1 // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0-only 2 /* 3 * Copyright (c) Meta Platforms, Inc. and affiliates. 4 * All rights reserved. 5 * 6 * This source code is licensed under both the BSD-style license (found in the 7 * LICENSE file in the root directory of this source tree) and the GPLv2 (found 8 * in the COPYING file in the root directory of this source tree). 9 * You may select, at your option, one of the above-listed licenses. 10 */ 11 12 #ifndef ZSTD_H_235446 13 #define ZSTD_H_235446 14 15 16 /* ====== Dependencies ======*/ 17 #include <stddef.h> /* size_t */ 18 19 #include "zstd_errors.h" /* list of errors */ 20 #if defined(ZSTD_STATIC_LINKING_ONLY) && !defined(ZSTD_H_ZSTD_STATIC_LINKING_ONLY) 21 #include <limits.h> /* INT_MAX */ 22 #endif /* ZSTD_STATIC_LINKING_ONLY */ 23 24 #if defined (__cplusplus) 25 extern "C" { 26 #endif 27 28 /* ===== ZSTDLIB_API : control library symbols visibility ===== */ 29 #ifndef ZSTDLIB_VISIBLE 30 /* Backwards compatibility with old macro name */ 31 # ifdef ZSTDLIB_VISIBILITY 32 # define ZSTDLIB_VISIBLE ZSTDLIB_VISIBILITY 33 # elif defined(__GNUC__) && (__GNUC__ >= 4) && !defined(__MINGW32__) 34 # define ZSTDLIB_VISIBLE __attribute__ ((visibility ("default"))) 35 # else 36 # define ZSTDLIB_VISIBLE 37 # endif 38 #endif 39 40 #ifndef ZSTDLIB_HIDDEN 41 # if defined(__GNUC__) && (__GNUC__ >= 4) && !defined(__MINGW32__) 42 # define ZSTDLIB_HIDDEN __attribute__ ((visibility ("hidden"))) 43 # else 44 # define ZSTDLIB_HIDDEN 45 # endif 46 #endif 47 48 #if defined(ZSTD_DLL_EXPORT) && (ZSTD_DLL_EXPORT==1) 49 # define ZSTDLIB_API __declspec(dllexport) ZSTDLIB_VISIBLE 50 #elif defined(ZSTD_DLL_IMPORT) && (ZSTD_DLL_IMPORT==1) 51 # define ZSTDLIB_API __declspec(dllimport) ZSTDLIB_VISIBLE /* It isn't required but allows to generate better code, saving a function pointer load from the IAT and an indirect jump.*/ 52 #else 53 # define ZSTDLIB_API ZSTDLIB_VISIBLE 54 #endif 55 56 /* Deprecation warnings : 57 * Should these warnings be a problem, it is generally possible to disable them, 58 * typically with -Wno-deprecated-declarations for gcc or _CRT_SECURE_NO_WARNINGS in Visual. 59 * Otherwise, it's also possible to define ZSTD_DISABLE_DEPRECATE_WARNINGS. 60 */ 61 #ifdef ZSTD_DISABLE_DEPRECATE_WARNINGS 62 # define ZSTD_DEPRECATED(message) /* disable deprecation warnings */ 63 #else 64 # if defined (__cplusplus) && (__cplusplus >= 201402) /* C++14 or greater */ 65 # define ZSTD_DEPRECATED(message) [[deprecated(message)]] 66 # elif (defined(GNUC) && (GNUC > 4 || (GNUC == 4 && GNUC_MINOR >= 5))) || defined(__clang__) || defined(__IAR_SYSTEMS_ICC__) 67 # define ZSTD_DEPRECATED(message) __attribute__((deprecated(message))) 68 # elif defined(__GNUC__) && (__GNUC__ >= 3) 69 # define ZSTD_DEPRECATED(message) __attribute__((deprecated)) 70 # elif defined(_MSC_VER) 71 # define ZSTD_DEPRECATED(message) __declspec(deprecated(message)) 72 # else 73 # pragma message("WARNING: You need to implement ZSTD_DEPRECATED for this compiler") 74 # define ZSTD_DEPRECATED(message) 75 # endif 76 #endif /* ZSTD_DISABLE_DEPRECATE_WARNINGS */ 77 78 79 /******************************************************************************* 80 Introduction 81 82 zstd, short for Zstandard, is a fast lossless compression algorithm, targeting 83 real-time compression scenarios at zlib-level and better compression ratios. 84 The zstd compression library provides in-memory compression and decompression 85 functions. 86 87 The library supports regular compression levels from 1 up to ZSTD_maxCLevel(), 88 which is currently 22. Levels >= 20, labeled `--ultra`, should be used with 89 caution, as they require more memory. The library also offers negative 90 compression levels, which extend the range of speed vs. ratio preferences. 91 The lower the level, the faster the speed (at the cost of compression). 92 93 Compression can be done in: 94 - a single step (described as Simple API) 95 - a single step, reusing a context (described as Explicit context) 96 - unbounded multiple steps (described as Streaming compression) 97 98 The compression ratio achievable on small data can be highly improved using 99 a dictionary. Dictionary compression can be performed in: 100 - a single step (described as Simple dictionary API) 101 - a single step, reusing a dictionary (described as Bulk-processing 102 dictionary API) 103 104 Advanced experimental functions can be accessed using 105 `#define ZSTD_STATIC_LINKING_ONLY` before including zstd.h. 106 107 Advanced experimental APIs should never be used with a dynamically-linked 108 library. They are not "stable"; their definitions or signatures may change in 109 the future. Only static linking is allowed. 110 *******************************************************************************/ 111 112 /*------ Version ------*/ 113 #define ZSTD_VERSION_MAJOR 1 114 #define ZSTD_VERSION_MINOR 5 115 #define ZSTD_VERSION_RELEASE 7 116 #define ZSTD_VERSION_NUMBER (ZSTD_VERSION_MAJOR *100*100 + ZSTD_VERSION_MINOR *100 + ZSTD_VERSION_RELEASE) 117 118 /*! ZSTD_versionNumber() : 119 * Return runtime library version, the value is (MAJOR*100*100 + MINOR*100 + RELEASE). */ 120 ZSTDLIB_API unsigned ZSTD_versionNumber(void); 121 122 #define ZSTD_LIB_VERSION ZSTD_VERSION_MAJOR.ZSTD_VERSION_MINOR.ZSTD_VERSION_RELEASE 123 #define ZSTD_QUOTE(str) #str 124 #define ZSTD_EXPAND_AND_QUOTE(str) ZSTD_QUOTE(str) 125 #define ZSTD_VERSION_STRING ZSTD_EXPAND_AND_QUOTE(ZSTD_LIB_VERSION) 126 127 /*! ZSTD_versionString() : 128 * Return runtime library version, like "1.4.5". Requires v1.3.0+. */ 129 ZSTDLIB_API const char* ZSTD_versionString(void); 130 131 /* ************************************* 132 * Default constant 133 ***************************************/ 134 #ifndef ZSTD_CLEVEL_DEFAULT 135 # define ZSTD_CLEVEL_DEFAULT 3 136 #endif 137 138 /* ************************************* 139 * Constants 140 ***************************************/ 141 142 /* All magic numbers are supposed read/written to/from files/memory using little-endian convention */ 143 #define ZSTD_MAGICNUMBER 0xFD2FB528 /* valid since v0.8.0 */ 144 #define ZSTD_MAGIC_DICTIONARY 0xEC30A437 /* valid since v0.7.0 */ 145 #define ZSTD_MAGIC_SKIPPABLE_START 0x184D2A50 /* all 16 values, from 0x184D2A50 to 0x184D2A5F, signal the beginning of a skippable frame */ 146 #define ZSTD_MAGIC_SKIPPABLE_MASK 0xFFFFFFF0 147 148 #define ZSTD_BLOCKSIZELOG_MAX 17 149 #define ZSTD_BLOCKSIZE_MAX (1<<ZSTD_BLOCKSIZELOG_MAX) 150 151 152 /*************************************** 153 * Simple Core API 154 ***************************************/ 155 /*! ZSTD_compress() : 156 * Compresses `src` content as a single zstd compressed frame into already allocated `dst`. 157 * NOTE: Providing `dstCapacity >= ZSTD_compressBound(srcSize)` guarantees that zstd will have 158 * enough space to successfully compress the data. 159 * @return : compressed size written into `dst` (<= `dstCapacity), 160 * or an error code if it fails (which can be tested using ZSTD_isError()). */ 161 ZSTDLIB_API size_t ZSTD_compress( void* dst, size_t dstCapacity, 162 const void* src, size_t srcSize, 163 int compressionLevel); 164 165 /*! ZSTD_decompress() : 166 * `compressedSize` : must be the _exact_ size of some number of compressed and/or skippable frames. 167 * Multiple compressed frames can be decompressed at once with this method. 168 * The result will be the concatenation of all decompressed frames, back to back. 169 * `dstCapacity` is an upper bound of originalSize to regenerate. 170 * First frame's decompressed size can be extracted using ZSTD_getFrameContentSize(). 171 * If maximum upper bound isn't known, prefer using streaming mode to decompress data. 172 * @return : the number of bytes decompressed into `dst` (<= `dstCapacity`), 173 * or an errorCode if it fails (which can be tested using ZSTD_isError()). */ 174 ZSTDLIB_API size_t ZSTD_decompress( void* dst, size_t dstCapacity, 175 const void* src, size_t compressedSize); 176 177 178 /*====== Decompression helper functions ======*/ 179 180 /*! ZSTD_getFrameContentSize() : requires v1.3.0+ 181 * `src` should point to the start of a ZSTD encoded frame. 182 * `srcSize` must be at least as large as the frame header. 183 * hint : any size >= `ZSTD_frameHeaderSize_max` is large enough. 184 * @return : - decompressed size of `src` frame content, if known 185 * - ZSTD_CONTENTSIZE_UNKNOWN if the size cannot be determined 186 * - ZSTD_CONTENTSIZE_ERROR if an error occurred (e.g. invalid magic number, srcSize too small) 187 * note 1 : a 0 return value means the frame is valid but "empty". 188 * When invoking this method on a skippable frame, it will return 0. 189 * note 2 : decompressed size is an optional field, it may not be present (typically in streaming mode). 190 * When `return==ZSTD_CONTENTSIZE_UNKNOWN`, data to decompress could be any size. 191 * In which case, it's necessary to use streaming mode to decompress data. 192 * Optionally, application can rely on some implicit limit, 193 * as ZSTD_decompress() only needs an upper bound of decompressed size. 194 * (For example, data could be necessarily cut into blocks <= 16 KB). 195 * note 3 : decompressed size is always present when compression is completed using single-pass functions, 196 * such as ZSTD_compress(), ZSTD_compressCCtx() ZSTD_compress_usingDict() or ZSTD_compress_usingCDict(). 197 * note 4 : decompressed size can be very large (64-bits value), 198 * potentially larger than what local system can handle as a single memory segment. 199 * In which case, it's necessary to use streaming mode to decompress data. 200 * note 5 : If source is untrusted, decompressed size could be wrong or intentionally modified. 201 * Always ensure return value fits within application's authorized limits. 202 * Each application can set its own limits. 203 * note 6 : This function replaces ZSTD_getDecompressedSize() */ 204 #define ZSTD_CONTENTSIZE_UNKNOWN (0ULL - 1) 205 #define ZSTD_CONTENTSIZE_ERROR (0ULL - 2) 206 ZSTDLIB_API unsigned long long ZSTD_getFrameContentSize(const void *src, size_t srcSize); 207 208 /*! ZSTD_getDecompressedSize() (obsolete): 209 * This function is now obsolete, in favor of ZSTD_getFrameContentSize(). 210 * Both functions work the same way, but ZSTD_getDecompressedSize() blends 211 * "empty", "unknown" and "error" results to the same return value (0), 212 * while ZSTD_getFrameContentSize() gives them separate return values. 213 * @return : decompressed size of `src` frame content _if known and not empty_, 0 otherwise. */ 214 ZSTD_DEPRECATED("Replaced by ZSTD_getFrameContentSize") 215 ZSTDLIB_API unsigned long long ZSTD_getDecompressedSize(const void* src, size_t srcSize); 216 217 /*! ZSTD_findFrameCompressedSize() : Requires v1.4.0+ 218 * `src` should point to the start of a ZSTD frame or skippable frame. 219 * `srcSize` must be >= first frame size 220 * @return : the compressed size of the first frame starting at `src`, 221 * suitable to pass as `srcSize` to `ZSTD_decompress` or similar, 222 * or an error code if input is invalid 223 * Note 1: this method is called _find*() because it's not enough to read the header, 224 * it may have to scan through the frame's content, to reach its end. 225 * Note 2: this method also works with Skippable Frames. In which case, 226 * it returns the size of the complete skippable frame, 227 * which is always equal to its content size + 8 bytes for headers. */ 228 ZSTDLIB_API size_t ZSTD_findFrameCompressedSize(const void* src, size_t srcSize); 229 230 231 /*====== Compression helper functions ======*/ 232 233 /*! ZSTD_compressBound() : 234 * maximum compressed size in worst case single-pass scenario. 235 * When invoking `ZSTD_compress()`, or any other one-pass compression function, 236 * it's recommended to provide @dstCapacity >= ZSTD_compressBound(srcSize) 237 * as it eliminates one potential failure scenario, 238 * aka not enough room in dst buffer to write the compressed frame. 239 * Note : ZSTD_compressBound() itself can fail, if @srcSize >= ZSTD_MAX_INPUT_SIZE . 240 * In which case, ZSTD_compressBound() will return an error code 241 * which can be tested using ZSTD_isError(). 242 * 243 * ZSTD_COMPRESSBOUND() : 244 * same as ZSTD_compressBound(), but as a macro. 245 * It can be used to produce constants, which can be useful for static allocation, 246 * for example to size a static array on stack. 247 * Will produce constant value 0 if srcSize is too large. 248 */ 249 #define ZSTD_MAX_INPUT_SIZE ((sizeof(size_t)==8) ? 0xFF00FF00FF00FF00ULL : 0xFF00FF00U) 250 #define ZSTD_COMPRESSBOUND(srcSize) (((size_t)(srcSize) >= ZSTD_MAX_INPUT_SIZE) ? 0 : (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 */ 251 ZSTDLIB_API size_t ZSTD_compressBound(size_t srcSize); /*!< maximum compressed size in worst case single-pass scenario */ 252 253 254 /*====== Error helper functions ======*/ 255 /* ZSTD_isError() : 256 * Most ZSTD_* functions returning a size_t value can be tested for error, 257 * using ZSTD_isError(). 258 * @return 1 if error, 0 otherwise 259 */ 260 ZSTDLIB_API unsigned ZSTD_isError(size_t result); /*!< tells if a `size_t` function result is an error code */ 261 ZSTDLIB_API ZSTD_ErrorCode ZSTD_getErrorCode(size_t functionResult); /* convert a result into an error code, which can be compared to error enum list */ 262 ZSTDLIB_API const char* ZSTD_getErrorName(size_t result); /*!< provides readable string from a function result */ 263 ZSTDLIB_API int ZSTD_minCLevel(void); /*!< minimum negative compression level allowed, requires v1.4.0+ */ 264 ZSTDLIB_API int ZSTD_maxCLevel(void); /*!< maximum compression level available */ 265 ZSTDLIB_API int ZSTD_defaultCLevel(void); /*!< default compression level, specified by ZSTD_CLEVEL_DEFAULT, requires v1.5.0+ */ 266 267 268 /*************************************** 269 * Explicit context 270 ***************************************/ 271 /*= Compression context 272 * When compressing many times, 273 * it is recommended to allocate a compression context just once, 274 * and reuse it for each successive compression operation. 275 * This will make the workload easier for system's memory. 276 * Note : re-using context is just a speed / resource optimization. 277 * It doesn't change the compression ratio, which remains identical. 278 * Note 2: For parallel execution in multi-threaded environments, 279 * use one different context per thread . 280 */ 281 typedef struct ZSTD_CCtx_s ZSTD_CCtx; 282 ZSTDLIB_API ZSTD_CCtx* ZSTD_createCCtx(void); 283 ZSTDLIB_API size_t ZSTD_freeCCtx(ZSTD_CCtx* cctx); /* compatible with NULL pointer */ 284 285 /*! ZSTD_compressCCtx() : 286 * Same as ZSTD_compress(), using an explicit ZSTD_CCtx. 287 * Important : in order to mirror `ZSTD_compress()` behavior, 288 * this function compresses at the requested compression level, 289 * __ignoring any other advanced parameter__ . 290 * If any advanced parameter was set using the advanced API, 291 * they will all be reset. Only @compressionLevel remains. 292 */ 293 ZSTDLIB_API size_t ZSTD_compressCCtx(ZSTD_CCtx* cctx, 294 void* dst, size_t dstCapacity, 295 const void* src, size_t srcSize, 296 int compressionLevel); 297 298 /*= Decompression context 299 * When decompressing many times, 300 * it is recommended to allocate a context only once, 301 * and reuse it for each successive compression operation. 302 * This will make workload friendlier for system's memory. 303 * Use one context per thread for parallel execution. */ 304 typedef struct ZSTD_DCtx_s ZSTD_DCtx; 305 ZSTDLIB_API ZSTD_DCtx* ZSTD_createDCtx(void); 306 ZSTDLIB_API size_t ZSTD_freeDCtx(ZSTD_DCtx* dctx); /* accept NULL pointer */ 307 308 /*! ZSTD_decompressDCtx() : 309 * Same as ZSTD_decompress(), 310 * requires an allocated ZSTD_DCtx. 311 * Compatible with sticky parameters (see below). 312 */ 313 ZSTDLIB_API size_t ZSTD_decompressDCtx(ZSTD_DCtx* dctx, 314 void* dst, size_t dstCapacity, 315 const void* src, size_t srcSize); 316 317 318 /********************************************* 319 * Advanced compression API (Requires v1.4.0+) 320 **********************************************/ 321 322 /* API design : 323 * Parameters are pushed one by one into an existing context, 324 * using ZSTD_CCtx_set*() functions. 325 * Pushed parameters are sticky : they are valid for next compressed frame, and any subsequent frame. 326 * "sticky" parameters are applicable to `ZSTD_compress2()` and `ZSTD_compressStream*()` ! 327 * __They do not apply to one-shot variants such as ZSTD_compressCCtx()__ . 328 * 329 * It's possible to reset all parameters to "default" using ZSTD_CCtx_reset(). 330 * 331 * This API supersedes all other "advanced" API entry points in the experimental section. 332 * In the future, we expect to remove API entry points from experimental which are redundant with this API. 333 */ 334 335 336 /* Compression strategies, listed from fastest to strongest */ 337 typedef enum { ZSTD_fast=1, 338 ZSTD_dfast=2, 339 ZSTD_greedy=3, 340 ZSTD_lazy=4, 341 ZSTD_lazy2=5, 342 ZSTD_btlazy2=6, 343 ZSTD_btopt=7, 344 ZSTD_btultra=8, 345 ZSTD_btultra2=9 346 /* note : new strategies _might_ be added in the future. 347 Only the order (from fast to strong) is guaranteed */ 348 } ZSTD_strategy; 349 350 typedef enum { 351 352 /* compression parameters 353 * Note: When compressing with a ZSTD_CDict these parameters are superseded 354 * by the parameters used to construct the ZSTD_CDict. 355 * See ZSTD_CCtx_refCDict() for more info (superseded-by-cdict). */ 356 ZSTD_c_compressionLevel=100, /* Set compression parameters according to pre-defined cLevel table. 357 * Note that exact compression parameters are dynamically determined, 358 * depending on both compression level and srcSize (when known). 359 * Default level is ZSTD_CLEVEL_DEFAULT==3. 360 * Special: value 0 means default, which is controlled by ZSTD_CLEVEL_DEFAULT. 