1 /* 2 * Copyright (c) 2016-present, Yann Collet, Facebook, Inc. 3 * All rights reserved. 4 * 5 * This source code is licensed under both the BSD-style license (found in the 6 * LICENSE file in the root directory of this source tree) and the GPLv2 (found 7 * in the COPYING file in the root directory of this source tree). 8 * You may select, at your option, one of the above-listed licenses. 9 */ 10 #if defined (__cplusplus) 11 extern "C" { 12 #endif 13 14 #ifndef ZSTD_H_235446 15 #define ZSTD_H_235446 16 17 /* ====== Dependency ======*/ 18 #include <limits.h> /* INT_MAX */ 19 #include <stddef.h> /* size_t */ 20 21 22 /* ===== ZSTDLIB_API : control library symbols visibility ===== */ 23 #ifndef ZSTDLIB_VISIBILITY 24 # if defined(__GNUC__) && (__GNUC__ >= 4) 25 # define ZSTDLIB_VISIBILITY __attribute__ ((visibility ("default"))) 26 # else 27 # define ZSTDLIB_VISIBILITY 28 # endif 29 #endif 30 #if defined(ZSTD_DLL_EXPORT) && (ZSTD_DLL_EXPORT==1) 31 # define ZSTDLIB_API __declspec(dllexport) ZSTDLIB_VISIBILITY 32 #elif defined(ZSTD_DLL_IMPORT) && (ZSTD_DLL_IMPORT==1) 33 # define ZSTDLIB_API __declspec(dllimport) ZSTDLIB_VISIBILITY /* It isn't required but allows to generate better code, saving a function pointer load from the IAT and an indirect jump.*/ 34 #else 35 # define ZSTDLIB_API ZSTDLIB_VISIBILITY 36 #endif 37 38 39 /******************************************************************************* 40 Introduction 41 42 zstd, short for Zstandard, is a fast lossless compression algorithm, targeting 43 real-time compression scenarios at zlib-level and better compression ratios. 44 The zstd compression library provides in-memory compression and decompression 45 functions. 46 47 The library supports regular compression levels from 1 up to ZSTD_maxCLevel(), 48 which is currently 22. Levels >= 20, labeled `--ultra`, should be used with 49 caution, as they require more memory. The library also offers negative 50 compression levels, which extend the range of speed vs. ratio preferences. 51 The lower the level, the faster the speed (at the cost of compression). 52 53 Compression can be done in: 54 - a single step (described as Simple API) 55 - a single step, reusing a context (described as Explicit context) 56 - unbounded multiple steps (described as Streaming compression) 57 58 The compression ratio achievable on small data can be highly improved using 59 a dictionary. Dictionary compression can be performed in: 60 - a single step (described as Simple dictionary API) 61 - a single step, reusing a dictionary (described as Bulk-processing 62 dictionary API) 63 64 Advanced experimental functions can be accessed using 65 `#define ZSTD_STATIC_LINKING_ONLY` before including zstd.h. 66 67 Advanced experimental APIs should never be used with a dynamically-linked 68 library. They are not "stable"; their definitions or signatures may change in 69 the future. Only static linking is allowed. 70 *******************************************************************************/ 71 72 /*------ Version ------*/ 73 #define ZSTD_VERSION_MAJOR 1 74 #define ZSTD_VERSION_MINOR 4 75 #define ZSTD_VERSION_RELEASE 4 76 77 #define ZSTD_VERSION_NUMBER (ZSTD_VERSION_MAJOR *100*100 + ZSTD_VERSION_MINOR *100 + ZSTD_VERSION_RELEASE) 78 ZSTDLIB_API unsigned ZSTD_versionNumber(void); /**< to check runtime library version */ 79 80 #define ZSTD_LIB_VERSION ZSTD_VERSION_MAJOR.ZSTD_VERSION_MINOR.ZSTD_VERSION_RELEASE 81 #define ZSTD_QUOTE(str) #str 82 #define ZSTD_EXPAND_AND_QUOTE(str) ZSTD_QUOTE(str) 83 #define ZSTD_VERSION_STRING ZSTD_EXPAND_AND_QUOTE(ZSTD_LIB_VERSION) 84 ZSTDLIB_API const char* ZSTD_versionString(void); /* requires v1.3.0+ */ 85 86 /* ************************************* 87 * Default constant 88 ***************************************/ 89 #ifndef ZSTD_CLEVEL_DEFAULT 90 # define ZSTD_CLEVEL_DEFAULT 3 91 #endif 92 93 /* ************************************* 94 * Constants 95 ***************************************/ 96 97 /* All magic numbers are supposed read/written to/from files/memory using little-endian convention */ 98 #define ZSTD_MAGICNUMBER 0xFD2FB528 /* valid since v0.8.0 */ 99 #define ZSTD_MAGIC_DICTIONARY 0xEC30A437 /* valid since v0.7.0 */ 100 #define ZSTD_MAGIC_SKIPPABLE_START 0x184D2A50 /* all 16 values, from 0x184D2A50 to 0x184D2A5F, signal the beginning of a skippable frame */ 101 #define ZSTD_MAGIC_SKIPPABLE_MASK 0xFFFFFFF0 102 103 #define ZSTD_BLOCKSIZELOG_MAX 17 104 #define ZSTD_BLOCKSIZE_MAX (1<<ZSTD_BLOCKSIZELOG_MAX) 105 106 107 108 /*************************************** 109 * Simple API 110 ***************************************/ 111 /*! ZSTD_compress() : 112 * Compresses `src` content as a single zstd compressed frame into already allocated `dst`. 113 * Hint : compression runs faster if `dstCapacity` >= `ZSTD_compressBound(srcSize)`. 114 * @return : compressed size written into `dst` (<= `dstCapacity), 115 * or an error code if it fails (which can be tested using ZSTD_isError()). */ 116 ZSTDLIB_API size_t ZSTD_compress( void* dst, size_t dstCapacity, 117 const void* src, size_t srcSize, 118 int compressionLevel); 119 120 /*! ZSTD_decompress() : 121 * `compressedSize` : must be the _exact_ size of some number of compressed and/or skippable frames. 122 * `dstCapacity` is an upper bound of originalSize to regenerate. 123 * If user cannot imply a maximum upper bound, it's better to use streaming mode to decompress data. 124 * @return : the number of bytes decompressed into `dst` (<= `dstCapacity`), 125 * or an errorCode if it fails (which can be tested using ZSTD_isError()). */ 126 ZSTDLIB_API size_t ZSTD_decompress( void* dst, size_t dstCapacity, 127 const void* src, size_t compressedSize); 128 129 /*! ZSTD_getFrameContentSize() : requires v1.3.0+ 130 * `src` should point to the start of a ZSTD encoded frame. 131 * `srcSize` must be at least as large as the frame header. 132 * hint : any size >= `ZSTD_frameHeaderSize_max` is large enough. 133 * @return : - decompressed size of `src` frame content, if known 134 * - ZSTD_CONTENTSIZE_UNKNOWN if the size cannot be determined 135 * - ZSTD_CONTENTSIZE_ERROR if an error occurred (e.g. invalid magic number, srcSize too small) 136 * note 1 : a 0 return value means the frame is valid but "empty". 137 * note 2 : decompressed size is an optional field, it may not be present, typically in streaming mode. 138 * When `return==ZSTD_CONTENTSIZE_UNKNOWN`, data to decompress could be any size. 139 * In which case, it's necessary to use streaming mode to decompress data. 140 * Optionally, application can rely on some implicit limit, 141 * as ZSTD_decompress() only needs an upper bound of decompressed size. 142 * (For example, data could be necessarily cut into blocks <= 16 KB). 143 * note 3 : decompressed size is always present when compression is completed using single-pass functions, 144 * such as ZSTD_compress(), ZSTD_compressCCtx() ZSTD_compress_usingDict() or ZSTD_compress_usingCDict(). 145 * note 4 : decompressed size can be very large (64-bits value), 146 * potentially larger than what local system can handle as a single memory segment. 147 * In which case, it's necessary to use streaming mode to decompress data. 148 * note 5 : If source is untrusted, decompressed size could be wrong or intentionally modified. 149 * Always ensure return value fits within application's authorized limits. 150 * Each application can set its own limits. 151 * note 6 : This function replaces ZSTD_getDecompressedSize() */ 152 #define ZSTD_CONTENTSIZE_UNKNOWN (0ULL - 1) 153 #define ZSTD_CONTENTSIZE_ERROR (0ULL - 2) 154 ZSTDLIB_API unsigned long long ZSTD_getFrameContentSize(const void *src, size_t srcSize); 155 156 /*! ZSTD_getDecompressedSize() : 157 * NOTE: This function is now obsolete, in favor of ZSTD_getFrameContentSize(). 158 * Both functions work the same way, but ZSTD_getDecompressedSize() blends 159 * "empty", "unknown" and "error" results to the same return value (0), 160 * while ZSTD_getFrameContentSize() gives them separate return values. 161 * @return : decompressed size of `src` frame content _if known and not empty_, 0 otherwise. */ 162 ZSTDLIB_API unsigned long long ZSTD_getDecompressedSize(const void* src, size_t srcSize); 163 164 /*! ZSTD_findFrameCompressedSize() : 165 * `src` should point to the start of a ZSTD frame or skippable frame. 166 * `srcSize` must be >= first frame size 167 * @return : the compressed size of the first frame starting at `src`, 168 * suitable to pass as `srcSize` to `ZSTD_decompress` or similar, 169 * or an error code if input is invalid */ 170 ZSTDLIB_API size_t ZSTD_findFrameCompressedSize(const void* src, size_t srcSize); 171 172 173 /*====== Helper functions ======*/ 174 #define ZSTD_COMPRESSBOUND(srcSize) ((srcSize) + ((srcSize)>>8) + (((srcSize) < (128<<10)) ? (((128<<10) - (srcSize)) >> 11) /* 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 */ 175 ZSTDLIB_API size_t ZSTD_compressBound(size_t srcSize); /*!< maximum compressed size in worst case single-pass scenario */ 176 ZSTDLIB_API unsigned ZSTD_isError(size_t code); /*!< tells if a `size_t` function result is an error code */ 177 ZSTDLIB_API const char* ZSTD_getErrorName(size_t code); /*!< provides readable string from an error code */ 178 ZSTDLIB_API int ZSTD_minCLevel(void); /*!< minimum negative compression level allowed */ 179 ZSTDLIB_API int ZSTD_maxCLevel(void); /*!< maximum compression level available */ 180 181 182 /*************************************** 183 * Explicit context 184 ***************************************/ 185 /*= Compression context 186 * When compressing many times, 187 * it is recommended to allocate a context just once, 188 * and re-use it for each successive compression operation. 189 * This will make workload friendlier for system's memory. 190 * Note : re-using context is just a speed / resource optimization. 191 * It doesn't change the compression ratio, which remains identical. 192 * Note 2 : In multi-threaded environments, 193 * use one different context per thread for parallel execution. 194 */ 195 typedef struct ZSTD_CCtx_s ZSTD_CCtx; 196 ZSTDLIB_API ZSTD_CCtx* ZSTD_createCCtx(void); 197 ZSTDLIB_API size_t ZSTD_freeCCtx(ZSTD_CCtx* cctx); 198 199 /*! ZSTD_compressCCtx() : 200 * Same as ZSTD_compress(), using an explicit ZSTD_CCtx. 201 * Important : in order to behave similarly to `ZSTD_compress()`, 202 * this function compresses at requested compression level, 203 * __ignoring any other parameter__ . 204 * If any advanced parameter was set using the advanced API, 205 * they will all be reset. Only `compressionLevel` remains. 206 */ 207 ZSTDLIB_API size_t ZSTD_compressCCtx(ZSTD_CCtx* cctx, 208 void* dst, size_t dstCapacity, 209 const void* src, size_t srcSize, 210 int compressionLevel); 211 212 /*= Decompression context 213 * When decompressing many times, 214 * it is recommended to allocate a context only once, 215 * and re-use it for each successive compression operation. 216 * This will make workload friendlier for system's memory. 217 * Use one context per thread for parallel execution. */ 218 typedef struct ZSTD_DCtx_s ZSTD_DCtx; 219 ZSTDLIB_API ZSTD_DCtx* ZSTD_createDCtx(void); 220 ZSTDLIB_API size_t ZSTD_freeDCtx(ZSTD_DCtx* dctx); 221 222 /*! ZSTD_decompressDCtx() : 223 * Same as ZSTD_decompress(), 224 * requires an allocated ZSTD_DCtx. 225 * Compatible with sticky parameters. 226 */ 227 ZSTDLIB_API size_t ZSTD_decompressDCtx(ZSTD_DCtx* dctx, 228 void* dst, size_t dstCapacity, 229 const void* src, size_t srcSize); 230 231 232 /*************************************** 233 * Advanced compression API 234 ***************************************/ 235 236 /* API design : 237 * Parameters are pushed one by one into an existing context, 238 * using ZSTD_CCtx_set*() functions. 239 * Pushed parameters are sticky : they are valid for next compressed frame, and any subsequent frame. 240 * "sticky" parameters are applicable to `ZSTD_compress2()` and `ZSTD_compressStream*()` ! 241 * __They do not apply to "simple" one-shot variants such as ZSTD_compressCCtx()__ . 242 * 243 * It's possible to reset all parameters to "default" using ZSTD_CCtx_reset(). 244 * 245 * This API supercedes all other "advanced" API entry points in the experimental section. 246 * In the future, we expect to remove from experimental API entry points which are redundant with this API. 247 */ 248 249 250 /* Compression strategies, listed from fastest to strongest */ 251 typedef enum { ZSTD_fast=1, 252 ZSTD_dfast=2, 253 ZSTD_greedy=3, 254 ZSTD_lazy=4, 255 ZSTD_lazy2=5, 256 ZSTD_btlazy2=6, 257 ZSTD_btopt=7, 258 ZSTD_btultra=8, 259 ZSTD_btultra2=9 260 /* note : new strategies _might_ be added in the future. 261 Only the order (from fast to strong) is guaranteed */ 262 } ZSTD_strategy; 263 264 265 typedef enum { 266 267 /* compression parameters 268 * Note: When compressing with a ZSTD_CDict these parameters are superseded 269 * by the parameters used to construct the ZSTD_CDict. 270 * See ZSTD_CCtx_refCDict() for more info (superseded-by-cdict). */ 271 ZSTD_c_compressionLevel=100, /* Set compression parameters according to pre-defined cLevel table. 272 * Note that exact compression parameters are dynamically determined, 273 * depending on both compression level and srcSize (when known). 274 * Default level is ZSTD_CLEVEL_DEFAULT==3. 275 * Special: value 0 means default, which is controlled by ZSTD_CLEVEL_DEFAULT. 276 * Note 1 : it's possible to pass a negative compression level. 277 * Note 2 : setting a level resets all other compression parameters to default */ 278 /* Advanced compression parameters : 279 * It's possible to pin down compression parameters to some specific values. 280 * In which case, these values are no longer dynamically selected by the compressor */ 281 ZSTD_c_windowLog=101, /* Maximum allowed back-reference distance, expressed as power of 2. 282 * This will set a memory budget for streaming decompression, 283 * with larger values requiring more memory 284 * and typically compressing more. 285 * Must be clamped between ZSTD_WINDOWLOG_MIN and ZSTD_WINDOWLOG_MAX. 286 * Special: value 0 means "use default windowLog". 287 * Note: Using a windowLog greater than ZSTD_WINDOWLOG_LIMIT_DEFAULT 288 * requires explicitly allowing such size at streaming decompression stage. */ 289 ZSTD_c_hashLog=102, /* Size of the initial probe table, as a power of 2. 290 * Resulting memory usage is (1 << (hashLog+2)). 291 * Must be clamped between ZSTD_HASHLOG_MIN and ZSTD_HASHLOG_MAX. 292 * Larger tables improve compression ratio of strategies <= dFast, 293 * and improve speed of strategies > dFast. 