cui - an error status field, which must be tested using ZSTD_isError() 547*01826a49SYabin Cui - both lower and upper bounds, inclusive 548*01826a49SYabin Cui 549*01826a49SYabin Cui</p></pre><BR> 550*01826a49SYabin Cui 551*01826a49SYabin Cui<pre><b>size_t ZSTD_DCtx_setParameter(ZSTD_DCtx* dctx, ZSTD_dParameter param, int value); 552*01826a49SYabin Cui</b><p> Set one compression parameter, selected by enum ZSTD_dParameter. 553*01826a49SYabin Cui All parameters have valid bounds. Bounds can be queried using ZSTD_dParam_getBounds(). 554*01826a49SYabin Cui Providing a value beyond bound will either clamp it, or trigger an error (depending on parameter). 555*01826a49SYabin Cui Setting a parameter is only possible during frame initialization (before starting decompression). 556*01826a49SYabin Cui @return : 0, or an error code (which can be tested using ZSTD_isError()). 557*01826a49SYabin Cui 558*01826a49SYabin Cui</p></pre><BR> 559*01826a49SYabin Cui 560*01826a49SYabin Cui<pre><b>size_t ZSTD_DCtx_reset(ZSTD_DCtx* dctx, ZSTD_ResetDirective reset); 561*01826a49SYabin Cui</b><p> Return a DCtx to clean state. 562*01826a49SYabin Cui Session and parameters can be reset jointly or separately. 563*01826a49SYabin Cui Parameters can only be reset when no active frame is being decompressed. 564*01826a49SYabin Cui @return : 0, or an error code, which can be tested with ZSTD_isError() 565*01826a49SYabin Cui 566*01826a49SYabin Cui</p></pre><BR> 567*01826a49SYabin Cui 568*01826a49SYabin Cui<a name="Chapter7"></a><h2>Streaming</h2><pre></pre> 569*01826a49SYabin Cui 570*01826a49SYabin Cui<pre><b>typedef struct ZSTD_inBuffer_s { 571*01826a49SYabin Cui const void* src; </b>/**< start of input buffer */<b> 572*01826a49SYabin Cui size_t size; </b>/**< size of input buffer */<b> 573*01826a49SYabin Cui size_t pos; </b>/**< position where reading stopped. Will be updated. Necessarily 0 <= pos <= size */<b> 574*01826a49SYabin Cui} ZSTD_inBuffer; 575*01826a49SYabin Cui</b></pre><BR> 576*01826a49SYabin Cui<pre><b>typedef struct ZSTD_outBuffer_s { 577*01826a49SYabin Cui void* dst; </b>/**< start of output buffer */<b> 578*01826a49SYabin Cui size_t size; </b>/**< size of output buffer */<b> 579*01826a49SYabin Cui size_t pos; </b>/**< position where writing stopped. Will be updated. Necessarily 0 <= pos <= size */<b> 580*01826a49SYabin Cui} ZSTD_outBuffer; 581*01826a49SYabin Cui</b></pre><BR> 582*01826a49SYabin Cui<a name="Chapter8"></a><h2>Streaming compression - HowTo</h2><pre> 583*01826a49SYabin Cui A ZSTD_CStream object is required to track streaming operation. 584*01826a49SYabin Cui Use ZSTD_createCStream() and ZSTD_freeCStream() to create/release resources. 585*01826a49SYabin Cui ZSTD_CStream objects can be reused multiple times on consecutive compression operations. 586*01826a49SYabin Cui It is recommended to reuse ZSTD_CStream since it will play nicer with system's memory, by re-using already allocated memory. 587*01826a49SYabin Cui 588*01826a49SYabin Cui For parallel execution, use one separate ZSTD_CStream per thread. 589*01826a49SYabin Cui 590*01826a49SYabin Cui note : since v1.3.0, ZSTD_CStream and ZSTD_CCtx are the same thing. 591*01826a49SYabin Cui 592*01826a49SYabin Cui Parameters are sticky : when starting a new compression on the same context, 593*01826a49SYabin Cui it will reuse the same sticky parameters as previous compression session. 594*01826a49SYabin Cui When in doubt, it's recommended to fully initialize the context before usage. 595*01826a49SYabin Cui Use ZSTD_CCtx_reset() to reset the context and ZSTD_CCtx_setParameter(), 596*01826a49SYabin Cui ZSTD_CCtx_setPledgedSrcSize(), or ZSTD_CCtx_loadDictionary() and friends to 597*01826a49SYabin Cui set more specific parameters, the pledged source size, or load a dictionary. 598*01826a49SYabin Cui 599*01826a49SYabin Cui Use ZSTD_compressStream2() with ZSTD_e_continue as many times as necessary to 600*01826a49SYabin Cui consume input stream. The function will automatically update both `pos` 601*01826a49SYabin Cui fields within `input` and `output`. 602*01826a49SYabin Cui Note that the function may not consume the entire input, for example, because 603*01826a49SYabin Cui the output buffer is already full, in which case `input.pos < input.size`. 604*01826a49SYabin Cui The caller must check if input has been entirely consumed. 605*01826a49SYabin Cui If not, the caller must make some room to receive more compressed data, 606*01826a49SYabin Cui and then present again remaining input data. 607*01826a49SYabin Cui note: ZSTD_e_continue is guaranteed to make some forward progress when called, 608*01826a49SYabin Cui but doesn't guarantee maximal forward progress. This is especially relevant 609*01826a49SYabin Cui when compressing with multiple threads. The call won't block if it can 610*01826a49SYabin Cui consume some input, but if it can't it will wait for some, but not all, 611*01826a49SYabin Cui output to be flushed. 612*01826a49SYabin Cui @return : provides a minimum amount of data remaining to be flushed from internal buffers 613*01826a49SYabin Cui or an error code, which can be tested using ZSTD_isError(). 614*01826a49SYabin Cui 615*01826a49SYabin Cui At any moment, it's possible to flush whatever data might remain stuck within internal buffer, 616*01826a49SYabin Cui using ZSTD_compressStream2() with ZSTD_e_flush. `output->pos` will be updated. 617*01826a49SYabin Cui Note that, if `output->size` is too small, a single invocation with ZSTD_e_flush might not be enough (return code > 0). 618*01826a49SYabin Cui In which case, make some room to receive more compressed data, and call again ZSTD_compressStream2() with ZSTD_e_flush. 619*01826a49SYabin Cui You must continue calling ZSTD_compressStream2() with ZSTD_e_flush until it returns 0, at which point you can change the 620*01826a49SYabin Cui operation. 621*01826a49SYabin Cui note: ZSTD_e_flush will flush as much output as possible, meaning when compressing with multiple threads, it will 622*01826a49SYabin Cui block until the flush is complete or the output buffer is full. 623*01826a49SYabin Cui @return : 0 if internal buffers are entirely flushed, 624*01826a49SYabin Cui >0 if some data still present within internal buffer (the value is minimal estimation of remaining size), 625*01826a49SYabin Cui or an error code, which can be tested using ZSTD_isError(). 626*01826a49SYabin Cui 627*01826a49SYabin Cui Calling ZSTD_compressStream2() with ZSTD_e_end instructs to finish a frame. 628*01826a49SYabin Cui It will perform a flush and write frame epilogue. 629*01826a49SYabin Cui The epilogue is required for decoders to consider a frame completed. 630*01826a49SYabin Cui flush operation is the same, and follows same rules as calling ZSTD_compressStream2() with ZSTD_e_flush. 631*01826a49SYabin Cui You must continue calling ZSTD_compressStream2() with ZSTD_e_end until it returns 0, at which point you are free to 632*01826a49SYabin Cui start a new frame. 633*01826a49SYabin Cui note: ZSTD_e_end will flush as much output as possible, meaning when compressing with multiple threads, it will 634*01826a49SYabin Cui block until the flush is complete or the output buffer is full. 635*01826a49SYabin Cui @return : 0 if frame fully completed and fully flushed, 636*01826a49SYabin Cui >0 if some data still present within internal buffer (the value is minimal estimation of remaining size), 637*01826a49SYabin Cui or an error code, which can be tested using ZSTD_isError(). 638*01826a49SYabin Cui 639*01826a49SYabin Cui 640*01826a49SYabin Cui<BR></pre> 641*01826a49SYabin Cui 642*01826a49SYabin Cui<pre><b>typedef ZSTD_CCtx ZSTD_CStream; </b>/**< CCtx and CStream are now effectively same object (>= v1.3.0) */<b> 643*01826a49SYabin Cui</b></pre><BR> 644*01826a49SYabin Cui<h3>ZSTD_CStream management functions</h3><pre></pre><b><pre>ZSTD_CStream* ZSTD_createCStream(void); 645*01826a49SYabin Cuisize_t ZSTD_freeCStream(ZSTD_CStream* zcs); </b>/* accept NULL pointer */<b> 646*01826a49SYabin Cui</pre></b><BR> 647*01826a49SYabin Cui<h3>Streaming compression functions</h3><pre></pre><b><pre>typedef enum { 648*01826a49SYabin Cui ZSTD_e_continue=0, </b>/* collect more data, encoder decides when to output compressed result, for optimal compression ratio */<b> 649*01826a49SYabin Cui ZSTD_e_flush=1, </b>/* flush any data provided so far,<b> 650*01826a49SYabin Cui * it creates (at least) one new block, that can be decoded immediately on reception; 651*01826a49SYabin Cui * frame will continue: any future data can still reference previously compressed data, improving compression. 652*01826a49SYabin Cui * note : multithreaded compression will block to flush as much output as possible. */ 653*01826a49SYabin Cui ZSTD_e_end=2 </b>/* flush any remaining data _and_ close current frame.<b> 654*01826a49SYabin Cui * note that frame is only closed after compressed data is fully flushed (return value == 0). 655*01826a49SYabin Cui * After that point, any additional data starts a new frame. 656*01826a49SYabin Cui * note : each frame is independent (does not reference any content from previous frame). 657*01826a49SYabin Cui : note : multithreaded compression will block to flush as much output as possible. */ 658*01826a49SYabin Cui} ZSTD_EndDirective; 659*01826a49SYabin Cui</pre></b><BR> 660*01826a49SYabin Cui<pre><b>size_t ZSTD_compressStream2( ZSTD_CCtx* cctx, 661*01826a49SYabin Cui ZSTD_outBuffer* output, 662*01826a49SYabin Cui ZSTD_inBuffer* input, 663*01826a49SYabin Cui ZSTD_EndDirective endOp); 664*01826a49SYabin Cui</b><p> Behaves about the same as ZSTD_compressStream, with additional control on end directive. 665*01826a49SYabin Cui - Compression parameters are pushed into CCtx before starting compression, using ZSTD_CCtx_set*() 666*01826a49SYabin Cui - Compression parameters cannot be changed once compression is started (save a list of exceptions in multi-threading mode) 667*01826a49SYabin Cui - output->pos must be <= dstCapacity, input->pos must be <= srcSize 668*01826a49SYabin Cui - output->pos and input->pos will be updated. They are guaranteed to remain below their respective limit. 669*01826a49SYabin Cui - endOp must be a valid directive 670*01826a49SYabin Cui - When nbWorkers==0 (default), function is blocking : it completes its job before returning to caller. 671*01826a49SYabin Cui - When nbWorkers>=1, function is non-blocking : it copies a portion of input, distributes jobs to internal worker threads, flush to output whatever is available, 672*01826a49SYabin Cui and then immediately returns, just indicating that there is some data remaining to be flushed. 673*01826a49SYabin Cui The function nonetheless guarantees forward progress : it will return only after it reads or write at least 1+ byte. 674*01826a49SYabin Cui - 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. 675*01826a49SYabin Cui - @return provides a minimum amount of data remaining to be flushed from internal buffers 676*01826a49SYabin Cui or an error code, which can be tested using ZSTD_isError(). 677*01826a49SYabin Cui if @return != 0, flush is not fully completed, there is still some data left within internal buffers. 678*01826a49SYabin Cui This is useful for ZSTD_e_flush, since in this case more flushes are necessary to empty all buffers. 679*01826a49SYabin Cui For ZSTD_e_end, @return == 0 when internal buffers are fully flushed and frame is completed. 680*01826a49SYabin Cui - after a ZSTD_e_end directive, if internal buffer is not fully flushed (@return != 0), 681*01826a49SYabin Cui only ZSTD_e_end or ZSTD_e_flush operations are allowed. 682*01826a49SYabin Cui Before starting a new compression job, or changing compression parameters, 683*01826a49SYabin Cui it is required to fully flush internal buffers. 684*01826a49SYabin Cui - note: if an operation ends with an error, it may leave @cctx in an undefined state. 685*01826a49SYabin Cui Therefore, it's UB to invoke ZSTD_compressStream2() of ZSTD_compressStream() on such a state. 686*01826a49SYabin Cui In order to be re-employed after an error, a state must be reset, 687*01826a49SYabin Cui which can be done explicitly (ZSTD_CCtx_reset()), 688*01826a49SYabin Cui or is sometimes implied by methods starting a new compression job (ZSTD_initCStream(), ZSTD_compressCCtx()) 689*01826a49SYabin Cui 690*01826a49SYabin Cui</p></pre><BR> 691*01826a49SYabin Cui 692*01826a49SYabin Cui<pre><b>size_t ZSTD_CStreamInSize(void); </b>/**< recommended size for input buffer */<b> 693*01826a49SYabin Cui</b></pre><BR> 694*01826a49SYabin Cui<pre><b>size_t ZSTD_CStreamOutSize(void); </b>/**< recommended size for output buffer. Guarantee to successfully flush at least one complete compressed block. */<b> 695*01826a49SYabin Cui</b></pre><BR> 696*01826a49SYabin Cui<pre><b>size_t ZSTD_initCStream(ZSTD_CStream* zcs, int compressionLevel); 697*01826a49SYabin Cui</b>/*!<b> 698*01826a49SYabin Cui * Alternative for ZSTD_compressStream2(zcs, output, input, ZSTD_e_continue). 699*01826a49SYabin Cui * NOTE: The return value is different. ZSTD_compressStream() returns a hint for 700*01826a49SYabin Cui * the next read size (if non-zero and not an error). ZSTD_compressStream2() 701*01826a49SYabin Cui * returns the minimum nb of bytes left to flush (if non-zero and not an error). 702*01826a49SYabin Cui */ 703*01826a49SYabin Cuisize_t ZSTD_compressStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output, ZSTD_inBuffer* input); 704*01826a49SYabin Cui</b>/*! Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_flush). */<b> 705*01826a49SYabin Cuisize_t ZSTD_flushStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output); 706*01826a49SYabin Cui</b>/*! Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_end). */<b> 707*01826a49SYabin Cuisize_t ZSTD_endStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output); 708*01826a49SYabin Cui</b><p> 709*01826a49SYabin Cui ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only); 710*01826a49SYabin Cui ZSTD_CCtx_refCDict(zcs, NULL); // clear the dictionary (if any) 711*01826a49SYabin Cui ZSTD_CCtx_setParameter(zcs, ZSTD_c_compressionLevel, compressionLevel); 712*01826a49SYabin Cui 713*01826a49SYabin Cui Note that ZSTD_initCStream() clears any previously set dictionary. Use the new API 714*01826a49SYabin Cui to compress with a dictionary. 715*01826a49SYabin Cui 716*01826a49SYabin Cui</p></pre><BR> 717*01826a49SYabin Cui 718*01826a49SYabin Cui<a name="Chapter9"></a><h2>Streaming decompression - HowTo</h2><pre> 719*01826a49SYabin Cui A ZSTD_DStream object is required to track streaming operations. 720*01826a49SYabin Cui Use ZSTD_createDStream() and ZSTD_freeDStream() to create/release resources. 721*01826a49SYabin Cui ZSTD_DStream objects can be reused multiple times. 722*01826a49SYabin Cui 723*01826a49SYabin Cui Use ZSTD_initDStream() to start a new decompression operation. 724*01826a49SYabin Cui @return : recommended first input size 725*01826a49SYabin Cui Alternatively, use advanced API to set specific properties. 726*01826a49SYabin Cui 727*01826a49SYabin Cui Use ZSTD_decompressStream() repetitively to consume your input. 728*01826a49SYabin Cui The function will update both `pos` fields. 729*01826a49SYabin Cui If `input.pos < input.size`, some input has not been consumed. 730*01826a49SYabin Cui It's up to the caller to present again remaining data. 731*01826a49SYabin Cui The function tries to flush all data decoded immediately, respecting output buffer size. 732*01826a49SYabin Cui If `output.pos < output.size`, decoder has flushed everything it could. 733*01826a49SYabin Cui But if `output.pos == output.size`, there might be some data left within internal buffers., 734*01826a49SYabin Cui In which case, call ZSTD_decompressStream() again to flush whatever remains in the buffer. 