361 * Note 1 : it's possible to pass a negative compression level. 362 * Note 2 : setting a level does not automatically set all other compression parameters 363 * to default. Setting this will however eventually dynamically impact the compression 364 * parameters which have not been manually set. The manually set 365 * ones will 'stick'. */ 366 /* Advanced compression parameters : 367 * It's possible to pin down compression parameters to some specific values. 368 * In which case, these values are no longer dynamically selected by the compressor */ 369 ZSTD_c_windowLog=101, /* Maximum allowed back-reference distance, expressed as power of 2. 370 * This will set a memory budget for streaming decompression, 371 * with larger values requiring more memory 372 * and typically compressing more. 373 * Must be clamped between ZSTD_WINDOWLOG_MIN and ZSTD_WINDOWLOG_MAX. 374 * Special: value 0 means "use default windowLog". 375 * Note: Using a windowLog greater than ZSTD_WINDOWLOG_LIMIT_DEFAULT 376 * requires explicitly allowing such size at streaming decompression stage. */ 377 ZSTD_c_hashLog=102, /* Size of the initial probe table, as a power of 2. 378 * Resulting memory usage is (1 << (hashLog+2)). 379 * Must be clamped between ZSTD_HASHLOG_MIN and ZSTD_HASHLOG_MAX. 380 * Larger tables improve compression ratio of strategies <= dFast, 381 * and improve speed of strategies > dFast. 382 * Special: value 0 means "use default hashLog". */ 383 ZSTD_c_chainLog=103, /* Size of the multi-probe search table, as a power of 2. 384 * Resulting memory usage is (1 << (chainLog+2)). 385 * Must be clamped between ZSTD_CHAINLOG_MIN and ZSTD_CHAINLOG_MAX. 386 * Larger tables result in better and slower compression. 387 * This parameter is useless for "fast" strategy. 388 * It's still useful when using "dfast" strategy, 389 * in which case it defines a secondary probe table. 390 * Special: value 0 means "use default chainLog". */ 391 ZSTD_c_searchLog=104, /* Number of search attempts, as a power of 2. 392 * More attempts result in better and slower compression. 393 * This parameter is useless for "fast" and "dFast" strategies. 394 * Special: value 0 means "use default searchLog". */ 395 ZSTD_c_minMatch=105, /* Minimum size of searched matches. 396 * Note that Zstandard can still find matches of smaller size, 397 * it just tweaks its search algorithm to look for this size and larger. 398 * Larger values increase compression and decompression speed, but decrease ratio. 399 * Must be clamped between ZSTD_MINMATCH_MIN and ZSTD_MINMATCH_MAX. 400 * Note that currently, for all strategies < btopt, effective minimum is 4. 401 * , for all strategies > fast, effective maximum is 6. 402 * Special: value 0 means "use default minMatchLength". */ 403 ZSTD_c_targetLength=106, /* Impact of this field depends on strategy. 404 * For strategies btopt, btultra & btultra2: 405 * Length of Match considered "good enough" to stop search. 406 * Larger values make compression stronger, and slower. 407 * For strategy fast: 408 * Distance between match sampling. 409 * Larger values make compression faster, and weaker. 410 * Special: value 0 means "use default targetLength". */ 411 ZSTD_c_strategy=107, /* See ZSTD_strategy enum definition. 412 * The higher the value of selected strategy, the more complex it is, 413 * resulting in stronger and slower compression. 414 * Special: value 0 means "use default strategy". */ 415 416 ZSTD_c_targetCBlockSize=130, /* v1.5.6+ 417 * Attempts to fit compressed block size into approximately targetCBlockSize. 418 * Bound by ZSTD_TARGETCBLOCKSIZE_MIN and ZSTD_TARGETCBLOCKSIZE_MAX. 419 * Note that it's not a guarantee, just a convergence target (default:0). 420 * No target when targetCBlockSize == 0. 421 * This is helpful in low bandwidth streaming environments to improve end-to-end latency, 422 * when a client can make use of partial documents (a prominent example being Chrome). 423 * Note: this parameter is stable since v1.5.6. 424 * It was present as an experimental parameter in earlier versions, 425 * but it's not recommended using it with earlier library versions 426 * due to massive performance regressions. 427 */ 428 /* LDM mode parameters */ 429 ZSTD_c_enableLongDistanceMatching=160, /* Enable long distance matching. 430 * This parameter is designed to improve compression ratio 431 * for large inputs, by finding large matches at long distance. 432 * It increases memory usage and window size. 433 * Note: enabling this parameter increases default ZSTD_c_windowLog to 128 MB 434 * except when expressly set to a different value. 435 * Note: will be enabled by default if ZSTD_c_windowLog >= 128 MB and 436 * compression strategy >= ZSTD_btopt (== compression level 16+) */ 437 ZSTD_c_ldmHashLog=161, /* Size of the table for long distance matching, as a power of 2. 438 * Larger values increase memory usage and compression ratio, 439 * but decrease compression speed. 440 * Must be clamped between ZSTD_HASHLOG_MIN and ZSTD_HASHLOG_MAX 441 * default: windowlog - 7. 442 * Special: value 0 means "automatically determine hashlog". */ 443 ZSTD_c_ldmMinMatch=162, /* Minimum match size for long distance matcher. 444 * Larger/too small values usually decrease compression ratio. 445 * Must be clamped between ZSTD_LDM_MINMATCH_MIN and ZSTD_LDM_MINMATCH_MAX. 446 * Special: value 0 means "use default value" (default: 64). */ 447 ZSTD_c_ldmBucketSizeLog=163, /* Log size of each bucket in the LDM hash table for collision resolution. 448 * Larger values improve collision resolution but decrease compression speed. 449 * The maximum value is ZSTD_LDM_BUCKETSIZELOG_MAX. 450 * Special: value 0 means "use default value" (default: 3). */ 451 ZSTD_c_ldmHashRateLog=164, /* Frequency of inserting/looking up entries into the LDM hash table. 452 * Must be clamped between 0 and (ZSTD_WINDOWLOG_MAX - ZSTD_HASHLOG_MIN). 453 * Default is MAX(0, (windowLog - ldmHashLog)), optimizing hash table usage. 454 * Larger values improve compression speed. 455 * Deviating far from default value will likely result in a compression ratio decrease. 456 * Special: value 0 means "automatically determine hashRateLog". */ 457 458 /* frame parameters */ 459 ZSTD_c_contentSizeFlag=200, /* Content size will be written into frame header _whenever known_ (default:1) 460 * Content size must be known at the beginning of compression. 461 * This is automatically the case when using ZSTD_compress2(), 462 * For streaming scenarios, content size must be provided with ZSTD_CCtx_setPledgedSrcSize() */ 463 ZSTD_c_checksumFlag=201, /* A 32-bits checksum of content is written at end of frame (default:0) */ 464 ZSTD_c_dictIDFlag=202, /* When applicable, dictionary's ID is written into frame header (default:1) */ 465 466 /* multi-threading parameters */ 467 /* These parameters are only active if multi-threading is enabled (compiled with build macro ZSTD_MULTITHREAD). 468 * Otherwise, trying to set any other value than default (0) will be a no-op and return an error. 469 * In a situation where it's unknown if the linked library supports multi-threading or not, 470 * setting ZSTD_c_nbWorkers to any value >= 1 and consulting the return value provides a quick way to check this property. 471 */ 472 ZSTD_c_nbWorkers=400, /* Select how many threads will be spawned to compress in parallel. 473 * When nbWorkers >= 1, triggers asynchronous mode when invoking ZSTD_compressStream*() : 474 * ZSTD_compressStream*() consumes input and flush output if possible, but immediately gives back control to caller, 475 * while compression is performed in parallel, within worker thread(s). 476 * (note : a strong exception to this rule is when first invocation of ZSTD_compressStream2() sets ZSTD_e_end : 477 * in which case, ZSTD_compressStream2() delegates to ZSTD_compress2(), which is always a blocking call). 478 * More workers improve speed, but also increase memory usage. 479 * Default value is `0`, aka "single-threaded mode" : no worker is spawned, 480 * compression is performed inside Caller's thread, and all invocations are blocking */ 481 ZSTD_c_jobSize=401, /* Size of a compression job. This value is enforced only when nbWorkers >= 1. 482 * Each compression job is completed in parallel, so this value can indirectly impact the nb of active threads. 483 * 0 means default, which is dynamically determined based on compression parameters. 484 * Job size must be a minimum of overlap size, or ZSTDMT_JOBSIZE_MIN (= 512 KB), whichever is largest. 485 * The minimum size is automatically and transparently enforced. */ 486 ZSTD_c_overlapLog=402, /* Control the overlap size, as a fraction of window size. 487 * The overlap size is an amount of data reloaded from previous job at the beginning of a new job. 488 * It helps preserve compression ratio, while each job is compressed in parallel. 489 * This value is enforced only when nbWorkers >= 1. 490 * Larger values increase compression ratio, but decrease speed. 491 * Possible values range from 0 to 9 : 492 * - 0 means "default" : value will be determined by the library, depending on strategy 493 * - 1 means "no overlap" 494 * - 9 means "full overlap", using a full window size. 495 * Each intermediate rank increases/decreases load size by a factor 2 : 496 * 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 497 * default value varies between 6 and 9, depending on strategy */ 498 499 /* note : additional experimental parameters are also available 500 * within the experimental section of the API. 501 * At the time of this writing, they include : 502 * ZSTD_c_rsyncable 503 * ZSTD_c_format 504 * ZSTD_c_forceMaxWindow 505 * ZSTD_c_forceAttachDict 506 * ZSTD_c_literalCompressionMode 507 * ZSTD_c_srcSizeHint 508 * ZSTD_c_enableDedicatedDictSearch 509 * ZSTD_c_stableInBuffer 510 * ZSTD_c_stableOutBuffer 511 * ZSTD_c_blockDelimiters 512 * ZSTD_c_validateSequences 513 * ZSTD_c_blockSplitterLevel 514 * ZSTD_c_splitAfterSequences 515 * ZSTD_c_useRowMatchFinder 516 * ZSTD_c_prefetchCDictTables 517 * ZSTD_c_enableSeqProducerFallback 518 * ZSTD_c_maxBlockSize 519 * Because they are not stable, it's necessary to define ZSTD_STATIC_LINKING_ONLY to access them. 520 * note : never ever use experimentalParam? names directly; 521 * also, the enums values themselves are unstable and can still change. 522 */ 523 ZSTD_c_experimentalParam1=500, 524 ZSTD_c_experimentalParam2=10, 525 ZSTD_c_experimentalParam3=1000, 526 ZSTD_c_experimentalParam4=1001, 527 ZSTD_c_experimentalParam5=1002, 528 /* was ZSTD_c_experimentalParam6=1003; is now ZSTD_c_targetCBlockSize */ 529 ZSTD_c_experimentalParam7=1004, 530 ZSTD_c_experimentalParam8=1005, 531 ZSTD_c_experimentalParam9=1006, 532 ZSTD_c_experimentalParam10=1007, 533 ZSTD_c_experimentalParam11=1008, 534 ZSTD_c_experimentalParam12=1009, 535 ZSTD_c_experimentalParam13=1010, 536 ZSTD_c_experimentalParam14=1011, 537 ZSTD_c_experimentalParam15=1012, 538 ZSTD_c_experimentalParam16=1013, 539 ZSTD_c_experimentalParam17=1014, 540 ZSTD_c_experimentalParam18=1015, 541 ZSTD_c_experimentalParam19=1016, 542 ZSTD_c_experimentalParam20=1017 543 } ZSTD_cParameter; 544 545 typedef struct { 546 size_t error; 547 int lowerBound; 548 int upperBound; 549 } ZSTD_bounds; 550 551 /*! ZSTD_cParam_getBounds() : 552 * All parameters must belong to an interval with lower and upper bounds, 553 * otherwise they will either trigger an error or be automatically clamped. 554 * @return : a structure, ZSTD_bounds, which contains 555 * - an error status field, which must be tested using ZSTD_isError() 556 * - lower and upper bounds, both inclusive 557 */ 558 ZSTDLIB_API ZSTD_bounds ZSTD_cParam_getBounds(ZSTD_cParameter cParam); 559 560 /*! ZSTD_CCtx_setParameter() : 561 * Set one compression parameter, selected by enum ZSTD_cParameter. 562 * All parameters have valid bounds. Bounds can be queried using ZSTD_cParam_getBounds(). 563 * Providing a value beyond bound will either clamp it, or trigger an error (depending on parameter). 564 * Setting a parameter is generally only possible during frame initialization (before starting compression). 565 * Exception : when using multi-threading mode (nbWorkers >= 1), 566 * the following parameters can be updated _during_ compression (within same frame): 567 * => compressionLevel, hashLog, chainLog, searchLog, minMatch, targetLength and strategy. 568 * new parameters will be active for next job only (after a flush()). 569 * @return : an error code (which can be tested using ZSTD_isError()). 570 */ 571 ZSTDLIB_API size_t ZSTD_CCtx_setParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, int value); 572 573 /*! ZSTD_CCtx_setPledgedSrcSize() : 574 * Total input data size to be compressed as a single frame. 575 * Value will be written in frame header, unless if explicitly forbidden using ZSTD_c_contentSizeFlag. 576 * This value will also be controlled at end of frame, and trigger an error if not respected. 577 * @result : 0, or an error code (which can be tested with ZSTD_isError()). 578 * Note 1 : pledgedSrcSize==0 actually means zero, aka an empty frame. 579 * In order to mean "unknown content size", pass constant ZSTD_CONTENTSIZE_UNKNOWN. 580 * ZSTD_CONTENTSIZE_UNKNOWN is default value for any new frame. 581 * Note 2 : pledgedSrcSize is only valid once, for the next frame. 582 * It's discarded at the end of the frame, and replaced by ZSTD_CONTENTSIZE_UNKNOWN. 583 * Note 3 : Whenever all input data is provided and consumed in a single round, 584 * for example with ZSTD_compress2(), 585 * or invoking immediately ZSTD_compressStream2(,,,ZSTD_e_end), 586 * this value is automatically overridden by srcSize instead. 587 */ 588 ZSTDLIB_API size_t ZSTD_CCtx_setPledgedSrcSize(ZSTD_CCtx* cctx, unsigned long long pledgedSrcSize); 589 590 typedef enum { 591 ZSTD_reset_session_only = 1, 592 ZSTD_reset_parameters = 2, 593 ZSTD_reset_session_and_parameters = 3 594 } ZSTD_ResetDirective; 595 596 /*! ZSTD_CCtx_reset() : 597 * There are 2 different things that can be reset, independently or jointly : 598 * - The session : will stop compressing current frame, and make CCtx ready to start a new one. 599 * Useful after an error, or to interrupt any ongoing compression. 600 * Any internal data not yet flushed is cancelled. 601 * Compression parameters and dictionary remain unchanged. 602 * They will be used to compress next frame. 603 * Resetting session never fails. 604 * - The parameters : changes all parameters back to "default". 605 * This also removes any reference to any dictionary or external sequence producer. 606 * Parameters can only be changed between 2 sessions (i.e. no compression is currently ongoing) 607 * otherwise the reset fails, and function returns an error value (which can be tested using ZSTD_isError()) 608 * - Both : similar to resetting the session, followed by resetting parameters. 609 */ 610 ZSTDLIB_API size_t ZSTD_CCtx_reset(ZSTD_CCtx* cctx, ZSTD_ResetDirective reset); 611 612 /*! ZSTD_compress2() : 613 * Behave the same as ZSTD_compressCCtx(), but compression parameters are set using the advanced API. 614 * (note that this entry point doesn't even expose a compression level parameter). 615 * ZSTD_compress2() always starts a new frame. 616 * Should cctx hold data from a previously unfinished frame, everything about it is forgotten. 617 * - Compression parameters are pushed into CCtx before starting compression, using ZSTD_CCtx_set*() 618 * - The function is always blocking, returns when compression is completed. 619 * NOTE: Providing `dstCapacity >= ZSTD_compressBound(srcSize)` guarantees that zstd will have 620 * enough space to successfully compress the data, though it is possible it fails for other reasons. 621 * @return : compressed size written into `dst` (<= `dstCapacity), 622 * or an error code if it fails (which can be tested using ZSTD_isError()). 623 */ 624 ZSTDLIB_API size_t ZSTD_compress2( ZSTD_CCtx* cctx, 625 void* dst, size_t dstCapacity, 626 const void* src, size_t srcSize); 627 628 629 /*********************************************** 630 * Advanced decompression API (Requires v1.4.0+) 631 ************************************************/ 632 633 /* The advanced API pushes parameters one by one into an existing DCtx context. 634 * Parameters are sticky, and remain valid for all following frames 635 * using the same DCtx context. 636 * It's possible to reset parameters to default values using ZSTD_DCtx_reset(). 637 * Note : This API is compatible with existing ZSTD_decompressDCtx() and ZSTD_decompressStream(). 638 * Therefore, no new decompression function is necessary. 639 */ 640 641 typedef enum { 642 643 ZSTD_d_windowLogMax=100, /* Select a size limit (in power of 2) beyond which 644 * the streaming API will refuse to allocate memory buffer 645 * in order to protect the host from unreasonable memory requirements. 646 * This parameter is only useful in streaming mode, since no internal buffer is allocated in single-pass mode. 647 * By default, a decompression context accepts window sizes <= (1 << ZSTD_WINDOWLOG_LIMIT_DEFAULT). 648 * Special: value 0 means "use default maximum windowLog". */ 649 650 /* note : additional experimental parameters are also available 651 * within the experimental section of the API. 652 * At the time of this writing, they include : 653 * ZSTD_d_format 654 * ZSTD_d_stableOutBuffer 655 * ZSTD_d_forceIgnoreChecksum 656 * ZSTD_d_refMultipleDDicts 657 * ZSTD_d_disableHuffmanAssembly 658 * ZSTD_d_maxBlockSize 659 * Because they are not stable, it's necessary to define ZSTD_STATIC_LINKING_ONLY to access them. 660 * note : never ever use experimentalParam? names directly 661 */ 662 ZSTD_d_experimentalParam1=1000, 663 ZSTD_d_experimentalParam2=1001, 664 ZSTD_d_experimentalParam3=1002, 665 ZSTD_d_experimentalParam4=1003, 666 ZSTD_d_experimentalParam5=1004, 667 ZSTD_d_experimentalParam6=1005 668 669 } ZSTD_dParameter; 670 671 /*! ZSTD_dParam_getBounds() : 672 * All parameters must belong to an interval with lower and upper bounds, 673 * otherwise they will either trigger an error or be automatically clamped. 