294 * Special: value 0 means "use default hashLog". */ 295 ZSTD_c_chainLog=103, /* Size of the multi-probe search table, as a power of 2. 296 * Resulting memory usage is (1 << (chainLog+2)). 297 * Must be clamped between ZSTD_CHAINLOG_MIN and ZSTD_CHAINLOG_MAX. 298 * Larger tables result in better and slower compression. 299 * This parameter is useless for "fast" strategy. 300 * It's still useful when using "dfast" strategy, 301 * in which case it defines a secondary probe table. 302 * Special: value 0 means "use default chainLog". */ 303 ZSTD_c_searchLog=104, /* Number of search attempts, as a power of 2. 304 * More attempts result in better and slower compression. 305 * This parameter is useless for "fast" and "dFast" strategies. 306 * Special: value 0 means "use default searchLog". */ 307 ZSTD_c_minMatch=105, /* Minimum size of searched matches. 308 * Note that Zstandard can still find matches of smaller size, 309 * it just tweaks its search algorithm to look for this size and larger. 310 * Larger values increase compression and decompression speed, but decrease ratio. 311 * Must be clamped between ZSTD_MINMATCH_MIN and ZSTD_MINMATCH_MAX. 312 * Note that currently, for all strategies < btopt, effective minimum is 4. 313 * , for all strategies > fast, effective maximum is 6. 314 * Special: value 0 means "use default minMatchLength". */ 315 ZSTD_c_targetLength=106, /* Impact of this field depends on strategy. 316 * For strategies btopt, btultra & btultra2: 317 * Length of Match considered "good enough" to stop search. 318 * Larger values make compression stronger, and slower. 319 * For strategy fast: 320 * Distance between match sampling. 321 * Larger values make compression faster, and weaker. 322 * Special: value 0 means "use default targetLength". */ 323 ZSTD_c_strategy=107, /* See ZSTD_strategy enum definition. 324 * The higher the value of selected strategy, the more complex it is, 325 * resulting in stronger and slower compression. 326 * Special: value 0 means "use default strategy". */ 327 328 /* LDM mode parameters */ 329 ZSTD_c_enableLongDistanceMatching=160, /* Enable long distance matching. 330 * This parameter is designed to improve compression ratio 331 * for large inputs, by finding large matches at long distance. 332 * It increases memory usage and window size. 333 * Note: enabling this parameter increases default ZSTD_c_windowLog to 128 MB 334 * except when expressly set to a different value. */ 335 ZSTD_c_ldmHashLog=161, /* Size of the table for long distance matching, as a power of 2. 336 * Larger values increase memory usage and compression ratio, 337 * but decrease compression speed. 338 * Must be clamped between ZSTD_HASHLOG_MIN and ZSTD_HASHLOG_MAX 339 * default: windowlog - 7. 340 * Special: value 0 means "automatically determine hashlog". */ 341 ZSTD_c_ldmMinMatch=162, /* Minimum match size for long distance matcher. 342 * Larger/too small values usually decrease compression ratio. 343 * Must be clamped between ZSTD_LDM_MINMATCH_MIN and ZSTD_LDM_MINMATCH_MAX. 344 * Special: value 0 means "use default value" (default: 64). */ 345 ZSTD_c_ldmBucketSizeLog=163, /* Log size of each bucket in the LDM hash table for collision resolution. 346 * Larger values improve collision resolution but decrease compression speed. 347 * The maximum value is ZSTD_LDM_BUCKETSIZELOG_MAX. 348 * Special: value 0 means "use default value" (default: 3). */ 349 ZSTD_c_ldmHashRateLog=164, /* Frequency of inserting/looking up entries into the LDM hash table. 350 * Must be clamped between 0 and (ZSTD_WINDOWLOG_MAX - ZSTD_HASHLOG_MIN). 351 * Default is MAX(0, (windowLog - ldmHashLog)), optimizing hash table usage. 352 * Larger values improve compression speed. 353 * Deviating far from default value will likely result in a compression ratio decrease. 354 * Special: value 0 means "automatically determine hashRateLog". */ 355 356 /* frame parameters */ 357 ZSTD_c_contentSizeFlag=200, /* Content size will be written into frame header _whenever known_ (default:1) 358 * Content size must be known at the beginning of compression. 359 * This is automatically the case when using ZSTD_compress2(), 360 * For streaming scenarios, content size must be provided with ZSTD_CCtx_setPledgedSrcSize() */ 361 ZSTD_c_checksumFlag=201, /* A 32-bits checksum of content is written at end of frame (default:0) */ 362 ZSTD_c_dictIDFlag=202, /* When applicable, dictionary's ID is written into frame header (default:1) */ 363 364 /* multi-threading parameters */ 365 /* These parameters are only useful if multi-threading is enabled (compiled with build macro ZSTD_MULTITHREAD). 366 * They return an error otherwise. */ 367 ZSTD_c_nbWorkers=400, /* Select how many threads will be spawned to compress in parallel. 368 * When nbWorkers >= 1, triggers asynchronous mode when used with ZSTD_compressStream*() : 369 * ZSTD_compressStream*() consumes input and flush output if possible, but immediately gives back control to caller, 370 * while compression work is performed in parallel, within worker threads. 371 * (note : a strong exception to this rule is when first invocation of ZSTD_compressStream2() sets ZSTD_e_end : 372 * in which case, ZSTD_compressStream2() delegates to ZSTD_compress2(), which is always a blocking call). 373 * More workers improve speed, but also increase memory usage. 374 * Default value is `0`, aka "single-threaded mode" : no worker is spawned, compression is performed inside Caller's thread, all invocations are blocking */ 375 ZSTD_c_jobSize=401, /* Size of a compression job. This value is enforced only when nbWorkers >= 1. 376 * Each compression job is completed in parallel, so this value can indirectly impact the nb of active threads. 377 * 0 means default, which is dynamically determined based on compression parameters. 378 * Job size must be a minimum of overlap size, or 1 MB, whichever is largest. 379 * The minimum size is automatically and transparently enforced. */ 380 ZSTD_c_overlapLog=402, /* Control the overlap size, as a fraction of window size. 381 * The overlap size is an amount of data reloaded from previous job at the beginning of a new job. 382 * It helps preserve compression ratio, while each job is compressed in parallel. 383 * This value is enforced only when nbWorkers >= 1. 384 * Larger values increase compression ratio, but decrease speed. 385 * Possible values range from 0 to 9 : 386 * - 0 means "default" : value will be determined by the library, depending on strategy 387 * - 1 means "no overlap" 388 * - 9 means "full overlap", using a full window size. 389 * Each intermediate rank increases/decreases load size by a factor 2 : 390 * 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 391 * default value varies between 6 and 9, depending on strategy */ 392 393 /* note : additional experimental parameters are also available 394 * within the experimental section of the API. 395 * At the time of this writing, they include : 396 * ZSTD_c_rsyncable 397 * ZSTD_c_format 398 * ZSTD_c_forceMaxWindow 399 * ZSTD_c_forceAttachDict 400 * ZSTD_c_literalCompressionMode 401 * ZSTD_c_targetCBlockSize 402 * ZSTD_c_srcSizeHint 403 * Because they are not stable, it's necessary to define ZSTD_STATIC_LINKING_ONLY to access them. 404 * note : never ever use experimentalParam? names directly; 405 * also, the enums values themselves are unstable and can still change. 406 */ 407 ZSTD_c_experimentalParam1=500, 408 ZSTD_c_experimentalParam2=10, 409 ZSTD_c_experimentalParam3=1000, 410 ZSTD_c_experimentalParam4=1001, 411 ZSTD_c_experimentalParam5=1002, 412 ZSTD_c_experimentalParam6=1003, 413 ZSTD_c_experimentalParam7=1004 414 } ZSTD_cParameter; 415 416 typedef struct { 417 size_t error; 418 int lowerBound; 419 int upperBound; 420 } ZSTD_bounds; 421 422 /*! ZSTD_cParam_getBounds() : 423 * All parameters must belong to an interval with lower and upper bounds, 424 * otherwise they will either trigger an error or be automatically clamped. 425 * @return : a structure, ZSTD_bounds, which contains 426 * - an error status field, which must be tested using ZSTD_isError() 427 * - lower and upper bounds, both inclusive 428 */ 429 ZSTDLIB_API ZSTD_bounds ZSTD_cParam_getBounds(ZSTD_cParameter cParam); 430 431 /*! ZSTD_CCtx_setParameter() : 432 * Set one compression parameter, selected by enum ZSTD_cParameter. 433 * All parameters have valid bounds. Bounds can be queried using ZSTD_cParam_getBounds(). 434 * Providing a value beyond bound will either clamp it, or trigger an error (depending on parameter). 435 * Setting a parameter is generally only possible during frame initialization (before starting compression). 436 * Exception : when using multi-threading mode (nbWorkers >= 1), 437 * the following parameters can be updated _during_ compression (within same frame): 438 * => compressionLevel, hashLog, chainLog, searchLog, minMatch, targetLength and strategy. 439 * new parameters will be active for next job only (after a flush()). 440 * @return : an error code (which can be tested using ZSTD_isError()). 441 */ 442 ZSTDLIB_API size_t ZSTD_CCtx_setParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, int value); 443 444 /*! ZSTD_CCtx_setPledgedSrcSize() : 445 * Total input data size to be compressed as a single frame. 446 * Value will be written in frame header, unless if explicitly forbidden using ZSTD_c_contentSizeFlag. 447 * This value will also be controlled at end of frame, and trigger an error if not respected. 448 * @result : 0, or an error code (which can be tested with ZSTD_isError()). 449 * Note 1 : pledgedSrcSize==0 actually means zero, aka an empty frame. 450 * In order to mean "unknown content size", pass constant ZSTD_CONTENTSIZE_UNKNOWN. 451 * ZSTD_CONTENTSIZE_UNKNOWN is default value for any new frame. 452 * Note 2 : pledgedSrcSize is only valid once, for the next frame. 453 * It's discarded at the end of the frame, and replaced by ZSTD_CONTENTSIZE_UNKNOWN. 454 * Note 3 : Whenever all input data is provided and consumed in a single round, 455 * for example with ZSTD_compress2(), 456 * or invoking immediately ZSTD_compressStream2(,,,ZSTD_e_end), 457 * this value is automatically overridden by srcSize instead. 458 */ 459 ZSTDLIB_API size_t ZSTD_CCtx_setPledgedSrcSize(ZSTD_CCtx* cctx, unsigned long long pledgedSrcSize); 460 461 typedef enum { 462 ZSTD_reset_session_only = 1, 463 ZSTD_reset_parameters = 2, 464 ZSTD_reset_session_and_parameters = 3 465 } ZSTD_ResetDirective; 466 467 /*! ZSTD_CCtx_reset() : 468 * There are 2 different things that can be reset, independently or jointly : 469 * - The session : will stop compressing current frame, and make CCtx ready to start a new one. 470 * Useful after an error, or to interrupt any ongoing compression. 471 * Any internal data not yet flushed is cancelled. 472 * Compression parameters and dictionary remain unchanged. 473 * They will be used to compress next frame. 474 * Resetting session never fails. 475 * - The parameters : changes all parameters back to "default". 476 * This removes any reference to any dictionary too. 477 * Parameters can only be changed between 2 sessions (i.e. no compression is currently ongoing) 478 * otherwise the reset fails, and function returns an error value (which can be tested using ZSTD_isError()) 479 * - Both : similar to resetting the session, followed by resetting parameters. 480 */ 481 ZSTDLIB_API size_t ZSTD_CCtx_reset(ZSTD_CCtx* cctx, ZSTD_ResetDirective reset); 482 483 /*! ZSTD_compress2() : 484 * Behave the same as ZSTD_compressCCtx(), but compression parameters are set using the advanced API. 485 * ZSTD_compress2() always starts a new frame. 486 * Should cctx hold data from a previously unfinished frame, everything about it is forgotten. 487 * - Compression parameters are pushed into CCtx before starting compression, using ZSTD_CCtx_set*() 488 * - The function is always blocking, returns when compression is completed. 489 * Hint : compression runs faster if `dstCapacity` >= `ZSTD_compressBound(srcSize)`. 490 * @return : compressed size written into `dst` (<= `dstCapacity), 491 * or an error code if it fails (which can be tested using ZSTD_isError()). 492 */ 493 ZSTDLIB_API size_t ZSTD_compress2( ZSTD_CCtx* cctx, 494 void* dst, size_t dstCapacity, 495 const void* src, size_t srcSize); 496 497 498 /*************************************** 499 * Advanced decompression API 500 ***************************************/ 501 502 /* The advanced API pushes parameters one by one into an existing DCtx context. 503 * Parameters are sticky, and remain valid for all following frames 504 * using the same DCtx context. 505 * It's possible to reset parameters to default values using ZSTD_DCtx_reset(). 506 * Note : This API is compatible with existing ZSTD_decompressDCtx() and ZSTD_decompressStream(). 507 * Therefore, no new decompression function is necessary. 508 */ 509 510 typedef enum { 511 512 ZSTD_d_windowLogMax=100, /* Select a size limit (in power of 2) beyond which 513 * the streaming API will refuse to allocate memory buffer 514 * in order to protect the host from unreasonable memory requirements. 515 * This parameter is only useful in streaming mode, since no internal buffer is allocated in single-pass mode. 516 * By default, a decompression context accepts window sizes <= (1 << ZSTD_WINDOWLOG_LIMIT_DEFAULT). 517 * Special: value 0 means "use default maximum windowLog". */ 518 519 /* note : additional experimental parameters are also available 520 * within the experimental section of the API. 521 * At the time of this writing, they include : 522 * ZSTD_c_format 523 * Because they are not stable, it's necessary to define ZSTD_STATIC_LINKING_ONLY to access them. 524 * note : never ever use experimentalParam? names directly 525 */ 526 ZSTD_d_experimentalParam1=1000 527 528 } ZSTD_dParameter; 529 530 /*! ZSTD_dParam_getBounds() : 531 * All parameters must belong to an interval with lower and upper bounds, 532 * otherwise they will either trigger an error or be automatically clamped. 533 * @return : a structure, ZSTD_bounds, which contains 534 * - an error status field, which must be tested using ZSTD_isError() 535 * - both lower and upper bounds, inclusive 536 */ 537 ZSTDLIB_API ZSTD_bounds ZSTD_dParam_getBounds(ZSTD_dParameter dParam); 538 539 /*! ZSTD_DCtx_setParameter() : 540 * Set one compression parameter, selected by enum ZSTD_dParameter. 541 * All parameters have valid bounds. Bounds can be queried using ZSTD_dParam_getBounds(). 542 * Providing a value beyond bound will either clamp it, or trigger an error (depending on parameter). 543 * Setting a parameter is only possible during frame initialization (before starting decompression). 544 * @return : 0, or an error code (which can be tested using ZSTD_isError()). 