735*01826a49SYabin Cui Note : with no additional input provided, amount of data flushed is necessarily <= ZSTD_BLOCKSIZE_MAX. 736*01826a49SYabin Cui @return : 0 when a frame is completely decoded and fully flushed, 737*01826a49SYabin Cui or an error code, which can be tested using ZSTD_isError(), 738*01826a49SYabin Cui or any other value > 0, which means there is still some decoding or flushing to do to complete current frame : 739*01826a49SYabin Cui the return value is a suggested next input size (just a hint for better latency) 740*01826a49SYabin Cui that will never request more than the remaining frame size. 741*01826a49SYabin Cui 742*01826a49SYabin Cui<BR></pre> 743*01826a49SYabin Cui 744*01826a49SYabin Cui<pre><b>typedef ZSTD_DCtx ZSTD_DStream; </b>/**< DCtx and DStream are now effectively same object (>= v1.3.0) */<b> 745*01826a49SYabin Cui</b></pre><BR> 746*01826a49SYabin Cui<h3>ZSTD_DStream management functions</h3><pre></pre><b><pre>ZSTD_DStream* ZSTD_createDStream(void); 747*01826a49SYabin Cuisize_t ZSTD_freeDStream(ZSTD_DStream* zds); </b>/* accept NULL pointer */<b> 748*01826a49SYabin Cui</pre></b><BR> 749*01826a49SYabin Cui<h3>Streaming decompression functions</h3><pre></pre><b><pre></pre></b><BR> 750*01826a49SYabin Cui<pre><b>size_t ZSTD_initDStream(ZSTD_DStream* zds); 751*01826a49SYabin Cui</b><p> Initialize/reset DStream state for new decompression operation. 752*01826a49SYabin Cui Call before new decompression operation using same DStream. 753*01826a49SYabin Cui 754*01826a49SYabin Cui Note : This function is redundant with the advanced API and equivalent to: 755*01826a49SYabin Cui ZSTD_DCtx_reset(zds, ZSTD_reset_session_only); 756*01826a49SYabin Cui ZSTD_DCtx_refDDict(zds, NULL); 757*01826a49SYabin Cui 758*01826a49SYabin Cui</p></pre><BR> 759*01826a49SYabin Cui 760*01826a49SYabin Cui<pre><b>size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inBuffer* input); 761*01826a49SYabin Cui</b><p> Streaming decompression function. 762*01826a49SYabin Cui Call repetitively to consume full input updating it as necessary. 763*01826a49SYabin Cui Function will update both input and output `pos` fields exposing current state via these fields: 764*01826a49SYabin Cui - `input.pos < input.size`, some input remaining and caller should provide remaining input 765*01826a49SYabin Cui on the next call. 766*01826a49SYabin Cui - `output.pos < output.size`, decoder finished and flushed all remaining buffers. 767*01826a49SYabin Cui - `output.pos == output.size`, potentially uncflushed data present in the internal buffers, 768*01826a49SYabin Cui call ZSTD_decompressStream() again to flush remaining data to output. 769*01826a49SYabin Cui Note : with no additional input, amount of data flushed <= ZSTD_BLOCKSIZE_MAX. 770*01826a49SYabin Cui 771*01826a49SYabin Cui @return : 0 when a frame is completely decoded and fully flushed, 772*01826a49SYabin Cui or an error code, which can be tested using ZSTD_isError(), 773*01826a49SYabin Cui or any other value > 0, which means there is some decoding or flushing to do to complete current frame. 774*01826a49SYabin Cui 775*01826a49SYabin Cui Note: when an operation returns with an error code, the @zds state may be left in undefined state. 776*01826a49SYabin Cui It's UB to invoke `ZSTD_decompressStream()` on such a state. 777*01826a49SYabin Cui In order to re-use such a state, it must be first reset, 778*01826a49SYabin Cui which can be done explicitly (`ZSTD_DCtx_reset()`), 779*01826a49SYabin Cui or is implied for operations starting some new decompression job (`ZSTD_initDStream`, `ZSTD_decompressDCtx()`, `ZSTD_decompress_usingDict()`) 780*01826a49SYabin Cui 781*01826a49SYabin Cui</p></pre><BR> 782*01826a49SYabin Cui 783*01826a49SYabin Cui<pre><b>size_t ZSTD_DStreamInSize(void); </b>/*!< recommended size for input buffer */<b> 784*01826a49SYabin Cui</b></pre><BR> 785*01826a49SYabin Cui<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> 786*01826a49SYabin Cui</b></pre><BR> 787*01826a49SYabin Cui<a name="Chapter10"></a><h2>Simple dictionary API</h2><pre></pre> 788*01826a49SYabin Cui 789*01826a49SYabin Cui<pre><b>size_t ZSTD_compress_usingDict(ZSTD_CCtx* ctx, 790*01826a49SYabin Cui void* dst, size_t dstCapacity, 791*01826a49SYabin Cui const void* src, size_t srcSize, 792*01826a49SYabin Cui const void* dict,size_t dictSize, 793*01826a49SYabin Cui int compressionLevel); 794*01826a49SYabin Cui</b><p> Compression at an explicit compression level using a Dictionary. 795*01826a49SYabin Cui A dictionary can be any arbitrary data segment (also called a prefix), 796*01826a49SYabin Cui or a buffer with specified information (see zdict.h). 797*01826a49SYabin Cui Note : This function loads the dictionary, resulting in significant startup delay. 798*01826a49SYabin Cui It's intended for a dictionary used only once. 799*01826a49SYabin Cui Note 2 : When `dict == NULL || dictSize < 8` no dictionary is used. 800*01826a49SYabin Cui</p></pre><BR> 801*01826a49SYabin Cui 802*01826a49SYabin Cui<pre><b>size_t ZSTD_decompress_usingDict(ZSTD_DCtx* dctx, 803*01826a49SYabin Cui void* dst, size_t dstCapacity, 804*01826a49SYabin Cui const void* src, size_t srcSize, 805*01826a49SYabin Cui const void* dict,size_t dictSize); 806*01826a49SYabin Cui</b><p> Decompression using a known Dictionary. 807*01826a49SYabin Cui Dictionary must be identical to the one used during compression. 808*01826a49SYabin Cui Note : This function loads the dictionary, resulting in significant startup delay. 809*01826a49SYabin Cui It's intended for a dictionary used only once. 810*01826a49SYabin Cui Note : When `dict == NULL || dictSize < 8` no dictionary is used. 811*01826a49SYabin Cui</p></pre><BR> 812*01826a49SYabin Cui 813*01826a49SYabin Cui<a name="Chapter11"></a><h2>Bulk processing dictionary API</h2><pre></pre> 814*01826a49SYabin Cui 815*01826a49SYabin Cui<pre><b>ZSTD_CDict* ZSTD_createCDict(const void* dictBuffer, size_t dictSize, 816*01826a49SYabin Cui int compressionLevel); 817*01826a49SYabin Cui</b><p> When compressing multiple messages or blocks using the same dictionary, 818*01826a49SYabin Cui it's recommended to digest the dictionary only once, since it's a costly operation. 819*01826a49SYabin Cui ZSTD_createCDict() will create a state from digesting a dictionary. 820*01826a49SYabin Cui The resulting state can be used for future compression operations with very limited startup cost. 821*01826a49SYabin Cui ZSTD_CDict can be created once and shared by multiple threads concurrently, since its usage is read-only. 822*01826a49SYabin Cui @dictBuffer can be released after ZSTD_CDict creation, because its content is copied within CDict. 823*01826a49SYabin Cui Note 1 : Consider experimental function `ZSTD_createCDict_byReference()` if you prefer to not duplicate @dictBuffer content. 824*01826a49SYabin Cui Note 2 : A ZSTD_CDict can be created from an empty @dictBuffer, 825*01826a49SYabin Cui in which case the only thing that it transports is the @compressionLevel. 826*01826a49SYabin Cui This can be useful in a pipeline featuring ZSTD_compress_usingCDict() exclusively, 827*01826a49SYabin Cui expecting a ZSTD_CDict parameter with any data, including those without a known dictionary. 828*01826a49SYabin Cui</p></pre><BR> 829*01826a49SYabin Cui 830*01826a49SYabin Cui<pre><b>size_t ZSTD_freeCDict(ZSTD_CDict* CDict); 831*01826a49SYabin Cui</b><p> Function frees memory allocated by ZSTD_createCDict(). 832*01826a49SYabin Cui If a NULL pointer is passed, no operation is performed. 833*01826a49SYabin Cui</p></pre><BR> 834*01826a49SYabin Cui 835*01826a49SYabin Cui<pre><b>size_t ZSTD_compress_usingCDict(ZSTD_CCtx* cctx, 836*01826a49SYabin Cui void* dst, size_t dstCapacity, 837*01826a49SYabin Cui const void* src, size_t srcSize, 838*01826a49SYabin Cui const ZSTD_CDict* cdict); 839*01826a49SYabin Cui</b><p> Compression using a digested Dictionary. 840*01826a49SYabin Cui Recommended when same dictionary is used multiple times. 841*01826a49SYabin Cui Note : compression level is _decided at dictionary creation time_, 842*01826a49SYabin Cui and frame parameters are hardcoded (dictID=yes, contentSize=yes, checksum=no) 843*01826a49SYabin Cui</p></pre><BR> 844*01826a49SYabin Cui 845*01826a49SYabin Cui<pre><b>ZSTD_DDict* ZSTD_createDDict(const void* dictBuffer, size_t dictSize); 846*01826a49SYabin Cui</b><p> Create a digested dictionary, ready to start decompression operation without startup delay. 847*01826a49SYabin Cui dictBuffer can be released after DDict creation, as its content is copied inside DDict. 848*01826a49SYabin Cui</p></pre><BR> 849*01826a49SYabin Cui 850*01826a49SYabin Cui<pre><b>size_t ZSTD_freeDDict(ZSTD_DDict* ddict); 851*01826a49SYabin Cui</b><p> Function frees memory allocated with ZSTD_createDDict() 852*01826a49SYabin Cui If a NULL pointer is passed, no operation is performed. 853*01826a49SYabin Cui</p></pre><BR> 854*01826a49SYabin Cui 855*01826a49SYabin Cui<pre><b>size_t ZSTD_decompress_usingDDict(ZSTD_DCtx* dctx, 856*01826a49SYabin Cui void* dst, size_t dstCapacity, 857*01826a49SYabin Cui const void* src, size_t srcSize, 858*01826a49SYabin Cui const ZSTD_DDict* ddict); 859*01826a49SYabin Cui</b><p> Decompression using a digested Dictionary. 860*01826a49SYabin Cui Recommended when same dictionary is used multiple times. 861*01826a49SYabin Cui</p></pre><BR> 862*01826a49SYabin Cui 863*01826a49SYabin Cui<a name="Chapter12"></a><h2>Dictionary helper functions</h2><pre></pre> 864*01826a49SYabin Cui 865*01826a49SYabin Cui<pre><b>unsigned ZSTD_getDictID_fromDict(const void* dict, size_t dictSize); 866*01826a49SYabin Cui</b><p> Provides the dictID stored within dictionary. 867*01826a49SYabin Cui if @return == 0, the dictionary is not conformant with Zstandard specification. 868*01826a49SYabin Cui It can still be loaded, but as a content-only dictionary. 869*01826a49SYabin Cui</p></pre><BR> 870*01826a49SYabin Cui 871*01826a49SYabin Cui<pre><b>unsigned ZSTD_getDictID_fromCDict(const ZSTD_CDict* cdict); 872*01826a49SYabin Cui</b><p> Provides the dictID of the dictionary loaded into `cdict`. 873*01826a49SYabin Cui If @return == 0, the dictionary is not conformant to Zstandard specification, or empty. 874*01826a49SYabin Cui Non-conformant dictionaries can still be loaded, but as content-only dictionaries. 875*01826a49SYabin Cui</p></pre><BR> 876*01826a49SYabin Cui 877*01826a49SYabin Cui<pre><b>unsigned ZSTD_getDictID_fromDDict(const ZSTD_DDict* ddict); 878*01826a49SYabin Cui</b><p> Provides the dictID of the dictionary loaded into `ddict`. 879*01826a49SYabin Cui If @return == 0, the dictionary is not conformant to Zstandard specification, or empty. 880*01826a49SYabin Cui Non-conformant dictionaries can still be loaded, but as content-only dictionaries. 881*01826a49SYabin Cui</p></pre><BR> 882*01826a49SYabin Cui 883*01826a49SYabin Cui<pre><b>unsigned ZSTD_getDictID_fromFrame(const void* src, size_t srcSize); 884*01826a49SYabin Cui</b><p> Provides the dictID required to decompressed the frame stored within `src`. 885*01826a49SYabin Cui If @return == 0, the dictID could not be decoded. 886*01826a49SYabin Cui This could for one of the following reasons : 887*01826a49SYabin Cui - The frame does not require a dictionary to be decoded (most common case). 888*01826a49SYabin Cui - The frame was built with dictID intentionally removed. Whatever dictionary is necessary is a hidden piece of information. 889*01826a49SYabin Cui Note : this use case also happens when using a non-conformant dictionary. 890*01826a49SYabin Cui - `srcSize` is too small, and as a result, the frame header could not be decoded (only possible if `srcSize < ZSTD_FRAMEHEADERSIZE_MAX`). 891*01826a49SYabin Cui - This is not a Zstandard frame. 892*01826a49SYabin Cui When identifying the exact failure cause, it's possible to use ZSTD_getFrameHeader(), which will provide a more precise error code. 893*01826a49SYabin Cui</p></pre><BR> 894*01826a49SYabin Cui 895*01826a49SYabin Cui<a name="Chapter13"></a><h2>Advanced dictionary and prefix API (Requires v1.4.0+)</h2><pre> 896*01826a49SYabin Cui This API allows dictionaries to be used with ZSTD_compress2(), 897*01826a49SYabin Cui ZSTD_compressStream2(), and ZSTD_decompressDCtx(). 898*01826a49SYabin Cui Dictionaries are sticky, they remain valid when same context is reused, 899*01826a49SYabin Cui they only reset when the context is reset 900*01826a49SYabin Cui with ZSTD_reset_parameters or ZSTD_reset_session_and_parameters. 901*01826a49SYabin Cui In contrast, Prefixes are single-use. 902*01826a49SYabin Cui<BR></pre> 903*01826a49SYabin Cui 904*01826a49SYabin Cui<pre><b>size_t ZSTD_CCtx_loadDictionary(ZSTD_CCtx* cctx, const void* dict, size_t dictSize); 905*01826a49SYabin Cui</b><p> Create an internal CDict from `dict` buffer. 906*01826a49SYabin Cui Decompression will have to use same dictionary. 907*01826a49SYabin Cui @result : 0, or an error code (which can be tested with ZSTD_isError()). 908*01826a49SYabin Cui Special: Loading a NULL (or 0-size) dictionary invalidates previous dictionary, 909*01826a49SYabin Cui meaning "return to no-dictionary mode". 910*01826a49SYabin Cui Note 1 : Dictionary is sticky, it will be used for all future compressed frames, 911*01826a49SYabin Cui until parameters are reset, a new dictionary is loaded, or the dictionary 912*01826a49SYabin Cui is explicitly invalidated by loading a NULL dictionary. 913*01826a49SYabin Cui Note 2 : Loading a dictionary involves building tables. 914*01826a49SYabin Cui It's also a CPU consuming operation, with non-negligible impact on latency. 915*01826a49SYabin Cui Tables are dependent on compression parameters, and for this reason, 916*01826a49SYabin Cui compression parameters can no longer be changed after loading a dictionary. 917*01826a49SYabin Cui Note 3 :`dict` content will be copied internally. 918*01826a49SYabin Cui Use experimental ZSTD_CCtx_loadDictionary_byReference() to reference content instead. 919*01826a49SYabin Cui In such a case, dictionary buffer must outlive its users. 920*01826a49SYabin Cui Note 4 : Use ZSTD_CCtx_loadDictionary_advanced() 921*01826a49SYabin Cui to precisely select how dictionary content must be interpreted. 922*01826a49SYabin Cui Note 5 : This method does not benefit from LDM (long distance mode). 923*01826a49SYabin Cui If you want to employ LDM on some large dictionary content, 924*01826a49SYabin Cui prefer employing ZSTD_CCtx_refPrefix() described below. 925*01826a49SYabin Cui 926*01826a49SYabin Cui</p></pre><BR> 927*01826a49SYabin Cui 928*01826a49SYabin Cui<pre><b>size_t ZSTD_CCtx_refCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict); 929*01826a49SYabin Cui</b><p> Reference a prepared dictionary, to be used for all future compressed frames. 930*01826a49SYabin Cui Note that compression parameters are enforced from within CDict, 931*01826a49SYabin Cui and supersede any compression parameter previously set within CCtx. 932*01826a49SYabin Cui The parameters ignored are labelled as "superseded-by-cdict" in the ZSTD_cParameter enum docs. 933*01826a49SYabin Cui The ignored parameters will be used again if the CCtx is returned to no-dictionary mode. 934*01826a49SYabin Cui The dictionary will remain valid for future compressed frames using same CCtx. 935*01826a49SYabin Cui @result : 0, or an error code (which can be tested with ZSTD_isError()). 936*01826a49SYabin Cui Special : Referencing a NULL CDict means "return to no-dictionary mode". 937*01826a49SYabin Cui Note 1 : Currently, only one dictionary can be managed. 938*01826a49SYabin Cui Referencing a new dictionary effectively "discards" any previous one. 939*01826a49SYabin Cui Note 2 : CDict is just referenced, its lifetime must outlive its usage within CCtx. 940*01826a49SYabin Cui</p></pre><BR> 941*01826a49SYabin Cui 942*01826a49SYabin Cui<pre><b>size_t ZSTD_CCtx_refPrefix(ZSTD_CCtx* cctx, 943*01826a49SYabin Cui const void* prefix, size_t prefixSize); 944*01826a49SYabin Cui</b><p> Reference a prefix (single-usage dictionary) for next compressed frame. 945*01826a49SYabin Cui A prefix is **only used once**. Tables are discarded at end of frame (ZSTD_e_end). 