674 * @return : a structure, ZSTD_bounds, which contains 675 * - an error status field, which must be tested using ZSTD_isError() 676 * - both lower and upper bounds, inclusive 677 */ 678 ZSTDLIB_API ZSTD_bounds ZSTD_dParam_getBounds(ZSTD_dParameter dParam); 679 680 /*! ZSTD_DCtx_setParameter() : 681 * Set one compression parameter, selected by enum ZSTD_dParameter. 682 * All parameters have valid bounds. Bounds can be queried using ZSTD_dParam_getBounds(). 683 * Providing a value beyond bound will either clamp it, or trigger an error (depending on parameter). 684 * Setting a parameter is only possible during frame initialization (before starting decompression). 685 * @return : 0, or an error code (which can be tested using ZSTD_isError()). 686 */ 687 ZSTDLIB_API size_t ZSTD_DCtx_setParameter(ZSTD_DCtx* dctx, ZSTD_dParameter param, int value); 688 689 /*! ZSTD_DCtx_reset() : 690 * Return a DCtx to clean state. 691 * Session and parameters can be reset jointly or separately. 692 * Parameters can only be reset when no active frame is being decompressed. 693 * @return : 0, or an error code, which can be tested with ZSTD_isError() 694 */ 695 ZSTDLIB_API size_t ZSTD_DCtx_reset(ZSTD_DCtx* dctx, ZSTD_ResetDirective reset); 696 697 698 /**************************** 699 * Streaming 700 ****************************/ 701 702 typedef struct ZSTD_inBuffer_s { 703 const void* src; /**< start of input buffer */ 704 size_t size; /**< size of input buffer */ 705 size_t pos; /**< position where reading stopped. Will be updated. Necessarily 0 <= pos <= size */ 706 } ZSTD_inBuffer; 707 708 typedef struct ZSTD_outBuffer_s { 709 void* dst; /**< start of output buffer */ 710 size_t size; /**< size of output buffer */ 711 size_t pos; /**< position where writing stopped. Will be updated. Necessarily 0 <= pos <= size */ 712 } ZSTD_outBuffer; 713 714 715 716 /*-*********************************************************************** 717 * Streaming compression - HowTo 718 * 719 * A ZSTD_CStream object is required to track streaming operation. 720 * Use ZSTD_createCStream() and ZSTD_freeCStream() to create/release resources. 721 * ZSTD_CStream objects can be reused multiple times on consecutive compression operations. 722 * It is recommended to reuse ZSTD_CStream since it will play nicer with system's memory, by re-using already allocated memory. 723 * 724 * For parallel execution, use one separate ZSTD_CStream per thread. 725 * 726 * note : since v1.3.0, ZSTD_CStream and ZSTD_CCtx are the same thing. 727 * 728 * Parameters are sticky : when starting a new compression on the same context, 729 * it will reuse the same sticky parameters as previous compression session. 730 * When in doubt, it's recommended to fully initialize the context before usage. 731 * Use ZSTD_CCtx_reset() to reset the context and ZSTD_CCtx_setParameter(), 732 * ZSTD_CCtx_setPledgedSrcSize(), or ZSTD_CCtx_loadDictionary() and friends to 733 * set more specific parameters, the pledged source size, or load a dictionary. 734 * 735 * Use ZSTD_compressStream2() with ZSTD_e_continue as many times as necessary to 736 * consume input stream. The function will automatically update both `pos` 737 * fields within `input` and `output`. 738 * Note that the function may not consume the entire input, for example, because 739 * the output buffer is already full, in which case `input.pos < input.size`. 740 * The caller must check if input has been entirely consumed. 741 * If not, the caller must make some room to receive more compressed data, 742 * and then present again remaining input data. 743 * note: ZSTD_e_continue is guaranteed to make some forward progress when called, 744 * but doesn't guarantee maximal forward progress. This is especially relevant 745 * when compressing with multiple threads. The call won't block if it can 746 * consume some input, but if it can't it will wait for some, but not all, 747 * output to be flushed. 748 * @return : provides a minimum amount of data remaining to be flushed from internal buffers 749 * or an error code, which can be tested using ZSTD_isError(). 750 * 751 * At any moment, it's possible to flush whatever data might remain stuck within internal buffer, 752 * using ZSTD_compressStream2() with ZSTD_e_flush. `output->pos` will be updated. 753 * Note that, if `output->size` is too small, a single invocation with ZSTD_e_flush might not be enough (return code > 0). 754 * In which case, make some room to receive more compressed data, and call again ZSTD_compressStream2() with ZSTD_e_flush. 755 * You must continue calling ZSTD_compressStream2() with ZSTD_e_flush until it returns 0, at which point you can change the 756 * operation. 757 * note: ZSTD_e_flush will flush as much output as possible, meaning when compressing with multiple threads, it will 758 * block until the flush is complete or the output buffer is full. 759 * @return : 0 if internal buffers are entirely flushed, 760 * >0 if some data still present within internal buffer (the value is minimal estimation of remaining size), 761 * or an error code, which can be tested using ZSTD_isError(). 762 * 763 * Calling ZSTD_compressStream2() with ZSTD_e_end instructs to finish a frame. 764 * It will perform a flush and write frame epilogue. 765 * The epilogue is required for decoders to consider a frame completed. 766 * flush operation is the same, and follows same rules as calling ZSTD_compressStream2() with ZSTD_e_flush. 767 * You must continue calling ZSTD_compressStream2() with ZSTD_e_end until it returns 0, at which point you are free to 768 * start a new frame. 769 * note: ZSTD_e_end will flush as much output as possible, meaning when compressing with multiple threads, it will 770 * block until the flush is complete or the output buffer is full. 771 * @return : 0 if frame fully completed and fully flushed, 772 * >0 if some data still present within internal buffer (the value is minimal estimation of remaining size), 773 * or an error code, which can be tested using ZSTD_isError(). 774 * 775 * *******************************************************************/ 776 777 typedef ZSTD_CCtx ZSTD_CStream; /**< CCtx and CStream are now effectively same object (>= v1.3.0) */ 778 /* Continue to distinguish them for compatibility with older versions <= v1.2.0 */ 779 /*===== ZSTD_CStream management functions =====*/ 780 ZSTDLIB_API ZSTD_CStream* ZSTD_createCStream(void); 781 ZSTDLIB_API size_t ZSTD_freeCStream(ZSTD_CStream* zcs); /* accept NULL pointer */ 782 783 /*===== Streaming compression functions =====*/ 784 typedef enum { 785 ZSTD_e_continue=0, /* collect more data, encoder decides when to output compressed result, for optimal compression ratio */ 786 ZSTD_e_flush=1, /* flush any data provided so far, 787 * it creates (at least) one new block, that can be decoded immediately on reception; 788 * frame will continue: any future data can still reference previously compressed data, improving compression. 789 * note : multithreaded compression will block to flush as much output as possible. */ 790 ZSTD_e_end=2 /* flush any remaining data _and_ close current frame. 791 * note that frame is only closed after compressed data is fully flushed (return value == 0). 792 * After that point, any additional data starts a new frame. 793 * note : each frame is independent (does not reference any content from previous frame). 794 : note : multithreaded compression will block to flush as much output as possible. */ 795 } ZSTD_EndDirective; 796 797 /*! ZSTD_compressStream2() : Requires v1.4.0+ 798 * Behaves about the same as ZSTD_compressStream, with additional control on end directive. 799 * - Compression parameters are pushed into CCtx before starting compression, using ZSTD_CCtx_set*() 800 * - Compression parameters cannot be changed once compression is started (save a list of exceptions in multi-threading mode) 801 * - output->pos must be <= dstCapacity, input->pos must be <= srcSize 802 * - output->pos and input->pos will be updated. They are guaranteed to remain below their respective limit. 803 * - endOp must be a valid directive 804 * - When nbWorkers==0 (default), function is blocking : it completes its job before returning to caller. 805 * - When nbWorkers>=1, function is non-blocking : it copies a portion of input, distributes jobs to internal worker threads, flush to output whatever is available, 806 * and then immediately returns, just indicating that there is some data remaining to be flushed. 807 * The function nonetheless guarantees forward progress : it will return only after it reads or write at least 1+ byte. 808 * - 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. 809 * - @return provides a minimum amount of data remaining to be flushed from internal buffers 810 * or an error code, which can be tested using ZSTD_isError(). 811 * if @return != 0, flush is not fully completed, there is still some data left within internal buffers. 812 * This is useful for ZSTD_e_flush, since in this case more flushes are necessary to empty all buffers. 813 * For ZSTD_e_end, @return == 0 when internal buffers are fully flushed and frame is completed. 814 * - after a ZSTD_e_end directive, if internal buffer is not fully flushed (@return != 0), 815 * only ZSTD_e_end or ZSTD_e_flush operations are allowed. 816 * Before starting a new compression job, or changing compression parameters, 817 * it is required to fully flush internal buffers. 818 * - note: if an operation ends with an error, it may leave @cctx in an undefined state. 819 * Therefore, it's UB to invoke ZSTD_compressStream2() of ZSTD_compressStream() on such a state. 820 * In order to be re-employed after an error, a state must be reset, 821 * which can be done explicitly (ZSTD_CCtx_reset()), 822 * or is sometimes implied by methods starting a new compression job (ZSTD_initCStream(), ZSTD_compressCCtx()) 823 */ 824 ZSTDLIB_API size_t ZSTD_compressStream2( ZSTD_CCtx* cctx, 825 ZSTD_outBuffer* output, 826 ZSTD_inBuffer* input, 827 ZSTD_EndDirective endOp); 828 829 830 /* These buffer sizes are softly recommended. 831 * They are not required : ZSTD_compressStream*() happily accepts any buffer size, for both input and output. 832 * Respecting the recommended size just makes it a bit easier for ZSTD_compressStream*(), 833 * reducing the amount of memory shuffling and buffering, resulting in minor performance savings. 834 * 835 * However, note that these recommendations are from the perspective of a C caller program. 836 * If the streaming interface is invoked from some other language, 837 * especially managed ones such as Java or Go, through a foreign function interface such as jni or cgo, 838 * a major performance rule is to reduce crossing such interface to an absolute minimum. 839 * It's not rare that performance ends being spent more into the interface, rather than compression itself. 840 * In which cases, prefer using large buffers, as large as practical, 841 * for both input and output, to reduce the nb of roundtrips. 842 */ 843 ZSTDLIB_API size_t ZSTD_CStreamInSize(void); /**< recommended size for input buffer */ 844 ZSTDLIB_API size_t ZSTD_CStreamOutSize(void); /**< recommended size for output buffer. Guarantee to successfully flush at least one complete compressed block. */ 845 846 847 /* ***************************************************************************** 848 * This following is a legacy streaming API, available since v1.0+ . 849 * It can be replaced by ZSTD_CCtx_reset() and ZSTD_compressStream2(). 850 * It is redundant, but remains fully supported. 851 ******************************************************************************/ 852 853 /*! 854 * Equivalent to: 855 * 856 * ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only); 857 * ZSTD_CCtx_refCDict(zcs, NULL); // clear the dictionary (if any) 858 * ZSTD_CCtx_setParameter(zcs, ZSTD_c_compressionLevel, compressionLevel); 859 * 860 * Note that ZSTD_initCStream() clears any previously set dictionary. Use the new API 861 * to compress with a dictionary. 862 */ 863 ZSTDLIB_API size_t ZSTD_initCStream(ZSTD_CStream* zcs, int compressionLevel); 864 /*! 865 * Alternative for ZSTD_compressStream2(zcs, output, input, ZSTD_e_continue). 866 * NOTE: The return value is different. ZSTD_compressStream() returns a hint for 867 * the next read size (if non-zero and not an error). ZSTD_compressStream2() 868 * returns the minimum nb of bytes left to flush (if non-zero and not an error). 869 */ 870 ZSTDLIB_API size_t ZSTD_compressStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output, ZSTD_inBuffer* input); 871 /*! Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_flush). */ 872 ZSTDLIB_API size_t ZSTD_flushStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output); 873 /*! Equivalent to ZSTD_compressStream2(zcs, output, &emptyInput, ZSTD_e_end). */ 874 ZSTDLIB_API size_t ZSTD_endStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output); 875 876 877 /*-*************************************************************************** 878 * Streaming decompression - HowTo 879 * 880 * A ZSTD_DStream object is required to track streaming operations. 881 * Use ZSTD_createDStream() and ZSTD_freeDStream() to create/release resources. 882 * ZSTD_DStream objects can be re-employed multiple times. 883 * 884 * Use ZSTD_initDStream() to start a new decompression operation. 885 * @return : recommended first input size 886 * Alternatively, use advanced API to set specific properties. 887 * 888 * Use ZSTD_decompressStream() repetitively to consume your input. 889 * The function will update both `pos` fields. 890 * If `input.pos < input.size`, some input has not been consumed. 891 * It's up to the caller to present again remaining data. 892 * 893 * The function tries to flush all data decoded immediately, respecting output buffer size. 894 * If `output.pos < output.size`, decoder has flushed everything it could. 895 * 896 * However, when `output.pos == output.size`, it's more difficult to know. 897 * If @return > 0, the frame is not complete, meaning 898 * either there is still some data left to flush within internal buffers, 899 * or there is more input to read to complete the frame (or both). 900 * In which case, call ZSTD_decompressStream() again to flush whatever remains in the buffer. 901 * Note : with no additional input provided, amount of data flushed is necessarily <= ZSTD_BLOCKSIZE_MAX. 902 * @return : 0 when a frame is completely decoded and fully flushed, 903 * or an error code, which can be tested using ZSTD_isError(), 904 * or any other value > 0, which means there is still some decoding or flushing to do to complete current frame : 905 * the return value is a suggested next input size (just a hint for better latency) 906 * that will never request more than the remaining content of the compressed frame. 907 * *******************************************************************************/ 908 909 typedef ZSTD_DCtx ZSTD_DStream; /**< DCtx and DStream are now effectively same object (>= v1.3.0) */ 910 /* For compatibility with versions <= v1.2.0, prefer differentiating them. */ 911 /*===== ZSTD_DStream management functions =====*/ 912 ZSTDLIB_API ZSTD_DStream* ZSTD_createDStream(void); 913 ZSTDLIB_API size_t ZSTD_freeDStream(ZSTD_DStream* zds); /* accept NULL pointer */ 914 915 /*===== Streaming decompression functions =====*/ 916 917 /*! ZSTD_initDStream() : 918 * Initialize/reset DStream state for new decompression operation. 919 * Call before new decompression operation using same DStream. 920 * 921 * Note : This function is redundant with the advanced API and equivalent to: 922 * ZSTD_DCtx_reset(zds, ZSTD_reset_session_only); 923 * ZSTD_DCtx_refDDict(zds, NULL); 924 */ 925 ZSTDLIB_API size_t ZSTD_initDStream(ZSTD_DStream* zds); 926 927 /*! ZSTD_decompressStream() : 928 * Streaming decompression function. 929 * Call repetitively to consume full input updating it as necessary. 930 * Function will update both input and output `pos` fields exposing current state via these fields: 931 * - `input.pos < input.size`, some input remaining and caller should provide remaining input 932 * on the next call. 933 * - `output.pos < output.size`, decoder flushed internal output buffer. 934 * - `output.pos == output.size`, unflushed data potentially present in the internal buffers, 935 * check ZSTD_decompressStream() @return value, 936 * if > 0, invoke it again to flush remaining data to output. 937 * Note : with no additional input, amount of data flushed <= ZSTD_BLOCKSIZE_MAX. 938 * 939 * @return : 0 when a frame is completely decoded and fully flushed, 940 * or an error code, which can be tested using ZSTD_isError(), 941 * or any other value > 0, which means there is some decoding or flushing to do to complete current frame. 942 * 943 * Note: when an operation returns with an error code, the @zds state may be left in undefined state. 944 * It's UB to invoke `ZSTD_decompressStream()` on such a state. 945 * In order to re-use such a state, it must be first reset, 946 * which can be done explicitly (`ZSTD_DCtx_reset()`), 947 * or is implied for operations starting some new decompression job (`ZSTD_initDStream`, `ZSTD_decompressDCtx()`, `ZSTD_decompress_usingDict()`) 948 */ 949 ZSTDLIB_API size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inBuffer* input); 950 951 ZSTDLIB_API size_t ZSTD_DStreamInSize(void); /*!< recommended size for input buffer */ 952 ZSTDLIB_API size_t ZSTD_DStreamOutSize(void); /*!< recommended size for output buffer. Guarantee to successfully flush at least one complete block in all circumstances. */ 953 954 955 /************************** 956 * Simple dictionary API 957 ***************************/ 958 /*! ZSTD_compress_usingDict() : 959 * Compression at an explicit compression level using a Dictionary. 