545 */ 546 ZSTDLIB_API size_t ZSTD_DCtx_setParameter(ZSTD_DCtx* dctx, ZSTD_dParameter param, int value); 547 548 /*! ZSTD_DCtx_reset() : 549 * Return a DCtx to clean state. 550 * Session and parameters can be reset jointly or separately. 551 * Parameters can only be reset when no active frame is being decompressed. 552 * @return : 0, or an error code, which can be tested with ZSTD_isError() 553 */ 554 ZSTDLIB_API size_t ZSTD_DCtx_reset(ZSTD_DCtx* dctx, ZSTD_ResetDirective reset); 555 556 557 /**************************** 558 * Streaming 559 ****************************/ 560 561 typedef struct ZSTD_inBuffer_s { 562 const void* src; /**< start of input buffer */ 563 size_t size; /**< size of input buffer */ 564 size_t pos; /**< position where reading stopped. Will be updated. Necessarily 0 <= pos <= size */ 565 } ZSTD_inBuffer; 566 567 typedef struct ZSTD_outBuffer_s { 568 void* dst; /**< start of output buffer */ 569 size_t size; /**< size of output buffer */ 570 size_t pos; /**< position where writing stopped. Will be updated. Necessarily 0 <= pos <= size */ 571 } ZSTD_outBuffer; 572 573 574 575 /*-*********************************************************************** 576 * Streaming compression - HowTo 577 * 578 * A ZSTD_CStream object is required to track streaming operation. 579 * Use ZSTD_createCStream() and ZSTD_freeCStream() to create/release resources. 580 * ZSTD_CStream objects can be reused multiple times on consecutive compression operations. 581 * It is recommended to re-use ZSTD_CStream since it will play nicer with system's memory, by re-using already allocated memory. 582 * 583 * For parallel execution, use one separate ZSTD_CStream per thread. 584 * 585 * note : since v1.3.0, ZSTD_CStream and ZSTD_CCtx are the same thing. 586 * 587 * Parameters are sticky : when starting a new compression on the same context, 588 * it will re-use the same sticky parameters as previous compression session. 589 * When in doubt, it's recommended to fully initialize the context before usage. 590 * Use ZSTD_CCtx_reset() to reset the context and ZSTD_CCtx_setParameter(), 591 * ZSTD_CCtx_setPledgedSrcSize(), or ZSTD_CCtx_loadDictionary() and friends to 592 * set more specific parameters, the pledged source size, or load a dictionary. 593 * 594 * Use ZSTD_compressStream2() with ZSTD_e_continue as many times as necessary to 595 * consume input stream. The function will automatically update both `pos` 596 * fields within `input` and `output`. 597 * Note that the function may not consume the entire input, for example, because 598 * the output buffer is already full, in which case `input.pos < input.size`. 599 * The caller must check if input has been entirely consumed. 600 * If not, the caller must make some room to receive more compressed data, 601 * and then present again remaining input data. 602 * note: ZSTD_e_continue is guaranteed to make some forward progress when called, 603 * but doesn't guarantee maximal forward progress. This is especially relevant 604 * when compressing with multiple threads. The call won't block if it can 605 * consume some input, but if it can't it will wait for some, but not all, 606 * output to be flushed. 607 * @return : provides a minimum amount of data remaining to be flushed from internal buffers 608 * or an error code, which can be tested using ZSTD_isError(). 609 * 610 * At any moment, it's possible to flush whatever data might remain stuck within internal buffer, 611 * using ZSTD_compressStream2() with ZSTD_e_flush. `output->pos` will be updated. 612 * Note that, if `output->size` is too small, a single invocation with ZSTD_e_flush might not be enough (return code > 0). 613 * In which case, make some room to receive more compressed data, and call again ZSTD_compressStream2() with ZSTD_e_flush. 614 * You must continue calling ZSTD_compressStream2() with ZSTD_e_flush until it returns 0, at which point you can change the 615 * operation. 616 * note: ZSTD_e_flush will flush as much output as possible, meaning when compressing with multiple threads, it will 617 * block until the flush is complete or the output buffer is full. 618 * @return : 0 if internal buffers are entirely flushed, 619 * >0 if some data still present within internal buffer (the value is minimal estimation of remaining size), 620 * or an error code, which can be tested using ZSTD_isError(). 621 * 622 * Calling ZSTD_compressStream2() with ZSTD_e_end instructs to finish a frame. 623 * It will perform a flush and write frame epilogue. 624 * The epilogue is required for decoders to consider a frame completed. 625 * flush operation is the same, and follows same rules as calling ZSTD_compressStream2() with ZSTD_e_flush. 626 * You must continue calling ZSTD_compressStream2() with ZSTD_e_end until it returns 0, at which point you are free to 627 * start a new frame. 628 * note: ZSTD_e_end will flush as much output as possible, meaning when compressing with multiple threads, it will 629 * block until the flush is complete or the output buffer is full. 630 * @return : 0 if frame fully completed and fully flushed, 631 * >0 if some data still present within internal buffer (the value is minimal estimation of remaining size), 632 * or an error code, which can be tested using ZSTD_isError(). 633 * 634 * *******************************************************************/ 635 636 typedef ZSTD_CCtx ZSTD_CStream; /**< CCtx and CStream are now effectively same object (>= v1.3.0) */ 637 /* Continue to distinguish them for compatibility with older versions <= v1.2.0 */ 638 /*===== ZSTD_CStream management functions =====*/ 639 ZSTDLIB_API ZSTD_CStream* ZSTD_createCStream(void); 640 ZSTDLIB_API size_t ZSTD_freeCStream(ZSTD_CStream* zcs); 641 642 /*===== Streaming compression functions =====*/ 643 typedef enum { 644 ZSTD_e_continue=0, /* collect more data, encoder decides when to output compressed result, for optimal compression ratio */ 645 ZSTD_e_flush=1, /* flush any data provided so far, 646 * it creates (at least) one new block, that can be decoded immediately on reception; 647 * frame will continue: any future data can still reference previously compressed data, improving compression. 648 * note : multithreaded compression will block to flush as much output as possible. */ 649 ZSTD_e_end=2 /* flush any remaining data _and_ close current frame. 650 * note that frame is only closed after compressed data is fully flushed (return value == 0). 651 * After that point, any additional data starts a new frame. 652 * note : each frame is independent (does not reference any content from previous frame). 653 : note : multithreaded compression will block to flush as much output as possible. */ 654 } ZSTD_EndDirective; 655 656 /*! ZSTD_compressStream2() : 657 * Behaves about the same as ZSTD_compressStream, with additional control on end directive. 658 * - Compression parameters are pushed into CCtx before starting compression, using ZSTD_CCtx_set*() 659 * - Compression parameters cannot be changed once compression is started (save a list of exceptions in multi-threading mode) 660 * - output->pos must be <= dstCapacity, input->pos must be <= srcSize 661 * - output->pos and input->pos will be updated. They are guaranteed to remain below their respective limit. 662 * - When nbWorkers==0 (default), function is blocking : it completes its job before returning to caller. 663 * - When nbWorkers>=1, function is non-blocking : it just acquires a copy of input, and distributes jobs to internal worker threads, flush whatever is available, 664 * and then immediately returns, just indicating that there is some data remaining to be flushed. 665 * The function nonetheless guarantees forward progress : it will return only after it reads or write at least 1+ byte. 666 * - 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. 667 * - @return provides a minimum amount of data remaining to be flushed from internal buffers 668 * or an error code, which can be tested using ZSTD_isError(). 669 * if @return != 0, flush is not fully completed, there is still some data left within internal buffers. 670 * This is useful for ZSTD_e_flush, since in this case more flushes are necessary to empty all buffers. 671 * For ZSTD_e_end, @return == 0 when internal buffers are fully flushed and frame is completed. 672 * - after a ZSTD_e_end directive, if internal buffer is not fully flushed (@return != 0), 673 * only ZSTD_e_end or ZSTD_e_flush operations are allowed. 674 * Before starting a new compression job, or changing compression parameters, 675 * it is required to fully flush internal buffers. 676 */ 677 ZSTDLIB_API size_t ZSTD_compressStream2( ZSTD_CCtx* cctx, 678 ZSTD_outBuffer* output, 679 ZSTD_inBuffer* input, 680 ZSTD_EndDirective endOp); 681 682 683 /* These buffer sizes are softly recommended. 684 * They are not required : ZSTD_compressStream*() happily accepts any buffer size, for both input and output. 685 * Respecting the recommended size just makes it a bit easier for ZSTD_compressStream*(), 686 * reducing the amount of memory shuffling and buffering, resulting in minor performance savings. 687 * 688 * However, note that these recommendations are from the perspective of a C caller program. 689 * If the streaming interface is invoked from some other language, 690 * especially managed ones such as Java or Go, through a foreign function interface such as jni or cgo, 691 * a major performance rule is to reduce crossing such interface to an absolute minimum. 692 * It's not rare that performance ends being spent more into the interface, rather than compression itself. 693 * In which cases, prefer using large buffers, as large as practical, 694 * for both input and output, to reduce the nb of roundtrips. 695 */ 696 ZSTDLIB_API size_t ZSTD_CStreamInSize(void); /**< recommended size for input buffer */ 697 ZSTDLIB_API size_t ZSTD_CStreamOutSize(void); /**< recommended size for output buffer. Guarantee to successfully flush at least one complete compressed block. */ 698 699 700 /* ***************************************************************************** 701 * This following is a legacy streaming API. 702 * It can be replaced by ZSTD_CCtx_reset() and ZSTD_compressStream2(). 703 * It is redundant, but remains fully supported. 704 * Advanced parameters and dictionary compression can only be used through the 705 * new API. 706 ******************************************************************************/ 707 708 /*! 709 * Equivalent to: 710 * 711 * ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only); 712 * ZSTD_CCtx_refCDict(zcs, NULL); // clear the dictionary (if any) 713 * ZSTD_CCtx_setParameter(zcs, ZSTD_c_compressionLevel, compressionLevel); 714 */ 715 ZSTDLIB_API size_t ZSTD_initCStream(ZSTD_CStream* zcs, int compressionLevel); 716 /*! 717 * Alternative for ZSTD_compressStream2(zcs, output, input, ZSTD_e_continue). 718 * NOTE: The return value is different. ZSTD_compressStream() returns a hint for 719 * the next read size (if non-zero and not an error). ZSTD_compressStream2() 720 * returns the minimum nb of bytes left to flush (if non-zero and not an error). 721 */ 722 ZSTDLIB_API size_t ZSTD_compressStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output, ZSTD_inBuffer* input); 723 /*! Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_flush). */ 724 ZSTDLIB_API size_t ZSTD_flushStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output); 725 /*! Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_end). */ 726 ZSTDLIB_API size_t ZSTD_endStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output); 727 728 729 /*-*************************************************************************** 730 * Streaming decompression - HowTo 731 * 732 * A ZSTD_DStream object is required to track streaming operations. 733 * Use ZSTD_createDStream() and ZSTD_freeDStream() to create/release resources. 734 * ZSTD_DStream objects can be re-used multiple times. 735 * 736 * Use ZSTD_initDStream() to start a new decompression operation. 737 * @return : recommended first input size 738 * Alternatively, use advanced API to set specific properties. 739 * 740 * Use ZSTD_decompressStream() repetitively to consume your input. 741 * The function will update both `pos` fields. 742 * If `input.pos < input.size`, some input has not been consumed. 743 * It's up to the caller to present again remaining data. 744 * The function tries to flush all data decoded immediately, respecting output buffer size. 745 * If `output.pos < output.size`, decoder has flushed everything it could. 746 * But if `output.pos == output.size`, there might be some data left within internal buffers., 747 * In which case, call ZSTD_decompressStream() again to flush whatever remains in the buffer. 748 * Note : with no additional input provided, amount of data flushed is necessarily <= ZSTD_BLOCKSIZE_MAX. 749 * @return : 0 when a frame is completely decoded and fully flushed, 750 * or an error code, which can be tested using ZSTD_isError(), 751 * or any other value > 0, which means there is still some decoding or flushing to do to complete current frame : 752 * the return value is a suggested next input size (just a hint for better latency) 753 * that will never request more than the remaining frame size. 754 * *******************************************************************************/ 755 756 typedef ZSTD_DCtx ZSTD_DStream; /**< DCtx and DStream are now effectively same object (>= v1.3.0) */ 757 /* For compatibility with versions <= v1.2.0, prefer differentiating them. */ 758 /*===== ZSTD_DStream management functions =====*/ 759 ZSTDLIB_API ZSTD_DStream* ZSTD_createDStream(void); 760 ZSTDLIB_API size_t ZSTD_freeDStream(ZSTD_DStream* zds); 761 762 /*===== Streaming decompression functions =====*/ 763 764 /* This function is redundant with the advanced API and equivalent to: 765 * 766 * ZSTD_DCtx_reset(zds); 767 * ZSTD_DCtx_refDDict(zds, NULL); 768 */ 769 ZSTDLIB_API size_t ZSTD_initDStream(ZSTD_DStream* zds); 770 771 ZSTDLIB_API size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inBuffer* input); 772 773 ZSTDLIB_API size_t ZSTD_DStreamInSize(void); /*!< recommended size for input buffer */ 774 ZSTDLIB_API size_t ZSTD_DStreamOutSize(void); /*!< recommended size for output buffer. Guarantee to successfully flush at least one complete block in all circumstances. */ 775 776 777 /************************** 778 * Simple dictionary API 779 ***************************/ 780 /*! ZSTD_compress_usingDict() : 781 * Compression at an explicit compression level using a Dictionary. 