946*01826a49SYabin Cui Decompression will need same prefix to properly regenerate data. 947*01826a49SYabin Cui Compressing with a prefix is similar in outcome as performing a diff and compressing it, 948*01826a49SYabin Cui but performs much faster, especially during decompression (compression speed is tunable with compression level). 949*01826a49SYabin Cui This method is compatible with LDM (long distance mode). 950*01826a49SYabin Cui @result : 0, or an error code (which can be tested with ZSTD_isError()). 951*01826a49SYabin Cui Special: Adding any prefix (including NULL) invalidates any previous prefix or dictionary 952*01826a49SYabin Cui Note 1 : Prefix buffer is referenced. It **must** outlive compression. 953*01826a49SYabin Cui Its content must remain unmodified during compression. 954*01826a49SYabin Cui Note 2 : If the intention is to diff some large src data blob with some prior version of itself, 955*01826a49SYabin Cui ensure that the window size is large enough to contain the entire source. 956*01826a49SYabin Cui See ZSTD_c_windowLog. 957*01826a49SYabin Cui Note 3 : Referencing a prefix involves building tables, which are dependent on compression parameters. 958*01826a49SYabin Cui It's a CPU consuming operation, with non-negligible impact on latency. 959*01826a49SYabin Cui If there is a need to use the same prefix multiple times, consider loadDictionary instead. 960*01826a49SYabin Cui Note 4 : By default, the prefix is interpreted as raw content (ZSTD_dct_rawContent). 961*01826a49SYabin Cui Use experimental ZSTD_CCtx_refPrefix_advanced() to alter dictionary interpretation. 962*01826a49SYabin Cui</p></pre><BR> 963*01826a49SYabin Cui 964*01826a49SYabin Cui<pre><b>size_t ZSTD_DCtx_loadDictionary(ZSTD_DCtx* dctx, const void* dict, size_t dictSize); 965*01826a49SYabin Cui</b><p> Create an internal DDict from dict buffer, to be used to decompress all future frames. 966*01826a49SYabin Cui The dictionary remains valid for all future frames, until explicitly invalidated, or 967*01826a49SYabin Cui a new dictionary is loaded. 968*01826a49SYabin Cui @result : 0, or an error code (which can be tested with ZSTD_isError()). 969*01826a49SYabin Cui Special : Adding a NULL (or 0-size) dictionary invalidates any previous dictionary, 970*01826a49SYabin Cui meaning "return to no-dictionary mode". 971*01826a49SYabin Cui Note 1 : Loading a dictionary involves building tables, 972*01826a49SYabin Cui which has a non-negligible impact on CPU usage and latency. 973*01826a49SYabin Cui It's recommended to "load once, use many times", to amortize the cost 974*01826a49SYabin Cui Note 2 :`dict` content will be copied internally, so `dict` can be released after loading. 975*01826a49SYabin Cui Use ZSTD_DCtx_loadDictionary_byReference() to reference dictionary content instead. 976*01826a49SYabin Cui Note 3 : Use ZSTD_DCtx_loadDictionary_advanced() to take control of 977*01826a49SYabin Cui how dictionary content is loaded and interpreted. 978*01826a49SYabin Cui 979*01826a49SYabin Cui</p></pre><BR> 980*01826a49SYabin Cui 981*01826a49SYabin Cui<pre><b>size_t ZSTD_DCtx_refDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict); 982*01826a49SYabin Cui</b><p> Reference a prepared dictionary, to be used to decompress next frames. 983*01826a49SYabin Cui The dictionary remains active for decompression of future frames using same DCtx. 984*01826a49SYabin Cui 985*01826a49SYabin Cui If called with ZSTD_d_refMultipleDDicts enabled, repeated calls of this function 986*01826a49SYabin Cui will store the DDict references in a table, and the DDict used for decompression 987*01826a49SYabin Cui will be determined at decompression time, as per the dict ID in the frame. 988*01826a49SYabin Cui The memory for the table is allocated on the first call to refDDict, and can be 989*01826a49SYabin Cui freed with ZSTD_freeDCtx(). 990*01826a49SYabin Cui 991*01826a49SYabin Cui If called with ZSTD_d_refMultipleDDicts disabled (the default), only one dictionary 992*01826a49SYabin Cui will be managed, and referencing a dictionary effectively "discards" any previous one. 993*01826a49SYabin Cui 994*01826a49SYabin Cui @result : 0, or an error code (which can be tested with ZSTD_isError()). 995*01826a49SYabin Cui Special: referencing a NULL DDict means "return to no-dictionary mode". 996*01826a49SYabin Cui Note 2 : DDict is just referenced, its lifetime must outlive its usage from DCtx. 997*01826a49SYabin Cui 998*01826a49SYabin Cui</p></pre><BR> 999*01826a49SYabin Cui 1000*01826a49SYabin Cui<pre><b>size_t ZSTD_DCtx_refPrefix(ZSTD_DCtx* dctx, 1001*01826a49SYabin Cui const void* prefix, size_t prefixSize); 1002*01826a49SYabin Cui</b><p> Reference a prefix (single-usage dictionary) to decompress next frame. 1003*01826a49SYabin Cui This is the reverse operation of ZSTD_CCtx_refPrefix(), 1004*01826a49SYabin Cui and must use the same prefix as the one used during compression. 1005*01826a49SYabin Cui Prefix is **only used once**. Reference is discarded at end of frame. 1006*01826a49SYabin Cui End of frame is reached when ZSTD_decompressStream() returns 0. 1007*01826a49SYabin Cui @result : 0, or an error code (which can be tested with ZSTD_isError()). 1008*01826a49SYabin Cui Note 1 : Adding any prefix (including NULL) invalidates any previously set prefix or dictionary 1009*01826a49SYabin Cui Note 2 : Prefix buffer is referenced. It **must** outlive decompression. 1010*01826a49SYabin Cui Prefix buffer must remain unmodified up to the end of frame, 1011*01826a49SYabin Cui reached when ZSTD_decompressStream() returns 0. 1012*01826a49SYabin Cui Note 3 : By default, the prefix is treated as raw content (ZSTD_dct_rawContent). 1013*01826a49SYabin Cui Use ZSTD_CCtx_refPrefix_advanced() to alter dictMode (Experimental section) 1014*01826a49SYabin Cui Note 4 : Referencing a raw content prefix has almost no cpu nor memory cost. 1015*01826a49SYabin Cui A full dictionary is more costly, as it requires building tables. 1016*01826a49SYabin Cui 1017*01826a49SYabin Cui</p></pre><BR> 1018*01826a49SYabin Cui 1019*01826a49SYabin Cui<pre><b>size_t ZSTD_sizeof_CCtx(const ZSTD_CCtx* cctx); 1020*01826a49SYabin Cuisize_t ZSTD_sizeof_DCtx(const ZSTD_DCtx* dctx); 1021*01826a49SYabin Cuisize_t ZSTD_sizeof_CStream(const ZSTD_CStream* zcs); 1022*01826a49SYabin Cuisize_t ZSTD_sizeof_DStream(const ZSTD_DStream* zds); 1023*01826a49SYabin Cuisize_t ZSTD_sizeof_CDict(const ZSTD_CDict* cdict); 1024*01826a49SYabin Cuisize_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict); 1025*01826a49SYabin Cui</b><p> These functions give the _current_ memory usage of selected object. 1026*01826a49SYabin Cui Note that object memory usage can evolve (increase or decrease) over time. 1027*01826a49SYabin Cui</p></pre><BR> 1028*01826a49SYabin Cui 1029*01826a49SYabin Cui<a name="Chapter14"></a><h2>experimental API (static linking only)</h2><pre> 1030*01826a49SYabin Cui The following symbols and constants 1031*01826a49SYabin Cui are not planned to join "stable API" status in the near future. 1032*01826a49SYabin Cui They can still change in future versions. 1033*01826a49SYabin Cui Some of them are planned to remain in the static_only section indefinitely. 1034*01826a49SYabin Cui Some of them might be removed in the future (especially when redundant with existing stable functions) 1035*01826a49SYabin Cui 1036*01826a49SYabin Cui<BR></pre> 1037*01826a49SYabin Cui 1038*01826a49SYabin Cui<pre><b>typedef struct { 1039*01826a49SYabin Cui unsigned int offset; </b>/* The offset of the match. (NOT the same as the offset code)<b> 1040*01826a49SYabin Cui * If offset == 0 and matchLength == 0, this sequence represents the last 1041*01826a49SYabin Cui * literals in the block of litLength size. 1042*01826a49SYabin Cui */ 1043*01826a49SYabin Cui 1044*01826a49SYabin Cui unsigned int litLength; </b>/* Literal length of the sequence. */<b> 1045*01826a49SYabin Cui unsigned int matchLength; </b>/* Match length of the sequence. */<b> 1046*01826a49SYabin Cui 1047*01826a49SYabin Cui </b>/* Note: Users of this API may provide a sequence with matchLength == litLength == offset == 0.<b> 1048*01826a49SYabin Cui * In this case, we will treat the sequence as a marker for a block boundary. 1049*01826a49SYabin Cui */ 1050*01826a49SYabin Cui 1051*01826a49SYabin Cui unsigned int rep; </b>/* Represents which repeat offset is represented by the field 'offset'.<b> 1052*01826a49SYabin Cui * Ranges from [0, 3]. 1053*01826a49SYabin Cui * 1054*01826a49SYabin Cui * Repeat offsets are essentially previous offsets from previous sequences sorted in 1055*01826a49SYabin Cui * recency order. For more detail, see doc/zstd_compression_format.md 1056*01826a49SYabin Cui * 1057*01826a49SYabin Cui * If rep == 0, then 'offset' does not contain a repeat offset. 1058*01826a49SYabin Cui * If rep > 0: 1059*01826a49SYabin Cui * If litLength != 0: 1060*01826a49SYabin Cui * rep == 1 --> offset == repeat_offset_1 1061*01826a49SYabin Cui * rep == 2 --> offset == repeat_offset_2 1062*01826a49SYabin Cui * rep == 3 --> offset == repeat_offset_3 1063*01826a49SYabin Cui * If litLength == 0: 1064*01826a49SYabin Cui * rep == 1 --> offset == repeat_offset_2 1065*01826a49SYabin Cui * rep == 2 --> offset == repeat_offset_3 1066*01826a49SYabin Cui * rep == 3 --> offset == repeat_offset_1 - 1 1067*01826a49SYabin Cui * 1068*01826a49SYabin Cui * Note: This field is optional. ZSTD_generateSequences() will calculate the value of 1069*01826a49SYabin Cui * 'rep', but repeat offsets do not necessarily need to be calculated from an external 1070*01826a49SYabin Cui * sequence provider's perspective. For example, ZSTD_compressSequences() does not 1071*01826a49SYabin Cui * use this 'rep' field at all (as of now). 1072*01826a49SYabin Cui */ 1073*01826a49SYabin Cui} ZSTD_Sequence; 1074*01826a49SYabin Cui</b></pre><BR> 1075*01826a49SYabin Cui<pre><b>typedef struct { 1076*01826a49SYabin Cui unsigned windowLog; </b>/**< largest match distance : larger == more compression, more memory needed during decompression */<b> 1077*01826a49SYabin Cui unsigned chainLog; </b>/**< fully searched segment : larger == more compression, slower, more memory (useless for fast) */<b> 1078*01826a49SYabin Cui unsigned hashLog; </b>/**< dispatch table : larger == faster, more memory */<b> 1079*01826a49SYabin Cui unsigned searchLog; </b>/**< nb of searches : larger == more compression, slower */<b> 1080*01826a49SYabin Cui unsigned minMatch; </b>/**< match length searched : larger == faster decompression, sometimes less compression */<b> 1081*01826a49SYabin Cui unsigned targetLength; </b>/**< acceptable match size for optimal parser (only) : larger == more compression, slower */<b> 1082*01826a49SYabin Cui ZSTD_strategy strategy; </b>/**< see ZSTD_strategy definition above */<b> 1083*01826a49SYabin Cui} ZSTD_compressionParameters; 1084*01826a49SYabin Cui</b></pre><BR> 1085*01826a49SYabin Cui<pre><b>typedef struct { 1086*01826a49SYabin Cui int contentSizeFlag; </b>/**< 1: content size will be in frame header (when known) */<b> 1087*01826a49SYabin Cui int checksumFlag; </b>/**< 1: generate a 32-bits checksum using XXH64 algorithm at end of frame, for error detection */<b> 1088*01826a49SYabin Cui int noDictIDFlag; </b>/**< 1: no dictID will be saved into frame header (dictID is only useful for dictionary compression) */<b> 1089*01826a49SYabin Cui} ZSTD_frameParameters; 1090*01826a49SYabin Cui</b></pre><BR> 1091*01826a49SYabin Cui<pre><b>typedef struct { 1092*01826a49SYabin Cui ZSTD_compressionParameters cParams; 1093*01826a49SYabin Cui ZSTD_frameParameters fParams; 1094*01826a49SYabin Cui} ZSTD_parameters; 1095*01826a49SYabin Cui</b></pre><BR> 1096*01826a49SYabin Cui<pre><b>typedef enum { 1097*01826a49SYabin Cui ZSTD_dct_auto = 0, </b>/* dictionary is "full" when starting with ZSTD_MAGIC_DICTIONARY, otherwise it is "rawContent" */<b> 1098*01826a49SYabin Cui ZSTD_dct_rawContent = 1, </b>/* ensures dictionary is always loaded as rawContent, even if it starts with ZSTD_MAGIC_DICTIONARY */<b> 1099*01826a49SYabin Cui ZSTD_dct_fullDict = 2 </b>/* refuses to load a dictionary if it does not respect Zstandard's specification, starting with ZSTD_MAGIC_DICTIONARY */<b> 1100*01826a49SYabin Cui} ZSTD_dictContentType_e; 1101*01826a49SYabin Cui</b></pre><BR> 1102*01826a49SYabin Cui<pre><b>typedef enum { 1103*01826a49SYabin Cui ZSTD_dlm_byCopy = 0, </b>/**< Copy dictionary content internally */<b> 1104*01826a49SYabin Cui ZSTD_dlm_byRef = 1 </b>/**< Reference dictionary content -- the dictionary buffer must outlive its users. */<b> 1105*01826a49SYabin Cui} ZSTD_dictLoadMethod_e; 1106*01826a49SYabin Cui</b></pre><BR> 1107*01826a49SYabin Cui<pre><b>typedef enum { 1108*01826a49SYabin Cui ZSTD_f_zstd1 = 0, </b>/* zstd frame format, specified in zstd_compression_format.md (default) */<b> 1109*01826a49SYabin Cui ZSTD_f_zstd1_magicless = 1 </b>/* Variant of zstd frame format, without initial 4-bytes magic number.<b> 1110*01826a49SYabin Cui * Useful to save 4 bytes per generated frame. 1111*01826a49SYabin Cui * Decoder cannot recognise automatically this format, requiring this instruction. */ 1112*01826a49SYabin Cui} ZSTD_format_e; 1113*01826a49SYabin Cui</b></pre><BR> 1114*01826a49SYabin Cui<pre><b>typedef enum { 1115*01826a49SYabin Cui </b>/* Note: this enum controls ZSTD_d_forceIgnoreChecksum */<b> 1116*01826a49SYabin Cui ZSTD_d_validateChecksum = 0, 1117*01826a49SYabin Cui ZSTD_d_ignoreChecksum = 1 1118*01826a49SYabin Cui} ZSTD_forceIgnoreChecksum_e; 1119*01826a49SYabin Cui</b></pre><BR> 1120*01826a49SYabin Cui<pre><b>typedef enum { 1121*01826a49SYabin Cui </b>/* Note: this enum controls ZSTD_d_refMultipleDDicts */<b> 1122*01826a49SYabin Cui ZSTD_rmd_refSingleDDict = 0, 1123*01826a49SYabin Cui ZSTD_rmd_refMultipleDDicts = 1 1124*01826a49SYabin Cui} ZSTD_refMultipleDDicts_e; 1125*01826a49SYabin Cui</b></pre><BR> 1126*01826a49SYabin Cui<pre><b>typedef enum { 1127*01826a49SYabin Cui </b>/* Note: this enum and the behavior it controls are effectively internal<b> 1128*01826a49SYabin Cui * implementation details of the compressor. They are expected to continue 1129*01826a49SYabin Cui * to evolve and should be considered only in the context of extremely 1130*01826a49SYabin Cui * advanced performance tuning. 1131*01826a49SYabin Cui * 1132*01826a49SYabin Cui * Zstd currently supports the use of a CDict in three ways: 1133*01826a49SYabin Cui * 1134*01826a49SYabin Cui * - The contents of the CDict can be copied into the working context. This 1135*01826a49SYabin Cui * means that the compression can search both the dictionary and input 1136*01826a49SYabin Cui * while operating on a single set of internal tables. This makes 1137*01826a49SYabin Cui * the compression faster per-byte of input. However, the initial copy of 1138*01826a49SYabin Cui * the CDict's tables incurs a fixed cost at the beginning of the 1139*01826a49SYabin Cui * compression. For small compressions (< 8 KB), that copy can dominate 1140*01826a49SYabin Cui * the cost of the compression. 1141*01826a49SYabin Cui * 1142*01826a49SYabin Cui * - The CDict's tables can be used in-place. In this model, compression is 1143*01826a49SYabin Cui * slower per input byte, because the compressor has to search two sets of 1144*01826a49SYabin Cui * tables. However, this model incurs no start-up cost (as long as the 1145*01826a49SYabin Cui * working context's tables can be reused). For small inputs, this can be 1146*01826a49SYabin Cui * faster than copying the CDict's tables. 1147*01826a49SYabin Cui * 1148*01826a49SYabin Cui * - The CDict's tables are not used at all, and instead we use the working 1149*01826a49SYabin Cui * context alone to reload the dictionary and use params based on the source 1150*01826a49SYabin Cui * size. See ZSTD_compress_insertDictionary() and ZSTD_compress_usingDict(). 