960 * A dictionary can be any arbitrary data segment (also called a prefix), 961 * or a buffer with specified information (see zdict.h). 962 * Note : This function loads the dictionary, resulting in significant startup delay. 963 * It's intended for a dictionary used only once. 964 * Note 2 : When `dict == NULL || dictSize < 8` no dictionary is used. */ 965 ZSTDLIB_API size_t ZSTD_compress_usingDict(ZSTD_CCtx* ctx, 966 void* dst, size_t dstCapacity, 967 const void* src, size_t srcSize, 968 const void* dict,size_t dictSize, 969 int compressionLevel); 970 971 /*! ZSTD_decompress_usingDict() : 972 * Decompression using a known Dictionary. 973 * Dictionary must be identical to the one used during compression. 974 * Note : This function loads the dictionary, resulting in significant startup delay. 975 * It's intended for a dictionary used only once. 976 * Note : When `dict == NULL || dictSize < 8` no dictionary is used. */ 977 ZSTDLIB_API size_t ZSTD_decompress_usingDict(ZSTD_DCtx* dctx, 978 void* dst, size_t dstCapacity, 979 const void* src, size_t srcSize, 980 const void* dict,size_t dictSize); 981 982 983 /*********************************** 984 * Bulk processing dictionary API 985 **********************************/ 986 typedef struct ZSTD_CDict_s ZSTD_CDict; 987 988 /*! ZSTD_createCDict() : 989 * When compressing multiple messages or blocks using the same dictionary, 990 * it's recommended to digest the dictionary only once, since it's a costly operation. 991 * ZSTD_createCDict() will create a state from digesting a dictionary. 992 * The resulting state can be used for future compression operations with very limited startup cost. 993 * ZSTD_CDict can be created once and shared by multiple threads concurrently, since its usage is read-only. 994 * @dictBuffer can be released after ZSTD_CDict creation, because its content is copied within CDict. 995 * Note 1 : Consider experimental function `ZSTD_createCDict_byReference()` if you prefer to not duplicate @dictBuffer content. 996 * Note 2 : A ZSTD_CDict can be created from an empty @dictBuffer, 997 * in which case the only thing that it transports is the @compressionLevel. 998 * This can be useful in a pipeline featuring ZSTD_compress_usingCDict() exclusively, 999 * expecting a ZSTD_CDict parameter with any data, including those without a known dictionary. */ 1000 ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict(const void* dictBuffer, size_t dictSize, 1001 int compressionLevel); 1002 1003 /*! ZSTD_freeCDict() : 1004 * Function frees memory allocated by ZSTD_createCDict(). 1005 * If a NULL pointer is passed, no operation is performed. */ 1006 ZSTDLIB_API size_t ZSTD_freeCDict(ZSTD_CDict* CDict); 1007 1008 /*! ZSTD_compress_usingCDict() : 1009 * Compression using a digested Dictionary. 1010 * Recommended when same dictionary is used multiple times. 1011 * Note : compression level is _decided at dictionary creation time_, 1012 * and frame parameters are hardcoded (dictID=yes, contentSize=yes, checksum=no) */ 1013 ZSTDLIB_API size_t ZSTD_compress_usingCDict(ZSTD_CCtx* cctx, 1014 void* dst, size_t dstCapacity, 1015 const void* src, size_t srcSize, 1016 const ZSTD_CDict* cdict); 1017 1018 1019 typedef struct ZSTD_DDict_s ZSTD_DDict; 1020 1021 /*! ZSTD_createDDict() : 1022 * Create a digested dictionary, ready to start decompression operation without startup delay. 1023 * dictBuffer can be released after DDict creation, as its content is copied inside DDict. */ 1024 ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict(const void* dictBuffer, size_t dictSize); 1025 1026 /*! ZSTD_freeDDict() : 1027 * Function frees memory allocated with ZSTD_createDDict() 1028 * If a NULL pointer is passed, no operation is performed. */ 1029 ZSTDLIB_API size_t ZSTD_freeDDict(ZSTD_DDict* ddict); 1030 1031 /*! ZSTD_decompress_usingDDict() : 1032 * Decompression using a digested Dictionary. 1033 * Recommended when same dictionary is used multiple times. */ 1034 ZSTDLIB_API size_t ZSTD_decompress_usingDDict(ZSTD_DCtx* dctx, 1035 void* dst, size_t dstCapacity, 1036 const void* src, size_t srcSize, 1037 const ZSTD_DDict* ddict); 1038 1039 1040 /******************************** 1041 * Dictionary helper functions 1042 *******************************/ 1043 1044 /*! ZSTD_getDictID_fromDict() : Requires v1.4.0+ 1045 * Provides the dictID stored within dictionary. 1046 * if @return == 0, the dictionary is not conformant with Zstandard specification. 1047 * It can still be loaded, but as a content-only dictionary. */ 1048 ZSTDLIB_API unsigned ZSTD_getDictID_fromDict(const void* dict, size_t dictSize); 1049 1050 /*! ZSTD_getDictID_fromCDict() : Requires v1.5.0+ 1051 * Provides the dictID of the dictionary loaded into `cdict`. 1052 * If @return == 0, the dictionary is not conformant to Zstandard specification, or empty. 1053 * Non-conformant dictionaries can still be loaded, but as content-only dictionaries. */ 1054 ZSTDLIB_API unsigned ZSTD_getDictID_fromCDict(const ZSTD_CDict* cdict); 1055 1056 /*! ZSTD_getDictID_fromDDict() : Requires v1.4.0+ 1057 * Provides the dictID of the dictionary loaded into `ddict`. 1058 * If @return == 0, the dictionary is not conformant to Zstandard specification, or empty. 1059 * Non-conformant dictionaries can still be loaded, but as content-only dictionaries. */ 1060 ZSTDLIB_API unsigned ZSTD_getDictID_fromDDict(const ZSTD_DDict* ddict); 1061 1062 /*! ZSTD_getDictID_fromFrame() : Requires v1.4.0+ 1063 * Provides the dictID required to decompressed the frame stored within `src`. 1064 * If @return == 0, the dictID could not be decoded. 1065 * This could for one of the following reasons : 1066 * - The frame does not require a dictionary to be decoded (most common case). 1067 * - The frame was built with dictID intentionally removed. Whatever dictionary is necessary is a hidden piece of information. 1068 * Note : this use case also happens when using a non-conformant dictionary. 1069 * - `srcSize` is too small, and as a result, the frame header could not be decoded (only possible if `srcSize < ZSTD_FRAMEHEADERSIZE_MAX`). 1070 * - This is not a Zstandard frame. 1071 * When identifying the exact failure cause, it's possible to use ZSTD_getFrameHeader(), which will provide a more precise error code. */ 1072 ZSTDLIB_API unsigned ZSTD_getDictID_fromFrame(const void* src, size_t srcSize); 1073 1074 1075 /******************************************************************************* 1076 * Advanced dictionary and prefix API (Requires v1.4.0+) 1077 * 1078 * This API allows dictionaries to be used with ZSTD_compress2(), 1079 * ZSTD_compressStream2(), and ZSTD_decompressDCtx(). 1080 * Dictionaries are sticky, they remain valid when same context is reused, 1081 * they only reset when the context is reset 1082 * with ZSTD_reset_parameters or ZSTD_reset_session_and_parameters. 1083 * In contrast, Prefixes are single-use. 1084 ******************************************************************************/ 1085 1086 1087 /*! ZSTD_CCtx_loadDictionary() : Requires v1.4.0+ 1088 * Create an internal CDict from `dict` buffer. 1089 * Decompression will have to use same dictionary. 1090 * @result : 0, or an error code (which can be tested with ZSTD_isError()). 1091 * Special: Loading a NULL (or 0-size) dictionary invalidates previous dictionary, 1092 * meaning "return to no-dictionary mode". 1093 * Note 1 : Dictionary is sticky, it will be used for all future compressed frames, 1094 * until parameters are reset, a new dictionary is loaded, or the dictionary 1095 * is explicitly invalidated by loading a NULL dictionary. 1096 * Note 2 : Loading a dictionary involves building tables. 1097 * It's also a CPU consuming operation, with non-negligible impact on latency. 1098 * Tables are dependent on compression parameters, and for this reason, 1099 * compression parameters can no longer be changed after loading a dictionary. 1100 * Note 3 :`dict` content will be copied internally. 1101 * Use experimental ZSTD_CCtx_loadDictionary_byReference() to reference content instead. 1102 * In such a case, dictionary buffer must outlive its users. 1103 * Note 4 : Use ZSTD_CCtx_loadDictionary_advanced() 1104 * to precisely select how dictionary content must be interpreted. 1105 * Note 5 : This method does not benefit from LDM (long distance mode). 1106 * If you want to employ LDM on some large dictionary content, 1107 * prefer employing ZSTD_CCtx_refPrefix() described below. 1108 */ 1109 ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary(ZSTD_CCtx* cctx, const void* dict, size_t dictSize); 1110 1111 /*! ZSTD_CCtx_refCDict() : Requires v1.4.0+ 1112 * Reference a prepared dictionary, to be used for all future compressed frames. 1113 * Note that compression parameters are enforced from within CDict, 1114 * and supersede any compression parameter previously set within CCtx. 1115 * The parameters ignored are labelled as "superseded-by-cdict" in the ZSTD_cParameter enum docs. 1116 * The ignored parameters will be used again if the CCtx is returned to no-dictionary mode. 1117 * The dictionary will remain valid for future compressed frames using same CCtx. 1118 * @result : 0, or an error code (which can be tested with ZSTD_isError()). 1119 * Special : Referencing a NULL CDict means "return to no-dictionary mode". 1120 * Note 1 : Currently, only one dictionary can be managed. 1121 * Referencing a new dictionary effectively "discards" any previous one. 1122 * Note 2 : CDict is just referenced, its lifetime must outlive its usage within CCtx. */ 1123 ZSTDLIB_API size_t ZSTD_CCtx_refCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict); 1124 1125 /*! ZSTD_CCtx_refPrefix() : Requires v1.4.0+ 1126 * Reference a prefix (single-usage dictionary) for next compressed frame. 1127 * A prefix is **only used once**. Tables are discarded at end of frame (ZSTD_e_end). 1128 * Decompression will need same prefix to properly regenerate data. 1129 * Compressing with a prefix is similar in outcome as performing a diff and compressing it, 1130 * but performs much faster, especially during decompression (compression speed is tunable with compression level). 1131 * This method is compatible with LDM (long distance mode). 1132 * @result : 0, or an error code (which can be tested with ZSTD_isError()). 1133 * Special: Adding any prefix (including NULL) invalidates any previous prefix or dictionary 1134 * Note 1 : Prefix buffer is referenced. It **must** outlive compression. 1135 * Its content must remain unmodified during compression. 1136 * Note 2 : If the intention is to diff some large src data blob with some prior version of itself, 1137 * ensure that the window size is large enough to contain the entire source. 1138 * See ZSTD_c_windowLog. 1139 * Note 3 : Referencing a prefix involves building tables, which are dependent on compression parameters. 1140 * It's a CPU consuming operation, with non-negligible impact on latency. 1141 * If there is a need to use the same prefix multiple times, consider loadDictionary instead. 1142 * Note 4 : By default, the prefix is interpreted as raw content (ZSTD_dct_rawContent). 1143 * Use experimental ZSTD_CCtx_refPrefix_advanced() to alter dictionary interpretation. */ 1144 ZSTDLIB_API size_t ZSTD_CCtx_refPrefix(ZSTD_CCtx* cctx, 1145 const void* prefix, size_t prefixSize); 1146 1147 /*! ZSTD_DCtx_loadDictionary() : Requires v1.4.0+ 1148 * Create an internal DDict from dict buffer, to be used to decompress all future frames. 1149 * The dictionary remains valid for all future frames, until explicitly invalidated, or 1150 * a new dictionary is loaded. 1151 * @result : 0, or an error code (which can be tested with ZSTD_isError()). 1152 * Special : Adding a NULL (or 0-size) dictionary invalidates any previous dictionary, 1153 * meaning "return to no-dictionary mode". 1154 * Note 1 : Loading a dictionary involves building tables, 1155 * which has a non-negligible impact on CPU usage and latency. 1156 * It's recommended to "load once, use many times", to amortize the cost 1157 * Note 2 :`dict` content will be copied internally, so `dict` can be released after loading. 1158 * Use ZSTD_DCtx_loadDictionary_byReference() to reference dictionary content instead. 1159 * Note 3 : Use ZSTD_DCtx_loadDictionary_advanced() to take control of 1160 * how dictionary content is loaded and interpreted. 1161 */ 1162 ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary(ZSTD_DCtx* dctx, const void* dict, size_t dictSize); 1163 1164 /*! ZSTD_DCtx_refDDict() : Requires v1.4.0+ 1165 * Reference a prepared dictionary, to be used to decompress next frames. 1166 * The dictionary remains active for decompression of future frames using same DCtx. 1167 * 1168 * If called with ZSTD_d_refMultipleDDicts enabled, repeated calls of this function 1169 * will store the DDict references in a table, and the DDict used for decompression 1170 * will be determined at decompression time, as per the dict ID in the frame. 1171 * The memory for the table is allocated on the first call to refDDict, and can be 1172 * freed with ZSTD_freeDCtx(). 1173 * 1174 * If called with ZSTD_d_refMultipleDDicts disabled (the default), only one dictionary 1175 * will be managed, and referencing a dictionary effectively "discards" any previous one. 1176 * 1177 * @result : 0, or an error code (which can be tested with ZSTD_isError()). 1178 * Special: referencing a NULL DDict means "return to no-dictionary mode". 1179 * Note 2 : DDict is just referenced, its lifetime must outlive its usage from DCtx. 1180 */ 1181 ZSTDLIB_API size_t ZSTD_DCtx_refDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict); 1182 1183 /*! ZSTD_DCtx_refPrefix() : Requires v1.4.0+ 1184 * Reference a prefix (single-usage dictionary) to decompress next frame. 1185 * This is the reverse operation of ZSTD_CCtx_refPrefix(), 1186 * and must use the same prefix as the one used during compression. 1187 * Prefix is **only used once**. Reference is discarded at end of frame. 1188 * End of frame is reached when ZSTD_decompressStream() returns 0. 1189 * @result : 0, or an error code (which can be tested with ZSTD_isError()). 1190 * Note 1 : Adding any prefix (including NULL) invalidates any previously set prefix or dictionary 1191 * Note 2 : Prefix buffer is referenced. It **must** outlive decompression. 1192 * Prefix buffer must remain unmodified up to the end of frame, 1193 * reached when ZSTD_decompressStream() returns 0. 1194 * Note 3 : By default, the prefix is treated as raw content (ZSTD_dct_rawContent). 1195 * Use ZSTD_CCtx_refPrefix_advanced() to alter dictMode (Experimental section) 1196 * Note 4 : Referencing a raw content prefix has almost no cpu nor memory cost. 1197 * A full dictionary is more costly, as it requires building tables. 1198 */ 1199 ZSTDLIB_API size_t ZSTD_DCtx_refPrefix(ZSTD_DCtx* dctx, 1200 const void* prefix, size_t prefixSize); 1201 1202 /* === Memory management === */ 1203 1204 /*! ZSTD_sizeof_*() : Requires v1.4.0+ 1205 * These functions give the _current_ memory usage of selected object. 1206 * Note that object memory usage can evolve (increase or decrease) over time. */ 1207 ZSTDLIB_API size_t ZSTD_sizeof_CCtx(const ZSTD_CCtx* cctx); 1208 ZSTDLIB_API size_t ZSTD_sizeof_DCtx(const ZSTD_DCtx* dctx); 1209 ZSTDLIB_API size_t ZSTD_sizeof_CStream(const ZSTD_CStream* zcs); 1210 ZSTDLIB_API size_t ZSTD_sizeof_DStream(const ZSTD_DStream* zds); 1211 ZSTDLIB_API size_t ZSTD_sizeof_CDict(const ZSTD_CDict* cdict); 1212 ZSTDLIB_API size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict); 1213 1214 #if defined (__cplusplus) 1215 } 1216 #endif 1217 1218 #endif /* ZSTD_H_235446 */ 1219 1220 1221 /* ************************************************************************************** 1222 * ADVANCED AND EXPERIMENTAL FUNCTIONS 1223 **************************************************************************************** 1224 * The definitions in the following section are considered experimental. 1225 * They are provided for advanced scenarios. 1226 * They should never be used with a dynamic library, as prototypes may change in the future. 1227 * Use them only in association with static linking. 1228 * ***************************************************************************************/ 1229 1230 #if defined(ZSTD_STATIC_LINKING_ONLY) && !defined(ZSTD_H_ZSTD_STATIC_LINKING_ONLY) 1231 #define ZSTD_H_ZSTD_STATIC_LINKING_ONLY 1232 1233 #if defined (__cplusplus) 1234 extern "C" { 1235 #endif 1236 1237 /* This can be overridden externally to hide static symbols. */ 1238 #ifndef ZSTDLIB_STATIC_API 1239 # if defined(ZSTD_DLL_EXPORT) && (ZSTD_DLL_EXPORT==1) 1240 # define ZSTDLIB_STATIC_API __declspec(dllexport) ZSTDLIB_VISIBLE 1241 # elif defined(ZSTD_DLL_IMPORT) && (ZSTD_DLL_IMPORT==1) 1242 # define ZSTDLIB_STATIC_API __declspec(dllimport) ZSTDLIB_VISIBLE 1243 # else 1244 # define ZSTDLIB_STATIC_API ZSTDLIB_VISIBLE 1245 # endif 1246 #endif 1247 1248 /**************************************************************************************** 1249 * experimental API (static linking only) 1250 **************************************************************************************** 1251 * The following symbols and constants 1252 * are not planned to join "stable API" status in the near future. 1253 * They can still change in future versions. 1254 * Some of them are planned to remain in the static_only section indefinitely. 1255 * Some of them might be removed in the future (especially when redundant with existing stable functions) 1256 * ***************************************************************************************/ 1257 1258 #define ZSTD_FRAMEHEADERSIZE_PREFIX(format) ((format) == ZSTD_f_zstd1 ? 5 : 1) /* minimum input size required to query frame header size */ 1259 #define ZSTD_FRAMEHEADERSIZE_MIN(format) ((format) == ZSTD_f_zstd1 ? 