782 * A dictionary can be any arbitrary data segment (also called a prefix), 783 * or a buffer with specified information (see dictBuilder/zdict.h). 784 * Note : This function loads the dictionary, resulting in significant startup delay. 785 * It's intended for a dictionary used only once. 786 * Note 2 : When `dict == NULL || dictSize < 8` no dictionary is used. */ 787 ZSTDLIB_API size_t ZSTD_compress_usingDict(ZSTD_CCtx* ctx, 788 void* dst, size_t dstCapacity, 789 const void* src, size_t srcSize, 790 const void* dict,size_t dictSize, 791 int compressionLevel); 792 793 /*! ZSTD_decompress_usingDict() : 794 * Decompression using a known Dictionary. 795 * Dictionary must be identical to the one used during compression. 796 * Note : This function loads the dictionary, resulting in significant startup delay. 797 * It's intended for a dictionary used only once. 798 * Note : When `dict == NULL || dictSize < 8` no dictionary is used. */ 799 ZSTDLIB_API size_t ZSTD_decompress_usingDict(ZSTD_DCtx* dctx, 800 void* dst, size_t dstCapacity, 801 const void* src, size_t srcSize, 802 const void* dict,size_t dictSize); 803 804 805 /*********************************** 806 * Bulk processing dictionary API 807 **********************************/ 808 typedef struct ZSTD_CDict_s ZSTD_CDict; 809 810 /*! ZSTD_createCDict() : 811 * When compressing multiple messages or blocks using the same dictionary, 812 * it's recommended to digest the dictionary only once, since it's a costly operation. 813 * ZSTD_createCDict() will create a state from digesting a dictionary. 814 * The resulting state can be used for future compression operations with very limited startup cost. 815 * ZSTD_CDict can be created once and shared by multiple threads concurrently, since its usage is read-only. 816 * @dictBuffer can be released after ZSTD_CDict creation, because its content is copied within CDict. 817 * Note 1 : Consider experimental function `ZSTD_createCDict_byReference()` if you prefer to not duplicate @dictBuffer content. 818 * Note 2 : A ZSTD_CDict can be created from an empty @dictBuffer, 819 * in which case the only thing that it transports is the @compressionLevel. 820 * This can be useful in a pipeline featuring ZSTD_compress_usingCDict() exclusively, 821 * expecting a ZSTD_CDict parameter with any data, including those without a known dictionary. */ 822 ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict(const void* dictBuffer, size_t dictSize, 823 int compressionLevel); 824 825 /*! ZSTD_freeCDict() : 826 * Function frees memory allocated by ZSTD_createCDict(). */ 827 ZSTDLIB_API size_t ZSTD_freeCDict(ZSTD_CDict* CDict); 828 829 /*! ZSTD_compress_usingCDict() : 830 * Compression using a digested Dictionary. 831 * Recommended when same dictionary is used multiple times. 832 * Note : compression level is _decided at dictionary creation time_, 833 * and frame parameters are hardcoded (dictID=yes, contentSize=yes, checksum=no) */ 834 ZSTDLIB_API size_t ZSTD_compress_usingCDict(ZSTD_CCtx* cctx, 835 void* dst, size_t dstCapacity, 836 const void* src, size_t srcSize, 837 const ZSTD_CDict* cdict); 838 839 840 typedef struct ZSTD_DDict_s ZSTD_DDict; 841 842 /*! ZSTD_createDDict() : 843 * Create a digested dictionary, ready to start decompression operation without startup delay. 844 * dictBuffer can be released after DDict creation, as its content is copied inside DDict. */ 845 ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict(const void* dictBuffer, size_t dictSize); 846 847 /*! ZSTD_freeDDict() : 848 * Function frees memory allocated with ZSTD_createDDict() */ 849 ZSTDLIB_API size_t ZSTD_freeDDict(ZSTD_DDict* ddict); 850 851 /*! ZSTD_decompress_usingDDict() : 852 * Decompression using a digested Dictionary. 853 * Recommended when same dictionary is used multiple times. */ 854 ZSTDLIB_API size_t ZSTD_decompress_usingDDict(ZSTD_DCtx* dctx, 855 void* dst, size_t dstCapacity, 856 const void* src, size_t srcSize, 857 const ZSTD_DDict* ddict); 858 859 860 /******************************** 861 * Dictionary helper functions 862 *******************************/ 863 864 /*! ZSTD_getDictID_fromDict() : 865 * Provides the dictID stored within dictionary. 866 * if @return == 0, the dictionary is not conformant with Zstandard specification. 867 * It can still be loaded, but as a content-only dictionary. */ 868 ZSTDLIB_API unsigned ZSTD_getDictID_fromDict(const void* dict, size_t dictSize); 869 870 /*! ZSTD_getDictID_fromDDict() : 871 * Provides the dictID of the dictionary loaded into `ddict`. 872 * If @return == 0, the dictionary is not conformant to Zstandard specification, or empty. 873 * Non-conformant dictionaries can still be loaded, but as content-only dictionaries. */ 874 ZSTDLIB_API unsigned ZSTD_getDictID_fromDDict(const ZSTD_DDict* ddict); 875 876 /*! ZSTD_getDictID_fromFrame() : 877 * Provides the dictID required to decompressed the frame stored within `src`. 878 * If @return == 0, the dictID could not be decoded. 879 * This could for one of the following reasons : 880 * - The frame does not require a dictionary to be decoded (most common case). 881 * - The frame was built with dictID intentionally removed. Whatever dictionary is necessary is a hidden information. 882 * Note : this use case also happens when using a non-conformant dictionary. 883 * - `srcSize` is too small, and as a result, the frame header could not be decoded (only possible if `srcSize < ZSTD_FRAMEHEADERSIZE_MAX`). 884 * - This is not a Zstandard frame. 885 * When identifying the exact failure cause, it's possible to use ZSTD_getFrameHeader(), which will provide a more precise error code. */ 886 ZSTDLIB_API unsigned ZSTD_getDictID_fromFrame(const void* src, size_t srcSize); 887 888 889 /******************************************************************************* 890 * Advanced dictionary and prefix API 891 * 892 * This API allows dictionaries to be used with ZSTD_compress2(), 893 * ZSTD_compressStream2(), and ZSTD_decompress(). Dictionaries are sticky, and 894 * only reset with the context is reset with ZSTD_reset_parameters or 895 * ZSTD_reset_session_and_parameters. Prefixes are single-use. 896 ******************************************************************************/ 897 898 899 /*! ZSTD_CCtx_loadDictionary() : 900 * Create an internal CDict from `dict` buffer. 901 * Decompression will have to use same dictionary. 902 * @result : 0, or an error code (which can be tested with ZSTD_isError()). 903 * Special: Loading a NULL (or 0-size) dictionary invalidates previous dictionary, 904 * meaning "return to no-dictionary mode". 905 * Note 1 : Dictionary is sticky, it will be used for all future compressed frames. 906 * To return to "no-dictionary" situation, load a NULL dictionary (or reset parameters). 907 * Note 2 : Loading a dictionary involves building tables. 908 * It's also a CPU consuming operation, with non-negligible impact on latency. 909 * Tables are dependent on compression parameters, and for this reason, 910 * compression parameters can no longer be changed after loading a dictionary. 911 * Note 3 :`dict` content will be copied internally. 912 * Use experimental ZSTD_CCtx_loadDictionary_byReference() to reference content instead. 913 * In such a case, dictionary buffer must outlive its users. 914 * Note 4 : Use ZSTD_CCtx_loadDictionary_advanced() 915 * to precisely select how dictionary content must be interpreted. */ 916 ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary(ZSTD_CCtx* cctx, const void* dict, size_t dictSize); 917 918 /*! ZSTD_CCtx_refCDict() : 919 * Reference a prepared dictionary, to be used for all next compressed frames. 920 * Note that compression parameters are enforced from within CDict, 921 * and supersede any compression parameter previously set within CCtx. 922 * The parameters ignored are labled as "superseded-by-cdict" in the ZSTD_cParameter enum docs. 923 * The ignored parameters will be used again if the CCtx is returned to no-dictionary mode. 924 * The dictionary will remain valid for future compressed frames using same CCtx. 925 * @result : 0, or an error code (which can be tested with ZSTD_isError()). 926 * Special : Referencing a NULL CDict means "return to no-dictionary mode". 927 * Note 1 : Currently, only one dictionary can be managed. 928 * Referencing a new dictionary effectively "discards" any previous one. 929 * Note 2 : CDict is just referenced, its lifetime must outlive its usage within CCtx. */ 930 ZSTDLIB_API size_t ZSTD_CCtx_refCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict); 931 932 /*! ZSTD_CCtx_refPrefix() : 933 * Reference a prefix (single-usage dictionary) for next compressed frame. 934 * A prefix is **only used once**. Tables are discarded at end of frame (ZSTD_e_end). 935 * Decompression will need same prefix to properly regenerate data. 936 * Compressing with a prefix is similar in outcome as performing a diff and compressing it, 937 * but performs much faster, especially during decompression (compression speed is tunable with compression level). 938 * @result : 0, or an error code (which can be tested with ZSTD_isError()). 939 * Special: Adding any prefix (including NULL) invalidates any previous prefix or dictionary 940 * Note 1 : Prefix buffer is referenced. It **must** outlive compression. 941 * Its content must remain unmodified during compression. 942 * Note 2 : If the intention is to diff some large src data blob with some prior version of itself, 943 * ensure that the window size is large enough to contain the entire source. 944 * See ZSTD_c_windowLog. 945 * Note 3 : Referencing a prefix involves building tables, which are dependent on compression parameters. 946 * It's a CPU consuming operation, with non-negligible impact on latency. 947 * If there is a need to use the same prefix multiple times, consider loadDictionary instead. 948 * Note 4 : By default, the prefix is interpreted as raw content (ZSTD_dct_rawContent). 949 * Use experimental ZSTD_CCtx_refPrefix_advanced() to alter dictionary interpretation. */ 950 ZSTDLIB_API size_t ZSTD_CCtx_refPrefix(ZSTD_CCtx* cctx, 951 const void* prefix, size_t prefixSize); 952 953 /*! ZSTD_DCtx_loadDictionary() : 954 * Create an internal DDict from dict buffer, 955 * to be used to decompress next frames. 956 * The dictionary remains valid for all future frames, until explicitly invalidated. 957 * @result : 0, or an error code (which can be tested with ZSTD_isError()). 958 * Special : Adding a NULL (or 0-size) dictionary invalidates any previous dictionary, 959 * meaning "return to no-dictionary mode". 960 * Note 1 : Loading a dictionary involves building tables, 961 * which has a non-negligible impact on CPU usage and latency. 962 * It's recommended to "load once, use many times", to amortize the cost 963 * Note 2 :`dict` content will be copied internally, so `dict` can be released after loading. 964 * Use ZSTD_DCtx_loadDictionary_byReference() to reference dictionary content instead. 965 * Note 3 : Use ZSTD_DCtx_loadDictionary_advanced() to take control of 966 * how dictionary content is loaded and interpreted. 967 */ 968 ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary(ZSTD_DCtx* dctx, const void* dict, size_t dictSize); 969 970 /*! ZSTD_DCtx_refDDict() : 971 * Reference a prepared dictionary, to be used to decompress next frames. 972 * The dictionary remains active for decompression of future frames using same DCtx. 973 * @result : 0, or an error code (which can be tested with ZSTD_isError()). 974 * Note 1 : Currently, only one dictionary can be managed. 975 * Referencing a new dictionary effectively "discards" any previous one. 976 * Special: referencing a NULL DDict means "return to no-dictionary mode". 977 * Note 2 : DDict is just referenced, its lifetime must outlive its usage from DCtx. 978 */ 979 ZSTDLIB_API size_t ZSTD_DCtx_refDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict); 980 981 /*! ZSTD_DCtx_refPrefix() : 982 * Reference a prefix (single-usage dictionary) to decompress next frame. 983 * This is the reverse operation of ZSTD_CCtx_refPrefix(), 984 * and must use the same prefix as the one used during compression. 985 * Prefix is **only used once**. Reference is discarded at end of frame. 986 * End of frame is reached when ZSTD_decompressStream() returns 0. 987 * @result : 0, or an error code (which can be tested with ZSTD_isError()). 988 * Note 1 : Adding any prefix (including NULL) invalidates any previously set prefix or dictionary 989 * Note 2 : Prefix buffer is referenced. It **must** outlive decompression. 990 * Prefix buffer must remain unmodified up to the end of frame, 991 * reached when ZSTD_decompressStream() returns 0. 992 * Note 3 : By default, the prefix is treated as raw content (ZSTD_dct_rawContent). 993 * Use ZSTD_CCtx_refPrefix_advanced() to alter dictMode (Experimental section) 994 * Note 4 : Referencing a raw content prefix has almost no cpu nor memory cost. 995 * A full dictionary is more costly, as it requires building tables. 996 */ 997 ZSTDLIB_API size_t ZSTD_DCtx_refPrefix(ZSTD_DCtx* dctx, 998 const void* prefix, size_t prefixSize); 999 1000 /* === Memory management === */ 1001 1002 /*! ZSTD_sizeof_*() : 1003 * These functions give the _current_ memory usage of selected object. 1004 * Note that object memory usage can evolve (increase or decrease) over time. */ 1005 ZSTDLIB_API size_t ZSTD_sizeof_CCtx(const ZSTD_CCtx* cctx); 1006 ZSTDLIB_API size_t ZSTD_sizeof_DCtx(const ZSTD_DCtx* dctx); 1007 ZSTDLIB_API size_t ZSTD_sizeof_CStream(const ZSTD_CStream* zcs); 1008 ZSTDLIB_API size_t ZSTD_sizeof_DStream(const ZSTD_DStream* zds); 1009 ZSTDLIB_API size_t ZSTD_sizeof_CDict(const ZSTD_CDict* cdict); 1010 ZSTDLIB_API size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict); 1011 1012 #endif /* ZSTD_H_235446 */ 1013 1014 1015 /* ************************************************************************************** 1016 * ADVANCED AND EXPERIMENTAL FUNCTIONS 1017 **************************************************************************************** 1018 * The definitions in the following section are considered experimental. 1019 * They are provided for advanced scenarios. 1020 * They should never be used with a dynamic library, as prototypes may change in the future. 1021 * Use them only in association with static linking. 1022 * ***************************************************************************************/ 1023 1024 #if defined(ZSTD_STATIC_LINKING_ONLY) && !defined(ZSTD_H_ZSTD_STATIC_LINKING_ONLY) 1025 #define ZSTD_H_ZSTD_STATIC_LINKING_ONLY 1026 1027 /**************************************************************************************** 1028 * experimental API (static linking only) 1029 **************************************************************************************** 1030 * The following symbols and constants 1031 * are not planned to join "stable API" status in the near future. 