1151*01826a49SYabin Cui * This method is effective when the dictionary sizes are very small relative 1152*01826a49SYabin Cui * to the input size, and the input size is fairly large to begin with. 1153*01826a49SYabin Cui * 1154*01826a49SYabin Cui * Zstd has a simple internal heuristic that selects which strategy to use 1155*01826a49SYabin Cui * at the beginning of a compression. However, if experimentation shows that 1156*01826a49SYabin Cui * Zstd is making poor choices, it is possible to override that choice with 1157*01826a49SYabin Cui * this enum. 1158*01826a49SYabin Cui */ 1159*01826a49SYabin Cui ZSTD_dictDefaultAttach = 0, </b>/* Use the default heuristic. */<b> 1160*01826a49SYabin Cui ZSTD_dictForceAttach = 1, </b>/* Never copy the dictionary. */<b> 1161*01826a49SYabin Cui ZSTD_dictForceCopy = 2, </b>/* Always copy the dictionary. */<b> 1162*01826a49SYabin Cui ZSTD_dictForceLoad = 3 </b>/* Always reload the dictionary */<b> 1163*01826a49SYabin Cui} ZSTD_dictAttachPref_e; 1164*01826a49SYabin Cui</b></pre><BR> 1165*01826a49SYabin Cui<pre><b>typedef enum { 1166*01826a49SYabin Cui ZSTD_lcm_auto = 0, </b>/**< Automatically determine the compression mode based on the compression level.<b> 1167*01826a49SYabin Cui * Negative compression levels will be uncompressed, and positive compression 1168*01826a49SYabin Cui * levels will be compressed. */ 1169*01826a49SYabin Cui ZSTD_lcm_huffman = 1, </b>/**< Always attempt Huffman compression. Uncompressed literals will still be<b> 1170*01826a49SYabin Cui * emitted if Huffman compression is not profitable. */ 1171*01826a49SYabin Cui ZSTD_lcm_uncompressed = 2 </b>/**< Always emit uncompressed literals. */<b> 1172*01826a49SYabin Cui} ZSTD_literalCompressionMode_e; 1173*01826a49SYabin Cui</b></pre><BR> 1174*01826a49SYabin Cui<pre><b>typedef enum { 1175*01826a49SYabin Cui </b>/* Note: This enum controls features which are conditionally beneficial. Zstd typically will make a final<b> 1176*01826a49SYabin Cui * decision on whether or not to enable the feature (ZSTD_ps_auto), but setting the switch to ZSTD_ps_enable 1177*01826a49SYabin Cui * or ZSTD_ps_disable allow for a force enable/disable the feature. 1178*01826a49SYabin Cui */ 1179*01826a49SYabin Cui ZSTD_ps_auto = 0, </b>/* Let the library automatically determine whether the feature shall be enabled */<b> 1180*01826a49SYabin Cui ZSTD_ps_enable = 1, </b>/* Force-enable the feature */<b> 1181*01826a49SYabin Cui ZSTD_ps_disable = 2 </b>/* Do not use the feature */<b> 1182*01826a49SYabin Cui} ZSTD_paramSwitch_e; 1183*01826a49SYabin Cui</b></pre><BR> 1184*01826a49SYabin Cui<a name="Chapter15"></a><h2>Frame header and size functions</h2><pre></pre> 1185*01826a49SYabin Cui 1186*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API unsigned long long ZSTD_findDecompressedSize(const void* src, size_t srcSize); 1187*01826a49SYabin Cui</b><p> `src` should point to the start of a series of ZSTD encoded and/or skippable frames 1188*01826a49SYabin Cui `srcSize` must be the _exact_ size of this series 1189*01826a49SYabin Cui (i.e. there should be a frame boundary at `src + srcSize`) 1190*01826a49SYabin Cui @return : - decompressed size of all data in all successive frames 1191*01826a49SYabin Cui - if the decompressed size cannot be determined: ZSTD_CONTENTSIZE_UNKNOWN 1192*01826a49SYabin Cui - if an error occurred: ZSTD_CONTENTSIZE_ERROR 1193*01826a49SYabin Cui 1194*01826a49SYabin Cui note 1 : decompressed size is an optional field, that may not be present, especially in streaming mode. 1195*01826a49SYabin Cui When `return==ZSTD_CONTENTSIZE_UNKNOWN`, data to decompress could be any size. 1196*01826a49SYabin Cui In which case, it's necessary to use streaming mode to decompress data. 1197*01826a49SYabin Cui note 2 : decompressed size is always present when compression is done with ZSTD_compress() 1198*01826a49SYabin Cui note 3 : decompressed size can be very large (64-bits value), 1199*01826a49SYabin Cui potentially larger than what local system can handle as a single memory segment. 1200*01826a49SYabin Cui In which case, it's necessary to use streaming mode to decompress data. 1201*01826a49SYabin Cui note 4 : If source is untrusted, decompressed size could be wrong or intentionally modified. 1202*01826a49SYabin Cui Always ensure result fits within application's authorized limits. 1203*01826a49SYabin Cui Each application can set its own limits. 1204*01826a49SYabin Cui note 5 : ZSTD_findDecompressedSize handles multiple frames, and so it must traverse the input to 1205*01826a49SYabin Cui read each contained frame header. This is fast as most of the data is skipped, 1206*01826a49SYabin Cui however it does mean that all frame data must be present and valid. 1207*01826a49SYabin Cui</p></pre><BR> 1208*01826a49SYabin Cui 1209*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API unsigned long long ZSTD_decompressBound(const void* src, size_t srcSize); 1210*01826a49SYabin Cui</b><p> `src` should point to the start of a series of ZSTD encoded and/or skippable frames 1211*01826a49SYabin Cui `srcSize` must be the _exact_ size of this series 1212*01826a49SYabin Cui (i.e. there should be a frame boundary at `src + srcSize`) 1213*01826a49SYabin Cui @return : - upper-bound for the decompressed size of all data in all successive frames 1214*01826a49SYabin Cui - if an error occurred: ZSTD_CONTENTSIZE_ERROR 1215*01826a49SYabin Cui 1216*01826a49SYabin Cui note 1 : an error can occur if `src` contains an invalid or incorrectly formatted frame. 1217*01826a49SYabin Cui note 2 : the upper-bound is exact when the decompressed size field is available in every ZSTD encoded frame of `src`. 1218*01826a49SYabin Cui in this case, `ZSTD_findDecompressedSize` and `ZSTD_decompressBound` return the same value. 1219*01826a49SYabin Cui note 3 : when the decompressed size field isn't available, the upper-bound for that frame is calculated by: 1220*01826a49SYabin Cui upper-bound = # blocks * min(128 KB, Window_Size) 1221*01826a49SYabin Cui 1222*01826a49SYabin Cui</p></pre><BR> 1223*01826a49SYabin Cui 1224*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_frameHeaderSize(const void* src, size_t srcSize); 1225*01826a49SYabin Cui</b><p> srcSize must be >= ZSTD_FRAMEHEADERSIZE_PREFIX. 1226*01826a49SYabin Cui @return : size of the Frame Header, 1227*01826a49SYabin Cui or an error code (if srcSize is too small) 1228*01826a49SYabin Cui</p></pre><BR> 1229*01826a49SYabin Cui 1230*01826a49SYabin Cui<pre><b>typedef enum { ZSTD_frame, ZSTD_skippableFrame } ZSTD_frameType_e; 1231*01826a49SYabin Cui</b></pre><BR> 1232*01826a49SYabin Cui<pre><b>typedef struct { 1233*01826a49SYabin Cui unsigned long long frameContentSize; </b>/* if == ZSTD_CONTENTSIZE_UNKNOWN, it means this field is not available. 0 means "empty" */<b> 1234*01826a49SYabin Cui unsigned long long windowSize; </b>/* can be very large, up to <= frameContentSize */<b> 1235*01826a49SYabin Cui unsigned blockSizeMax; 1236*01826a49SYabin Cui ZSTD_frameType_e frameType; </b>/* if == ZSTD_skippableFrame, frameContentSize is the size of skippable content */<b> 1237*01826a49SYabin Cui unsigned headerSize; 1238*01826a49SYabin Cui unsigned dictID; 1239*01826a49SYabin Cui unsigned checksumFlag; 1240*01826a49SYabin Cui unsigned _reserved1; 1241*01826a49SYabin Cui unsigned _reserved2; 1242*01826a49SYabin Cui} ZSTD_frameHeader; 1243*01826a49SYabin Cui</b></pre><BR> 1244*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_getFrameHeader(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize); </b>/**< doesn't consume input */<b> 1245*01826a49SYabin Cui</b>/*! ZSTD_getFrameHeader_advanced() :<b> 1246*01826a49SYabin Cui * same as ZSTD_getFrameHeader(), 1247*01826a49SYabin Cui * with added capability to select a format (like ZSTD_f_zstd1_magicless) */ 1248*01826a49SYabin CuiZSTDLIB_STATIC_API size_t ZSTD_getFrameHeader_advanced(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize, ZSTD_format_e format); 1249*01826a49SYabin Cui</b><p> decode Frame Header, or requires larger `srcSize`. 1250*01826a49SYabin Cui @return : 0, `zfhPtr` is correctly filled, 1251*01826a49SYabin Cui >0, `srcSize` is too small, value is wanted `srcSize` amount, 1252*01826a49SYabin Cui or an error code, which can be tested using ZSTD_isError() 1253*01826a49SYabin Cui</p></pre><BR> 1254*01826a49SYabin Cui 1255*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_decompressionMargin(const void* src, size_t srcSize); 1256*01826a49SYabin Cui</b><p> Zstd supports in-place decompression, where the input and output buffers overlap. 1257*01826a49SYabin Cui In this case, the output buffer must be at least (Margin + Output_Size) bytes large, 1258*01826a49SYabin Cui and the input buffer must be at the end of the output buffer. 1259*01826a49SYabin Cui 1260*01826a49SYabin Cui _______________________ Output Buffer ________________________ 1261*01826a49SYabin Cui | | 1262*01826a49SYabin Cui | ____ Input Buffer ____| 1263*01826a49SYabin Cui | | | 1264*01826a49SYabin Cui v v v 1265*01826a49SYabin Cui |---------------------------------------|-----------|----------| 1266*01826a49SYabin Cui ^ ^ ^ 1267*01826a49SYabin Cui |___________________ Output_Size ___________________|_ Margin _| 1268*01826a49SYabin Cui 1269*01826a49SYabin Cui NOTE: See also ZSTD_DECOMPRESSION_MARGIN(). 1270*01826a49SYabin Cui NOTE: This applies only to single-pass decompression through ZSTD_decompress() or 1271*01826a49SYabin Cui ZSTD_decompressDCtx(). 1272*01826a49SYabin Cui NOTE: This function supports multi-frame input. 1273*01826a49SYabin Cui 1274*01826a49SYabin Cui @param src The compressed frame(s) 1275*01826a49SYabin Cui @param srcSize The size of the compressed frame(s) 1276*01826a49SYabin Cui @returns The decompression margin or an error that can be checked with ZSTD_isError(). 1277*01826a49SYabin Cui 1278*01826a49SYabin Cui</p></pre><BR> 1279*01826a49SYabin Cui 1280*01826a49SYabin Cui<pre><b>#define ZSTD_DECOMPRESSION_MARGIN(originalSize, blockSize) ((size_t)( \ 1281*01826a49SYabin Cui ZSTD_FRAMEHEADERSIZE_MAX </b>/* Frame header */ + \<b> 1282*01826a49SYabin Cui 4 </b>/* checksum */ + \<b> 1283*01826a49SYabin Cui ((originalSize) == 0 ? 0 : 3 * (((originalSize) + (blockSize) - 1) / blockSize)) </b>/* 3 bytes per block */ + \<b> 1284*01826a49SYabin Cui (blockSize) </b>/* One block of margin */ \<b> 1285*01826a49SYabin Cui )) 1286*01826a49SYabin Cui</b><p> Similar to ZSTD_decompressionMargin(), but instead of computing the margin from 1287*01826a49SYabin Cui the compressed frame, compute it from the original size and the blockSizeLog. 1288*01826a49SYabin Cui See ZSTD_decompressionMargin() for details. 1289*01826a49SYabin Cui 1290*01826a49SYabin Cui WARNING: This macro does not support multi-frame input, the input must be a single 1291*01826a49SYabin Cui zstd frame. If you need that support use the function, or implement it yourself. 1292*01826a49SYabin Cui 1293*01826a49SYabin Cui @param originalSize The original uncompressed size of the data. 1294*01826a49SYabin Cui @param blockSize The block size == MIN(windowSize, ZSTD_BLOCKSIZE_MAX). 1295*01826a49SYabin Cui Unless you explicitly set the windowLog smaller than 1296*01826a49SYabin Cui ZSTD_BLOCKSIZELOG_MAX you can just use ZSTD_BLOCKSIZE_MAX. 1297*01826a49SYabin Cui 1298*01826a49SYabin Cui</p></pre><BR> 1299*01826a49SYabin Cui 1300*01826a49SYabin Cui<pre><b>typedef enum { 1301*01826a49SYabin Cui ZSTD_sf_noBlockDelimiters = 0, </b>/* Representation of ZSTD_Sequence has no block delimiters, sequences only */<b> 1302*01826a49SYabin Cui ZSTD_sf_explicitBlockDelimiters = 1 </b>/* Representation of ZSTD_Sequence contains explicit block delimiters */<b> 1303*01826a49SYabin Cui} ZSTD_sequenceFormat_e; 1304*01826a49SYabin Cui</b></pre><BR> 1305*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_sequenceBound(size_t srcSize); 1306*01826a49SYabin Cui</b><p> `srcSize` : size of the input buffer 1307*01826a49SYabin Cui @return : upper-bound for the number of sequences that can be generated 1308*01826a49SYabin Cui from a buffer of srcSize bytes 1309*01826a49SYabin Cui 1310*01826a49SYabin Cui note : returns number of sequences - to get bytes, multiply by sizeof(ZSTD_Sequence). 1311*01826a49SYabin Cui 1312*01826a49SYabin Cui</p></pre><BR> 1313*01826a49SYabin Cui 1314*01826a49SYabin Cui<pre><b></b><p> Generate sequences using ZSTD_compress2(), given a source buffer. 1315*01826a49SYabin Cui 1316*01826a49SYabin Cui Each block will end with a dummy sequence 1317*01826a49SYabin Cui with offset == 0, matchLength == 0, and litLength == length of last literals. 1318*01826a49SYabin Cui litLength may be == 0, and if so, then the sequence of (of: 0 ml: 0 ll: 0) 1319*01826a49SYabin Cui simply acts as a block delimiter. 1320*01826a49SYabin Cui 1321*01826a49SYabin Cui @zc can be used to insert custom compression params. 1322*01826a49SYabin Cui This function invokes ZSTD_compress2(). 1323*01826a49SYabin Cui 1324*01826a49SYabin Cui The output of this function can be fed into ZSTD_compressSequences() with CCtx 1325*01826a49SYabin Cui setting of ZSTD_c_blockDelimiters as ZSTD_sf_explicitBlockDelimiters 1326*01826a49SYabin Cui @return : number of sequences generated 1327*01826a49SYabin Cui 1328*01826a49SYabin Cui</p></pre><BR> 1329*01826a49SYabin Cui 1330*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_mergeBlockDelimiters(ZSTD_Sequence* sequences, size_t seqsSize); 1331*01826a49SYabin Cui</b><p> Given an array of ZSTD_Sequence, remove all sequences that represent block delimiters/last literals 1332*01826a49SYabin Cui by merging them into the literals of the next sequence. 1333*01826a49SYabin Cui 1334*01826a49SYabin Cui As such, the final generated result has no explicit representation of block boundaries, 1335*01826a49SYabin Cui and the final last literals segment is not represented in the sequences. 1336*01826a49SYabin Cui 1337*01826a49SYabin Cui The output of this function can be fed into ZSTD_compressSequences() with CCtx 1338*01826a49SYabin Cui setting of ZSTD_c_blockDelimiters as ZSTD_sf_noBlockDelimiters 1339*01826a49SYabin Cui @return : number of sequences left after merging 1340*01826a49SYabin Cui 1341*01826a49SYabin Cui</p></pre><BR> 1342*01826a49SYabin Cui 1343*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t 1344*01826a49SYabin CuiZSTD_compressSequences( ZSTD_CCtx* cctx, void* dst, size_t dstSize, 1345*01826a49SYabin Cui const ZSTD_Sequence* inSeqs, size_t inSeqsSize, 1346*01826a49SYabin Cui const void* src, size_t srcSize); 1347*01826a49SYabin Cui</b><p> Compress an array of ZSTD_Sequence, associated with @src buffer, into dst. 1348*01826a49SYabin Cui @src contains the entire input (not just the literals). 1349*01826a49SYabin Cui If @srcSize > sum(sequence.length), the remaining bytes are considered all literals 1350*01826a49SYabin Cui If a dictionary is included, then the cctx should reference the dict. (see: ZSTD_CCtx_refCDict(), ZSTD_CCtx_loadDictionary(), etc.) 1351*01826a49SYabin Cui The entire source is compressed into a single frame. 1352*01826a49SYabin Cui 1353*01826a49SYabin Cui The compression behavior changes based on cctx params. In particular: 1354*01826a49SYabin Cui If ZSTD_c_blockDelimiters == ZSTD_sf_noBlockDelimiters, the array of ZSTD_Sequence is expected to contain 1355*01826a49SYabin Cui no block delimiters (defined in ZSTD_Sequence). Block boundaries are roughly determined based on 1356*01826a49SYabin Cui the block size derived from the cctx, and sequences may be split. This is the default setting. 1357*01826a49SYabin Cui 1358*01826a49SYabin Cui If ZSTD_c_blockDelimiters == ZSTD_sf_explicitBlockDelimiters, the array of ZSTD_Sequence is expected to contain 1359*01826a49SYabin Cui block delimiters (defined in ZSTD_Sequence). Behavior is undefined if no block delimiters are provided. 1360*01826a49SYabin Cui 1361*01826a49SYabin Cui If ZSTD_c_validateSequences == 0, this function will blindly accept the sequences provided. Invalid sequences cause undefined 1362*01826a49SYabin Cui behavior. If ZSTD_c_validateSequences == 1, then if sequence is invalid (see doc/zstd_compression_format.md for 1363*01826a49SYabin Cui specifics regarding offset/matchlength requirements) then the function will bail out and return an error. 