6 : 2) 1260 #define ZSTD_FRAMEHEADERSIZE_MAX 18 /* can be useful for static allocation */ 1261 #define ZSTD_SKIPPABLEHEADERSIZE 8 1262 1263 /* compression parameter bounds */ 1264 #define ZSTD_WINDOWLOG_MAX_32 30 1265 #define ZSTD_WINDOWLOG_MAX_64 31 1266 #define ZSTD_WINDOWLOG_MAX ((int)(sizeof(size_t) == 4 ? ZSTD_WINDOWLOG_MAX_32 : ZSTD_WINDOWLOG_MAX_64)) 1267 #define ZSTD_WINDOWLOG_MIN 10 1268 #define ZSTD_HASHLOG_MAX ((ZSTD_WINDOWLOG_MAX < 30) ? ZSTD_WINDOWLOG_MAX : 30) 1269 #define ZSTD_HASHLOG_MIN 6 1270 #define ZSTD_CHAINLOG_MAX_32 29 1271 #define ZSTD_CHAINLOG_MAX_64 30 1272 #define ZSTD_CHAINLOG_MAX ((int)(sizeof(size_t) == 4 ? ZSTD_CHAINLOG_MAX_32 : ZSTD_CHAINLOG_MAX_64)) 1273 #define ZSTD_CHAINLOG_MIN ZSTD_HASHLOG_MIN 1274 #define ZSTD_SEARCHLOG_MAX (ZSTD_WINDOWLOG_MAX-1) 1275 #define ZSTD_SEARCHLOG_MIN 1 1276 #define ZSTD_MINMATCH_MAX 7 /* only for ZSTD_fast, other strategies are limited to 6 */ 1277 #define ZSTD_MINMATCH_MIN 3 /* only for ZSTD_btopt+, faster strategies are limited to 4 */ 1278 #define ZSTD_TARGETLENGTH_MAX ZSTD_BLOCKSIZE_MAX 1279 #define ZSTD_TARGETLENGTH_MIN 0 /* note : comparing this constant to an unsigned results in a tautological test */ 1280 #define ZSTD_STRATEGY_MIN ZSTD_fast 1281 #define ZSTD_STRATEGY_MAX ZSTD_btultra2 1282 #define ZSTD_BLOCKSIZE_MAX_MIN (1 << 10) /* The minimum valid max blocksize. Maximum blocksizes smaller than this make compressBound() inaccurate. */ 1283 1284 1285 #define ZSTD_OVERLAPLOG_MIN 0 1286 #define ZSTD_OVERLAPLOG_MAX 9 1287 1288 #define ZSTD_WINDOWLOG_LIMIT_DEFAULT 27 /* by default, the streaming decoder will refuse any frame 1289 * requiring larger than (1<<ZSTD_WINDOWLOG_LIMIT_DEFAULT) window size, 1290 * to preserve host's memory from unreasonable requirements. 1291 * This limit can be overridden using ZSTD_DCtx_setParameter(,ZSTD_d_windowLogMax,). 1292 * The limit does not apply for one-pass decoders (such as ZSTD_decompress()), since no additional memory is allocated */ 1293 1294 1295 /* LDM parameter bounds */ 1296 #define ZSTD_LDM_HASHLOG_MIN ZSTD_HASHLOG_MIN 1297 #define ZSTD_LDM_HASHLOG_MAX ZSTD_HASHLOG_MAX 1298 #define ZSTD_LDM_MINMATCH_MIN 4 1299 #define ZSTD_LDM_MINMATCH_MAX 4096 1300 #define ZSTD_LDM_BUCKETSIZELOG_MIN 1 1301 #define ZSTD_LDM_BUCKETSIZELOG_MAX 8 1302 #define ZSTD_LDM_HASHRATELOG_MIN 0 1303 #define ZSTD_LDM_HASHRATELOG_MAX (ZSTD_WINDOWLOG_MAX - ZSTD_HASHLOG_MIN) 1304 1305 /* Advanced parameter bounds */ 1306 #define ZSTD_TARGETCBLOCKSIZE_MIN 1340 /* suitable to fit into an ethernet / wifi / 4G transport frame */ 1307 #define ZSTD_TARGETCBLOCKSIZE_MAX ZSTD_BLOCKSIZE_MAX 1308 #define ZSTD_SRCSIZEHINT_MIN 0 1309 #define ZSTD_SRCSIZEHINT_MAX INT_MAX 1310 1311 1312 /* --- Advanced types --- */ 1313 1314 typedef struct ZSTD_CCtx_params_s ZSTD_CCtx_params; 1315 1316 typedef struct { 1317 unsigned int offset; /* The offset of the match. (NOT the same as the offset code) 1318 * If offset == 0 and matchLength == 0, this sequence represents the last 1319 * literals in the block of litLength size. 1320 */ 1321 1322 unsigned int litLength; /* Literal length of the sequence. */ 1323 unsigned int matchLength; /* Match length of the sequence. */ 1324 1325 /* Note: Users of this API may provide a sequence with matchLength == litLength == offset == 0. 1326 * In this case, we will treat the sequence as a marker for a block boundary. 1327 */ 1328 1329 unsigned int rep; /* Represents which repeat offset is represented by the field 'offset'. 1330 * Ranges from [0, 3]. 1331 * 1332 * Repeat offsets are essentially previous offsets from previous sequences sorted in 1333 * recency order. For more detail, see doc/zstd_compression_format.md 1334 * 1335 * If rep == 0, then 'offset' does not contain a repeat offset. 1336 * If rep > 0: 1337 * If litLength != 0: 1338 * rep == 1 --> offset == repeat_offset_1 1339 * rep == 2 --> offset == repeat_offset_2 1340 * rep == 3 --> offset == repeat_offset_3 1341 * If litLength == 0: 1342 * rep == 1 --> offset == repeat_offset_2 1343 * rep == 2 --> offset == repeat_offset_3 1344 * rep == 3 --> offset == repeat_offset_1 - 1 1345 * 1346 * Note: This field is optional. ZSTD_generateSequences() will calculate the value of 1347 * 'rep', but repeat offsets do not necessarily need to be calculated from an external 1348 * sequence provider perspective. For example, ZSTD_compressSequences() does not 1349 * use this 'rep' field at all (as of now). 1350 */ 1351 } ZSTD_Sequence; 1352 1353 typedef struct { 1354 unsigned windowLog; /**< largest match distance : larger == more compression, more memory needed during decompression */ 1355 unsigned chainLog; /**< fully searched segment : larger == more compression, slower, more memory (useless for fast) */ 1356 unsigned hashLog; /**< dispatch table : larger == faster, more memory */ 1357 unsigned searchLog; /**< nb of searches : larger == more compression, slower */ 1358 unsigned minMatch; /**< match length searched : larger == faster decompression, sometimes less compression */ 1359 unsigned targetLength; /**< acceptable match size for optimal parser (only) : larger == more compression, slower */ 1360 ZSTD_strategy strategy; /**< see ZSTD_strategy definition above */ 1361 } ZSTD_compressionParameters; 1362 1363 typedef struct { 1364 int contentSizeFlag; /**< 1: content size will be in frame header (when known) */ 1365 int checksumFlag; /**< 1: generate a 32-bits checksum using XXH64 algorithm at end of frame, for error detection */ 1366 int noDictIDFlag; /**< 1: no dictID will be saved into frame header (dictID is only useful for dictionary compression) */ 1367 } ZSTD_frameParameters; 1368 1369 typedef struct { 1370 ZSTD_compressionParameters cParams; 1371 ZSTD_frameParameters fParams; 1372 } ZSTD_parameters; 1373 1374 typedef enum { 1375 ZSTD_dct_auto = 0, /* dictionary is "full" when starting with ZSTD_MAGIC_DICTIONARY, otherwise it is "rawContent" */ 1376 ZSTD_dct_rawContent = 1, /* ensures dictionary is always loaded as rawContent, even if it starts with ZSTD_MAGIC_DICTIONARY */ 1377 ZSTD_dct_fullDict = 2 /* refuses to load a dictionary if it does not respect Zstandard's specification, starting with ZSTD_MAGIC_DICTIONARY */ 1378 } ZSTD_dictContentType_e; 1379 1380 typedef enum { 1381 ZSTD_dlm_byCopy = 0, /**< Copy dictionary content internally */ 1382 ZSTD_dlm_byRef = 1 /**< Reference dictionary content -- the dictionary buffer must outlive its users. */ 1383 } ZSTD_dictLoadMethod_e; 1384 1385 typedef enum { 1386 ZSTD_f_zstd1 = 0, /* zstd frame format, specified in zstd_compression_format.md (default) */ 1387 ZSTD_f_zstd1_magicless = 1 /* Variant of zstd frame format, without initial 4-bytes magic number. 1388 * Useful to save 4 bytes per generated frame. 1389 * Decoder cannot recognise automatically this format, requiring this instruction. */ 1390 } ZSTD_format_e; 1391 1392 typedef enum { 1393 /* Note: this enum controls ZSTD_d_forceIgnoreChecksum */ 1394 ZSTD_d_validateChecksum = 0, 1395 ZSTD_d_ignoreChecksum = 1 1396 } ZSTD_forceIgnoreChecksum_e; 1397 1398 typedef enum { 1399 /* Note: this enum controls ZSTD_d_refMultipleDDicts */ 1400 ZSTD_rmd_refSingleDDict = 0, 1401 ZSTD_rmd_refMultipleDDicts = 1 1402 } ZSTD_refMultipleDDicts_e; 1403 1404 typedef enum { 1405 /* Note: this enum and the behavior it controls are effectively internal 1406 * implementation details of the compressor. They are expected to continue 1407 * to evolve and should be considered only in the context of extremely 1408 * advanced performance tuning. 1409 * 1410 * Zstd currently supports the use of a CDict in three ways: 1411 * 1412 * - The contents of the CDict can be copied into the working context. This 1413 * means that the compression can search both the dictionary and input 1414 * while operating on a single set of internal tables. This makes 1415 * the compression faster per-byte of input. However, the initial copy of 1416 * the CDict's tables incurs a fixed cost at the beginning of the 1417 * compression. For small compressions (< 8 KB), that copy can dominate 1418 * the cost of the compression. 1419 * 1420 * - The CDict's tables can be used in-place. In this model, compression is 1421 * slower per input byte, because the compressor has to search two sets of 1422 * tables. However, this model incurs no start-up cost (as long as the 1423 * working context's tables can be reused). For small inputs, this can be 1424 * faster than copying the CDict's tables. 1425 * 1426 * - The CDict's tables are not used at all, and instead we use the working 1427 * context alone to reload the dictionary and use params based on the source 1428 * size. See ZSTD_compress_insertDictionary() and ZSTD_compress_usingDict(). 1429 * This method is effective when the dictionary sizes are very small relative 1430 * to the input size, and the input size is fairly large to begin with. 1431 * 1432 * Zstd has a simple internal heuristic that selects which strategy to use 1433 * at the beginning of a compression. However, if experimentation shows that 1434 * Zstd is making poor choices, it is possible to override that choice with 1435 * this enum. 1436 */ 1437 ZSTD_dictDefaultAttach = 0, /* Use the default heuristic. */ 1438 ZSTD_dictForceAttach = 1, /* Never copy the dictionary. */ 1439 ZSTD_dictForceCopy = 2, /* Always copy the dictionary. */ 1440 ZSTD_dictForceLoad = 3 /* Always reload the dictionary */ 1441 } ZSTD_dictAttachPref_e; 1442 1443 typedef enum { 1444 ZSTD_lcm_auto = 0, /**< Automatically determine the compression mode based on the compression level. 1445 * Negative compression levels will be uncompressed, and positive compression 1446 * levels will be compressed. */ 1447 ZSTD_lcm_huffman = 1, /**< Always attempt Huffman compression. Uncompressed literals will still be 1448 * emitted if Huffman compression is not profitable. */ 1449 ZSTD_lcm_uncompressed = 2 /**< Always emit uncompressed literals. */ 1450 } ZSTD_literalCompressionMode_e; 1451 1452 typedef enum { 1453 /* Note: This enum controls features which are conditionally beneficial. 1454 * Zstd can take a decision on whether or not to enable the feature (ZSTD_ps_auto), 1455 * but setting the switch to ZSTD_ps_enable or ZSTD_ps_disable force enable/disable the feature. 1456 */ 1457 ZSTD_ps_auto = 0, /* Let the library automatically determine whether the feature shall be enabled */ 1458 ZSTD_ps_enable = 1, /* Force-enable the feature */ 1459 ZSTD_ps_disable = 2 /* Do not use the feature */ 1460 } ZSTD_ParamSwitch_e; 1461 #define ZSTD_paramSwitch_e ZSTD_ParamSwitch_e /* old name */ 1462 1463 /*************************************** 1464 * Frame header and size functions 1465 ***************************************/ 1466 1467 /*! ZSTD_findDecompressedSize() : 1468 * `src` should point to the start of a series of ZSTD encoded and/or skippable frames 1469 * `srcSize` must be the _exact_ size of this series 1470 * (i.e. there should be a frame boundary at `src + srcSize`) 1471 * @return : - decompressed size of all data in all successive frames 1472 * - if the decompressed size cannot be determined: ZSTD_CONTENTSIZE_UNKNOWN 1473 * - if an error occurred: ZSTD_CONTENTSIZE_ERROR 1474 * 1475 * note 1 : decompressed size is an optional field, that may not be present, especially in streaming mode. 1476 * When `return==ZSTD_CONTENTSIZE_UNKNOWN`, data to decompress could be any size. 1477 * In which case, it's necessary to use streaming mode to decompress data. 1478 * note 2 : decompressed size is always present when compression is done with ZSTD_compress() 1479 * note 3 : decompressed size can be very large (64-bits value), 1480 * potentially larger than what local system can handle as a single memory segment. 1481 * In which case, it's necessary to use streaming mode to decompress data. 1482 * note 4 : If source is untrusted, decompressed size could be wrong or intentionally modified. 1483 * Always ensure result fits within application's authorized limits. 1484 * Each application can set its own limits. 1485 * note 5 : ZSTD_findDecompressedSize handles multiple frames, and so it must traverse the input to 1486 * read each contained frame header. This is fast as most of the data is skipped, 1487 * however it does mean that all frame data must be present and valid. */ 1488 ZSTDLIB_STATIC_API unsigned long long ZSTD_findDecompressedSize(const void* src, size_t srcSize); 1489 1490 /*! ZSTD_decompressBound() : 1491 * `src` should point to the start of a series of ZSTD encoded and/or skippable frames 1492 * `srcSize` must be the _exact_ size of this series 1493 * (i.e. there should be a frame boundary at `src + srcSize`) 1494 * @return : - upper-bound for the decompressed size of all data in all successive frames 1495 * - if an error occurred: ZSTD_CONTENTSIZE_ERROR 1496 * 1497 * note 1 : an error can occur if `src` contains an invalid or incorrectly formatted frame. 1498 * note 2 : the upper-bound is exact when the decompressed size field is available in every ZSTD encoded frame of `src`. 1499 * in this case, `ZSTD_findDecompressedSize` and `ZSTD_decompressBound` return the same value. 1500 * note 3 : when the decompressed size field isn't available, the upper-bound for that frame is calculated by: 1501 * upper-bound = # blocks * min(128 KB, Window_Size) 1502 */ 1503 ZSTDLIB_STATIC_API unsigned long long ZSTD_decompressBound(const void* src, size_t srcSize); 1504 1505 /*! ZSTD_frameHeaderSize() : 1506 * srcSize must be large enough, aka >= ZSTD_FRAMEHEADERSIZE_PREFIX. 1507 * @return : size of the Frame Header, 1508 * or an error code (if srcSize is too small) */ 1509 ZSTDLIB_STATIC_API size_t ZSTD_frameHeaderSize(const void* src, size_t srcSize); 1510 1511 typedef enum { ZSTD_frame, ZSTD_skippableFrame } ZSTD_FrameType_e; 1512 #define ZSTD_frameType_e ZSTD_FrameType_e /* old name */ 1513 typedef struct { 1514 unsigned long long frameContentSize; /* if == ZSTD_CONTENTSIZE_UNKNOWN, it means this field is not available. 0 means "empty" */ 1515 unsigned long long windowSize; /* can be very large, up to <= frameContentSize */ 1516 unsigned blockSizeMax; 1517 ZSTD_FrameType_e frameType; /* if == ZSTD_skippableFrame, frameContentSize is the size of skippable content */ 1518 unsigned headerSize; 1519 unsigned dictID; /* for ZSTD_skippableFrame, contains the skippable magic variant [0-15] */ 1520 unsigned checksumFlag; 1521 unsigned _reserved1; 1522 unsigned _reserved2; 1523 } ZSTD_FrameHeader; 1524 #define ZSTD_frameHeader ZSTD_FrameHeader /* old name */ 1525 1526 /*! ZSTD_getFrameHeader() : 1527 * decode Frame Header into `zfhPtr`, or requires larger `srcSize`. 1528 * @return : 0 => header is complete, `zfhPtr` is correctly filled, 1529 * >0 => `srcSize` is too small, @return value is the wanted `srcSize` amount, `zfhPtr` is not filled, 1530 * or an error code, which can be tested using ZSTD_isError() */ 1531 ZSTDLIB_STATIC_API size_t ZSTD_getFrameHeader(ZSTD_FrameHeader* zfhPtr, const void* src, size_t srcSize); 1532 /*! ZSTD_getFrameHeader_advanced() : 1533 * same as ZSTD_getFrameHeader(), 1534 * with added capability to select a format (like ZSTD_f_zstd1_magicless) */ 1535 ZSTDLIB_STATIC_API size_t ZSTD_getFrameHeader_advanced(ZSTD_FrameHeader* zfhPtr, const void* src, size_t srcSize, ZSTD_format_e format); 1536 1537 /*! ZSTD_decompressionMargin() : 1538 * Zstd supports in-place decompression, where the input and output buffers overlap. 1539 * In this case, the output buffer must be at least (Margin + Output_Size) bytes large, 1540 * and the input buffer must be at the end of the output buffer. 1541 * 1542 * _______________________ Output Buffer ________________________ 1543 * | | 1544 * | ____ Input Buffer ____| 1545 * | | | 1546 * v v v 1547 * |---------------------------------------|-----------|----------| 1548 * ^ ^ ^ 1549 * |___________________ Output_Size ___________________|_ Margin _| 1550 * 1551 * NOTE: See also ZSTD_DECOMPRESSION_MARGIN(). 1552 * NOTE: This applies only to single-pass decompression through ZSTD_decompress() or 1553 * ZSTD_decompressDCtx(). 1554 * NOTE: This function supports multi-frame input. 1555 * 1556 * @param src The compressed frame(s) 1557 * @param srcSize The size of the compressed frame(s) 1558 * @returns The decompression margin or an error that can be checked with ZSTD_isError(). 1559 */ 1560 ZSTDLIB_STATIC_API size_t ZSTD_decompressionMargin(const void* src, size_t srcSize); 1561 1562 /*! ZSTD_DECOMPRESS_MARGIN() : 1563 * Similar to ZSTD_decompressionMargin(), but instead of computing the margin from 1564 * the compressed frame, compute it from the original size and the blockSizeLog. 1565 * See ZSTD_decompressionMargin() for details. 1566 * 1567 * WARNING: This macro does not support multi-frame input, the input must be a single 1568 * zstd frame. If you need that support use the function, or implement it yourself. 1569 * 1570 * @param originalSize The original uncompressed size of the data. 1571 * @param blockSize The block size == MIN(windowSize, ZSTD_BLOCKSIZE_MAX). 1572 * Unless you explicitly set the windowLog smaller than 1573 * ZSTD_BLOCKSIZELOG_MAX you can just use ZSTD_BLOCKSIZE_MAX. 1574 */ 1575 #define ZSTD_DECOMPRESSION_MARGIN(originalSize, blockSize) ((size_t)( \ 1576 ZSTD_FRAMEHEADERSIZE_MAX /* Frame header */ + \ 1577 4 /* checksum */ + \ 1578 ((originalSize) == 0 ? 0 : 3 * (((originalSize) + (blockSize) - 1) / blockSize)) /* 3 bytes per block */ + \ 1579 (blockSize) /* One block of margin */ \ 1580 )) 1581 1582 typedef enum { 1583 ZSTD_sf_noBlockDelimiters = 0, /* ZSTD_Sequence[] has no block delimiters, just sequences */ 1584 ZSTD_sf_explicitBlockDelimiters = 1 /* ZSTD_Sequence[] contains explicit block delimiters */ 1585 } ZSTD_SequenceFormat_e; 1586 #define ZSTD_sequenceFormat_e ZSTD_SequenceFormat_e /* old name */ 1587 1588 /*! ZSTD_sequenceBound() : 1589 * `srcSize` : size of the input buffer 1590 * @return : upper-bound for the number of sequences that can be generated 1591 * from a buffer of srcSize bytes 1592 * 1593 * note : returns number of sequences - to get bytes, multiply by sizeof(ZSTD_Sequence). 