1032 * They can still change in future versions. 1033 * Some of them are planned to remain in the static_only section indefinitely. 1034 * Some of them might be removed in the future (especially when redundant with existing stable functions) 1035 * ***************************************************************************************/ 1036 1037 #define ZSTD_FRAMEHEADERSIZE_PREFIX(format) ((format) == ZSTD_f_zstd1 ? 5 : 1) /* minimum input size required to query frame header size */ 1038 #define ZSTD_FRAMEHEADERSIZE_MIN(format) ((format) == ZSTD_f_zstd1 ? 6 : 2) 1039 #define ZSTD_FRAMEHEADERSIZE_MAX 18 /* can be useful for static allocation */ 1040 #define ZSTD_SKIPPABLEHEADERSIZE 8 1041 1042 /* compression parameter bounds */ 1043 #define ZSTD_WINDOWLOG_MAX_32 30 1044 #define ZSTD_WINDOWLOG_MAX_64 31 1045 #define ZSTD_WINDOWLOG_MAX ((int)(sizeof(size_t) == 4 ? ZSTD_WINDOWLOG_MAX_32 : ZSTD_WINDOWLOG_MAX_64)) 1046 #define ZSTD_WINDOWLOG_MIN 10 1047 #define ZSTD_HASHLOG_MAX ((ZSTD_WINDOWLOG_MAX < 30) ? ZSTD_WINDOWLOG_MAX : 30) 1048 #define ZSTD_HASHLOG_MIN 6 1049 #define ZSTD_CHAINLOG_MAX_32 29 1050 #define ZSTD_CHAINLOG_MAX_64 30 1051 #define ZSTD_CHAINLOG_MAX ((int)(sizeof(size_t) == 4 ? ZSTD_CHAINLOG_MAX_32 : ZSTD_CHAINLOG_MAX_64)) 1052 #define ZSTD_CHAINLOG_MIN ZSTD_HASHLOG_MIN 1053 #define ZSTD_SEARCHLOG_MAX (ZSTD_WINDOWLOG_MAX-1) 1054 #define ZSTD_SEARCHLOG_MIN 1 1055 #define ZSTD_MINMATCH_MAX 7 /* only for ZSTD_fast, other strategies are limited to 6 */ 1056 #define ZSTD_MINMATCH_MIN 3 /* only for ZSTD_btopt+, faster strategies are limited to 4 */ 1057 #define ZSTD_TARGETLENGTH_MAX ZSTD_BLOCKSIZE_MAX 1058 #define ZSTD_TARGETLENGTH_MIN 0 /* note : comparing this constant to an unsigned results in a tautological test */ 1059 #define ZSTD_STRATEGY_MIN ZSTD_fast 1060 #define ZSTD_STRATEGY_MAX ZSTD_btultra2 1061 1062 1063 #define ZSTD_OVERLAPLOG_MIN 0 1064 #define ZSTD_OVERLAPLOG_MAX 9 1065 1066 #define ZSTD_WINDOWLOG_LIMIT_DEFAULT 27 /* by default, the streaming decoder will refuse any frame 1067 * requiring larger than (1<<ZSTD_WINDOWLOG_LIMIT_DEFAULT) window size, 1068 * to preserve host's memory from unreasonable requirements. 1069 * This limit can be overridden using ZSTD_DCtx_setParameter(,ZSTD_d_windowLogMax,). 1070 * The limit does not apply for one-pass decoders (such as ZSTD_decompress()), since no additional memory is allocated */ 1071 1072 1073 /* LDM parameter bounds */ 1074 #define ZSTD_LDM_HASHLOG_MIN ZSTD_HASHLOG_MIN 1075 #define ZSTD_LDM_HASHLOG_MAX ZSTD_HASHLOG_MAX 1076 #define ZSTD_LDM_MINMATCH_MIN 4 1077 #define ZSTD_LDM_MINMATCH_MAX 4096 1078 #define ZSTD_LDM_BUCKETSIZELOG_MIN 1 1079 #define ZSTD_LDM_BUCKETSIZELOG_MAX 8 1080 #define ZSTD_LDM_HASHRATELOG_MIN 0 1081 #define ZSTD_LDM_HASHRATELOG_MAX (ZSTD_WINDOWLOG_MAX - ZSTD_HASHLOG_MIN) 1082 1083 /* Advanced parameter bounds */ 1084 #define ZSTD_TARGETCBLOCKSIZE_MIN 64 1085 #define ZSTD_TARGETCBLOCKSIZE_MAX ZSTD_BLOCKSIZE_MAX 1086 #define ZSTD_SRCSIZEHINT_MIN 0 1087 #define ZSTD_SRCSIZEHINT_MAX INT_MAX 1088 1089 /* internal */ 1090 #define ZSTD_HASHLOG3_MAX 17 1091 1092 1093 /* --- Advanced types --- */ 1094 1095 typedef struct ZSTD_CCtx_params_s ZSTD_CCtx_params; 1096 1097 typedef struct { 1098 unsigned int matchPos; /* Match pos in dst */ 1099 /* If seqDef.offset > 3, then this is seqDef.offset - 3 1100 * If seqDef.offset < 3, then this is the corresponding repeat offset 1101 * But if seqDef.offset < 3 and litLength == 0, this is the 1102 * repeat offset before the corresponding repeat offset 1103 * And if seqDef.offset == 3 and litLength == 0, this is the 1104 * most recent repeat offset - 1 1105 */ 1106 unsigned int offset; 1107 unsigned int litLength; /* Literal length */ 1108 unsigned int matchLength; /* Match length */ 1109 /* 0 when seq not rep and seqDef.offset otherwise 1110 * when litLength == 0 this will be <= 4, otherwise <= 3 like normal 1111 */ 1112 unsigned int rep; 1113 } ZSTD_Sequence; 1114 1115 typedef struct { 1116 unsigned windowLog; /**< largest match distance : larger == more compression, more memory needed during decompression */ 1117 unsigned chainLog; /**< fully searched segment : larger == more compression, slower, more memory (useless for fast) */ 1118 unsigned hashLog; /**< dispatch table : larger == faster, more memory */ 1119 unsigned searchLog; /**< nb of searches : larger == more compression, slower */ 1120 unsigned minMatch; /**< match length searched : larger == faster decompression, sometimes less compression */ 1121 unsigned targetLength; /**< acceptable match size for optimal parser (only) : larger == more compression, slower */ 1122 ZSTD_strategy strategy; /**< see ZSTD_strategy definition above */ 1123 } ZSTD_compressionParameters; 1124 1125 typedef struct { 1126 int contentSizeFlag; /**< 1: content size will be in frame header (when known) */ 1127 int checksumFlag; /**< 1: generate a 32-bits checksum using XXH64 algorithm at end of frame, for error detection */ 1128 int noDictIDFlag; /**< 1: no dictID will be saved into frame header (dictID is only useful for dictionary compression) */ 1129 } ZSTD_frameParameters; 1130 1131 typedef struct { 1132 ZSTD_compressionParameters cParams; 1133 ZSTD_frameParameters fParams; 1134 } ZSTD_parameters; 1135 1136 typedef enum { 1137 ZSTD_dct_auto = 0, /* dictionary is "full" when starting with ZSTD_MAGIC_DICTIONARY, otherwise it is "rawContent" */ 1138 ZSTD_dct_rawContent = 1, /* ensures dictionary is always loaded as rawContent, even if it starts with ZSTD_MAGIC_DICTIONARY */ 1139 ZSTD_dct_fullDict = 2 /* refuses to load a dictionary if it does not respect Zstandard's specification, starting with ZSTD_MAGIC_DICTIONARY */ 1140 } ZSTD_dictContentType_e; 1141 1142 typedef enum { 1143 ZSTD_dlm_byCopy = 0, /**< Copy dictionary content internally */ 1144 ZSTD_dlm_byRef = 1 /**< Reference dictionary content -- the dictionary buffer must outlive its users. */ 1145 } ZSTD_dictLoadMethod_e; 1146 1147 typedef enum { 1148 ZSTD_f_zstd1 = 0, /* zstd frame format, specified in zstd_compression_format.md (default) */ 1149 ZSTD_f_zstd1_magicless = 1 /* Variant of zstd frame format, without initial 4-bytes magic number. 1150 * Useful to save 4 bytes per generated frame. 1151 * Decoder cannot recognise automatically this format, requiring this instruction. */ 1152 } ZSTD_format_e; 1153 1154 typedef enum { 1155 /* Note: this enum and the behavior it controls are effectively internal 1156 * implementation details of the compressor. They are expected to continue 1157 * to evolve and should be considered only in the context of extremely 1158 * advanced performance tuning. 1159 * 1160 * Zstd currently supports the use of a CDict in three ways: 1161 * 1162 * - The contents of the CDict can be copied into the working context. This 1163 * means that the compression can search both the dictionary and input 1164 * while operating on a single set of internal tables. This makes 1165 * the compression faster per-byte of input. However, the initial copy of 1166 * the CDict's tables incurs a fixed cost at the beginning of the 1167 * compression. For small compressions (< 8 KB), that copy can dominate 1168 * the cost of the compression. 1169 * 1170 * - The CDict's tables can be used in-place. In this model, compression is 1171 * slower per input byte, because the compressor has to search two sets of 1172 * tables. However, this model incurs no start-up cost (as long as the 1173 * working context's tables can be reused). For small inputs, this can be 1174 * faster than copying the CDict's tables. 1175 * 1176 * - The CDict's tables are not used at all, and instead we use the working 1177 * context alone to reload the dictionary and use params based on the source 1178 * size. See ZSTD_compress_insertDictionary() and ZSTD_compress_usingDict(). 1179 * This method is effective when the dictionary sizes are very small relative 1180 * to the input size, and the input size is fairly large to begin with. 1181 * 1182 * Zstd has a simple internal heuristic that selects which strategy to use 1183 * at the beginning of a compression. However, if experimentation shows that 1184 * Zstd is making poor choices, it is possible to override that choice with 1185 * this enum. 1186 */ 1187 ZSTD_dictDefaultAttach = 0, /* Use the default heuristic. */ 1188 ZSTD_dictForceAttach = 1, /* Never copy the dictionary. */ 1189 ZSTD_dictForceCopy = 2, /* Always copy the dictionary. */ 1190 ZSTD_dictForceLoad = 3 /* Always reload the dictionary */ 1191 } ZSTD_dictAttachPref_e; 1192 1193 typedef enum { 1194 ZSTD_lcm_auto = 0, /**< Automatically determine the compression mode based on the compression level. 1195 * Negative compression levels will be uncompressed, and positive compression 1196 * levels will be compressed. */ 1197 ZSTD_lcm_huffman = 1, /**< Always attempt Huffman compression. Uncompressed literals will still be 1198 * emitted if Huffman compression is not profitable. */ 1199 ZSTD_lcm_uncompressed = 2 /**< Always emit uncompressed literals. */ 1200 } ZSTD_literalCompressionMode_e; 1201 1202 1203 /*************************************** 1204 * Frame size functions 1205 ***************************************/ 1206 1207 /*! ZSTD_findDecompressedSize() : 1208 * `src` should point to the start of a series of ZSTD encoded and/or skippable frames 1209 * `srcSize` must be the _exact_ size of this series 1210 * (i.e. there should be a frame boundary at `src + srcSize`) 1211 * @return : - decompressed size of all data in all successive frames 1212 * - if the decompressed size cannot be determined: ZSTD_CONTENTSIZE_UNKNOWN 1213 * - if an error occurred: ZSTD_CONTENTSIZE_ERROR 1214 * 1215 * note 1 : decompressed size is an optional field, that may not be present, especially in streaming mode. 1216 * When `return==ZSTD_CONTENTSIZE_UNKNOWN`, data to decompress could be any size. 1217 * In which case, it's necessary to use streaming mode to decompress data. 1218 * note 2 : decompressed size is always present when compression is done with ZSTD_compress() 1219 * note 3 : decompressed size can be very large (64-bits value), 1220 * potentially larger than what local system can handle as a single memory segment. 1221 * In which case, it's necessary to use streaming mode to decompress data. 1222 * note 4 : If source is untrusted, decompressed size could be wrong or intentionally modified. 1223 * Always ensure result fits within application's authorized limits. 1224 * Each application can set its own limits. 1225 * note 5 : ZSTD_findDecompressedSize handles multiple frames, and so it must traverse the input to 1226 * read each contained frame header. This is fast as most of the data is skipped, 1227 * however it does mean that all frame data must be present and valid. */ 1228 ZSTDLIB_API unsigned long long ZSTD_findDecompressedSize(const void* src, size_t srcSize); 1229 1230 /*! ZSTD_decompressBound() : 1231 * `src` should point to the start of a series of ZSTD encoded and/or skippable frames 1232 * `srcSize` must be the _exact_ size of this series 1233 * (i.e. there should be a frame boundary at `src + srcSize`) 1234 * @return : - upper-bound for the decompressed size of all data in all successive frames 1235 * - if an error occured: ZSTD_CONTENTSIZE_ERROR 1236 * 1237 * note 1 : an error can occur if `src` contains an invalid or incorrectly formatted frame. 1238 * note 2 : the upper-bound is exact when the decompressed size field is available in every ZSTD encoded frame of `src`. 1239 * in this case, `ZSTD_findDecompressedSize` and `ZSTD_decompressBound` return the same value. 1240 * note 3 : when the decompressed size field isn't available, the upper-bound for that frame is calculated by: 1241 * upper-bound = # blocks * min(128 KB, Window_Size) 1242 */ 1243 ZSTDLIB_API unsigned long long ZSTD_decompressBound(const void* src, size_t srcSize); 1244 1245 /*! ZSTD_frameHeaderSize() : 1246 * srcSize must be >= ZSTD_FRAMEHEADERSIZE_PREFIX. 1247 * @return : size of the Frame Header, 1248 * or an error code (if srcSize is too small) */ 1249 ZSTDLIB_API size_t ZSTD_frameHeaderSize(const void* src, size_t srcSize); 1250 1251 /*! ZSTD_getSequences() : 1252 * Extract sequences from the sequence store 1253 * zc can be used to insert custom compression params. 1254 * This function invokes ZSTD_compress2 1255 * @return : number of sequences extracted 1256 */ 1257 ZSTDLIB_API size_t ZSTD_getSequences(ZSTD_CCtx* zc, ZSTD_Sequence* outSeqs, 1258 size_t outSeqsSize, const void* src, size_t srcSize); 1259 1260 1261 /*************************************** 1262 * Memory management 1263 ***************************************/ 1264 1265 /*! ZSTD_estimate*() : 1266 * These functions make it possible to estimate memory usage of a future 1267 * {D,C}Ctx, before its creation. 1268 * 1269 * ZSTD_estimateCCtxSize() will provide a budget large enough for any 1270 * compression level up to selected one. Unlike ZSTD_estimateCStreamSize*(), 1271 * this estimate does not include space for a window buffer, so this estimate 1272 * is guaranteed to be enough for single-shot compressions, but not streaming 1273 * compressions. It will however assume the input may be arbitrarily large, 1274 * which is the worst case. If srcSize is known to always be small, 1275 * ZSTD_estimateCCtxSize_usingCParams() can provide a tighter estimation. 1276 * ZSTD_estimateCCtxSize_usingCParams() can be used in tandem with 1277 * ZSTD_getCParams() to create cParams from compressionLevel. 1278 * ZSTD_estimateCCtxSize_usingCCtxParams() can be used in tandem with 1279 * ZSTD_CCtxParams_setParameter(). 1280 * 1281 * Note: only single-threaded compression is supported. This function will 1282 * return an error code if ZSTD_c_nbWorkers is >= 1. */ 1283 ZSTDLIB_API size_t ZSTD_estimateCCtxSize(int compressionLevel); 1284 ZSTDLIB_API size_t ZSTD_estimateCCtxSize_usingCParams(ZSTD_compressionParameters cParams); 1285 ZSTDLIB_API size_t ZSTD_estimateCCtxSize_usingCCtxParams(const ZSTD_CCtx_params* params); 1286 ZSTDLIB_API size_t ZSTD_estimateDCtxSize(void); 1287 1288 /*! ZSTD_estimateCStreamSize() : 1289 * ZSTD_estimateCStreamSize() will provide a budget large enough for any compression level up to selected one. 1290 * It will also consider src size to be arbitrarily "large", which is worst case. 1291 * If srcSize is known to always be small, ZSTD_estimateCStreamSize_usingCParams() can provide a tighter estimation. 