1364*01826a49SYabin Cui 1365*01826a49SYabin Cui In addition to the two adjustable experimental params, there are other important cctx params. 1366*01826a49SYabin Cui - ZSTD_c_minMatch MUST be set as less than or equal to the smallest match generated by the match finder. It has a minimum value of ZSTD_MINMATCH_MIN. 1367*01826a49SYabin Cui - ZSTD_c_compressionLevel accordingly adjusts the strength of the entropy coder, as it would in typical compression. 1368*01826a49SYabin Cui - ZSTD_c_windowLog affects offset validation: this function will return an error at higher debug levels if a provided offset 1369*01826a49SYabin Cui is larger than what the spec allows for a given window log and dictionary (if present). See: doc/zstd_compression_format.md 1370*01826a49SYabin Cui 1371*01826a49SYabin Cui Note: Repcodes are, as of now, always re-calculated within this function, so ZSTD_Sequence::rep is unused. 1372*01826a49SYabin Cui Note 2: Once we integrate ability to ingest repcodes, the explicit block delims mode must respect those repcodes exactly, 1373*01826a49SYabin Cui and cannot emit an RLE block that disagrees with the repcode history 1374*01826a49SYabin Cui @return : final compressed size, or a ZSTD error code. 1375*01826a49SYabin Cui 1376*01826a49SYabin Cui</p></pre><BR> 1377*01826a49SYabin Cui 1378*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_writeSkippableFrame(void* dst, size_t dstCapacity, 1379*01826a49SYabin Cui const void* src, size_t srcSize, unsigned magicVariant); 1380*01826a49SYabin Cui</b><p> Generates a zstd skippable frame containing data given by src, and writes it to dst buffer. 1381*01826a49SYabin Cui 1382*01826a49SYabin Cui Skippable frames begin with a 4-byte magic number. There are 16 possible choices of magic number, 1383*01826a49SYabin Cui ranging from ZSTD_MAGIC_SKIPPABLE_START to ZSTD_MAGIC_SKIPPABLE_START+15. 1384*01826a49SYabin Cui As such, the parameter magicVariant controls the exact skippable frame magic number variant used, so 1385*01826a49SYabin Cui the magic number used will be ZSTD_MAGIC_SKIPPABLE_START + magicVariant. 1386*01826a49SYabin Cui 1387*01826a49SYabin Cui Returns an error if destination buffer is not large enough, if the source size is not representable 1388*01826a49SYabin Cui with a 4-byte unsigned int, or if the parameter magicVariant is greater than 15 (and therefore invalid). 1389*01826a49SYabin Cui 1390*01826a49SYabin Cui @return : number of bytes written or a ZSTD error. 1391*01826a49SYabin Cui 1392*01826a49SYabin Cui</p></pre><BR> 1393*01826a49SYabin Cui 1394*01826a49SYabin Cui<pre><b>size_t ZSTD_readSkippableFrame(void* dst, size_t dstCapacity, unsigned* magicVariant, 1395*01826a49SYabin Cui const void* src, size_t srcSize); 1396*01826a49SYabin Cui</b><p> Retrieves a zstd skippable frame containing data given by src, and writes it to dst buffer. 1397*01826a49SYabin Cui 1398*01826a49SYabin Cui The parameter magicVariant will receive the magicVariant that was supplied when the frame was written, 1399*01826a49SYabin Cui i.e. magicNumber - ZSTD_MAGIC_SKIPPABLE_START. This can be NULL if the caller is not interested 1400*01826a49SYabin Cui in the magicVariant. 1401*01826a49SYabin Cui 1402*01826a49SYabin Cui Returns an error if destination buffer is not large enough, or if the frame is not skippable. 1403*01826a49SYabin Cui 1404*01826a49SYabin Cui @return : number of bytes written or a ZSTD error. 1405*01826a49SYabin Cui 1406*01826a49SYabin Cui</p></pre><BR> 1407*01826a49SYabin Cui 1408*01826a49SYabin Cui<pre><b>unsigned ZSTD_isSkippableFrame(const void* buffer, size_t size); 1409*01826a49SYabin Cui</b><p> Tells if the content of `buffer` starts with a valid Frame Identifier for a skippable frame. 1410*01826a49SYabin Cui 1411*01826a49SYabin Cui</p></pre><BR> 1412*01826a49SYabin Cui 1413*01826a49SYabin Cui<a name="Chapter16"></a><h2>Memory management</h2><pre></pre> 1414*01826a49SYabin Cui 1415*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_estimateCCtxSize(int maxCompressionLevel); 1416*01826a49SYabin CuiZSTDLIB_STATIC_API size_t ZSTD_estimateCCtxSize_usingCParams(ZSTD_compressionParameters cParams); 1417*01826a49SYabin CuiZSTDLIB_STATIC_API size_t ZSTD_estimateCCtxSize_usingCCtxParams(const ZSTD_CCtx_params* params); 1418*01826a49SYabin CuiZSTDLIB_STATIC_API size_t ZSTD_estimateDCtxSize(void); 1419*01826a49SYabin Cui</b><p> These functions make it possible to estimate memory usage 1420*01826a49SYabin Cui of a future {D,C}Ctx, before its creation. 1421*01826a49SYabin Cui This is useful in combination with ZSTD_initStatic(), 1422*01826a49SYabin Cui which makes it possible to employ a static buffer for ZSTD_CCtx* state. 1423*01826a49SYabin Cui 1424*01826a49SYabin Cui ZSTD_estimateCCtxSize() will provide a memory budget large enough 1425*01826a49SYabin Cui to compress data of any size using one-shot compression ZSTD_compressCCtx() or ZSTD_compress2() 1426*01826a49SYabin Cui associated with any compression level up to max specified one. 1427*01826a49SYabin Cui The estimate will assume the input may be arbitrarily large, 1428*01826a49SYabin Cui which is the worst case. 1429*01826a49SYabin Cui 1430*01826a49SYabin Cui Note that the size estimation is specific for one-shot compression, 1431*01826a49SYabin Cui it is not valid for streaming (see ZSTD_estimateCStreamSize*()) 1432*01826a49SYabin Cui nor other potential ways of using a ZSTD_CCtx* state. 1433*01826a49SYabin Cui 1434*01826a49SYabin Cui When srcSize can be bound by a known and rather "small" value, 1435*01826a49SYabin Cui this knowledge can be used to provide a tighter budget estimation 1436*01826a49SYabin Cui because the ZSTD_CCtx* state will need less memory for small inputs. 1437*01826a49SYabin Cui This tighter estimation can be provided by employing more advanced functions 1438*01826a49SYabin Cui ZSTD_estimateCCtxSize_usingCParams(), which can be used in tandem with ZSTD_getCParams(), 1439*01826a49SYabin Cui and ZSTD_estimateCCtxSize_usingCCtxParams(), which can be used in tandem with ZSTD_CCtxParams_setParameter(). 1440*01826a49SYabin Cui Both can be used to estimate memory using custom compression parameters and arbitrary srcSize limits. 1441*01826a49SYabin Cui 1442*01826a49SYabin Cui Note : only single-threaded compression is supported. 1443*01826a49SYabin Cui ZSTD_estimateCCtxSize_usingCCtxParams() will return an error code if ZSTD_c_nbWorkers is >= 1. 1444*01826a49SYabin Cui 1445*01826a49SYabin Cui</p></pre><BR> 1446*01826a49SYabin Cui 1447*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_estimateCStreamSize(int maxCompressionLevel); 1448*01826a49SYabin CuiZSTDLIB_STATIC_API size_t ZSTD_estimateCStreamSize_usingCParams(ZSTD_compressionParameters cParams); 1449*01826a49SYabin CuiZSTDLIB_STATIC_API size_t ZSTD_estimateCStreamSize_usingCCtxParams(const ZSTD_CCtx_params* params); 1450*01826a49SYabin CuiZSTDLIB_STATIC_API size_t ZSTD_estimateDStreamSize(size_t maxWindowSize); 1451*01826a49SYabin CuiZSTDLIB_STATIC_API size_t ZSTD_estimateDStreamSize_fromFrame(const void* src, size_t srcSize); 1452*01826a49SYabin Cui</b><p> ZSTD_estimateCStreamSize() will provide a memory budget large enough for streaming compression 1453*01826a49SYabin Cui using any compression level up to the max specified one. 1454*01826a49SYabin Cui It will also consider src size to be arbitrarily "large", which is a worst case scenario. 1455*01826a49SYabin Cui If srcSize is known to always be small, ZSTD_estimateCStreamSize_usingCParams() can provide a tighter estimation. 1456*01826a49SYabin Cui ZSTD_estimateCStreamSize_usingCParams() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel. 1457*01826a49SYabin Cui 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. 1458*01826a49SYabin Cui Note : CStream size estimation is only correct for single-threaded compression. 1459*01826a49SYabin Cui ZSTD_estimateCStreamSize_usingCCtxParams() will return an error code if ZSTD_c_nbWorkers is >= 1. 1460*01826a49SYabin Cui Note 2 : ZSTD_estimateCStreamSize* functions are not compatible with the Block-Level Sequence Producer API at this time. 1461*01826a49SYabin Cui Size estimates assume that no external sequence producer is registered. 1462*01826a49SYabin Cui 1463*01826a49SYabin Cui ZSTD_DStream memory budget depends on frame's window Size. 1464*01826a49SYabin Cui This information can be passed manually, using ZSTD_estimateDStreamSize, 1465*01826a49SYabin Cui or deducted from a valid frame Header, using ZSTD_estimateDStreamSize_fromFrame(); 1466*01826a49SYabin Cui Any frame requesting a window size larger than max specified one will be rejected. 1467*01826a49SYabin Cui Note : if streaming is init with function ZSTD_init?Stream_usingDict(), 1468*01826a49SYabin Cui an internal ?Dict will be created, which additional size is not estimated here. 1469*01826a49SYabin Cui In this case, get total size by adding ZSTD_estimate?DictSize 1470*01826a49SYabin Cui 1471*01826a49SYabin Cui</p></pre><BR> 1472*01826a49SYabin Cui 1473*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_estimateCDictSize(size_t dictSize, int compressionLevel); 1474*01826a49SYabin CuiZSTDLIB_STATIC_API size_t ZSTD_estimateCDictSize_advanced(size_t dictSize, ZSTD_compressionParameters cParams, ZSTD_dictLoadMethod_e dictLoadMethod); 1475*01826a49SYabin CuiZSTDLIB_STATIC_API size_t ZSTD_estimateDDictSize(size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod); 1476*01826a49SYabin Cui</b><p> ZSTD_estimateCDictSize() will bet that src size is relatively "small", and content is copied, like ZSTD_createCDict(). 1477*01826a49SYabin Cui ZSTD_estimateCDictSize_advanced() makes it possible to control compression parameters precisely, like ZSTD_createCDict_advanced(). 1478*01826a49SYabin Cui Note : dictionaries created by reference (`ZSTD_dlm_byRef`) are logically smaller. 1479*01826a49SYabin Cui 1480*01826a49SYabin Cui</p></pre><BR> 1481*01826a49SYabin Cui 1482*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API ZSTD_CCtx* ZSTD_initStaticCCtx(void* workspace, size_t workspaceSize); 1483*01826a49SYabin CuiZSTDLIB_STATIC_API ZSTD_CStream* ZSTD_initStaticCStream(void* workspace, size_t workspaceSize); </b>/**< same as ZSTD_initStaticCCtx() */<b> 1484*01826a49SYabin Cui</b><p> Initialize an object using a pre-allocated fixed-size buffer. 1485*01826a49SYabin Cui workspace: The memory area to emplace the object into. 1486*01826a49SYabin Cui Provided pointer *must be 8-bytes aligned*. 1487*01826a49SYabin Cui Buffer must outlive object. 1488*01826a49SYabin Cui workspaceSize: Use ZSTD_estimate*Size() to determine 1489*01826a49SYabin Cui how large workspace must be to support target scenario. 1490*01826a49SYabin Cui @return : pointer to object (same address as workspace, just different type), 1491*01826a49SYabin Cui or NULL if error (size too small, incorrect alignment, etc.) 1492*01826a49SYabin Cui Note : zstd will never resize nor malloc() when using a static buffer. 1493*01826a49SYabin Cui If the object requires more memory than available, 1494*01826a49SYabin Cui zstd will just error out (typically ZSTD_error_memory_allocation). 1495*01826a49SYabin Cui Note 2 : there is no corresponding "free" function. 1496*01826a49SYabin Cui Since workspace is allocated externally, it must be freed externally too. 1497*01826a49SYabin Cui Note 3 : cParams : use ZSTD_getCParams() to convert a compression level 1498*01826a49SYabin Cui into its associated cParams. 1499*01826a49SYabin Cui Limitation 1 : currently not compatible with internal dictionary creation, triggered by 1500*01826a49SYabin Cui ZSTD_CCtx_loadDictionary(), ZSTD_initCStream_usingDict() or ZSTD_initDStream_usingDict(). 1501*01826a49SYabin Cui Limitation 2 : static cctx currently not compatible with multi-threading. 1502*01826a49SYabin Cui Limitation 3 : static dctx is incompatible with legacy support. 1503*01826a49SYabin Cui 1504*01826a49SYabin Cui</p></pre><BR> 1505*01826a49SYabin Cui 1506*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API ZSTD_DStream* ZSTD_initStaticDStream(void* workspace, size_t workspaceSize); </b>/**< same as ZSTD_initStaticDCtx() */<b> 1507*01826a49SYabin Cui</b></pre><BR> 1508*01826a49SYabin Cui<pre><b>typedef void* (*ZSTD_allocFunction) (void* opaque, size_t size); 1509*01826a49SYabin Cuitypedef void (*ZSTD_freeFunction) (void* opaque, void* address); 1510*01826a49SYabin Cuitypedef struct { ZSTD_allocFunction customAlloc; ZSTD_freeFunction customFree; void* opaque; } ZSTD_customMem; 1511*01826a49SYabin Cuistatic 1512*01826a49SYabin Cui#ifdef __GNUC__ 1513*01826a49SYabin Cui__attribute__((__unused__)) 1514*01826a49SYabin Cui#endif 1515*01826a49SYabin CuiZSTD_customMem const ZSTD_defaultCMem = { NULL, NULL, NULL }; </b>/**< this constant defers to stdlib's functions */<b> 1516*01826a49SYabin Cui</b><p> These prototypes make it possible to pass your own allocation/free functions. 1517*01826a49SYabin Cui ZSTD_customMem is provided at creation time, using ZSTD_create*_advanced() variants listed below. 1518*01826a49SYabin Cui All allocation/free operations will be completed using these custom variants instead of regular <stdlib.h> ones. 1519*01826a49SYabin Cui 1520*01826a49SYabin Cui</p></pre><BR> 1521*01826a49SYabin Cui 1522*01826a49SYabin Cui<pre><b>typedef struct POOL_ctx_s ZSTD_threadPool; 1523*01826a49SYabin CuiZSTDLIB_STATIC_API ZSTD_threadPool* ZSTD_createThreadPool(size_t numThreads); 1524*01826a49SYabin CuiZSTDLIB_STATIC_API void ZSTD_freeThreadPool (ZSTD_threadPool* pool); </b>/* accept NULL pointer */<b> 1525*01826a49SYabin CuiZSTDLIB_STATIC_API size_t ZSTD_CCtx_refThreadPool(ZSTD_CCtx* cctx, ZSTD_threadPool* pool); 1526*01826a49SYabin Cui</b><p> These prototypes make it possible to share a thread pool among multiple compression contexts. 1527*01826a49SYabin Cui This can limit resources for applications with multiple threads where each one uses 1528*01826a49SYabin Cui a threaded compression mode (via ZSTD_c_nbWorkers parameter). 1529*01826a49SYabin Cui ZSTD_createThreadPool creates a new thread pool with a given number of threads. 1530*01826a49SYabin Cui Note that the lifetime of such pool must exist while being used. 1531*01826a49SYabin Cui ZSTD_CCtx_refThreadPool assigns a thread pool to a context (use NULL argument value 1532*01826a49SYabin Cui to use an internal thread pool). 1533*01826a49SYabin Cui ZSTD_freeThreadPool frees a thread pool, accepts NULL pointer. 1534*01826a49SYabin Cui 1535*01826a49SYabin Cui</p></pre><BR> 1536*01826a49SYabin Cui 1537*01826a49SYabin Cui<a name="Chapter17"></a><h2>Advanced compression functions</h2><pre></pre> 1538*01826a49SYabin Cui 1539*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API ZSTD_CDict* ZSTD_createCDict_byReference(const void* dictBuffer, size_t dictSize, int compressionLevel); 1540*01826a49SYabin Cui</b><p> Create a digested dictionary for compression 1541*01826a49SYabin Cui Dictionary content is just referenced, not duplicated. 1542*01826a49SYabin Cui As a consequence, `dictBuffer` **must** outlive CDict, 1543*01826a49SYabin Cui and its content must remain unmodified throughout the lifetime of CDict. 1544*01826a49SYabin Cui note: equivalent to ZSTD_createCDict_advanced(), with dictLoadMethod==ZSTD_dlm_byRef 1545*01826a49SYabin Cui</p></pre><BR> 1546*01826a49SYabin Cui 1547*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API ZSTD_compressionParameters ZSTD_getCParams(int compressionLevel, unsigned long long estimatedSrcSize, size_t dictSize); 1548*01826a49SYabin Cui</b><p> @return ZSTD_compressionParameters structure for a selected compression level and estimated srcSize. 