1594 */ 1595 ZSTDLIB_STATIC_API size_t ZSTD_sequenceBound(size_t srcSize); 1596 1597 /*! ZSTD_generateSequences() : 1598 * WARNING: This function is meant for debugging and informational purposes ONLY! 1599 * Its implementation is flawed, and it will be deleted in a future version. 1600 * It is not guaranteed to succeed, as there are several cases where it will give 1601 * up and fail. You should NOT use this function in production code. 1602 * 1603 * This function is deprecated, and will be removed in a future version. 1604 * 1605 * Generate sequences using ZSTD_compress2(), given a source buffer. 1606 * 1607 * @param zc The compression context to be used for ZSTD_compress2(). Set any 1608 * compression parameters you need on this context. 1609 * @param outSeqs The output sequences buffer of size @p outSeqsSize 1610 * @param outSeqsCapacity The size of the output sequences buffer. 1611 * ZSTD_sequenceBound(srcSize) is an upper bound on the number 1612 * of sequences that can be generated. 1613 * @param src The source buffer to generate sequences from of size @p srcSize. 1614 * @param srcSize The size of the source buffer. 1615 * 1616 * Each block will end with a dummy sequence 1617 * with offset == 0, matchLength == 0, and litLength == length of last literals. 1618 * litLength may be == 0, and if so, then the sequence of (of: 0 ml: 0 ll: 0) 1619 * simply acts as a block delimiter. 1620 * 1621 * @returns The number of sequences generated, necessarily less than 1622 * ZSTD_sequenceBound(srcSize), or an error code that can be checked 1623 * with ZSTD_isError(). 1624 */ 1625 ZSTD_DEPRECATED("For debugging only, will be replaced by ZSTD_extractSequences()") 1626 ZSTDLIB_STATIC_API size_t 1627 ZSTD_generateSequences(ZSTD_CCtx* zc, 1628 ZSTD_Sequence* outSeqs, size_t outSeqsCapacity, 1629 const void* src, size_t srcSize); 1630 1631 /*! ZSTD_mergeBlockDelimiters() : 1632 * Given an array of ZSTD_Sequence, remove all sequences that represent block delimiters/last literals 1633 * by merging them into the literals of the next sequence. 1634 * 1635 * As such, the final generated result has no explicit representation of block boundaries, 1636 * and the final last literals segment is not represented in the sequences. 1637 * 1638 * The output of this function can be fed into ZSTD_compressSequences() with CCtx 1639 * setting of ZSTD_c_blockDelimiters as ZSTD_sf_noBlockDelimiters 1640 * @return : number of sequences left after merging 1641 */ 1642 ZSTDLIB_STATIC_API size_t ZSTD_mergeBlockDelimiters(ZSTD_Sequence* sequences, size_t seqsSize); 1643 1644 /*! ZSTD_compressSequences() : 1645 * Compress an array of ZSTD_Sequence, associated with @src buffer, into dst. 1646 * @src contains the entire input (not just the literals). 1647 * If @srcSize > sum(sequence.length), the remaining bytes are considered all literals 1648 * If a dictionary is included, then the cctx should reference the dict (see: ZSTD_CCtx_refCDict(), ZSTD_CCtx_loadDictionary(), etc.). 1649 * The entire source is compressed into a single frame. 1650 * 1651 * The compression behavior changes based on cctx params. In particular: 1652 * If ZSTD_c_blockDelimiters == ZSTD_sf_noBlockDelimiters, the array of ZSTD_Sequence is expected to contain 1653 * no block delimiters (defined in ZSTD_Sequence). Block boundaries are roughly determined based on 1654 * the block size derived from the cctx, and sequences may be split. This is the default setting. 1655 * 1656 * If ZSTD_c_blockDelimiters == ZSTD_sf_explicitBlockDelimiters, the array of ZSTD_Sequence is expected to contain 1657 * valid block delimiters (defined in ZSTD_Sequence). Behavior is undefined if no block delimiters are provided. 1658 * 1659 * When ZSTD_c_blockDelimiters == ZSTD_sf_explicitBlockDelimiters, it's possible to decide generating repcodes 1660 * using the advanced parameter ZSTD_c_repcodeResolution. Repcodes will improve compression ratio, though the benefit 1661 * can vary greatly depending on Sequences. On the other hand, repcode resolution is an expensive operation. 1662 * By default, it's disabled at low (<10) compression levels, and enabled above the threshold (>=10). 1663 * ZSTD_c_repcodeResolution makes it possible to directly manage this processing in either direction. 1664 * 1665 * If ZSTD_c_validateSequences == 0, this function blindly accepts the Sequences provided. Invalid Sequences cause undefined 1666 * behavior. If ZSTD_c_validateSequences == 1, then the function will detect invalid Sequences (see doc/zstd_compression_format.md for 1667 * specifics regarding offset/matchlength requirements) and then bail out and return an error. 1668 * 1669 * In addition to the two adjustable experimental params, there are other important cctx params. 1670 * - ZSTD_c_minMatch MUST be set as less than or equal to the smallest match generated by the match finder. It has a minimum value of ZSTD_MINMATCH_MIN. 1671 * - ZSTD_c_compressionLevel accordingly adjusts the strength of the entropy coder, as it would in typical compression. 1672 * - ZSTD_c_windowLog affects offset validation: this function will return an error at higher debug levels if a provided offset 1673 * is larger than what the spec allows for a given window log and dictionary (if present). See: doc/zstd_compression_format.md 1674 * 1675 * Note: Repcodes are, as of now, always re-calculated within this function, ZSTD_Sequence.rep is effectively unused. 1676 * Dev Note: Once ability to ingest repcodes become available, the explicit block delims mode must respect those repcodes exactly, 1677 * and cannot emit an RLE block that disagrees with the repcode history. 1678 * @return : final compressed size, or a ZSTD error code. 1679 */ 1680 ZSTDLIB_STATIC_API size_t 1681 ZSTD_compressSequences(ZSTD_CCtx* cctx, 1682 void* dst, size_t dstCapacity, 1683 const ZSTD_Sequence* inSeqs, size_t inSeqsSize, 1684 const void* src, size_t srcSize); 1685 1686 1687 /*! ZSTD_compressSequencesAndLiterals() : 1688 * This is a variant of ZSTD_compressSequences() which, 1689 * instead of receiving (src,srcSize) as input parameter, receives (literals,litSize), 1690 * aka all the literals, already extracted and laid out into a single continuous buffer. 1691 * This can be useful if the process generating the sequences also happens to generate the buffer of literals, 1692 * thus skipping an extraction + caching stage. 1693 * It's a speed optimization, useful when the right conditions are met, 1694 * but it also features the following limitations: 1695 * - Only supports explicit delimiter mode 1696 * - Currently does not support Sequences validation (so input Sequences are trusted) 1697 * - Not compatible with frame checksum, which must be disabled 1698 * - If any block is incompressible, will fail and return an error 1699 * - @litSize must be == sum of all @.litLength fields in @inSeqs. Any discrepancy will generate an error. 1700 * - @litBufCapacity is the size of the underlying buffer into which literals are written, starting at address @literals. 1701 * @litBufCapacity must be at least 8 bytes larger than @litSize. 1702 * - @decompressedSize must be correct, and correspond to the sum of all Sequences. Any discrepancy will generate an error. 1703 * @return : final compressed size, or a ZSTD error code. 1704 */ 1705 ZSTDLIB_STATIC_API size_t 1706 ZSTD_compressSequencesAndLiterals(ZSTD_CCtx* cctx, 1707 void* dst, size_t dstCapacity, 1708 const ZSTD_Sequence* inSeqs, size_t nbSequences, 1709 const void* literals, size_t litSize, size_t litBufCapacity, 1710 size_t decompressedSize); 1711 1712 1713 /*! ZSTD_writeSkippableFrame() : 1714 * Generates a zstd skippable frame containing data given by src, and writes it to dst buffer. 1715 * 1716 * Skippable frames begin with a 4-byte magic number. There are 16 possible choices of magic number, 1717 * ranging from ZSTD_MAGIC_SKIPPABLE_START to ZSTD_MAGIC_SKIPPABLE_START+15. 1718 * As such, the parameter magicVariant controls the exact skippable frame magic number variant used, 1719 * so the magic number used will be ZSTD_MAGIC_SKIPPABLE_START + magicVariant. 1720 * 1721 * Returns an error if destination buffer is not large enough, if the source size is not representable 1722 * with a 4-byte unsigned int, or if the parameter magicVariant is greater than 15 (and therefore invalid). 1723 * 1724 * @return : number of bytes written or a ZSTD error. 1725 */ 1726 ZSTDLIB_STATIC_API size_t ZSTD_writeSkippableFrame(void* dst, size_t dstCapacity, 1727 const void* src, size_t srcSize, 1728 unsigned magicVariant); 1729 1730 /*! ZSTD_readSkippableFrame() : 1731 * Retrieves the content of a zstd skippable frame starting at @src, and writes it to @dst buffer. 1732 * 1733 * The parameter @magicVariant will receive the magicVariant that was supplied when the frame was written, 1734 * i.e. magicNumber - ZSTD_MAGIC_SKIPPABLE_START. 1735 * This can be NULL if the caller is not interested in the magicVariant. 1736 * 1737 * Returns an error if destination buffer is not large enough, or if the frame is not skippable. 1738 * 1739 * @return : number of bytes written or a ZSTD error. 1740 */ 1741 ZSTDLIB_STATIC_API size_t ZSTD_readSkippableFrame(void* dst, size_t dstCapacity, 1742 unsigned* magicVariant, 1743 const void* src, size_t srcSize); 1744 1745 /*! ZSTD_isSkippableFrame() : 1746 * Tells if the content of `buffer` starts with a valid Frame Identifier for a skippable frame. 1747 */ 1748 ZSTDLIB_STATIC_API unsigned ZSTD_isSkippableFrame(const void* buffer, size_t size); 1749 1750 1751 1752 /*************************************** 1753 * Memory management 1754 ***************************************/ 1755 1756 /*! ZSTD_estimate*() : 1757 * These functions make it possible to estimate memory usage 1758 * of a future {D,C}Ctx, before its creation. 1759 * This is useful in combination with ZSTD_initStatic(), 1760 * which makes it possible to employ a static buffer for ZSTD_CCtx* state. 1761 * 1762 * ZSTD_estimateCCtxSize() will provide a memory budget large enough 1763 * to compress data of any size using one-shot compression ZSTD_compressCCtx() or ZSTD_compress2() 1764 * associated with any compression level up to max specified one. 1765 * The estimate will assume the input may be arbitrarily large, 1766 * which is the worst case. 1767 * 1768 * Note that the size estimation is specific for one-shot compression, 1769 * it is not valid for streaming (see ZSTD_estimateCStreamSize*()) 1770 * nor other potential ways of using a ZSTD_CCtx* state. 1771 * 1772 * When srcSize can be bound by a known and rather "small" value, 1773 * this knowledge can be used to provide a tighter budget estimation 1774 * because the ZSTD_CCtx* state will need less memory for small inputs. 1775 * This tighter estimation can be provided by employing more advanced functions 1776 * ZSTD_estimateCCtxSize_usingCParams(), which can be used in tandem with ZSTD_getCParams(), 1777 * and ZSTD_estimateCCtxSize_usingCCtxParams(), which can be used in tandem with ZSTD_CCtxParams_setParameter(). 1778 * Both can be used to estimate memory using custom compression parameters and arbitrary srcSize limits. 1779 * 1780 * Note : only single-threaded compression is supported. 1781 * ZSTD_estimateCCtxSize_usingCCtxParams() will return an error code if ZSTD_c_nbWorkers is >= 1. 1782 */ 1783 ZSTDLIB_STATIC_API size_t ZSTD_estimateCCtxSize(int maxCompressionLevel); 1784 ZSTDLIB_STATIC_API size_t ZSTD_estimateCCtxSize_usingCParams(ZSTD_compressionParameters cParams); 1785 ZSTDLIB_STATIC_API size_t ZSTD_estimateCCtxSize_usingCCtxParams(const ZSTD_CCtx_params* params); 1786 ZSTDLIB_STATIC_API size_t ZSTD_estimateDCtxSize(void); 1787 1788 /*! ZSTD_estimateCStreamSize() : 1789 * ZSTD_estimateCStreamSize() will provide a memory budget large enough for streaming compression 1790 * using any compression level up to the max specified one. 1791 * It will also consider src size to be arbitrarily "large", which is a worst case scenario. 1792 * If srcSize is known to always be small, ZSTD_estimateCStreamSize_usingCParams() can provide a tighter estimation. 1793 * ZSTD_estimateCStreamSize_usingCParams() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel. 1794 * 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. 1795 * Note : CStream size estimation is only correct for single-threaded compression. 1796 * ZSTD_estimateCStreamSize_usingCCtxParams() will return an error code if ZSTD_c_nbWorkers is >= 1. 1797 * Note 2 : ZSTD_estimateCStreamSize* functions are not compatible with the Block-Level Sequence Producer API at this time. 1798 * Size estimates assume that no external sequence producer is registered. 1799 * 1800 * ZSTD_DStream memory budget depends on frame's window Size. 1801 * This information can be passed manually, using ZSTD_estimateDStreamSize, 1802 * or deducted from a valid frame Header, using ZSTD_estimateDStreamSize_fromFrame(); 1803 * Any frame requesting a window size larger than max specified one will be rejected. 1804 * Note : if streaming is init with function ZSTD_init?Stream_usingDict(), 1805 * an internal ?Dict will be created, which additional size is not estimated here. 1806 * In this case, get total size by adding ZSTD_estimate?DictSize 1807 */ 1808 ZSTDLIB_STATIC_API size_t ZSTD_estimateCStreamSize(int maxCompressionLevel); 1809 ZSTDLIB_STATIC_API size_t ZSTD_estimateCStreamSize_usingCParams(ZSTD_compressionParameters cParams); 1810 ZSTDLIB_STATIC_API size_t ZSTD_estimateCStreamSize_usingCCtxParams(const ZSTD_CCtx_params* params); 1811 ZSTDLIB_STATIC_API size_t ZSTD_estimateDStreamSize(size_t maxWindowSize); 1812 ZSTDLIB_STATIC_API size_t ZSTD_estimateDStreamSize_fromFrame(const void* src, size_t srcSize); 1813 1814 /*! ZSTD_estimate?DictSize() : 1815 * ZSTD_estimateCDictSize() will bet that src size is relatively "small", and content is copied, like ZSTD_createCDict(). 1816 * ZSTD_estimateCDictSize_advanced() makes it possible to control compression parameters precisely, like ZSTD_createCDict_advanced(). 1817 * Note : dictionaries created by reference (`ZSTD_dlm_byRef`) are logically smaller. 1818 */ 1819 ZSTDLIB_STATIC_API size_t ZSTD_estimateCDictSize(size_t dictSize, int compressionLevel); 1820 ZSTDLIB_STATIC_API size_t ZSTD_estimateCDictSize_advanced(size_t dictSize, ZSTD_compressionParameters cParams, ZSTD_dictLoadMethod_e dictLoadMethod); 1821 ZSTDLIB_STATIC_API size_t ZSTD_estimateDDictSize(size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod); 1822 1823 /*! ZSTD_initStatic*() : 1824 * Initialize an object using a pre-allocated fixed-size buffer. 1825 * workspace: The memory area to emplace the object into. 1826 * Provided pointer *must be 8-bytes aligned*. 1827 * Buffer must outlive object. 1828 * workspaceSize: Use ZSTD_estimate*Size() to determine 1829 * how large workspace must be to support target scenario. 1830 * @return : pointer to object (same address as workspace, just different type), 1831 * or NULL if error (size too small, incorrect alignment, etc.) 1832 * Note : zstd will never resize nor malloc() when using a static buffer. 1833 * If the object requires more memory than available, 1834 * zstd will just error out (typically ZSTD_error_memory_allocation). 1835 * Note 2 : there is no corresponding "free" function. 1836 * Since workspace is allocated externally, it must be freed externally too. 1837 * Note 3 : cParams : use ZSTD_getCParams() to convert a compression level 1838 * into its associated cParams. 1839 * Limitation 1 : currently not compatible with internal dictionary creation, triggered by 1840 * ZSTD_CCtx_loadDictionary(), ZSTD_initCStream_usingDict() or ZSTD_initDStream_usingDict(). 1841 * Limitation 2 : static cctx currently not compatible with multi-threading. 1842 * Limitation 3 : static dctx is incompatible with legacy support. 1843 */ 1844 ZSTDLIB_STATIC_API ZSTD_CCtx* ZSTD_initStaticCCtx(void* workspace, size_t workspaceSize); 1845 ZSTDLIB_STATIC_API ZSTD_CStream* ZSTD_initStaticCStream(void* workspace, size_t workspaceSize); /**< same as ZSTD_initStaticCCtx() */ 1846 1847 ZSTDLIB_STATIC_API ZSTD_DCtx* ZSTD_initStaticDCtx(void* workspace, size_t workspaceSize); 1848 ZSTDLIB_STATIC_API ZSTD_DStream* ZSTD_initStaticDStream(void* workspace, size_t workspaceSize); /**< same as ZSTD_initStaticDCtx() */ 1849 1850 ZSTDLIB_STATIC_API const ZSTD_CDict* ZSTD_initStaticCDict( 1851 void* workspace, size_t workspaceSize, 1852 const void* dict, size_t dictSize, 1853 ZSTD_dictLoadMethod_e dictLoadMethod, 1854 ZSTD_dictContentType_e dictContentType, 1855 ZSTD_compressionParameters cParams); 1856 1857 ZSTDLIB_STATIC_API const ZSTD_DDict* ZSTD_initStaticDDict( 1858 void* workspace, size_t workspaceSize, 1859 const void* dict, size_t dictSize, 1860 ZSTD_dictLoadMethod_e dictLoadMethod, 1861 ZSTD_dictContentType_e dictContentType); 1862 1863 1864 /*! Custom memory allocation : 1865 * These prototypes make it possible to pass your own allocation/free functions. 1866 * ZSTD_customMem is provided at creation time, using ZSTD_create*_advanced() variants listed below. 