1292 * ZSTD_estimateCStreamSize_usingCParams() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel. 1293 * 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. 1294 * Note : CStream size estimation is only correct for single-threaded compression. 1295 * ZSTD_DStream memory budget depends on window Size. 1296 * This information can be passed manually, using ZSTD_estimateDStreamSize, 1297 * or deducted from a valid frame Header, using ZSTD_estimateDStreamSize_fromFrame(); 1298 * Note : if streaming is init with function ZSTD_init?Stream_usingDict(), 1299 * an internal ?Dict will be created, which additional size is not estimated here. 1300 * In this case, get total size by adding ZSTD_estimate?DictSize */ 1301 ZSTDLIB_API size_t ZSTD_estimateCStreamSize(int compressionLevel); 1302 ZSTDLIB_API size_t ZSTD_estimateCStreamSize_usingCParams(ZSTD_compressionParameters cParams); 1303 ZSTDLIB_API size_t ZSTD_estimateCStreamSize_usingCCtxParams(const ZSTD_CCtx_params* params); 1304 ZSTDLIB_API size_t ZSTD_estimateDStreamSize(size_t windowSize); 1305 ZSTDLIB_API size_t ZSTD_estimateDStreamSize_fromFrame(const void* src, size_t srcSize); 1306 1307 /*! ZSTD_estimate?DictSize() : 1308 * ZSTD_estimateCDictSize() will bet that src size is relatively "small", and content is copied, like ZSTD_createCDict(). 1309 * ZSTD_estimateCDictSize_advanced() makes it possible to control compression parameters precisely, like ZSTD_createCDict_advanced(). 1310 * Note : dictionaries created by reference (`ZSTD_dlm_byRef`) are logically smaller. 1311 */ 1312 ZSTDLIB_API size_t ZSTD_estimateCDictSize(size_t dictSize, int compressionLevel); 1313 ZSTDLIB_API size_t ZSTD_estimateCDictSize_advanced(size_t dictSize, ZSTD_compressionParameters cParams, ZSTD_dictLoadMethod_e dictLoadMethod); 1314 ZSTDLIB_API size_t ZSTD_estimateDDictSize(size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod); 1315 1316 /*! ZSTD_initStatic*() : 1317 * Initialize an object using a pre-allocated fixed-size buffer. 1318 * workspace: The memory area to emplace the object into. 1319 * Provided pointer *must be 8-bytes aligned*. 1320 * Buffer must outlive object. 1321 * workspaceSize: Use ZSTD_estimate*Size() to determine 1322 * how large workspace must be to support target scenario. 1323 * @return : pointer to object (same address as workspace, just different type), 1324 * or NULL if error (size too small, incorrect alignment, etc.) 1325 * Note : zstd will never resize nor malloc() when using a static buffer. 1326 * If the object requires more memory than available, 1327 * zstd will just error out (typically ZSTD_error_memory_allocation). 1328 * Note 2 : there is no corresponding "free" function. 1329 * Since workspace is allocated externally, it must be freed externally too. 1330 * Note 3 : cParams : use ZSTD_getCParams() to convert a compression level 1331 * into its associated cParams. 1332 * Limitation 1 : currently not compatible with internal dictionary creation, triggered by 1333 * ZSTD_CCtx_loadDictionary(), ZSTD_initCStream_usingDict() or ZSTD_initDStream_usingDict(). 1334 * Limitation 2 : static cctx currently not compatible with multi-threading. 1335 * Limitation 3 : static dctx is incompatible with legacy support. 1336 */ 1337 ZSTDLIB_API ZSTD_CCtx* ZSTD_initStaticCCtx(void* workspace, size_t workspaceSize); 1338 ZSTDLIB_API ZSTD_CStream* ZSTD_initStaticCStream(void* workspace, size_t workspaceSize); /**< same as ZSTD_initStaticCCtx() */ 1339 1340 ZSTDLIB_API ZSTD_DCtx* ZSTD_initStaticDCtx(void* workspace, size_t workspaceSize); 1341 ZSTDLIB_API ZSTD_DStream* ZSTD_initStaticDStream(void* workspace, size_t workspaceSize); /**< same as ZSTD_initStaticDCtx() */ 1342 1343 ZSTDLIB_API const ZSTD_CDict* ZSTD_initStaticCDict( 1344 void* workspace, size_t workspaceSize, 1345 const void* dict, size_t dictSize, 1346 ZSTD_dictLoadMethod_e dictLoadMethod, 1347 ZSTD_dictContentType_e dictContentType, 1348 ZSTD_compressionParameters cParams); 1349 1350 ZSTDLIB_API const ZSTD_DDict* ZSTD_initStaticDDict( 1351 void* workspace, size_t workspaceSize, 1352 const void* dict, size_t dictSize, 1353 ZSTD_dictLoadMethod_e dictLoadMethod, 1354 ZSTD_dictContentType_e dictContentType); 1355 1356 1357 /*! Custom memory allocation : 1358 * These prototypes make it possible to pass your own allocation/free functions. 1359 * ZSTD_customMem is provided at creation time, using ZSTD_create*_advanced() variants listed below. 1360 * All allocation/free operations will be completed using these custom variants instead of regular <stdlib.h> ones. 1361 */ 1362 typedef void* (*ZSTD_allocFunction) (void* opaque, size_t size); 1363 typedef void (*ZSTD_freeFunction) (void* opaque, void* address); 1364 typedef struct { ZSTD_allocFunction customAlloc; ZSTD_freeFunction customFree; void* opaque; } ZSTD_customMem; 1365 static ZSTD_customMem const ZSTD_defaultCMem = { NULL, NULL, NULL }; /**< this constant defers to stdlib's functions */ 1366 1367 ZSTDLIB_API ZSTD_CCtx* ZSTD_createCCtx_advanced(ZSTD_customMem customMem); 1368 ZSTDLIB_API ZSTD_CStream* ZSTD_createCStream_advanced(ZSTD_customMem customMem); 1369 ZSTDLIB_API ZSTD_DCtx* ZSTD_createDCtx_advanced(ZSTD_customMem customMem); 1370 ZSTDLIB_API ZSTD_DStream* ZSTD_createDStream_advanced(ZSTD_customMem customMem); 1371 1372 ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict_advanced(const void* dict, size_t dictSize, 1373 ZSTD_dictLoadMethod_e dictLoadMethod, 1374 ZSTD_dictContentType_e dictContentType, 1375 ZSTD_compressionParameters cParams, 1376 ZSTD_customMem customMem); 1377 1378 ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict_advanced(const void* dict, size_t dictSize, 1379 ZSTD_dictLoadMethod_e dictLoadMethod, 1380 ZSTD_dictContentType_e dictContentType, 1381 ZSTD_customMem customMem); 1382 1383 1384 1385 /*************************************** 1386 * Advanced compression functions 1387 ***************************************/ 1388 1389 /*! ZSTD_createCDict_byReference() : 1390 * Create a digested dictionary for compression 1391 * Dictionary content is just referenced, not duplicated. 1392 * As a consequence, `dictBuffer` **must** outlive CDict, 1393 * and its content must remain unmodified throughout the lifetime of CDict. 1394 * note: equivalent to ZSTD_createCDict_advanced(), with dictLoadMethod==ZSTD_dlm_byRef */ 1395 ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict_byReference(const void* dictBuffer, size_t dictSize, int compressionLevel); 1396 1397 /*! ZSTD_getCParams() : 1398 * @return ZSTD_compressionParameters structure for a selected compression level and estimated srcSize. 1399 * `estimatedSrcSize` value is optional, select 0 if not known */ 1400 ZSTDLIB_API ZSTD_compressionParameters ZSTD_getCParams(int compressionLevel, unsigned long long estimatedSrcSize, size_t dictSize); 1401 1402 /*! ZSTD_getParams() : 1403 * same as ZSTD_getCParams(), but @return a full `ZSTD_parameters` object instead of sub-component `ZSTD_compressionParameters`. 1404 * All fields of `ZSTD_frameParameters` are set to default : contentSize=1, checksum=0, noDictID=0 */ 1405 ZSTDLIB_API ZSTD_parameters ZSTD_getParams(int compressionLevel, unsigned long long estimatedSrcSize, size_t dictSize); 1406 1407 /*! ZSTD_checkCParams() : 1408 * Ensure param values remain within authorized range. 1409 * @return 0 on success, or an error code (can be checked with ZSTD_isError()) */ 1410 ZSTDLIB_API size_t ZSTD_checkCParams(ZSTD_compressionParameters params); 1411 1412 /*! ZSTD_adjustCParams() : 1413 * optimize params for a given `srcSize` and `dictSize`. 1414 * `srcSize` can be unknown, in which case use ZSTD_CONTENTSIZE_UNKNOWN. 1415 * `dictSize` must be `0` when there is no dictionary. 1416 * cPar can be invalid : all parameters will be clamped within valid range in the @return struct. 1417 * This function never fails (wide contract) */ 1418 ZSTDLIB_API ZSTD_compressionParameters ZSTD_adjustCParams(ZSTD_compressionParameters cPar, unsigned long long srcSize, size_t dictSize); 1419 1420 /*! ZSTD_compress_advanced() : 1421 * Note : this function is now DEPRECATED. 1422 * It can be replaced by ZSTD_compress2(), in combination with ZSTD_CCtx_setParameter() and other parameter setters. 1423 * This prototype will be marked as deprecated and generate compilation warning on reaching v1.5.x */ 1424 ZSTDLIB_API size_t ZSTD_compress_advanced(ZSTD_CCtx* cctx, 1425 void* dst, size_t dstCapacity, 1426 const void* src, size_t srcSize, 1427 const void* dict,size_t dictSize, 1428 ZSTD_parameters params); 1429 1430 /*! ZSTD_compress_usingCDict_advanced() : 1431 * Note : this function is now REDUNDANT. 1432 * It can be replaced by ZSTD_compress2(), in combination with ZSTD_CCtx_loadDictionary() and other parameter setters. 1433 * This prototype will be marked as deprecated and generate compilation warning in some future version */ 1434 ZSTDLIB_API size_t ZSTD_compress_usingCDict_advanced(ZSTD_CCtx* cctx, 1435 void* dst, size_t dstCapacity, 1436 const void* src, size_t srcSize, 1437 const ZSTD_CDict* cdict, 1438 ZSTD_frameParameters fParams); 1439 1440 1441 /*! ZSTD_CCtx_loadDictionary_byReference() : 1442 * Same as ZSTD_CCtx_loadDictionary(), but dictionary content is referenced, instead of being copied into CCtx. 1443 * It saves some memory, but also requires that `dict` outlives its usage within `cctx` */ 1444 ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary_byReference(ZSTD_CCtx* cctx, const void* dict, size_t dictSize); 1445 1446 /*! ZSTD_CCtx_loadDictionary_advanced() : 1447 * Same as ZSTD_CCtx_loadDictionary(), but gives finer control over 1448 * how to load the dictionary (by copy ? by reference ?) 1449 * and how to interpret it (automatic ? force raw mode ? full mode only ?) */ 1450 ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary_advanced(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod, ZSTD_dictContentType_e dictContentType); 1451 1452 /*! ZSTD_CCtx_refPrefix_advanced() : 1453 * Same as ZSTD_CCtx_refPrefix(), but gives finer control over 1454 * how to interpret prefix content (automatic ? force raw mode (default) ? full mode only ?) */ 1455 ZSTDLIB_API size_t ZSTD_CCtx_refPrefix_advanced(ZSTD_CCtx* cctx, const void* prefix, size_t prefixSize, ZSTD_dictContentType_e dictContentType); 1456 1457 /* === experimental parameters === */ 1458 /* these parameters can be used with ZSTD_setParameter() 1459 * they are not guaranteed to remain supported in the future */ 1460 1461 /* Enables rsyncable mode, 1462 * which makes compressed files more rsync friendly 1463 * by adding periodic synchronization points to the compressed data. 1464 * The target average block size is ZSTD_c_jobSize / 2. 1465 * It's possible to modify the job size to increase or decrease 1466 * the granularity of the synchronization point. 1467 * Once the jobSize is smaller than the window size, 1468 * it will result in compression ratio degradation. 1469 * NOTE 1: rsyncable mode only works when multithreading is enabled. 1470 * NOTE 2: rsyncable performs poorly in combination with long range mode, 1471 * since it will decrease the effectiveness of synchronization points, 1472 * though mileage may vary. 1473 * NOTE 3: Rsyncable mode limits maximum compression speed to ~400 MB/s. 1474 * If the selected compression level is already running significantly slower, 1475 * the overall speed won't be significantly impacted. 1476 */ 1477 #define ZSTD_c_rsyncable ZSTD_c_experimentalParam1 1478 1479 /* Select a compression format. 1480 * The value must be of type ZSTD_format_e. 1481 * See ZSTD_format_e enum definition for details */ 1482 #define ZSTD_c_format ZSTD_c_experimentalParam2 1483 1484 /* Force back-reference distances to remain < windowSize, 1485 * even when referencing into Dictionary content (default:0) */ 1486 #define ZSTD_c_forceMaxWindow ZSTD_c_experimentalParam3 1487 1488 /* Controls whether the contents of a CDict 1489 * are used in place, or copied into the working context. 1490 * Accepts values from the ZSTD_dictAttachPref_e enum. 1491 * See the comments on that enum for an explanation of the feature. */ 1492 #define ZSTD_c_forceAttachDict ZSTD_c_experimentalParam4 1493 1494 /* Controls how the literals are compressed (default is auto). 1495 * The value must be of type ZSTD_literalCompressionMode_e. 1496 * See ZSTD_literalCompressionMode_t enum definition for details. 1497 */ 1498 #define ZSTD_c_literalCompressionMode ZSTD_c_experimentalParam5 1499 1500 /* Tries to fit compressed block size to be around targetCBlockSize. 1501 * No target when targetCBlockSize == 0. 1502 * There is no guarantee on compressed block size (default:0) */ 1503 #define ZSTD_c_targetCBlockSize ZSTD_c_experimentalParam6 1504 1505 /* User's best guess of source size. 1506 * Hint is not valid when srcSizeHint == 0. 1507 * There is no guarantee that hint is close to actual source size, 1508 * but compression ratio may regress significantly if guess considerably underestimates */ 1509 #define ZSTD_c_srcSizeHint ZSTD_c_experimentalParam7 1510 1511 /*! ZSTD_CCtx_getParameter() : 1512 * Get the requested compression parameter value, selected by enum ZSTD_cParameter, 1513 * and store it into int* value. 1514 * @return : 0, or an error code (which can be tested with ZSTD_isError()). 1515 */ 1516 ZSTDLIB_API size_t ZSTD_CCtx_getParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, int* value); 1517 1518 1519 /*! ZSTD_CCtx_params : 1520 * Quick howto : 1521 * - ZSTD_createCCtxParams() : Create a ZSTD_CCtx_params structure 1522 * - ZSTD_CCtxParams_setParameter() : Push parameters one by one into 1523 * an existing ZSTD_CCtx_params structure. 1524 * This is similar to 1525 * ZSTD_CCtx_setParameter(). 1526 * - ZSTD_CCtx_setParametersUsingCCtxParams() : Apply parameters to 1527 * an existing CCtx. 1528 * These parameters will be applied to 1529 * all subsequent frames. 1530 * - ZSTD_compressStream2() : Do compression using the CCtx. 1531 * - ZSTD_freeCCtxParams() : Free the memory. 1532 * 1533 * This can be used with ZSTD_estimateCCtxSize_advanced_usingCCtxParams() 1534 * for static allocation of CCtx for single-threaded compression. 1535 */ 1536 ZSTDLIB_API ZSTD_CCtx_params* ZSTD_createCCtxParams(void); 1537 ZSTDLIB_API size_t ZSTD_freeCCtxParams(ZSTD_CCtx_params* params); 1538 1539 /*! ZSTD_CCtxParams_reset() : 1540 * Reset params to default values. 1541 */ 1542 ZSTDLIB_API size_t ZSTD_CCtxParams_reset(ZSTD_CCtx_params* params); 1543 1544 /*! ZSTD_CCtxParams_init() : 1545 * Initializes the compression parameters of cctxParams according to 1546 * compression level. All other parameters are reset to their default values. 