1549*01826a49SYabin Cui `estimatedSrcSize` value is optional, select 0 if not known 1550*01826a49SYabin Cui</p></pre><BR> 1551*01826a49SYabin Cui 1552*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API ZSTD_parameters ZSTD_getParams(int compressionLevel, unsigned long long estimatedSrcSize, size_t dictSize); 1553*01826a49SYabin Cui</b><p> same as ZSTD_getCParams(), but @return a full `ZSTD_parameters` object instead of sub-component `ZSTD_compressionParameters`. 1554*01826a49SYabin Cui All fields of `ZSTD_frameParameters` are set to default : contentSize=1, checksum=0, noDictID=0 1555*01826a49SYabin Cui</p></pre><BR> 1556*01826a49SYabin Cui 1557*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_checkCParams(ZSTD_compressionParameters params); 1558*01826a49SYabin Cui</b><p> Ensure param values remain within authorized range. 1559*01826a49SYabin Cui @return 0 on success, or an error code (can be checked with ZSTD_isError()) 1560*01826a49SYabin Cui</p></pre><BR> 1561*01826a49SYabin Cui 1562*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API ZSTD_compressionParameters ZSTD_adjustCParams(ZSTD_compressionParameters cPar, unsigned long long srcSize, size_t dictSize); 1563*01826a49SYabin Cui</b><p> optimize params for a given `srcSize` and `dictSize`. 1564*01826a49SYabin Cui `srcSize` can be unknown, in which case use ZSTD_CONTENTSIZE_UNKNOWN. 1565*01826a49SYabin Cui `dictSize` must be `0` when there is no dictionary. 1566*01826a49SYabin Cui cPar can be invalid : all parameters will be clamped within valid range in the @return struct. 1567*01826a49SYabin Cui This function never fails (wide contract) 1568*01826a49SYabin Cui</p></pre><BR> 1569*01826a49SYabin Cui 1570*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_CCtx_setCParams(ZSTD_CCtx* cctx, ZSTD_compressionParameters cparams); 1571*01826a49SYabin Cui</b><p> Set all parameters provided within @p cparams into the working @p cctx. 1572*01826a49SYabin Cui Note : if modifying parameters during compression (MT mode only), 1573*01826a49SYabin Cui note that changes to the .windowLog parameter will be ignored. 1574*01826a49SYabin Cui @return 0 on success, or an error code (can be checked with ZSTD_isError()). 1575*01826a49SYabin Cui On failure, no parameters are updated. 1576*01826a49SYabin Cui 1577*01826a49SYabin Cui</p></pre><BR> 1578*01826a49SYabin Cui 1579*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_CCtx_setFParams(ZSTD_CCtx* cctx, ZSTD_frameParameters fparams); 1580*01826a49SYabin Cui</b><p> Set all parameters provided within @p fparams into the working @p cctx. 1581*01826a49SYabin Cui @return 0 on success, or an error code (can be checked with ZSTD_isError()). 1582*01826a49SYabin Cui 1583*01826a49SYabin Cui</p></pre><BR> 1584*01826a49SYabin Cui 1585*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_CCtx_setParams(ZSTD_CCtx* cctx, ZSTD_parameters params); 1586*01826a49SYabin Cui</b><p> Set all parameters provided within @p params into the working @p cctx. 1587*01826a49SYabin Cui @return 0 on success, or an error code (can be checked with ZSTD_isError()). 1588*01826a49SYabin Cui 1589*01826a49SYabin Cui</p></pre><BR> 1590*01826a49SYabin Cui 1591*01826a49SYabin Cui<pre><b>ZSTD_DEPRECATED("use ZSTD_compress2") 1592*01826a49SYabin CuiZSTDLIB_STATIC_API 1593*01826a49SYabin Cuisize_t ZSTD_compress_advanced(ZSTD_CCtx* cctx, 1594*01826a49SYabin Cui void* dst, size_t dstCapacity, 1595*01826a49SYabin Cui const void* src, size_t srcSize, 1596*01826a49SYabin Cui const void* dict,size_t dictSize, 1597*01826a49SYabin Cui ZSTD_parameters params); 1598*01826a49SYabin Cui</b><p> Note : this function is now DEPRECATED. 1599*01826a49SYabin Cui It can be replaced by ZSTD_compress2(), in combination with ZSTD_CCtx_setParameter() and other parameter setters. 1600*01826a49SYabin Cui This prototype will generate compilation warnings. 1601*01826a49SYabin Cui</p></pre><BR> 1602*01826a49SYabin Cui 1603*01826a49SYabin Cui<pre><b>ZSTD_DEPRECATED("use ZSTD_compress2 with ZSTD_CCtx_loadDictionary") 1604*01826a49SYabin CuiZSTDLIB_STATIC_API 1605*01826a49SYabin Cuisize_t ZSTD_compress_usingCDict_advanced(ZSTD_CCtx* cctx, 1606*01826a49SYabin Cui void* dst, size_t dstCapacity, 1607*01826a49SYabin Cui const void* src, size_t srcSize, 1608*01826a49SYabin Cui const ZSTD_CDict* cdict, 1609*01826a49SYabin Cui ZSTD_frameParameters fParams); 1610*01826a49SYabin Cui</b><p> Note : this function is now DEPRECATED. 1611*01826a49SYabin Cui It can be replaced by ZSTD_compress2(), in combination with ZSTD_CCtx_loadDictionary() and other parameter setters. 1612*01826a49SYabin Cui This prototype will generate compilation warnings. 1613*01826a49SYabin Cui</p></pre><BR> 1614*01826a49SYabin Cui 1615*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_CCtx_loadDictionary_byReference(ZSTD_CCtx* cctx, const void* dict, size_t dictSize); 1616*01826a49SYabin Cui</b><p> Same as ZSTD_CCtx_loadDictionary(), but dictionary content is referenced, instead of being copied into CCtx. 1617*01826a49SYabin Cui It saves some memory, but also requires that `dict` outlives its usage within `cctx` 1618*01826a49SYabin Cui</p></pre><BR> 1619*01826a49SYabin Cui 1620*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_CCtx_loadDictionary_advanced(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod, ZSTD_dictContentType_e dictContentType); 1621*01826a49SYabin Cui</b><p> Same as ZSTD_CCtx_loadDictionary(), but gives finer control over 1622*01826a49SYabin Cui how to load the dictionary (by copy ? by reference ?) 1623*01826a49SYabin Cui and how to interpret it (automatic ? force raw mode ? full mode only ?) 1624*01826a49SYabin Cui</p></pre><BR> 1625*01826a49SYabin Cui 1626*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_CCtx_refPrefix_advanced(ZSTD_CCtx* cctx, const void* prefix, size_t prefixSize, ZSTD_dictContentType_e dictContentType); 1627*01826a49SYabin Cui</b><p> Same as ZSTD_CCtx_refPrefix(), but gives finer control over 1628*01826a49SYabin Cui how to interpret prefix content (automatic ? force raw mode (default) ? full mode only ?) 1629*01826a49SYabin Cui</p></pre><BR> 1630*01826a49SYabin Cui 1631*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_CCtx_getParameter(const ZSTD_CCtx* cctx, ZSTD_cParameter param, int* value); 1632*01826a49SYabin Cui</b><p> Get the requested compression parameter value, selected by enum ZSTD_cParameter, 1633*01826a49SYabin Cui and store it into int* value. 1634*01826a49SYabin Cui @return : 0, or an error code (which can be tested with ZSTD_isError()). 1635*01826a49SYabin Cui 1636*01826a49SYabin Cui</p></pre><BR> 1637*01826a49SYabin Cui 1638*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API ZSTD_CCtx_params* ZSTD_createCCtxParams(void); 1639*01826a49SYabin CuiZSTDLIB_STATIC_API size_t ZSTD_freeCCtxParams(ZSTD_CCtx_params* params); </b>/* accept NULL pointer */<b> 1640*01826a49SYabin Cui</b><p> Quick howto : 1641*01826a49SYabin Cui - ZSTD_createCCtxParams() : Create a ZSTD_CCtx_params structure 1642*01826a49SYabin Cui - ZSTD_CCtxParams_setParameter() : Push parameters one by one into 1643*01826a49SYabin Cui an existing ZSTD_CCtx_params structure. 1644*01826a49SYabin Cui This is similar to 1645*01826a49SYabin Cui ZSTD_CCtx_setParameter(). 1646*01826a49SYabin Cui - ZSTD_CCtx_setParametersUsingCCtxParams() : Apply parameters to 1647*01826a49SYabin Cui an existing CCtx. 1648*01826a49SYabin Cui These parameters will be applied to 1649*01826a49SYabin Cui all subsequent frames. 1650*01826a49SYabin Cui - ZSTD_compressStream2() : Do compression using the CCtx. 1651*01826a49SYabin Cui - ZSTD_freeCCtxParams() : Free the memory, accept NULL pointer. 1652*01826a49SYabin Cui 1653*01826a49SYabin Cui This can be used with ZSTD_estimateCCtxSize_advanced_usingCCtxParams() 1654*01826a49SYabin Cui for static allocation of CCtx for single-threaded compression. 1655*01826a49SYabin Cui 1656*01826a49SYabin Cui</p></pre><BR> 1657*01826a49SYabin Cui 1658*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_CCtxParams_reset(ZSTD_CCtx_params* params); 1659*01826a49SYabin Cui</b><p> Reset params to default values. 1660*01826a49SYabin Cui 1661*01826a49SYabin Cui</p></pre><BR> 1662*01826a49SYabin Cui 1663*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_CCtxParams_init(ZSTD_CCtx_params* cctxParams, int compressionLevel); 1664*01826a49SYabin Cui</b><p> Initializes the compression parameters of cctxParams according to 1665*01826a49SYabin Cui compression level. All other parameters are reset to their default values. 1666*01826a49SYabin Cui 1667*01826a49SYabin Cui</p></pre><BR> 1668*01826a49SYabin Cui 1669*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_CCtxParams_init_advanced(ZSTD_CCtx_params* cctxParams, ZSTD_parameters params); 1670*01826a49SYabin Cui</b><p> Initializes the compression and frame parameters of cctxParams according to 1671*01826a49SYabin Cui params. All other parameters are reset to their default values. 1672*01826a49SYabin Cui 1673*01826a49SYabin Cui</p></pre><BR> 1674*01826a49SYabin Cui 1675*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_CCtxParams_setParameter(ZSTD_CCtx_params* params, ZSTD_cParameter param, int value); 1676*01826a49SYabin Cui</b><p> Similar to ZSTD_CCtx_setParameter. 1677*01826a49SYabin Cui Set one compression parameter, selected by enum ZSTD_cParameter. 1678*01826a49SYabin Cui Parameters must be applied to a ZSTD_CCtx using 1679*01826a49SYabin Cui ZSTD_CCtx_setParametersUsingCCtxParams(). 1680*01826a49SYabin Cui @result : a code representing success or failure (which can be tested with 1681*01826a49SYabin Cui ZSTD_isError()). 1682*01826a49SYabin Cui 1683*01826a49SYabin Cui</p></pre><BR> 1684*01826a49SYabin Cui 1685*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_CCtxParams_getParameter(const ZSTD_CCtx_params* params, ZSTD_cParameter param, int* value); 1686*01826a49SYabin Cui</b><p> Similar to ZSTD_CCtx_getParameter. 1687*01826a49SYabin Cui Get the requested value of one compression parameter, selected by enum ZSTD_cParameter. 1688*01826a49SYabin Cui @result : 0, or an error code (which can be tested with ZSTD_isError()). 1689*01826a49SYabin Cui 1690*01826a49SYabin Cui</p></pre><BR> 1691*01826a49SYabin Cui 1692*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_CCtx_setParametersUsingCCtxParams( 1693*01826a49SYabin Cui ZSTD_CCtx* cctx, const ZSTD_CCtx_params* params); 1694*01826a49SYabin Cui</b><p> Apply a set of ZSTD_CCtx_params to the compression context. 1695*01826a49SYabin Cui This can be done even after compression is started, 1696*01826a49SYabin Cui if nbWorkers==0, this will have no impact until a new compression is started. 1697*01826a49SYabin Cui if nbWorkers>=1, new parameters will be picked up at next job, 1698*01826a49SYabin Cui with a few restrictions (windowLog, pledgedSrcSize, nbWorkers, jobSize, and overlapLog are not updated). 1699*01826a49SYabin Cui 1700*01826a49SYabin Cui</p></pre><BR> 1701*01826a49SYabin Cui 1702*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_compressStream2_simpleArgs ( 1703*01826a49SYabin Cui ZSTD_CCtx* cctx, 1704*01826a49SYabin Cui void* dst, size_t dstCapacity, size_t* dstPos, 1705*01826a49SYabin Cui const void* src, size_t srcSize, size_t* srcPos, 1706*01826a49SYabin Cui ZSTD_EndDirective endOp); 1707*01826a49SYabin Cui</b><p> Same as ZSTD_compressStream2(), 1708*01826a49SYabin Cui but using only integral types as arguments. 1709*01826a49SYabin Cui This variant might be helpful for binders from dynamic languages 1710*01826a49SYabin Cui which have troubles handling structures containing memory pointers. 1711*01826a49SYabin Cui 1712*01826a49SYabin Cui</p></pre><BR> 1713*01826a49SYabin Cui 1714*01826a49SYabin Cui<a name="Chapter18"></a><h2>Advanced decompression functions</h2><pre></pre> 1715*01826a49SYabin Cui 1716*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API unsigned ZSTD_isFrame(const void* buffer, size_t size); 1717*01826a49SYabin Cui</b><p> Tells if the content of `buffer` starts with a valid Frame Identifier. 1718*01826a49SYabin Cui Note : Frame Identifier is 4 bytes. If `size < 4`, @return will always be 0. 1719*01826a49SYabin Cui Note 2 : Legacy Frame Identifiers are considered valid only if Legacy Support is enabled. 1720*01826a49SYabin Cui Note 3 : Skippable Frame Identifiers are considered valid. 1721*01826a49SYabin Cui</p></pre><BR> 1722*01826a49SYabin Cui 1723*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API ZSTD_DDict* ZSTD_createDDict_byReference(const void* dictBuffer, size_t dictSize); 1724*01826a49SYabin Cui</b><p> Create a digested dictionary, ready to start decompression operation without startup delay. 1725*01826a49SYabin Cui Dictionary content is referenced, and therefore stays in dictBuffer. 1726*01826a49SYabin Cui It is important that dictBuffer outlives DDict, 1727*01826a49SYabin Cui it must remain read accessible throughout the lifetime of DDict 1728*01826a49SYabin Cui</p></pre><BR> 1729*01826a49SYabin Cui 1730*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_DCtx_loadDictionary_byReference(ZSTD_DCtx* dctx, const void* dict, size_t dictSize); 1731*01826a49SYabin Cui</b><p> Same as ZSTD_DCtx_loadDictionary(), 1732*01826a49SYabin Cui but references `dict` content instead of copying it into `dctx`. 1733*01826a49SYabin Cui This saves memory if `dict` remains around., 1734*01826a49SYabin Cui However, it's imperative that `dict` remains accessible (and unmodified) while being used, so it must outlive decompression. 1735*01826a49SYabin Cui</p></pre><BR> 1736*01826a49SYabin Cui 1737*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_DCtx_loadDictionary_advanced(ZSTD_DCtx* dctx, const void* dict, size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod, ZSTD_dictContentType_e dictContentType); 1738*01826a49SYabin Cui</b><p> Same as ZSTD_DCtx_loadDictionary(), 1739*01826a49SYabin Cui but gives direct control over 1740*01826a49SYabin Cui how to load the dictionary (by copy ? by reference ?) 1741*01826a49SYabin Cui and how to interpret it (automatic ? force raw mode ? full mode only ?). 1742*01826a49SYabin Cui</p></pre><BR> 1743*01826a49SYabin Cui 1744*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_DCtx_refPrefix_advanced(ZSTD_DCtx* dctx, const void* prefix, size_t prefixSize, ZSTD_dictContentType_e dictContentType); 1745*01826a49SYabin Cui</b><p> Same as ZSTD_DCtx_refPrefix(), but gives finer control over 1746*01826a49SYabin Cui how to interpret prefix content (automatic ? force raw mode (default) ? full mode only ?) 1747*01826a49SYabin Cui</p></pre><BR> 1748*01826a49SYabin Cui 1749*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_DCtx_setMaxWindowSize(ZSTD_DCtx* dctx, size_t maxWindowSize); 1750*01826a49SYabin Cui</b><p> Refuses allocating internal buffers for frames requiring a window size larger than provided limit. 1751*01826a49SYabin Cui This protects a decoder context from reserving too much memory for itself (potential attack scenario). 1752*01826a49SYabin Cui This parameter is only useful in streaming mode, since no internal buffer is allocated in single-pass mode. 1753*01826a49SYabin Cui By default, a decompression context accepts all window sizes <= (1 << ZSTD_WINDOWLOG_LIMIT_DEFAULT) 1754*01826a49SYabin Cui @return : 0, or an error code (which can be tested using ZSTD_isError()). 1755*01826a49SYabin Cui 1756*01826a49SYabin Cui</p></pre><BR> 1757*01826a49SYabin Cui 1758*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_DCtx_getParameter(ZSTD_DCtx* dctx, ZSTD_dParameter param, int* value); 1759*01826a49SYabin Cui</b><p> Get the requested decompression parameter value, selected by enum ZSTD_dParameter, 1760*01826a49SYabin Cui and store it into int* value. 1761*01826a49SYabin Cui @return : 0, or an error code (which can be tested with ZSTD_isError()). 1762*01826a49SYabin Cui 1763*01826a49SYabin Cui</p></pre><BR> 1764*01826a49SYabin Cui 1765*01826a49SYabin Cui<pre><b>ZSTD_DEPRECATED("use ZSTD_DCtx_setParameter() instead") 1766*01826a49SYabin CuiZSTDLIB_STATIC_API 1767*01826a49SYabin Cuisize_t ZSTD_DCtx_setFormat(ZSTD_DCtx* dctx, ZSTD_format_e format); 1768*01826a49SYabin Cui</b><p> This function is REDUNDANT. Prefer ZSTD_DCtx_setParameter(). 