1867 * All allocation/free operations will be completed using these custom variants instead of regular <stdlib.h> ones. 1868 */ 1869 typedef void* (*ZSTD_allocFunction) (void* opaque, size_t size); 1870 typedef void (*ZSTD_freeFunction) (void* opaque, void* address); 1871 typedef struct { ZSTD_allocFunction customAlloc; ZSTD_freeFunction customFree; void* opaque; } ZSTD_customMem; 1872 static 1873 #ifdef __GNUC__ 1874 __attribute__((__unused__)) 1875 #endif 1876 1877 #if defined(__clang__) && __clang_major__ >= 5 1878 #pragma clang diagnostic push 1879 #pragma clang diagnostic ignored "-Wzero-as-null-pointer-constant" 1880 #endif 1881 ZSTD_customMem const ZSTD_defaultCMem = { NULL, NULL, NULL }; /**< this constant defers to stdlib's functions */ 1882 #if defined(__clang__) && __clang_major__ >= 5 1883 #pragma clang diagnostic pop 1884 #endif 1885 1886 ZSTDLIB_STATIC_API ZSTD_CCtx* ZSTD_createCCtx_advanced(ZSTD_customMem customMem); 1887 ZSTDLIB_STATIC_API ZSTD_CStream* ZSTD_createCStream_advanced(ZSTD_customMem customMem); 1888 ZSTDLIB_STATIC_API ZSTD_DCtx* ZSTD_createDCtx_advanced(ZSTD_customMem customMem); 1889 ZSTDLIB_STATIC_API ZSTD_DStream* ZSTD_createDStream_advanced(ZSTD_customMem customMem); 1890 1891 ZSTDLIB_STATIC_API ZSTD_CDict* ZSTD_createCDict_advanced(const void* dict, size_t dictSize, 1892 ZSTD_dictLoadMethod_e dictLoadMethod, 1893 ZSTD_dictContentType_e dictContentType, 1894 ZSTD_compressionParameters cParams, 1895 ZSTD_customMem customMem); 1896 1897 /*! Thread pool : 1898 * These prototypes make it possible to share a thread pool among multiple compression contexts. 1899 * This can limit resources for applications with multiple threads where each one uses 1900 * a threaded compression mode (via ZSTD_c_nbWorkers parameter). 1901 * ZSTD_createThreadPool creates a new thread pool with a given number of threads. 1902 * Note that the lifetime of such pool must exist while being used. 1903 * ZSTD_CCtx_refThreadPool assigns a thread pool to a context (use NULL argument value 1904 * to use an internal thread pool). 1905 * ZSTD_freeThreadPool frees a thread pool, accepts NULL pointer. 1906 */ 1907 typedef struct POOL_ctx_s ZSTD_threadPool; 1908 ZSTDLIB_STATIC_API ZSTD_threadPool* ZSTD_createThreadPool(size_t numThreads); 1909 ZSTDLIB_STATIC_API void ZSTD_freeThreadPool (ZSTD_threadPool* pool); /* accept NULL pointer */ 1910 ZSTDLIB_STATIC_API size_t ZSTD_CCtx_refThreadPool(ZSTD_CCtx* cctx, ZSTD_threadPool* pool); 1911 1912 1913 /* 1914 * This API is temporary and is expected to change or disappear in the future! 1915 */ 1916 ZSTDLIB_STATIC_API ZSTD_CDict* ZSTD_createCDict_advanced2( 1917 const void* dict, size_t dictSize, 1918 ZSTD_dictLoadMethod_e dictLoadMethod, 1919 ZSTD_dictContentType_e dictContentType, 1920 const ZSTD_CCtx_params* cctxParams, 1921 ZSTD_customMem customMem); 1922 1923 ZSTDLIB_STATIC_API ZSTD_DDict* ZSTD_createDDict_advanced( 1924 const void* dict, size_t dictSize, 1925 ZSTD_dictLoadMethod_e dictLoadMethod, 1926 ZSTD_dictContentType_e dictContentType, 1927 ZSTD_customMem customMem); 1928 1929 1930 /*************************************** 1931 * Advanced compression functions 1932 ***************************************/ 1933 1934 /*! ZSTD_createCDict_byReference() : 1935 * Create a digested dictionary for compression 1936 * Dictionary content is just referenced, not duplicated. 1937 * As a consequence, `dictBuffer` **must** outlive CDict, 1938 * and its content must remain unmodified throughout the lifetime of CDict. 1939 * note: equivalent to ZSTD_createCDict_advanced(), with dictLoadMethod==ZSTD_dlm_byRef */ 1940 ZSTDLIB_STATIC_API ZSTD_CDict* ZSTD_createCDict_byReference(const void* dictBuffer, size_t dictSize, int compressionLevel); 1941 1942 /*! ZSTD_getCParams() : 1943 * @return ZSTD_compressionParameters structure for a selected compression level and estimated srcSize. 1944 * `estimatedSrcSize` value is optional, select 0 if not known */ 1945 ZSTDLIB_STATIC_API ZSTD_compressionParameters ZSTD_getCParams(int compressionLevel, unsigned long long estimatedSrcSize, size_t dictSize); 1946 1947 /*! ZSTD_getParams() : 1948 * same as ZSTD_getCParams(), but @return a full `ZSTD_parameters` object instead of sub-component `ZSTD_compressionParameters`. 1949 * All fields of `ZSTD_frameParameters` are set to default : contentSize=1, checksum=0, noDictID=0 */ 1950 ZSTDLIB_STATIC_API ZSTD_parameters ZSTD_getParams(int compressionLevel, unsigned long long estimatedSrcSize, size_t dictSize); 1951 1952 /*! ZSTD_checkCParams() : 1953 * Ensure param values remain within authorized range. 1954 * @return 0 on success, or an error code (can be checked with ZSTD_isError()) */ 1955 ZSTDLIB_STATIC_API size_t ZSTD_checkCParams(ZSTD_compressionParameters params); 1956 1957 /*! ZSTD_adjustCParams() : 1958 * optimize params for a given `srcSize` and `dictSize`. 1959 * `srcSize` can be unknown, in which case use ZSTD_CONTENTSIZE_UNKNOWN. 1960 * `dictSize` must be `0` when there is no dictionary. 1961 * cPar can be invalid : all parameters will be clamped within valid range in the @return struct. 1962 * This function never fails (wide contract) */ 1963 ZSTDLIB_STATIC_API ZSTD_compressionParameters ZSTD_adjustCParams(ZSTD_compressionParameters cPar, unsigned long long srcSize, size_t dictSize); 1964 1965 /*! ZSTD_CCtx_setCParams() : 1966 * Set all parameters provided within @p cparams into the working @p cctx. 1967 * Note : if modifying parameters during compression (MT mode only), 1968 * note that changes to the .windowLog parameter will be ignored. 1969 * @return 0 on success, or an error code (can be checked with ZSTD_isError()). 1970 * On failure, no parameters are updated. 1971 */ 1972 ZSTDLIB_STATIC_API size_t ZSTD_CCtx_setCParams(ZSTD_CCtx* cctx, ZSTD_compressionParameters cparams); 1973 1974 /*! ZSTD_CCtx_setFParams() : 1975 * Set all parameters provided within @p fparams into the working @p cctx. 1976 * @return 0 on success, or an error code (can be checked with ZSTD_isError()). 1977 */ 1978 ZSTDLIB_STATIC_API size_t ZSTD_CCtx_setFParams(ZSTD_CCtx* cctx, ZSTD_frameParameters fparams); 1979 1980 /*! ZSTD_CCtx_setParams() : 1981 * Set all parameters provided within @p params into the working @p cctx. 1982 * @return 0 on success, or an error code (can be checked with ZSTD_isError()). 1983 */ 1984 ZSTDLIB_STATIC_API size_t ZSTD_CCtx_setParams(ZSTD_CCtx* cctx, ZSTD_parameters params); 1985 1986 /*! ZSTD_compress_advanced() : 1987 * Note : this function is now DEPRECATED. 1988 * It can be replaced by ZSTD_compress2(), in combination with ZSTD_CCtx_setParameter() and other parameter setters. 1989 * This prototype will generate compilation warnings. */ 1990 ZSTD_DEPRECATED("use ZSTD_compress2") 1991 ZSTDLIB_STATIC_API 1992 size_t ZSTD_compress_advanced(ZSTD_CCtx* cctx, 1993 void* dst, size_t dstCapacity, 1994 const void* src, size_t srcSize, 1995 const void* dict,size_t dictSize, 1996 ZSTD_parameters params); 1997 1998 /*! ZSTD_compress_usingCDict_advanced() : 1999 * Note : this function is now DEPRECATED. 2000 * It can be replaced by ZSTD_compress2(), in combination with ZSTD_CCtx_loadDictionary() and other parameter setters. 2001 * This prototype will generate compilation warnings. */ 2002 ZSTD_DEPRECATED("use ZSTD_compress2 with ZSTD_CCtx_loadDictionary") 2003 ZSTDLIB_STATIC_API 2004 size_t ZSTD_compress_usingCDict_advanced(ZSTD_CCtx* cctx, 2005 void* dst, size_t dstCapacity, 2006 const void* src, size_t srcSize, 2007 const ZSTD_CDict* cdict, 2008 ZSTD_frameParameters fParams); 2009 2010 2011 /*! ZSTD_CCtx_loadDictionary_byReference() : 2012 * Same as ZSTD_CCtx_loadDictionary(), but dictionary content is referenced, instead of being copied into CCtx. 2013 * It saves some memory, but also requires that `dict` outlives its usage within `cctx` */ 2014 ZSTDLIB_STATIC_API size_t ZSTD_CCtx_loadDictionary_byReference(ZSTD_CCtx* cctx, const void* dict, size_t dictSize); 2015 2016 /*! ZSTD_CCtx_loadDictionary_advanced() : 2017 * Same as ZSTD_CCtx_loadDictionary(), but gives finer control over 2018 * how to load the dictionary (by copy ? by reference ?) 2019 * and how to interpret it (automatic ? force raw mode ? full mode only ?) */ 2020 ZSTDLIB_STATIC_API size_t ZSTD_CCtx_loadDictionary_advanced(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod, ZSTD_dictContentType_e dictContentType); 2021 2022 /*! ZSTD_CCtx_refPrefix_advanced() : 2023 * Same as ZSTD_CCtx_refPrefix(), but gives finer control over 2024 * how to interpret prefix content (automatic ? force raw mode (default) ? full mode only ?) */ 2025 ZSTDLIB_STATIC_API size_t ZSTD_CCtx_refPrefix_advanced(ZSTD_CCtx* cctx, const void* prefix, size_t prefixSize, ZSTD_dictContentType_e dictContentType); 2026 2027 /* === experimental parameters === */ 2028 /* these parameters can be used with ZSTD_setParameter() 2029 * they are not guaranteed to remain supported in the future */ 2030 2031 /* Enables rsyncable mode, 2032 * which makes compressed files more rsync friendly 2033 * by adding periodic synchronization points to the compressed data. 2034 * The target average block size is ZSTD_c_jobSize / 2. 2035 * It's possible to modify the job size to increase or decrease 2036 * the granularity of the synchronization point. 2037 * Once the jobSize is smaller than the window size, 2038 * it will result in compression ratio degradation. 2039 * NOTE 1: rsyncable mode only works when multithreading is enabled. 2040 * NOTE 2: rsyncable performs poorly in combination with long range mode, 2041 * since it will decrease the effectiveness of synchronization points, 2042 * though mileage may vary. 2043 * NOTE 3: Rsyncable mode limits maximum compression speed to ~400 MB/s. 2044 * If the selected compression level is already running significantly slower, 2045 * the overall speed won't be significantly impacted. 2046 */ 2047 #define ZSTD_c_rsyncable ZSTD_c_experimentalParam1 2048 2049 /* Select a compression format. 2050 * The value must be of type ZSTD_format_e. 2051 * See ZSTD_format_e enum definition for details */ 2052 #define ZSTD_c_format ZSTD_c_experimentalParam2 2053 2054 /* Force back-reference distances to remain < windowSize, 2055 * even when referencing into Dictionary content (default:0) */ 2056 #define ZSTD_c_forceMaxWindow ZSTD_c_experimentalParam3 2057 2058 /* Controls whether the contents of a CDict 2059 * are used in place, or copied into the working context. 2060 * Accepts values from the ZSTD_dictAttachPref_e enum. 2061 * See the comments on that enum for an explanation of the feature. */ 2062 #define ZSTD_c_forceAttachDict ZSTD_c_experimentalParam4 2063 2064 /* Controlled with ZSTD_ParamSwitch_e enum. 2065 * Default is ZSTD_ps_auto. 2066 * Set to ZSTD_ps_disable to never compress literals. 2067 * Set to ZSTD_ps_enable to always compress literals. (Note: uncompressed literals 2068 * may still be emitted if huffman is not beneficial to use.) 2069 * 2070 * By default, in ZSTD_ps_auto, the library will decide at runtime whether to use 2071 * literals compression based on the compression parameters - specifically, 2072 * negative compression levels do not use literal compression. 2073 */ 2074 #define ZSTD_c_literalCompressionMode ZSTD_c_experimentalParam5 2075 2076 /* User's best guess of source size. 2077 * Hint is not valid when srcSizeHint == 0. 2078 * There is no guarantee that hint is close to actual source size, 2079 * but compression ratio may regress significantly if guess considerably underestimates */ 2080 #define ZSTD_c_srcSizeHint ZSTD_c_experimentalParam7 2081 2082 /* Controls whether the new and experimental "dedicated dictionary search 2083 * structure" can be used. This feature is still rough around the edges, be 2084 * prepared for surprising behavior! 2085 * 2086 * How to use it: 2087 * 2088 * When using a CDict, whether to use this feature or not is controlled at 2089 * CDict creation, and it must be set in a CCtxParams set passed into that 2090 * construction (via ZSTD_createCDict_advanced2()). A compression will then 2091 * use the feature or not based on how the CDict was constructed; the value of 2092 * this param, set in the CCtx, will have no effect. 2093 * 2094 * However, when a dictionary buffer is passed into a CCtx, such as via 2095 * ZSTD_CCtx_loadDictionary(), this param can be set on the CCtx to control 2096 * whether the CDict that is created internally can use the feature or not. 2097 * 2098 * What it does: 2099 * 2100 * Normally, the internal data structures of the CDict are analogous to what 2101 * would be stored in a CCtx after compressing the contents of a dictionary. 2102 * To an approximation, a compression using a dictionary can then use those 2103 * data structures to simply continue what is effectively a streaming 2104 * compression where the simulated compression of the dictionary left off. 2105 * Which is to say, the search structures in the CDict are normally the same 2106 * format as in the CCtx. 2107 * 2108 * It is possible to do better, since the CDict is not like a CCtx: the search 2109 * structures are written once during CDict creation, and then are only read 2110 * after that, while the search structures in the CCtx are both read and 2111 * written as the compression goes along. This means we can choose a search 2112 * structure for the dictionary that is read-optimized. 2113 * 2114 * This feature enables the use of that different structure. 2115 * 2116 * Note that some of the members of the ZSTD_compressionParameters struct have 2117 * different semantics and constraints in the dedicated search structure. It is 2118 * highly recommended that you simply set a compression level in the CCtxParams 2119 * you pass into the CDict creation call, and avoid messing with the cParams 2120 * directly. 2121 * 2122 * Effects: 2123 * 2124 * This will only have any effect when the selected ZSTD_strategy 2125 * implementation supports this feature. Currently, that's limited to 2126 * ZSTD_greedy, ZSTD_lazy, and ZSTD_lazy2. 2127 * 2128 * Note that this means that the CDict tables can no longer be copied into the 2129 * CCtx, so the dict attachment mode ZSTD_dictForceCopy will no longer be 2130 * usable. The dictionary can only be attached or reloaded. 2131 * 2132 * In general, you should expect compression to be faster--sometimes very much 2133 * so--and CDict creation to be slightly slower. Eventually, we will probably 2134 * make this mode the default. 2135 */ 2136 #define ZSTD_c_enableDedicatedDictSearch ZSTD_c_experimentalParam8 2137 2138 /* ZSTD_c_stableInBuffer 2139 * Experimental parameter. 2140 * Default is 0 == disabled. Set to 1 to enable. 2141 * 2142 * Tells the compressor that input data presented with ZSTD_inBuffer 2143 * will ALWAYS be the same between calls. 2144 * Technically, the @src pointer must never be changed, 2145 * and the @pos field can only be updated by zstd. 2146 * However, it's possible to increase the @size field, 2147 * allowing scenarios where more data can be appended after compressions starts. 2148 * These conditions are checked by the compressor, 2149 * and compression will fail if they are not respected. 2150 * Also, data in the ZSTD_inBuffer within the range [src, src + pos) 2151 * MUST not be modified during compression or it will result in data corruption. 2152 * 2153 * When this flag is enabled zstd won't allocate an input window buffer, 2154 * because the user guarantees it can reference the ZSTD_inBuffer until 2155 * the frame is complete. But, it will still allocate an output buffer 2156 * large enough to fit a block (see ZSTD_c_stableOutBuffer). This will also 2157 * avoid the memcpy() from the input buffer to the input window buffer. 2158 * 2159 * NOTE: So long as the ZSTD_inBuffer always points to valid memory, using 2160 * this flag is ALWAYS memory safe, and will never access out-of-bounds 2161 * memory. However, compression WILL fail if conditions are not respected. 2162 * 2163 * WARNING: The data in the ZSTD_inBuffer in the range [src, src + pos) MUST 2164 * not be modified during compression or it will result in data corruption. 2165 * This is because zstd needs to reference data in the ZSTD_inBuffer to find 2166 * matches. Normally zstd maintains its own window buffer for this purpose, 2167 * but passing this flag tells zstd to rely on user provided buffer instead. 2168 */ 2169 #define ZSTD_c_stableInBuffer ZSTD_c_experimentalParam9 2170 2171 /* ZSTD_c_stableOutBuffer 2172 * Experimental parameter. 2173 * Default is 0 == disabled. Set to 1 to enable. 2174 * 2175 * Tells he compressor that the ZSTD_outBuffer will not be resized between 2176 * calls. Specifically: (out.size - out.pos) will never grow. This gives the 2177 * compressor the freedom to say: If the compressed data doesn't fit in the 2178 * output buffer then return ZSTD_error_dstSizeTooSmall. This allows us to 2179 * always decompress directly into the output buffer, instead of decompressing 2180 * into an internal buffer and copying to the output buffer. 2181 * 2182 * When this flag is enabled zstd won't allocate an output buffer, because 2183 * it can write directly to the ZSTD_outBuffer. It will still allocate the 2184 * input window buffer (see ZSTD_c_stableInBuffer). 2185 * 2186 * Zstd will check that (out.size - out.pos) never grows and return an error 2187 * if it does. While not strictly necessary, this should prevent surprises. 2188 */ 2189 #define ZSTD_c_stableOutBuffer ZSTD_c_experimentalParam10 2190 2191 /* ZSTD_c_blockDelimiters 2192 * Default is 0 == ZSTD_sf_noBlockDelimiters. 2193 * 2194 * For use with sequence compression API: ZSTD_compressSequences(). 2195 * 2196 * Designates whether or not the given array of ZSTD_Sequence contains block delimiters 2197 * and last literals, which are defined as sequences with offset == 0 and matchLength == 0. 2198 * See the definition of ZSTD_Sequence for more specifics. 2199 */ 2200 #define ZSTD_c_blockDelimiters ZSTD_c_experimentalParam11 2201 2202 /* ZSTD_c_validateSequences 2203 * Default is 0 == disabled. Set to 1 to enable sequence validation. 2204 * 2205 * For use with sequence compression API: ZSTD_compressSequences*(). 2206 * Designates whether or not provided sequences are validated within ZSTD_compressSequences*() 2207 * during function execution. 2208 * 2209 * When Sequence validation is disabled (default), Sequences are compressed as-is, 2210 * so they must correct, otherwise it would result in a corruption error. 