1547 */ 1548 ZSTDLIB_API size_t ZSTD_CCtxParams_init(ZSTD_CCtx_params* cctxParams, int compressionLevel); 1549 1550 /*! ZSTD_CCtxParams_init_advanced() : 1551 * Initializes the compression and frame parameters of cctxParams according to 1552 * params. All other parameters are reset to their default values. 1553 */ 1554 ZSTDLIB_API size_t ZSTD_CCtxParams_init_advanced(ZSTD_CCtx_params* cctxParams, ZSTD_parameters params); 1555 1556 /*! ZSTD_CCtxParams_setParameter() : 1557 * Similar to ZSTD_CCtx_setParameter. 1558 * Set one compression parameter, selected by enum ZSTD_cParameter. 1559 * Parameters must be applied to a ZSTD_CCtx using ZSTD_CCtx_setParametersUsingCCtxParams(). 1560 * @result : 0, or an error code (which can be tested with ZSTD_isError()). 1561 */ 1562 ZSTDLIB_API size_t ZSTD_CCtxParams_setParameter(ZSTD_CCtx_params* params, ZSTD_cParameter param, int value); 1563 1564 /*! ZSTD_CCtxParams_getParameter() : 1565 * Similar to ZSTD_CCtx_getParameter. 1566 * Get the requested value of one compression parameter, selected by enum ZSTD_cParameter. 1567 * @result : 0, or an error code (which can be tested with ZSTD_isError()). 1568 */ 1569 ZSTDLIB_API size_t ZSTD_CCtxParams_getParameter(ZSTD_CCtx_params* params, ZSTD_cParameter param, int* value); 1570 1571 /*! ZSTD_CCtx_setParametersUsingCCtxParams() : 1572 * Apply a set of ZSTD_CCtx_params to the compression context. 1573 * This can be done even after compression is started, 1574 * if nbWorkers==0, this will have no impact until a new compression is started. 1575 * if nbWorkers>=1, new parameters will be picked up at next job, 1576 * with a few restrictions (windowLog, pledgedSrcSize, nbWorkers, jobSize, and overlapLog are not updated). 1577 */ 1578 ZSTDLIB_API size_t ZSTD_CCtx_setParametersUsingCCtxParams( 1579 ZSTD_CCtx* cctx, const ZSTD_CCtx_params* params); 1580 1581 /*! ZSTD_compressStream2_simpleArgs() : 1582 * Same as ZSTD_compressStream2(), 1583 * but using only integral types as arguments. 1584 * This variant might be helpful for binders from dynamic languages 1585 * which have troubles handling structures containing memory pointers. 1586 */ 1587 ZSTDLIB_API size_t ZSTD_compressStream2_simpleArgs ( 1588 ZSTD_CCtx* cctx, 1589 void* dst, size_t dstCapacity, size_t* dstPos, 1590 const void* src, size_t srcSize, size_t* srcPos, 1591 ZSTD_EndDirective endOp); 1592 1593 1594 /*************************************** 1595 * Advanced decompression functions 1596 ***************************************/ 1597 1598 /*! ZSTD_isFrame() : 1599 * Tells if the content of `buffer` starts with a valid Frame Identifier. 1600 * Note : Frame Identifier is 4 bytes. If `size < 4`, @return will always be 0. 1601 * Note 2 : Legacy Frame Identifiers are considered valid only if Legacy Support is enabled. 1602 * Note 3 : Skippable Frame Identifiers are considered valid. */ 1603 ZSTDLIB_API unsigned ZSTD_isFrame(const void* buffer, size_t size); 1604 1605 /*! ZSTD_createDDict_byReference() : 1606 * Create a digested dictionary, ready to start decompression operation without startup delay. 1607 * Dictionary content is referenced, and therefore stays in dictBuffer. 1608 * It is important that dictBuffer outlives DDict, 1609 * it must remain read accessible throughout the lifetime of DDict */ 1610 ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict_byReference(const void* dictBuffer, size_t dictSize); 1611 1612 /*! ZSTD_DCtx_loadDictionary_byReference() : 1613 * Same as ZSTD_DCtx_loadDictionary(), 1614 * but references `dict` content instead of copying it into `dctx`. 1615 * This saves memory if `dict` remains around., 1616 * However, it's imperative that `dict` remains accessible (and unmodified) while being used, so it must outlive decompression. */ 1617 ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary_byReference(ZSTD_DCtx* dctx, const void* dict, size_t dictSize); 1618 1619 /*! ZSTD_DCtx_loadDictionary_advanced() : 1620 * Same as ZSTD_DCtx_loadDictionary(), 1621 * but gives direct control over 1622 * how to load the dictionary (by copy ? by reference ?) 1623 * and how to interpret it (automatic ? force raw mode ? full mode only ?). */ 1624 ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary_advanced(ZSTD_DCtx* dctx, const void* dict, size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod, ZSTD_dictContentType_e dictContentType); 1625 1626 /*! ZSTD_DCtx_refPrefix_advanced() : 1627 * Same as ZSTD_DCtx_refPrefix(), but gives finer control over 1628 * how to interpret prefix content (automatic ? force raw mode (default) ? full mode only ?) */ 1629 ZSTDLIB_API size_t ZSTD_DCtx_refPrefix_advanced(ZSTD_DCtx* dctx, const void* prefix, size_t prefixSize, ZSTD_dictContentType_e dictContentType); 1630 1631 /*! ZSTD_DCtx_setMaxWindowSize() : 1632 * Refuses allocating internal buffers for frames requiring a window size larger than provided limit. 1633 * This protects a decoder context from reserving too much memory for itself (potential attack scenario). 1634 * This parameter is only useful in streaming mode, since no internal buffer is allocated in single-pass mode. 1635 * By default, a decompression context accepts all window sizes <= (1 << ZSTD_WINDOWLOG_LIMIT_DEFAULT) 1636 * @return : 0, or an error code (which can be tested using ZSTD_isError()). 1637 */ 1638 ZSTDLIB_API size_t ZSTD_DCtx_setMaxWindowSize(ZSTD_DCtx* dctx, size_t maxWindowSize); 1639 1640 /* ZSTD_d_format 1641 * experimental parameter, 1642 * allowing selection between ZSTD_format_e input compression formats 1643 */ 1644 #define ZSTD_d_format ZSTD_d_experimentalParam1 1645 1646 /*! ZSTD_DCtx_setFormat() : 1647 * Instruct the decoder context about what kind of data to decode next. 1648 * This instruction is mandatory to decode data without a fully-formed header, 1649 * such ZSTD_f_zstd1_magicless for example. 1650 * @return : 0, or an error code (which can be tested using ZSTD_isError()). */ 1651 ZSTDLIB_API size_t ZSTD_DCtx_setFormat(ZSTD_DCtx* dctx, ZSTD_format_e format); 1652 1653 /*! ZSTD_decompressStream_simpleArgs() : 1654 * Same as ZSTD_decompressStream(), 1655 * but using only integral types as arguments. 1656 * This can be helpful for binders from dynamic languages 1657 * which have troubles handling structures containing memory pointers. 1658 */ 1659 ZSTDLIB_API size_t ZSTD_decompressStream_simpleArgs ( 1660 ZSTD_DCtx* dctx, 1661 void* dst, size_t dstCapacity, size_t* dstPos, 1662 const void* src, size_t srcSize, size_t* srcPos); 1663 1664 1665 /******************************************************************** 1666 * Advanced streaming functions 1667 * Warning : most of these functions are now redundant with the Advanced API. 1668 * Once Advanced API reaches "stable" status, 1669 * redundant functions will be deprecated, and then at some point removed. 1670 ********************************************************************/ 1671 1672 /*===== Advanced Streaming compression functions =====*/ 1673 /**! ZSTD_initCStream_srcSize() : 1674 * This function is deprecated, and equivalent to: 1675 * ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only); 1676 * ZSTD_CCtx_refCDict(zcs, NULL); // clear the dictionary (if any) 1677 * ZSTD_CCtx_setParameter(zcs, ZSTD_c_compressionLevel, compressionLevel); 1678 * ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize); 1679 * 1680 * pledgedSrcSize must be correct. If it is not known at init time, use 1681 * ZSTD_CONTENTSIZE_UNKNOWN. Note that, for compatibility with older programs, 1682 * "0" also disables frame content size field. It may be enabled in the future. 1683 * Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x 1684 */ 1685 ZSTDLIB_API size_t 1686 ZSTD_initCStream_srcSize(ZSTD_CStream* zcs, 1687 int compressionLevel, 1688 unsigned long long pledgedSrcSize); 1689 1690 /**! ZSTD_initCStream_usingDict() : 1691 * This function is deprecated, and is equivalent to: 1692 * ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only); 1693 * ZSTD_CCtx_setParameter(zcs, ZSTD_c_compressionLevel, compressionLevel); 1694 * ZSTD_CCtx_loadDictionary(zcs, dict, dictSize); 1695 * 1696 * Creates of an internal CDict (incompatible with static CCtx), except if 1697 * dict == NULL or dictSize < 8, in which case no dict is used. 1698 * Note: dict is loaded with ZSTD_dct_auto (treated as a full zstd dictionary if 1699 * it begins with ZSTD_MAGIC_DICTIONARY, else as raw content) and ZSTD_dlm_byCopy. 1700 * Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x 1701 */ 1702 ZSTDLIB_API size_t 1703 ZSTD_initCStream_usingDict(ZSTD_CStream* zcs, 1704 const void* dict, size_t dictSize, 1705 int compressionLevel); 1706 1707 /**! ZSTD_initCStream_advanced() : 1708 * This function is deprecated, and is approximately equivalent to: 1709 * ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only); 1710 * // Pseudocode: Set each zstd parameter and leave the rest as-is. 1711 * for ((param, value) : params) { 1712 * ZSTD_CCtx_setParameter(zcs, param, value); 1713 * } 1714 * ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize); 1715 * ZSTD_CCtx_loadDictionary(zcs, dict, dictSize); 1716 * 1717 * dict is loaded with ZSTD_dct_auto and ZSTD_dlm_byCopy. 1718 * pledgedSrcSize must be correct. 1719 * If srcSize is not known at init time, use value ZSTD_CONTENTSIZE_UNKNOWN. 1720 * Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x 1721 */ 1722 ZSTDLIB_API size_t 1723 ZSTD_initCStream_advanced(ZSTD_CStream* zcs, 1724 const void* dict, size_t dictSize, 1725 ZSTD_parameters params, 1726 unsigned long long pledgedSrcSize); 1727 1728 /**! ZSTD_initCStream_usingCDict() : 1729 * This function is deprecated, and equivalent to: 1730 * ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only); 1731 * ZSTD_CCtx_refCDict(zcs, cdict); 1732 * 1733 * note : cdict will just be referenced, and must outlive compression session 1734 * Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x 1735 */ 1736 ZSTDLIB_API size_t ZSTD_initCStream_usingCDict(ZSTD_CStream* zcs, const ZSTD_CDict* cdict); 1737 1738 /**! ZSTD_initCStream_usingCDict_advanced() : 1739 * This function is DEPRECATED, and is approximately equivalent to: 1740 * ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only); 1741 * // Pseudocode: Set each zstd frame parameter and leave the rest as-is. 1742 * for ((fParam, value) : fParams) { 1743 * ZSTD_CCtx_setParameter(zcs, fParam, value); 1744 * } 1745 * ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize); 1746 * ZSTD_CCtx_refCDict(zcs, cdict); 1747 * 1748 * same as ZSTD_initCStream_usingCDict(), with control over frame parameters. 1749 * pledgedSrcSize must be correct. If srcSize is not known at init time, use 1750 * value ZSTD_CONTENTSIZE_UNKNOWN. 1751 * Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x 1752 */ 1753 ZSTDLIB_API size_t 1754 ZSTD_initCStream_usingCDict_advanced(ZSTD_CStream* zcs, 1755 const ZSTD_CDict* cdict, 1756 ZSTD_frameParameters fParams, 1757 unsigned long long pledgedSrcSize); 1758 1759 /*! ZSTD_resetCStream() : 1760 * This function is deprecated, and is equivalent to: 1761 * ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only); 1762 * ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize); 1763 * 1764 * start a new frame, using same parameters from previous frame. 1765 * This is typically useful to skip dictionary loading stage, since it will re-use it in-place. 1766 * Note that zcs must be init at least once before using ZSTD_resetCStream(). 1767 * If pledgedSrcSize is not known at reset time, use macro ZSTD_CONTENTSIZE_UNKNOWN. 1768 * If pledgedSrcSize > 0, its value must be correct, as it will be written in header, and controlled at the end. 1769 * For the time being, pledgedSrcSize==0 is interpreted as "srcSize unknown" for compatibility with older programs, 1770 * but it will change to mean "empty" in future version, so use macro ZSTD_CONTENTSIZE_UNKNOWN instead. 1771 * @return : 0, or an error code (which can be tested using ZSTD_isError()) 1772 * Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x 1773 */ 1774 ZSTDLIB_API size_t ZSTD_resetCStream(ZSTD_CStream* zcs, unsigned long long pledgedSrcSize); 1775 1776 1777 typedef struct { 1778 unsigned long long ingested; /* nb input bytes read and buffered */ 1779 unsigned long long consumed; /* nb input bytes actually compressed */ 1780 unsigned long long produced; /* nb of compressed bytes generated and buffered */ 1781 unsigned long long flushed; /* nb of compressed bytes flushed : not provided; can be tracked from caller side */ 1782 unsigned currentJobID; /* MT only : latest started job nb */ 1783 unsigned nbActiveWorkers; /* MT only : nb of workers actively compressing at probe time */ 1784 } ZSTD_frameProgression; 1785 1786 /* ZSTD_getFrameProgression() : 1787 * tells how much data has been ingested (read from input) 1788 * consumed (input actually compressed) and produced (output) for current frame. 1789 * Note : (ingested - consumed) is amount of input data buffered internally, not yet compressed. 1790 * Aggregates progression inside active worker threads. 1791 */ 1792 ZSTDLIB_API ZSTD_frameProgression ZSTD_getFrameProgression(const ZSTD_CCtx* cctx); 1793 1794 /*! ZSTD_toFlushNow() : 1795 * Tell how many bytes are ready to be flushed immediately. 1796 * Useful for multithreading scenarios (nbWorkers >= 1). 1797 * Probe the oldest active job, defined as oldest job not yet entirely flushed, 1798 * and check its output buffer. 1799 * @return : amount of data stored in oldest job and ready to be flushed immediately. 1800 * if @return == 0, it means either : 1801 * + there is no active job (could be checked with ZSTD_frameProgression()), or 1802 * + oldest job is still actively compressing data, 1803 * but everything it has produced has also been flushed so far, 1804 * therefore flush speed is limited by production speed of oldest job 1805 * irrespective of the speed of concurrent (and newer) jobs. 1806 */ 1807 ZSTDLIB_API size_t ZSTD_toFlushNow(ZSTD_CCtx* cctx); 1808 1809 1810 /*===== Advanced Streaming decompression functions =====*/ 1811 /** 1812 * This function is deprecated, and is equivalent to: 1813 * 1814 * ZSTD_DCtx_reset(zds, ZSTD_reset_session_only); 1815 * ZSTD_DCtx_loadDictionary(zds, dict, dictSize); 1816 * 1817 * note: no dictionary will be used if dict == NULL or dictSize < 8 1818 * Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x 1819 */ 1820 ZSTDLIB_API size_t ZSTD_initDStream_usingDict(ZSTD_DStream* zds, const void* dict, size_t dictSize); 1821 1822 /** 1823 * This function is deprecated, and is equivalent to: 1824 * 1825 * ZSTD_DCtx_reset(zds, ZSTD_reset_session_only); 1826 * ZSTD_DCtx_refDDict(zds, ddict); 1827 * 1828 * note : ddict is referenced, it must outlive decompression session 1829 * Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x 1830 */ 1831 ZSTDLIB_API size_t ZSTD_initDStream_usingDDict(ZSTD_DStream* zds, const ZSTD_DDict* ddict); 1832 1833 /** 1834 * This function is deprecated, and is equivalent to: 1835 * 1836 * ZSTD_DCtx_reset(zds, ZSTD_reset_session_only); 1837 * 1838 * re-use decompression parameters from previous init; saves dictionary loading 1839 * Note : this prototype will be marked as deprecated and generate compilation warnings on reaching v1.5.x 1840 */ 1841 ZSTDLIB_API size_t ZSTD_resetDStream(ZSTD_DStream* zds); 1842 1843 1844 /********************************************************************* 1845 * Buffer-less and synchronous inner streaming functions 1846 * 1847 * This is an advanced API, giving full control over buffer management, for users which need direct control over memory. 