1769*01826a49SYabin Cui Instruct the decoder context about what kind of data to decode next. 1770*01826a49SYabin Cui This instruction is mandatory to decode data without a fully-formed header, 1771*01826a49SYabin Cui such ZSTD_f_zstd1_magicless for example. 1772*01826a49SYabin Cui @return : 0, or an error code (which can be tested using ZSTD_isError()). 1773*01826a49SYabin Cui</p></pre><BR> 1774*01826a49SYabin Cui 1775*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_decompressStream_simpleArgs ( 1776*01826a49SYabin Cui ZSTD_DCtx* dctx, 1777*01826a49SYabin Cui void* dst, size_t dstCapacity, size_t* dstPos, 1778*01826a49SYabin Cui const void* src, size_t srcSize, size_t* srcPos); 1779*01826a49SYabin Cui</b><p> Same as ZSTD_decompressStream(), 1780*01826a49SYabin Cui but using only integral types as arguments. 1781*01826a49SYabin Cui This can be helpful for binders from dynamic languages 1782*01826a49SYabin Cui which have troubles handling structures containing memory pointers. 1783*01826a49SYabin Cui 1784*01826a49SYabin Cui</p></pre><BR> 1785*01826a49SYabin Cui 1786*01826a49SYabin Cui<a name="Chapter19"></a><h2>Advanced streaming functions</h2><pre> Warning : most of these functions are now redundant with the Advanced API. 1787*01826a49SYabin Cui Once Advanced API reaches "stable" status, 1788*01826a49SYabin Cui redundant functions will be deprecated, and then at some point removed. 1789*01826a49SYabin Cui<BR></pre> 1790*01826a49SYabin Cui 1791*01826a49SYabin Cui<h3>Advanced Streaming compression functions</h3><pre></pre><b><pre></pre></b><BR> 1792*01826a49SYabin Cui<pre><b>ZSTD_DEPRECATED("use ZSTD_CCtx_reset, see zstd.h for detailed instructions") 1793*01826a49SYabin CuiZSTDLIB_STATIC_API 1794*01826a49SYabin Cuisize_t ZSTD_initCStream_srcSize(ZSTD_CStream* zcs, 1795*01826a49SYabin Cui int compressionLevel, 1796*01826a49SYabin Cui unsigned long long pledgedSrcSize); 1797*01826a49SYabin Cui</b><p> This function is DEPRECATED, and equivalent to: 1798*01826a49SYabin Cui ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only); 1799*01826a49SYabin Cui ZSTD_CCtx_refCDict(zcs, NULL); // clear the dictionary (if any) 1800*01826a49SYabin Cui ZSTD_CCtx_setParameter(zcs, ZSTD_c_compressionLevel, compressionLevel); 1801*01826a49SYabin Cui ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize); 1802*01826a49SYabin Cui 1803*01826a49SYabin Cui pledgedSrcSize must be correct. If it is not known at init time, use 1804*01826a49SYabin Cui ZSTD_CONTENTSIZE_UNKNOWN. Note that, for compatibility with older programs, 1805*01826a49SYabin Cui "0" also disables frame content size field. It may be enabled in the future. 1806*01826a49SYabin Cui This prototype will generate compilation warnings. 1807*01826a49SYabin Cui 1808*01826a49SYabin Cui</p></pre><BR> 1809*01826a49SYabin Cui 1810*01826a49SYabin Cui<pre><b>ZSTD_DEPRECATED("use ZSTD_CCtx_reset, see zstd.h for detailed instructions") 1811*01826a49SYabin CuiZSTDLIB_STATIC_API 1812*01826a49SYabin Cuisize_t ZSTD_initCStream_usingDict(ZSTD_CStream* zcs, 1813*01826a49SYabin Cui const void* dict, size_t dictSize, 1814*01826a49SYabin Cui int compressionLevel); 1815*01826a49SYabin Cui</b><p> This function is DEPRECATED, and is equivalent to: 1816*01826a49SYabin Cui ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only); 1817*01826a49SYabin Cui ZSTD_CCtx_setParameter(zcs, ZSTD_c_compressionLevel, compressionLevel); 1818*01826a49SYabin Cui ZSTD_CCtx_loadDictionary(zcs, dict, dictSize); 1819*01826a49SYabin Cui 1820*01826a49SYabin Cui Creates of an internal CDict (incompatible with static CCtx), except if 1821*01826a49SYabin Cui dict == NULL or dictSize < 8, in which case no dict is used. 1822*01826a49SYabin Cui Note: dict is loaded with ZSTD_dct_auto (treated as a full zstd dictionary if 1823*01826a49SYabin Cui it begins with ZSTD_MAGIC_DICTIONARY, else as raw content) and ZSTD_dlm_byCopy. 1824*01826a49SYabin Cui This prototype will generate compilation warnings. 1825*01826a49SYabin Cui 1826*01826a49SYabin Cui</p></pre><BR> 1827*01826a49SYabin Cui 1828*01826a49SYabin Cui<pre><b>ZSTD_DEPRECATED("use ZSTD_CCtx_reset, see zstd.h for detailed instructions") 1829*01826a49SYabin CuiZSTDLIB_STATIC_API 1830*01826a49SYabin Cuisize_t ZSTD_initCStream_advanced(ZSTD_CStream* zcs, 1831*01826a49SYabin Cui const void* dict, size_t dictSize, 1832*01826a49SYabin Cui ZSTD_parameters params, 1833*01826a49SYabin Cui unsigned long long pledgedSrcSize); 1834*01826a49SYabin Cui</b><p> This function is DEPRECATED, and is equivalent to: 1835*01826a49SYabin Cui ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only); 1836*01826a49SYabin Cui ZSTD_CCtx_setParams(zcs, params); 1837*01826a49SYabin Cui ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize); 1838*01826a49SYabin Cui ZSTD_CCtx_loadDictionary(zcs, dict, dictSize); 1839*01826a49SYabin Cui 1840*01826a49SYabin Cui dict is loaded with ZSTD_dct_auto and ZSTD_dlm_byCopy. 1841*01826a49SYabin Cui pledgedSrcSize must be correct. 1842*01826a49SYabin Cui If srcSize is not known at init time, use value ZSTD_CONTENTSIZE_UNKNOWN. 1843*01826a49SYabin Cui This prototype will generate compilation warnings. 1844*01826a49SYabin Cui 1845*01826a49SYabin Cui</p></pre><BR> 1846*01826a49SYabin Cui 1847*01826a49SYabin Cui<pre><b>ZSTD_DEPRECATED("use ZSTD_CCtx_reset and ZSTD_CCtx_refCDict, see zstd.h for detailed instructions") 1848*01826a49SYabin CuiZSTDLIB_STATIC_API 1849*01826a49SYabin Cuisize_t ZSTD_initCStream_usingCDict(ZSTD_CStream* zcs, const ZSTD_CDict* cdict); 1850*01826a49SYabin Cui</b><p> This function is DEPRECATED, and equivalent to: 1851*01826a49SYabin Cui ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only); 1852*01826a49SYabin Cui ZSTD_CCtx_refCDict(zcs, cdict); 1853*01826a49SYabin Cui 1854*01826a49SYabin Cui note : cdict will just be referenced, and must outlive compression session 1855*01826a49SYabin Cui This prototype will generate compilation warnings. 1856*01826a49SYabin Cui 1857*01826a49SYabin Cui</p></pre><BR> 1858*01826a49SYabin Cui 1859*01826a49SYabin Cui<pre><b>ZSTD_DEPRECATED("use ZSTD_CCtx_reset and ZSTD_CCtx_refCDict, see zstd.h for detailed instructions") 1860*01826a49SYabin CuiZSTDLIB_STATIC_API 1861*01826a49SYabin Cuisize_t ZSTD_initCStream_usingCDict_advanced(ZSTD_CStream* zcs, 1862*01826a49SYabin Cui const ZSTD_CDict* cdict, 1863*01826a49SYabin Cui ZSTD_frameParameters fParams, 1864*01826a49SYabin Cui unsigned long long pledgedSrcSize); 1865*01826a49SYabin Cui</b><p> This function is DEPRECATED, and is equivalent to: 1866*01826a49SYabin Cui ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only); 1867*01826a49SYabin Cui ZSTD_CCtx_setFParams(zcs, fParams); 1868*01826a49SYabin Cui ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize); 1869*01826a49SYabin Cui ZSTD_CCtx_refCDict(zcs, cdict); 1870*01826a49SYabin Cui 1871*01826a49SYabin Cui same as ZSTD_initCStream_usingCDict(), with control over frame parameters. 1872*01826a49SYabin Cui pledgedSrcSize must be correct. If srcSize is not known at init time, use 1873*01826a49SYabin Cui value ZSTD_CONTENTSIZE_UNKNOWN. 1874*01826a49SYabin Cui This prototype will generate compilation warnings. 1875*01826a49SYabin Cui 1876*01826a49SYabin Cui</p></pre><BR> 1877*01826a49SYabin Cui 1878*01826a49SYabin Cui<pre><b>ZSTD_DEPRECATED("use ZSTD_CCtx_reset, see zstd.h for detailed instructions") 1879*01826a49SYabin CuiZSTDLIB_STATIC_API 1880*01826a49SYabin Cuisize_t ZSTD_resetCStream(ZSTD_CStream* zcs, unsigned long long pledgedSrcSize); 1881*01826a49SYabin Cui</b><p> This function is DEPRECATED, and is equivalent to: 1882*01826a49SYabin Cui ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only); 1883*01826a49SYabin Cui ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize); 1884*01826a49SYabin Cui Note: ZSTD_resetCStream() interprets pledgedSrcSize == 0 as ZSTD_CONTENTSIZE_UNKNOWN, but 1885*01826a49SYabin Cui ZSTD_CCtx_setPledgedSrcSize() does not do the same, so ZSTD_CONTENTSIZE_UNKNOWN must be 1886*01826a49SYabin Cui explicitly specified. 1887*01826a49SYabin Cui 1888*01826a49SYabin Cui start a new frame, using same parameters from previous frame. 1889*01826a49SYabin Cui This is typically useful to skip dictionary loading stage, since it will reuse it in-place. 1890*01826a49SYabin Cui Note that zcs must be init at least once before using ZSTD_resetCStream(). 1891*01826a49SYabin Cui If pledgedSrcSize is not known at reset time, use macro ZSTD_CONTENTSIZE_UNKNOWN. 1892*01826a49SYabin Cui If pledgedSrcSize > 0, its value must be correct, as it will be written in header, and controlled at the end. 1893*01826a49SYabin Cui For the time being, pledgedSrcSize==0 is interpreted as "srcSize unknown" for compatibility with older programs, 1894*01826a49SYabin Cui but it will change to mean "empty" in future version, so use macro ZSTD_CONTENTSIZE_UNKNOWN instead. 1895*01826a49SYabin Cui @return : 0, or an error code (which can be tested using ZSTD_isError()) 1896*01826a49SYabin Cui This prototype will generate compilation warnings. 1897*01826a49SYabin Cui 1898*01826a49SYabin Cui</p></pre><BR> 1899*01826a49SYabin Cui 1900*01826a49SYabin Cui<pre><b>typedef struct { 1901*01826a49SYabin Cui unsigned long long ingested; </b>/* nb input bytes read and buffered */<b> 1902*01826a49SYabin Cui unsigned long long consumed; </b>/* nb input bytes actually compressed */<b> 1903*01826a49SYabin Cui unsigned long long produced; </b>/* nb of compressed bytes generated and buffered */<b> 1904*01826a49SYabin Cui unsigned long long flushed; </b>/* nb of compressed bytes flushed : not provided; can be tracked from caller side */<b> 1905*01826a49SYabin Cui unsigned currentJobID; </b>/* MT only : latest started job nb */<b> 1906*01826a49SYabin Cui unsigned nbActiveWorkers; </b>/* MT only : nb of workers actively compressing at probe time */<b> 1907*01826a49SYabin Cui} ZSTD_frameProgression; 1908*01826a49SYabin Cui</b></pre><BR> 1909*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_toFlushNow(ZSTD_CCtx* cctx); 1910*01826a49SYabin Cui</b><p> Tell how many bytes are ready to be flushed immediately. 1911*01826a49SYabin Cui Useful for multithreading scenarios (nbWorkers >= 1). 1912*01826a49SYabin Cui Probe the oldest active job, defined as oldest job not yet entirely flushed, 1913*01826a49SYabin Cui and check its output buffer. 1914*01826a49SYabin Cui @return : amount of data stored in oldest job and ready to be flushed immediately. 1915*01826a49SYabin Cui if @return == 0, it means either : 1916*01826a49SYabin Cui + there is no active job (could be checked with ZSTD_frameProgression()), or 1917*01826a49SYabin Cui + oldest job is still actively compressing data, 1918*01826a49SYabin Cui but everything it has produced has also been flushed so far, 1919*01826a49SYabin Cui therefore flush speed is limited by production speed of oldest job 1920*01826a49SYabin Cui irrespective of the speed of concurrent (and newer) jobs. 1921*01826a49SYabin Cui 1922*01826a49SYabin Cui</p></pre><BR> 1923*01826a49SYabin Cui 1924*01826a49SYabin Cui<h3>Advanced Streaming decompression functions</h3><pre></pre><b><pre></pre></b><BR> 1925*01826a49SYabin Cui<pre><b>ZSTD_DEPRECATED("use ZSTD_DCtx_reset + ZSTD_DCtx_loadDictionary, see zstd.h for detailed instructions") 1926*01826a49SYabin CuiZSTDLIB_STATIC_API size_t ZSTD_initDStream_usingDict(ZSTD_DStream* zds, const void* dict, size_t dictSize); 1927*01826a49SYabin Cui</b><p> 1928*01826a49SYabin Cui ZSTD_DCtx_reset(zds, ZSTD_reset_session_only); 1929*01826a49SYabin Cui ZSTD_DCtx_loadDictionary(zds, dict, dictSize); 1930*01826a49SYabin Cui 1931*01826a49SYabin Cui note: no dictionary will be used if dict == NULL or dictSize < 8 1932*01826a49SYabin Cui 1933*01826a49SYabin Cui</p></pre><BR> 1934*01826a49SYabin Cui 1935*01826a49SYabin Cui<pre><b>ZSTD_DEPRECATED("use ZSTD_DCtx_reset + ZSTD_DCtx_refDDict, see zstd.h for detailed instructions") 1936*01826a49SYabin CuiZSTDLIB_STATIC_API size_t ZSTD_initDStream_usingDDict(ZSTD_DStream* zds, const ZSTD_DDict* ddict); 1937*01826a49SYabin Cui</b><p> 1938*01826a49SYabin Cui ZSTD_DCtx_reset(zds, ZSTD_reset_session_only); 1939*01826a49SYabin Cui ZSTD_DCtx_refDDict(zds, ddict); 1940*01826a49SYabin Cui 1941*01826a49SYabin Cui note : ddict is referenced, it must outlive decompression session 1942*01826a49SYabin Cui 1943*01826a49SYabin Cui</p></pre><BR> 1944*01826a49SYabin Cui 1945*01826a49SYabin Cui<pre><b>ZSTD_DEPRECATED("use ZSTD_DCtx_reset, see zstd.h for detailed instructions") 1946*01826a49SYabin CuiZSTDLIB_STATIC_API size_t ZSTD_resetDStream(ZSTD_DStream* zds); 1947*01826a49SYabin Cui</b><p> 1948*01826a49SYabin Cui ZSTD_DCtx_reset(zds, ZSTD_reset_session_only); 1949*01826a49SYabin Cui 1950*01826a49SYabin Cui reuse decompression parameters from previous init; saves dictionary loading 1951*01826a49SYabin Cui 1952*01826a49SYabin Cui</p></pre><BR> 1953*01826a49SYabin Cui 1954*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API void 1955*01826a49SYabin CuiZSTD_registerSequenceProducer( 1956*01826a49SYabin Cui ZSTD_CCtx* cctx, 1957*01826a49SYabin Cui void* sequenceProducerState, 1958*01826a49SYabin Cui ZSTD_sequenceProducer_F sequenceProducer 1959*01826a49SYabin Cui); 1960*01826a49SYabin Cui</b><p> Instruct zstd to use a block-level external sequence producer function. 1961*01826a49SYabin Cui 1962*01826a49SYabin Cui The sequenceProducerState must be initialized by the caller, and the caller is 1963*01826a49SYabin Cui responsible for managing its lifetime. This parameter is sticky across 1964*01826a49SYabin Cui compressions. It will remain set until the user explicitly resets compression 1965*01826a49SYabin Cui parameters. 1966*01826a49SYabin Cui 1967*01826a49SYabin Cui Sequence producer registration is considered to be an "advanced parameter", 1968*01826a49SYabin Cui part of the "advanced API". This means it will only have an effect on compression 1969*01826a49SYabin Cui APIs which respect advanced parameters, such as compress2() and compressStream2(). 1970*01826a49SYabin Cui Older compression APIs such as compressCCtx(), which predate the introduction of 1971*01826a49SYabin Cui "advanced parameters", will ignore any external sequence producer setting. 1972*01826a49SYabin Cui 1973*01826a49SYabin Cui The sequence producer can be "cleared" by registering a NULL function pointer. This 1974*01826a49SYabin Cui removes all limitations described above in the "LIMITATIONS" section of the API docs. 1975*01826a49SYabin Cui 1976*01826a49SYabin Cui The user is strongly encouraged to read the full API documentation (above) before 1977*01826a49SYabin Cui calling this function. 1978*01826a49SYabin Cui</p></pre><BR> 1979*01826a49SYabin Cui 1980*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API void 1981*01826a49SYabin CuiZSTD_CCtxParams_registerSequenceProducer( 1982*01826a49SYabin Cui ZSTD_CCtx_params* params, 1983*01826a49SYabin Cui void* sequenceProducerState, 1984*01826a49SYabin Cui ZSTD_sequenceProducer_F sequenceProducer 1985*01826a49SYabin Cui); 1986*01826a49SYabin Cui</b><p> Same as ZSTD_registerSequenceProducer(), but operates on ZSTD_CCtx_params. 1987*01826a49SYabin Cui This is used for accurate size estimation with ZSTD_estimateCCtxSize_usingCCtxParams(), 1988*01826a49SYabin Cui which is needed when creating a ZSTD_CCtx with ZSTD_initStaticCCtx(). 1989*01826a49SYabin Cui 1990*01826a49SYabin Cui If you are using the external sequence producer API in a scenario where ZSTD_initStaticCCtx() 1991*01826a49SYabin Cui is required, then this function is for you. Otherwise, you probably don't need it. 1992*01826a49SYabin Cui 1993*01826a49SYabin Cui See tests/zstreamtest.c for example usage. 1994*01826a49SYabin Cui</p></pre><BR> 1995*01826a49SYabin Cui 1996*01826a49SYabin Cui<a name="Chapter20"></a><h2>Buffer-less and synchronous inner streaming functions (DEPRECATED)</h2><pre> 1997*01826a49SYabin Cui This API is deprecated, and will be removed in a future version. 1998*01826a49SYabin Cui It allows streaming (de)compression with user allocated buffers. 1999*01826a49SYabin Cui However, it is hard to use, and not as well tested as the rest of 2000*01826a49SYabin Cui our API. 2001*01826a49SYabin Cui 2002*01826a49SYabin Cui Please use the normal streaming API instead: ZSTD_compressStream2, 2003*01826a49SYabin Cui and ZSTD_decompressStream. 2004*01826a49SYabin Cui If there is functionality that you need, but it doesn't provide, 2005*01826a49SYabin Cui please open an issue on our GitHub. 2006*01826a49SYabin Cui 2007*01826a49SYabin Cui<BR></pre> 2008*01826a49SYabin Cui 2009*01826a49SYabin Cui<a name="Chapter21"></a><h2>Buffer-less streaming compression (synchronous mode)</h2><pre> 2010*01826a49SYabin Cui A ZSTD_CCtx object is required to track streaming operations. 2011*01826a49SYabin Cui Use ZSTD_createCCtx() / ZSTD_freeCCtx() to manage resource. 2012*01826a49SYabin Cui ZSTD_CCtx object can be reused multiple times within successive compression operations. 2013*01826a49SYabin Cui 2014*01826a49SYabin Cui Start by initializing a context. 2015*01826a49SYabin Cui Use ZSTD_compressBegin(), or ZSTD_compressBegin_usingDict() for dictionary compression. 2016*01826a49SYabin Cui 2017*01826a49SYabin Cui Then, consume your input using ZSTD_compressContinue(). 2018*01826a49SYabin Cui There are some important considerations to keep in mind when using this advanced function : 2019*01826a49SYabin Cui - ZSTD_compressContinue() has no internal buffer. It uses externally provided buffers only. 2020*01826a49SYabin Cui - Interface is synchronous : input is consumed entirely and produces 1+ compressed blocks. 2021*01826a49SYabin Cui - Caller must ensure there is enough space in `dst` to store compressed data under worst case scenario. 2022*01826a49SYabin Cui Worst case evaluation is provided by ZSTD_compressBound(). 2023*01826a49SYabin Cui ZSTD_compressContinue() doesn't guarantee recover after a failed compression. 2024*01826a49SYabin Cui - ZSTD_compressContinue() presumes prior input ***is still accessible and unmodified*** (up to maximum distance size, see WindowLog). 2025*01826a49SYabin Cui It remembers all previous contiguous blocks, plus one separated memory segment (which can itself consists of multiple contiguous blocks) 2026*01826a49SYabin Cui - ZSTD_compressContinue() detects that prior input has been overwritten when `src` buffer overlaps. 2027*01826a49SYabin Cui In which case, it will "discard" the relevant memory section from its history. 2028*01826a49SYabin Cui 2029*01826a49SYabin Cui Finish a frame with ZSTD_compressEnd(), which will write the last block(s) and optional checksum. 2030*01826a49SYabin Cui It's possible to use srcSize==0, in which case, it will write a final empty block to end the frame. 2031*01826a49SYabin Cui Without last block mark, frames are considered unfinished (hence corrupted) by compliant decoders. 2032*01826a49SYabin Cui 2033*01826a49SYabin Cui `ZSTD_CCtx` object can be reused (ZSTD_compressBegin()) to compress again. 2034*01826a49SYabin Cui<BR></pre> 2035*01826a49SYabin Cui 2036*01826a49SYabin Cui<h3>Buffer-less streaming compression functions</h3><pre></pre><b><pre>ZSTD_DEPRECATED("The buffer-less API is deprecated in favor of the normal streaming API. See docs.") 2037*01826a49SYabin CuiZSTDLIB_STATIC_API size_t ZSTD_compressBegin(ZSTD_CCtx* cctx, int compressionLevel); 2038*01826a49SYabin CuiZSTD_DEPRECATED("The buffer-less API is deprecated in favor of the normal streaming API. See docs.") 2039*01826a49SYabin CuiZSTDLIB_STATIC_API size_t ZSTD_compressBegin_usingDict(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, int compressionLevel); 2040*01826a49SYabin CuiZSTD_DEPRECATED("The buffer-less API is deprecated in favor of the normal streaming API. See docs.") 2041*01826a49SYabin CuiZSTDLIB_STATIC_API size_t ZSTD_compressBegin_usingCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict); </b>/**< note: fails if cdict==NULL */<b> 2042*01826a49SYabin Cui</pre></b><BR> 2043*01826a49SYabin Cui<pre><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> 2044*01826a49SYabin Cui</b></pre><BR> 2045*01826a49SYabin Cui<pre><b>size_t ZSTD_compressBegin_advanced(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, ZSTD_parameters params, unsigned long long pledgedSrcSize); </b>/**< pledgedSrcSize : If srcSize is not known at init time, use ZSTD_CONTENTSIZE_UNKNOWN */<b> 2046*01826a49SYabin Cui</b></pre><BR> 2047*01826a49SYabin Cui<a name="Chapter22"></a><h2>Buffer-less streaming decompression (synchronous mode)</h2><pre> 2048*01826a49SYabin Cui A ZSTD_DCtx object is required to track streaming operations. 2049*01826a49SYabin Cui Use ZSTD_createDCtx() / ZSTD_freeDCtx() to manage it. 2050*01826a49SYabin Cui A ZSTD_DCtx object can be reused multiple times. 2051*01826a49SYabin Cui 2052*01826a49SYabin Cui First typical operation is to retrieve frame parameters, using ZSTD_getFrameHeader(). 2053*01826a49SYabin Cui Frame header is extracted from the beginning of compressed frame, so providing only the frame's beginning is enough. 2054*01826a49SYabin Cui Data fragment must be large enough to ensure successful decoding. 2055*01826a49SYabin Cui `ZSTD_frameHeaderSize_max` bytes is guaranteed to always be large enough. 2056*01826a49SYabin Cui result : 0 : successful decoding, the `ZSTD_frameHeader` structure is correctly filled. 2057*01826a49SYabin Cui >0 : `srcSize` is too small, please provide at least result bytes on next attempt. 2058*01826a49SYabin Cui errorCode, which can be tested using ZSTD_isError(). 2059*01826a49SYabin Cui 2060*01826a49SYabin Cui It fills a ZSTD_frameHeader structure with important information to correctly decode the frame, 2061*01826a49SYabin Cui such as the dictionary ID, content size, or maximum back-reference distance (`windowSize`). 2062*01826a49SYabin Cui Note that these values could be wrong, either because of data corruption, or because a 3rd party deliberately spoofs false information. 2063*01826a49SYabin Cui As a consequence, check that values remain within valid application range. 2064*01826a49SYabin Cui For example, do not allocate memory blindly, check that `windowSize` is within expectation. 2065*01826a49SYabin Cui Each application can set its own limits, depending on local restrictions. 2066*01826a49SYabin Cui For extended interoperability, it is recommended to support `windowSize` of at least 8 MB. 2067*01826a49SYabin Cui 2068*01826a49SYabin Cui ZSTD_decompressContinue() needs previous data blocks during decompression, up to `windowSize` bytes. 2069*01826a49SYabin Cui ZSTD_decompressContinue() is very sensitive to contiguity, 2070*01826a49SYabin Cui if 2 blocks don't follow each other, make sure that either the compressor breaks contiguity at the same place, 2071*01826a49SYabin Cui or that previous contiguous segment is large enough to properly handle maximum back-reference distance. 2072*01826a49SYabin Cui There are multiple ways to guarantee this condition. 2073*01826a49SYabin Cui 2074*01826a49SYabin Cui The most memory efficient way is to use a round buffer of sufficient size. 2075*01826a49SYabin Cui Sufficient size is determined by invoking ZSTD_decodingBufferSize_min(), 2076*01826a49SYabin Cui which can return an error code if required value is too large for current system (in 32-bits mode). 2077*01826a49SYabin Cui In a round buffer methodology, ZSTD_decompressContinue() decompresses each block next to previous one, 2078*01826a49SYabin Cui up to the moment there is not enough room left in the buffer to guarantee decoding another full block, 2079*01826a49SYabin Cui which maximum size is provided in `ZSTD_frameHeader` structure, field `blockSizeMax`. 2080*01826a49SYabin Cui At which point, decoding can resume from the beginning of the buffer. 2081*01826a49SYabin Cui Note that already decoded data stored in the buffer should be flushed before being overwritten. 2082*01826a49SYabin Cui 2083*01826a49SYabin Cui There are alternatives possible, for example using two or more buffers of size `windowSize` each, though they consume more memory. 2084*01826a49SYabin Cui 2085*01826a49SYabin Cui Finally, if you control the compression process, you can also ignore all buffer size rules, 2086*01826a49SYabin Cui as long as the encoder and decoder progress in "lock-step", 2087*01826a49SYabin Cui aka use exactly the same buffer sizes, break contiguity at the same place, etc. 2088*01826a49SYabin Cui 2089*01826a49SYabin Cui Once buffers are setup, start decompression, with ZSTD_decompressBegin(). 2090*01826a49SYabin Cui If decompression requires a dictionary, use ZSTD_decompressBegin_usingDict() or ZSTD_decompressBegin_usingDDict(). 2091*01826a49SYabin Cui 2092*01826a49SYabin Cui Then use ZSTD_nextSrcSizeToDecompress() and ZSTD_decompressContinue() alternatively. 2093*01826a49SYabin Cui ZSTD_nextSrcSizeToDecompress() tells how many bytes to provide as 'srcSize' to ZSTD_decompressContinue(). 2094*01826a49SYabin Cui ZSTD_decompressContinue() requires this _exact_ amount of bytes, or it will fail. 2095*01826a49SYabin Cui 2096*01826a49SYabin Cui result of ZSTD_decompressContinue() is the number of bytes regenerated within 'dst' (necessarily <= dstCapacity). 2097*01826a49SYabin Cui It can be zero : it just means ZSTD_decompressContinue() has decoded some metadata item. 2098*01826a49SYabin Cui It can also be an error code, which can be tested with ZSTD_isError(). 2099*01826a49SYabin Cui 2100*01826a49SYabin Cui A frame is fully decoded when ZSTD_nextSrcSizeToDecompress() returns zero. 2101*01826a49SYabin Cui Context can then be reset to start a new decompression. 2102*01826a49SYabin Cui 2103*01826a49SYabin Cui Note : it's possible to know if next input to present is a header or a block, using ZSTD_nextInputType(). 2104*01826a49SYabin Cui This information is not required to properly decode a frame. 2105*01826a49SYabin Cui 2106*01826a49SYabin Cui == Special case : skippable frames 2107*01826a49SYabin Cui 2108*01826a49SYabin Cui Skippable frames allow integration of user-defined data into a flow of concatenated frames. 2109*01826a49SYabin Cui Skippable frames will be ignored (skipped) by decompressor. 2110*01826a49SYabin Cui The format of skippable frames is as follows : 2111*01826a49SYabin Cui a) Skippable frame ID - 4 Bytes, Little endian format, any value from 0x184D2A50 to 0x184D2A5F 2112*01826a49SYabin Cui b) Frame Size - 4 Bytes, Little endian format, unsigned 32-bits 2113*01826a49SYabin Cui c) Frame Content - any content (User Data) of length equal to Frame Size 2114*01826a49SYabin Cui For skippable frames ZSTD_getFrameHeader() returns zfhPtr->frameType==ZSTD_skippableFrame. 2115*01826a49SYabin Cui For skippable frames ZSTD_decompressContinue() always returns 0 : it only skips the content. 2116*01826a49SYabin Cui<BR></pre> 2117*01826a49SYabin Cui 2118*01826a49SYabin Cui<h3>Buffer-less streaming decompression functions</h3><pre></pre><b><pre></pre></b><BR> 2119*01826a49SYabin Cui<pre><b>ZSTDLIB_STATIC_API size_t ZSTD_decodingBufferSize_min(unsigned long long windowSize, unsigned long long frameContentSize); </b>/**< when frame content size is not known, pass in frameContentSize == ZSTD_CONTENTSIZE_UNKNOWN */<b> 2120*01826a49SYabin Cui</b></pre><BR> 2121*01826a49SYabin Cui<pre><b>typedef enum { ZSTDnit_frameHeader, ZSTDnit_blockHeader, ZSTDnit_block, ZSTDnit_lastBlock, ZSTDnit_checksum, ZSTDnit_skippableFrame } ZSTD_nextInputType_e; 2122*01826a49SYabin Cui</b></pre><BR> 2123*01826a49SYabin Cui<a name="Chapter23"></a><h2>Block level API (DEPRECATED)</h2><pre></pre> 2124*01826a49SYabin Cui 2125*01826a49SYabin Cui<pre><b></b><p> You can get the frame header down to 2 bytes by setting: 2126*01826a49SYabin Cui - ZSTD_c_format = ZSTD_f_zstd1_magicless 2127*01826a49SYabin Cui - ZSTD_c_contentSizeFlag = 0 2128*01826a49SYabin Cui - ZSTD_c_checksumFlag = 0 2129*01826a49SYabin Cui - ZSTD_c_dictIDFlag = 0 2130*01826a49SYabin Cui 2131*01826a49SYabin Cui This API is not as well tested as our normal API, so we recommend not using it. 2132*01826a49SYabin Cui We will be removing it in a future version. If the normal API doesn't provide 2133*01826a49SYabin Cui the functionality you need, please open a GitHub issue. 2134*01826a49SYabin Cui 2135*01826a49SYabin Cui Block functions produce and decode raw zstd blocks, without frame metadata. 2136*01826a49SYabin Cui Frame metadata cost is typically ~12 bytes, which can be non-negligible for very small blocks (< 100 bytes). 2137*01826a49SYabin Cui But users will have to take in charge needed metadata to regenerate data, such as compressed and content sizes. 2138*01826a49SYabin Cui 2139*01826a49SYabin Cui A few rules to respect : 2140*01826a49SYabin Cui - Compressing and decompressing require a context structure 2141*01826a49SYabin Cui + Use ZSTD_createCCtx() and ZSTD_createDCtx() 2142*01826a49SYabin Cui - It is necessary to init context before starting 2143*01826a49SYabin Cui + compression : any ZSTD_compressBegin*() variant, including with dictionary 2144*01826a49SYabin Cui + decompression : any ZSTD_decompressBegin*() variant, including with dictionary 2145*01826a49SYabin Cui - Block size is limited, it must be <= ZSTD_getBlockSize() <= ZSTD_BLOCKSIZE_MAX == 128 KB 2146*01826a49SYabin Cui + If input is larger than a block size, it's necessary to split input data into multiple blocks 2147*01826a49SYabin Cui + For inputs larger than a single block, consider using regular ZSTD_compress() instead. 2148*01826a49SYabin Cui Frame metadata is not that costly, and quickly becomes negligible as source size grows larger than a block. 2149*01826a49SYabin Cui - When a block is considered not compressible enough, ZSTD_compressBlock() result will be 0 (zero) ! 2150*01826a49SYabin Cui ===> In which case, nothing is produced into `dst` ! 2151*01826a49SYabin Cui + User __must__ test for such outcome and deal directly with uncompressed data 2152*01826a49SYabin Cui + A block cannot be declared incompressible if ZSTD_compressBlock() return value was != 0. 2153*01826a49SYabin Cui Doing so would mess up with statistics history, leading to potential data corruption. 2154*01826a49SYabin Cui + ZSTD_decompressBlock() _doesn't accept uncompressed data as input_ !! 2155*01826a49SYabin Cui + In case of multiple successive blocks, should some of them be uncompressed, 2156*01826a49SYabin Cui decoder must be informed of their existence in order to follow proper history. 2157*01826a49SYabin Cui Use ZSTD_insertBlock() for such a case. 2158*01826a49SYabin Cui</p></pre><BR> 2159*01826a49SYabin Cui 2160*01826a49SYabin Cui<h3>Raw zstd block functions</h3><pre></pre><b><pre>ZSTD_DEPRECATED("The block API is deprecated in favor of the normal compression API. See docs.") 2161*01826a49SYabin CuiZSTDLIB_STATIC_API size_t ZSTD_getBlockSize (const ZSTD_CCtx* cctx); 2162*01826a49SYabin CuiZSTD_DEPRECATED("The block API is deprecated in favor of the normal compression API. See docs.") 2163*01826a49SYabin CuiZSTDLIB_STATIC_API size_t ZSTD_compressBlock (ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize); 2164*01826a49SYabin CuiZSTD_DEPRECATED("The block API is deprecated in favor of the normal compression API. See docs.") 2165*01826a49SYabin CuiZSTDLIB_STATIC_API size_t ZSTD_decompressBlock(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize); 2166*01826a49SYabin CuiZSTD_DEPRECATED("The block API is deprecated in favor of the normal compression API. See docs.") 2167*01826a49SYabin CuiZSTDLIB_STATIC_API size_t ZSTD_insertBlock (ZSTD_DCtx* dctx, const void* blockStart, size_t blockSize); </b>/**< insert uncompressed block into `dctx` history. Useful for multi-blocks decompression. */<b> 2168*01826a49SYabin Cui</pre></b><BR> 2169*01826a49SYabin Cui</html> 2170*01826a49SYabin Cui</body> 2171