1848 * But it's also a complex one, with several restrictions, documented below. 1849 * Prefer normal streaming API for an easier experience. 1850 ********************************************************************* */ 1851 1852 /** 1853 Buffer-less streaming compression (synchronous mode) 1854 1855 A ZSTD_CCtx object is required to track streaming operations. 1856 Use ZSTD_createCCtx() / ZSTD_freeCCtx() to manage resource. 1857 ZSTD_CCtx object can be re-used multiple times within successive compression operations. 1858 1859 Start by initializing a context. 1860 Use ZSTD_compressBegin(), or ZSTD_compressBegin_usingDict() for dictionary compression, 1861 or ZSTD_compressBegin_advanced(), for finer parameter control. 1862 It's also possible to duplicate a reference context which has already been initialized, using ZSTD_copyCCtx() 1863 1864 Then, consume your input using ZSTD_compressContinue(). 1865 There are some important considerations to keep in mind when using this advanced function : 1866 - ZSTD_compressContinue() has no internal buffer. It uses externally provided buffers only. 1867 - Interface is synchronous : input is consumed entirely and produces 1+ compressed blocks. 1868 - Caller must ensure there is enough space in `dst` to store compressed data under worst case scenario. 1869 Worst case evaluation is provided by ZSTD_compressBound(). 1870 ZSTD_compressContinue() doesn't guarantee recover after a failed compression. 1871 - ZSTD_compressContinue() presumes prior input ***is still accessible and unmodified*** (up to maximum distance size, see WindowLog). 1872 It remembers all previous contiguous blocks, plus one separated memory segment (which can itself consists of multiple contiguous blocks) 1873 - ZSTD_compressContinue() detects that prior input has been overwritten when `src` buffer overlaps. 1874 In which case, it will "discard" the relevant memory section from its history. 1875 1876 Finish a frame with ZSTD_compressEnd(), which will write the last block(s) and optional checksum. 1877 It's possible to use srcSize==0, in which case, it will write a final empty block to end the frame. 1878 Without last block mark, frames are considered unfinished (hence corrupted) by compliant decoders. 1879 1880 `ZSTD_CCtx` object can be re-used (ZSTD_compressBegin()) to compress again. 1881 */ 1882 1883 /*===== Buffer-less streaming compression functions =====*/ 1884 ZSTDLIB_API size_t ZSTD_compressBegin(ZSTD_CCtx* cctx, int compressionLevel); 1885 ZSTDLIB_API size_t ZSTD_compressBegin_usingDict(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, int compressionLevel); 1886 ZSTDLIB_API size_t ZSTD_compressBegin_advanced(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, ZSTD_parameters params, unsigned long long pledgedSrcSize); /**< pledgedSrcSize : If srcSize is not known at init time, use ZSTD_CONTENTSIZE_UNKNOWN */ 1887 ZSTDLIB_API size_t ZSTD_compressBegin_usingCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict); /**< note: fails if cdict==NULL */ 1888 ZSTDLIB_API size_t ZSTD_compressBegin_usingCDict_advanced(ZSTD_CCtx* const cctx, const ZSTD_CDict* const cdict, ZSTD_frameParameters const fParams, unsigned long long const pledgedSrcSize); /* compression parameters are already set within cdict. pledgedSrcSize must be correct. If srcSize is not known, use macro ZSTD_CONTENTSIZE_UNKNOWN */ 1889 ZSTDLIB_API size_t ZSTD_copyCCtx(ZSTD_CCtx* cctx, const ZSTD_CCtx* preparedCCtx, unsigned long long pledgedSrcSize); /**< note: if pledgedSrcSize is not known, use ZSTD_CONTENTSIZE_UNKNOWN */ 1890 1891 ZSTDLIB_API size_t ZSTD_compressContinue(ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize); 1892 ZSTDLIB_API size_t ZSTD_compressEnd(ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize); 1893 1894 1895 /*- 1896 Buffer-less streaming decompression (synchronous mode) 1897 1898 A ZSTD_DCtx object is required to track streaming operations. 1899 Use ZSTD_createDCtx() / ZSTD_freeDCtx() to manage it. 1900 A ZSTD_DCtx object can be re-used multiple times. 1901 1902 First typical operation is to retrieve frame parameters, using ZSTD_getFrameHeader(). 1903 Frame header is extracted from the beginning of compressed frame, so providing only the frame's beginning is enough. 1904 Data fragment must be large enough to ensure successful decoding. 1905 `ZSTD_frameHeaderSize_max` bytes is guaranteed to always be large enough. 1906 @result : 0 : successful decoding, the `ZSTD_frameHeader` structure is correctly filled. 1907 >0 : `srcSize` is too small, please provide at least @result bytes on next attempt. 1908 errorCode, which can be tested using ZSTD_isError(). 1909 1910 It fills a ZSTD_frameHeader structure with important information to correctly decode the frame, 1911 such as the dictionary ID, content size, or maximum back-reference distance (`windowSize`). 1912 Note that these values could be wrong, either because of data corruption, or because a 3rd party deliberately spoofs false information. 1913 As a consequence, check that values remain within valid application range. 1914 For example, do not allocate memory blindly, check that `windowSize` is within expectation. 1915 Each application can set its own limits, depending on local restrictions. 1916 For extended interoperability, it is recommended to support `windowSize` of at least 8 MB. 1917 1918 ZSTD_decompressContinue() needs previous data blocks during decompression, up to `windowSize` bytes. 1919 ZSTD_decompressContinue() is very sensitive to contiguity, 1920 if 2 blocks don't follow each other, make sure that either the compressor breaks contiguity at the same place, 1921 or that previous contiguous segment is large enough to properly handle maximum back-reference distance. 1922 There are multiple ways to guarantee this condition. 1923 1924 The most memory efficient way is to use a round buffer of sufficient size. 1925 Sufficient size is determined by invoking ZSTD_decodingBufferSize_min(), 1926 which can @return an error code if required value is too large for current system (in 32-bits mode). 1927 In a round buffer methodology, ZSTD_decompressContinue() decompresses each block next to previous one, 1928 up to the moment there is not enough room left in the buffer to guarantee decoding another full block, 1929 which maximum size is provided in `ZSTD_frameHeader` structure, field `blockSizeMax`. 1930 At which point, decoding can resume from the beginning of the buffer. 1931 Note that already decoded data stored in the buffer should be flushed before being overwritten. 1932 1933 There are alternatives possible, for example using two or more buffers of size `windowSize` each, though they consume more memory. 1934 1935 Finally, if you control the compression process, you can also ignore all buffer size rules, 1936 as long as the encoder and decoder progress in "lock-step", 1937 aka use exactly the same buffer sizes, break contiguity at the same place, etc. 1938 1939 Once buffers are setup, start decompression, with ZSTD_decompressBegin(). 1940 If decompression requires a dictionary, use ZSTD_decompressBegin_usingDict() or ZSTD_decompressBegin_usingDDict(). 1941 1942 Then use ZSTD_nextSrcSizeToDecompress() and ZSTD_decompressContinue() alternatively. 1943 ZSTD_nextSrcSizeToDecompress() tells how many bytes to provide as 'srcSize' to ZSTD_decompressContinue(). 1944 ZSTD_decompressContinue() requires this _exact_ amount of bytes, or it will fail. 1945 1946 @result of ZSTD_decompressContinue() is the number of bytes regenerated within 'dst' (necessarily <= dstCapacity). 1947 It can be zero : it just means ZSTD_decompressContinue() has decoded some metadata item. 1948 It can also be an error code, which can be tested with ZSTD_isError(). 1949 1950 A frame is fully decoded when ZSTD_nextSrcSizeToDecompress() returns zero. 1951 Context can then be reset to start a new decompression. 1952 1953 Note : it's possible to know if next input to present is a header or a block, using ZSTD_nextInputType(). 1954 This information is not required to properly decode a frame. 1955 1956 == Special case : skippable frames == 1957 1958 Skippable frames allow integration of user-defined data into a flow of concatenated frames. 1959 Skippable frames will be ignored (skipped) by decompressor. 1960 The format of skippable frames is as follows : 1961 a) Skippable frame ID - 4 Bytes, Little endian format, any value from 0x184D2A50 to 0x184D2A5F 1962 b) Frame Size - 4 Bytes, Little endian format, unsigned 32-bits 1963 c) Frame Content - any content (User Data) of length equal to Frame Size 1964 For skippable frames ZSTD_getFrameHeader() returns zfhPtr->frameType==ZSTD_skippableFrame. 1965 For skippable frames ZSTD_decompressContinue() always returns 0 : it only skips the content. 1966 */ 1967 1968 /*===== Buffer-less streaming decompression functions =====*/ 1969 typedef enum { ZSTD_frame, ZSTD_skippableFrame } ZSTD_frameType_e; 1970 typedef struct { 1971 unsigned long long frameContentSize; /* if == ZSTD_CONTENTSIZE_UNKNOWN, it means this field is not available. 0 means "empty" */ 1972 unsigned long long windowSize; /* can be very large, up to <= frameContentSize */ 1973 unsigned blockSizeMax; 1974 ZSTD_frameType_e frameType; /* if == ZSTD_skippableFrame, frameContentSize is the size of skippable content */ 1975 unsigned headerSize; 1976 unsigned dictID; 1977 unsigned checksumFlag; 1978 } ZSTD_frameHeader; 1979 1980 /*! ZSTD_getFrameHeader() : 1981 * decode Frame Header, or requires larger `srcSize`. 1982 * @return : 0, `zfhPtr` is correctly filled, 1983 * >0, `srcSize` is too small, value is wanted `srcSize` amount, 1984 * or an error code, which can be tested using ZSTD_isError() */ 1985 ZSTDLIB_API size_t ZSTD_getFrameHeader(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize); /**< doesn't consume input */ 1986 /*! ZSTD_getFrameHeader_advanced() : 1987 * same as ZSTD_getFrameHeader(), 1988 * with added capability to select a format (like ZSTD_f_zstd1_magicless) */ 1989 ZSTDLIB_API size_t ZSTD_getFrameHeader_advanced(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize, ZSTD_format_e format); 1990 ZSTDLIB_API size_t ZSTD_decodingBufferSize_min(unsigned long long windowSize, unsigned long long frameContentSize); /**< when frame content size is not known, pass in frameContentSize == ZSTD_CONTENTSIZE_UNKNOWN */ 1991 1992 ZSTDLIB_API size_t ZSTD_decompressBegin(ZSTD_DCtx* dctx); 1993 ZSTDLIB_API size_t ZSTD_decompressBegin_usingDict(ZSTD_DCtx* dctx, const void* dict, size_t dictSize); 1994 ZSTDLIB_API size_t ZSTD_decompressBegin_usingDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict); 1995 1996 ZSTDLIB_API size_t ZSTD_nextSrcSizeToDecompress(ZSTD_DCtx* dctx); 1997 ZSTDLIB_API size_t ZSTD_decompressContinue(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize); 1998 1999 /* misc */ 2000 ZSTDLIB_API void ZSTD_copyDCtx(ZSTD_DCtx* dctx, const ZSTD_DCtx* preparedDCtx); 2001 typedef enum { ZSTDnit_frameHeader, ZSTDnit_blockHeader, ZSTDnit_block, ZSTDnit_lastBlock, ZSTDnit_checksum, ZSTDnit_skippableFrame } ZSTD_nextInputType_e; 2002 ZSTDLIB_API ZSTD_nextInputType_e ZSTD_nextInputType(ZSTD_DCtx* dctx); 2003 2004 2005 2006 2007 /* ============================ */ 2008 /** Block level API */ 2009 /* ============================ */ 2010 2011 /*! 2012 Block functions produce and decode raw zstd blocks, without frame metadata. 2013 Frame metadata cost is typically ~12 bytes, which can be non-negligible for very small blocks (< 100 bytes). 2014 But users will have to take in charge needed metadata to regenerate data, such as compressed and content sizes. 2015 2016 A few rules to respect : 2017 - Compressing and decompressing require a context structure 2018 + Use ZSTD_createCCtx() and ZSTD_createDCtx() 2019 - It is necessary to init context before starting 2020 + compression : any ZSTD_compressBegin*() variant, including with dictionary 2021 + decompression : any ZSTD_decompressBegin*() variant, including with dictionary 2022 + copyCCtx() and copyDCtx() can be used too 2023 - Block size is limited, it must be <= ZSTD_getBlockSize() <= ZSTD_BLOCKSIZE_MAX == 128 KB 2024 + If input is larger than a block size, it's necessary to split input data into multiple blocks 2025 + For inputs larger than a single block, consider using regular ZSTD_compress() instead. 2026 Frame metadata is not that costly, and quickly becomes negligible as source size grows larger than a block. 2027 - When a block is considered not compressible enough, ZSTD_compressBlock() result will be 0 (zero) ! 2028 ===> In which case, nothing is produced into `dst` ! 2029 + User __must__ test for such outcome and deal directly with uncompressed data 2030 + A block cannot be declared incompressible if ZSTD_compressBlock() return value was != 0. 2031 Doing so would mess up with statistics history, leading to potential data corruption. 2032 + ZSTD_decompressBlock() _doesn't accept uncompressed data as input_ !! 2033 + In case of multiple successive blocks, should some of them be uncompressed, 2034 decoder must be informed of their existence in order to follow proper history. 2035 Use ZSTD_insertBlock() for such a case. 2036 */ 2037 2038 /*===== Raw zstd block functions =====*/ 2039 ZSTDLIB_API size_t ZSTD_getBlockSize (const ZSTD_CCtx* cctx); 2040 ZSTDLIB_API size_t ZSTD_compressBlock (ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize); 2041 ZSTDLIB_API size_t ZSTD_decompressBlock(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize); 2042 ZSTDLIB_API size_t ZSTD_insertBlock (ZSTD_DCtx* dctx, const void* blockStart, size_t blockSize); /**< insert uncompressed block into `dctx` history. Useful for multi-blocks decompression. */ 2043 2044 2045 #endif /* ZSTD_H_ZSTD_STATIC_LINKING_ONLY */ 2046 2047 #if defined (__cplusplus) 2048 } 2049 #endif 2050