2211 * 2212 * Sequence validation adds some protection, by ensuring that all values respect boundary conditions. 2213 * If a Sequence is detected invalid (see doc/zstd_compression_format.md for 2214 * specifics regarding offset/matchlength requirements) then the function will bail out and 2215 * return an error. 2216 */ 2217 #define ZSTD_c_validateSequences ZSTD_c_experimentalParam12 2218 2219 /* ZSTD_c_blockSplitterLevel 2220 * note: this parameter only influences the first splitter stage, 2221 * which is active before producing the sequences. 2222 * ZSTD_c_splitAfterSequences controls the next splitter stage, 2223 * which is active after sequence production. 2224 * Note that both can be combined. 2225 * Allowed values are between 0 and ZSTD_BLOCKSPLITTER_LEVEL_MAX included. 2226 * 0 means "auto", which will select a value depending on current ZSTD_c_strategy. 2227 * 1 means no splitting. 2228 * Then, values from 2 to 6 are sorted in increasing cpu load order. 2229 * 2230 * Note that currently the first block is never split, 2231 * to ensure expansion guarantees in presence of incompressible data. 2232 */ 2233 #define ZSTD_BLOCKSPLITTER_LEVEL_MAX 6 2234 #define ZSTD_c_blockSplitterLevel ZSTD_c_experimentalParam20 2235 2236 /* ZSTD_c_splitAfterSequences 2237 * This is a stronger splitter algorithm, 2238 * based on actual sequences previously produced by the selected parser. 2239 * It's also slower, and as a consequence, mostly used for high compression levels. 2240 * While the post-splitter does overlap with the pre-splitter, 2241 * both can nonetheless be combined, 2242 * notably with ZSTD_c_blockSplitterLevel at ZSTD_BLOCKSPLITTER_LEVEL_MAX, 2243 * resulting in higher compression ratio than just one of them. 2244 * 2245 * Default is ZSTD_ps_auto. 2246 * Set to ZSTD_ps_disable to never use block splitter. 2247 * Set to ZSTD_ps_enable to always use block splitter. 2248 * 2249 * By default, in ZSTD_ps_auto, the library will decide at runtime whether to use 2250 * block splitting based on the compression parameters. 2251 */ 2252 #define ZSTD_c_splitAfterSequences ZSTD_c_experimentalParam13 2253 2254 /* ZSTD_c_useRowMatchFinder 2255 * Controlled with ZSTD_ParamSwitch_e enum. 2256 * Default is ZSTD_ps_auto. 2257 * Set to ZSTD_ps_disable to never use row-based matchfinder. 2258 * Set to ZSTD_ps_enable to force usage of row-based matchfinder. 2259 * 2260 * By default, in ZSTD_ps_auto, the library will decide at runtime whether to use 2261 * the row-based matchfinder based on support for SIMD instructions and the window log. 2262 * Note that this only pertains to compression strategies: greedy, lazy, and lazy2 2263 */ 2264 #define ZSTD_c_useRowMatchFinder ZSTD_c_experimentalParam14 2265 2266 /* ZSTD_c_deterministicRefPrefix 2267 * Default is 0 == disabled. Set to 1 to enable. 2268 * 2269 * Zstd produces different results for prefix compression when the prefix is 2270 * directly adjacent to the data about to be compressed vs. when it isn't. 2271 * This is because zstd detects that the two buffers are contiguous and it can 2272 * use a more efficient match finding algorithm. However, this produces different 2273 * results than when the two buffers are non-contiguous. This flag forces zstd 2274 * to always load the prefix in non-contiguous mode, even if it happens to be 2275 * adjacent to the data, to guarantee determinism. 2276 * 2277 * If you really care about determinism when using a dictionary or prefix, 2278 * like when doing delta compression, you should select this option. It comes 2279 * at a speed penalty of about ~2.5% if the dictionary and data happened to be 2280 * contiguous, and is free if they weren't contiguous. We don't expect that 2281 * intentionally making the dictionary and data contiguous will be worth the 2282 * cost to memcpy() the data. 2283 */ 2284 #define ZSTD_c_deterministicRefPrefix ZSTD_c_experimentalParam15 2285 2286 /* ZSTD_c_prefetchCDictTables 2287 * Controlled with ZSTD_ParamSwitch_e enum. Default is ZSTD_ps_auto. 2288 * 2289 * In some situations, zstd uses CDict tables in-place rather than copying them 2290 * into the working context. (See docs on ZSTD_dictAttachPref_e above for details). 2291 * In such situations, compression speed is seriously impacted when CDict tables are 2292 * "cold" (outside CPU cache). This parameter instructs zstd to prefetch CDict tables 2293 * when they are used in-place. 2294 * 2295 * For sufficiently small inputs, the cost of the prefetch will outweigh the benefit. 2296 * For sufficiently large inputs, zstd will by default memcpy() CDict tables 2297 * into the working context, so there is no need to prefetch. This parameter is 2298 * targeted at a middle range of input sizes, where a prefetch is cheap enough to be 2299 * useful but memcpy() is too expensive. The exact range of input sizes where this 2300 * makes sense is best determined by careful experimentation. 2301 * 2302 * Note: for this parameter, ZSTD_ps_auto is currently equivalent to ZSTD_ps_disable, 2303 * but in the future zstd may conditionally enable this feature via an auto-detection 2304 * heuristic for cold CDicts. 2305 * Use ZSTD_ps_disable to opt out of prefetching under any circumstances. 2306 */ 2307 #define ZSTD_c_prefetchCDictTables ZSTD_c_experimentalParam16 2308 2309 /* ZSTD_c_enableSeqProducerFallback 2310 * Allowed values are 0 (disable) and 1 (enable). The default setting is 0. 2311 * 2312 * Controls whether zstd will fall back to an internal sequence producer if an 2313 * external sequence producer is registered and returns an error code. This fallback 2314 * is block-by-block: the internal sequence producer will only be called for blocks 2315 * where the external sequence producer returns an error code. Fallback parsing will 2316 * follow any other cParam settings, such as compression level, the same as in a 2317 * normal (fully-internal) compression operation. 2318 * 2319 * The user is strongly encouraged to read the full Block-Level Sequence Producer API 2320 * documentation (below) before setting this parameter. */ 2321 #define ZSTD_c_enableSeqProducerFallback ZSTD_c_experimentalParam17 2322 2323 /* ZSTD_c_maxBlockSize 2324 * Allowed values are between 1KB and ZSTD_BLOCKSIZE_MAX (128KB). 2325 * The default is ZSTD_BLOCKSIZE_MAX, and setting to 0 will set to the default. 2326 * 2327 * This parameter can be used to set an upper bound on the blocksize 2328 * that overrides the default ZSTD_BLOCKSIZE_MAX. It cannot be used to set upper 2329 * bounds greater than ZSTD_BLOCKSIZE_MAX or bounds lower than 1KB (will make 2330 * compressBound() inaccurate). Only currently meant to be used for testing. 2331 */ 2332 #define ZSTD_c_maxBlockSize ZSTD_c_experimentalParam18 2333 2334 /* ZSTD_c_repcodeResolution 2335 * This parameter only has an effect if ZSTD_c_blockDelimiters is 2336 * set to ZSTD_sf_explicitBlockDelimiters (may change in the future). 2337 * 2338 * This parameter affects how zstd parses external sequences, 2339 * provided via the ZSTD_compressSequences*() API 2340 * or from an external block-level sequence producer. 2341 * 2342 * If set to ZSTD_ps_enable, the library will check for repeated offsets within 2343 * external sequences, even if those repcodes are not explicitly indicated in 2344 * the "rep" field. Note that this is the only way to exploit repcode matches 2345 * while using compressSequences*() or an external sequence producer, since zstd 2346 * currently ignores the "rep" field of external sequences. 2347 * 2348 * If set to ZSTD_ps_disable, the library will not exploit repeated offsets in 2349 * external sequences, regardless of whether the "rep" field has been set. This 2350 * reduces sequence compression overhead by about 25% while sacrificing some 2351 * compression ratio. 2352 * 2353 * The default value is ZSTD_ps_auto, for which the library will enable/disable 2354 * based on compression level (currently: level<10 disables, level>=10 enables). 2355 */ 2356 #define ZSTD_c_repcodeResolution ZSTD_c_experimentalParam19 2357 #define ZSTD_c_searchForExternalRepcodes ZSTD_c_experimentalParam19 /* older name */ 2358 2359 2360 /*! ZSTD_CCtx_getParameter() : 2361 * Get the requested compression parameter value, selected by enum ZSTD_cParameter, 2362 * and store it into int* value. 2363 * @return : 0, or an error code (which can be tested with ZSTD_isError()). 2364 */ 2365 ZSTDLIB_STATIC_API size_t ZSTD_CCtx_getParameter(const ZSTD_CCtx* cctx, ZSTD_cParameter param, int* value); 2366 2367 2368 /*! ZSTD_CCtx_params : 2369 * Quick howto : 2370 * - ZSTD_createCCtxParams() : Create a ZSTD_CCtx_params structure 2371 * - ZSTD_CCtxParams_setParameter() : Push parameters one by one into 2372 * an existing ZSTD_CCtx_params structure. 2373 * This is similar to 2374 * ZSTD_CCtx_setParameter(). 2375 * - ZSTD_CCtx_setParametersUsingCCtxParams() : Apply parameters to 2376 * an existing CCtx. 2377 * These parameters will be applied to 2378 * all subsequent frames. 2379 * - ZSTD_compressStream2() : Do compression using the CCtx. 2380 * - ZSTD_freeCCtxParams() : Free the memory, accept NULL pointer. 2381 * 2382 * This can be used with ZSTD_estimateCCtxSize_advanced_usingCCtxParams() 2383 * for static allocation of CCtx for single-threaded compression. 2384 */ 2385 ZSTDLIB_STATIC_API ZSTD_CCtx_params* ZSTD_createCCtxParams(void); 2386 ZSTDLIB_STATIC_API size_t ZSTD_freeCCtxParams(ZSTD_CCtx_params* params); /* accept NULL pointer */ 2387 2388 /*! ZSTD_CCtxParams_reset() : 2389 * Reset params to default values. 2390 */ 2391 ZSTDLIB_STATIC_API size_t ZSTD_CCtxParams_reset(ZSTD_CCtx_params* params); 2392 2393 /*! ZSTD_CCtxParams_init() : 2394 * Initializes the compression parameters of cctxParams according to 2395 * compression level. All other parameters are reset to their default values. 2396 */ 2397 ZSTDLIB_STATIC_API size_t ZSTD_CCtxParams_init(ZSTD_CCtx_params* cctxParams, int compressionLevel); 2398 2399 /*! ZSTD_CCtxParams_init_advanced() : 2400 * Initializes the compression and frame parameters of cctxParams according to 2401 * params. All other parameters are reset to their default values. 2402 */ 2403 ZSTDLIB_STATIC_API size_t ZSTD_CCtxParams_init_advanced(ZSTD_CCtx_params* cctxParams, ZSTD_parameters params); 2404 2405 /*! ZSTD_CCtxParams_setParameter() : Requires v1.4.0+ 2406 * Similar to ZSTD_CCtx_setParameter. 2407 * Set one compression parameter, selected by enum ZSTD_cParameter. 2408 * Parameters must be applied to a ZSTD_CCtx using 2409 * ZSTD_CCtx_setParametersUsingCCtxParams(). 2410 * @result : a code representing success or failure (which can be tested with 2411 * ZSTD_isError()). 2412 */ 2413 ZSTDLIB_STATIC_API size_t ZSTD_CCtxParams_setParameter(ZSTD_CCtx_params* params, ZSTD_cParameter param, int value); 2414 2415 /*! ZSTD_CCtxParams_getParameter() : 2416 * Similar to ZSTD_CCtx_getParameter. 2417 * Get the requested value of one compression parameter, selected by enum ZSTD_cParameter. 2418 * @result : 0, or an error code (which can be tested with ZSTD_isError()). 2419 */ 2420 ZSTDLIB_STATIC_API size_t ZSTD_CCtxParams_getParameter(const ZSTD_CCtx_params* params, ZSTD_cParameter param, int* value); 2421 2422 /*! ZSTD_CCtx_setParametersUsingCCtxParams() : 2423 * Apply a set of ZSTD_CCtx_params to the compression context. 2424 * This can be done even after compression is started, 2425 * if nbWorkers==0, this will have no impact until a new compression is started. 2426 * if nbWorkers>=1, new parameters will be picked up at next job, 2427 * with a few restrictions (windowLog, pledgedSrcSize, nbWorkers, jobSize, and overlapLog are not updated). 2428 */ 2429 ZSTDLIB_STATIC_API size_t ZSTD_CCtx_setParametersUsingCCtxParams( 2430 ZSTD_CCtx* cctx, const ZSTD_CCtx_params* params); 2431 2432 /*! ZSTD_compressStream2_simpleArgs() : 2433 * Same as ZSTD_compressStream2(), 2434 * but using only integral types as arguments. 2435 * This variant might be helpful for binders from dynamic languages 2436 * which have troubles handling structures containing memory pointers. 2437 */ 2438 ZSTDLIB_STATIC_API size_t ZSTD_compressStream2_simpleArgs ( 2439 ZSTD_CCtx* cctx, 2440 void* dst, size_t dstCapacity, size_t* dstPos, 2441 const void* src, size_t srcSize, size_t* srcPos, 2442 ZSTD_EndDirective endOp); 2443 2444 2445 /*************************************** 2446 * Advanced decompression functions 2447 ***************************************/ 2448 2449 /*! ZSTD_isFrame() : 2450 * Tells if the content of `buffer` starts with a valid Frame Identifier. 2451 * Note : Frame Identifier is 4 bytes. If `size < 4`, @return will always be 0. 2452 * Note 2 : Legacy Frame Identifiers are considered valid only if Legacy Support is enabled. 2453 * Note 3 : Skippable Frame Identifiers are considered valid. */ 2454 ZSTDLIB_STATIC_API unsigned ZSTD_isFrame(const void* buffer, size_t size); 2455 2456 /*! ZSTD_createDDict_byReference() : 2457 * Create a digested dictionary, ready to start decompression operation without startup delay. 2458 * Dictionary content is referenced, and therefore stays in dictBuffer. 2459 * It is important that dictBuffer outlives DDict, 2460 * it must remain read accessible throughout the lifetime of DDict */ 2461 ZSTDLIB_STATIC_API ZSTD_DDict* ZSTD_createDDict_byReference(const void* dictBuffer, size_t dictSize); 2462 2463 /*! ZSTD_DCtx_loadDictionary_byReference() : 2464 * Same as ZSTD_DCtx_loadDictionary(), 2465 * but references `dict` content instead of copying it into `dctx`. 2466 * This saves memory if `dict` remains around., 2467 * However, it's imperative that `dict` remains accessible (and unmodified) while being used, so it must outlive decompression. */ 2468 ZSTDLIB_STATIC_API size_t ZSTD_DCtx_loadDictionary_byReference(ZSTD_DCtx* dctx, const void* dict, size_t dictSize); 2469 2470 /*! ZSTD_DCtx_loadDictionary_advanced() : 2471 * Same as ZSTD_DCtx_loadDictionary(), 2472 * but gives direct control over 2473 * how to load the dictionary (by copy ? by reference ?) 2474 * and how to interpret it (automatic ? force raw mode ? full mode only ?). */ 2475 ZSTDLIB_STATIC_API size_t ZSTD_DCtx_loadDictionary_advanced(ZSTD_DCtx* dctx, const void* dict, size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod, ZSTD_dictContentType_e dictContentType); 2476 2477 /*! ZSTD_DCtx_refPrefix_advanced() : 2478 * Same as ZSTD_DCtx_refPrefix(), but gives finer control over 2479 * how to interpret prefix content (automatic ? force raw mode (default) ? full mode only ?) */ 2480 ZSTDLIB_STATIC_API size_t ZSTD_DCtx_refPrefix_advanced(ZSTD_DCtx* dctx, const void* prefix, size_t prefixSize, ZSTD_dictContentType_e dictContentType); 2481 2482 /*! ZSTD_DCtx_setMaxWindowSize() : 2483 * Refuses allocating internal buffers for frames requiring a window size larger than provided limit. 2484 * This protects a decoder context from reserving too much memory for itself (potential attack scenario). 2485 * This parameter is only useful in streaming mode, since no internal buffer is allocated in single-pass mode. 2486 * By default, a decompression context accepts all window sizes <= (1 << ZSTD_WINDOWLOG_LIMIT_DEFAULT) 2487 * @return : 0, or an error code (which can be tested using ZSTD_isError()). 2488 */ 2489 ZSTDLIB_STATIC_API size_t ZSTD_DCtx_setMaxWindowSize(ZSTD_DCtx* dctx, size_t maxWindowSize); 2490 2491 /*! ZSTD_DCtx_getParameter() : 2492 * Get the requested decompression parameter value, selected by enum ZSTD_dParameter, 2493 * and store it into int* value. 2494 * @return : 0, or an error code (which can be tested with ZSTD_isError()). 2495 */ 2496 ZSTDLIB_STATIC_API size_t ZSTD_DCtx_getParameter(ZSTD_DCtx* dctx, ZSTD_dParameter param, int* value); 2497 2498 /* ZSTD_d_format 2499 * experimental parameter, 2500 * allowing selection between ZSTD_format_e input compression formats 2501 */ 2502 #define ZSTD_d_format ZSTD_d_experimentalParam1 2503 /* ZSTD_d_stableOutBuffer 2504 * Experimental parameter. 2505 * Default is 0 == disabled. Set to 1 to enable. 2506 * 2507 * Tells the decompressor that the ZSTD_outBuffer will ALWAYS be the same 2508 * between calls, except for the modifications that zstd makes to pos (the 2509 * caller must not modify pos). This is checked by the decompressor, and 2510 * decompression will fail if it ever changes. Therefore the ZSTD_outBuffer 2511 * MUST be large enough to fit the entire decompressed frame. This will be 2512 * checked when the frame content size is known. The data in the ZSTD_outBuffer 2513 * in the range [dst, dst + pos) MUST not be modified during decompression 2514 * or you will get data corruption. 2515 * 2516 * When this flag is enabled zstd won't allocate an output buffer, because 2517 * it can write directly to the ZSTD_outBuffer, but it will still allocate 2518 * an input buffer large enough to fit any compressed block. This will also 2519 * avoid the memcpy() from the internal output buffer to the ZSTD_outBuffer. 2520 * If you need to avoid the input buffer allocation use the buffer-less 2521 * streaming API. 2522 * 2523 * NOTE: So long as the ZSTD_outBuffer always points to valid memory, using 2524 * this flag is ALWAYS memory safe, and will never access out-of-bounds 2525 * memory. However, decompression WILL fail if you violate the preconditions. 2526 * 2527 * WARNING: The data in the ZSTD_outBuffer in the range [dst, dst + pos) MUST 2528 * not be modified during decompression or you will get data corruption. This 2529 * is because zstd needs to reference data in the ZSTD_outBuffer to regenerate 2530 * matches. Normally zstd maintains its own buffer for this purpose, but passing 2531 * this flag tells zstd to use the user provided buffer. 2532 */ 2533 #define ZSTD_d_stableOutBuffer ZSTD_d_experimentalParam2 2534 2535 /* ZSTD_d_forceIgnoreChecksum 2536 * Experimental parameter. 2537 * Default is 0 == disabled. Set to 1 to enable 2538 * 2539 * Tells the decompressor to skip checksum validation during decompression, regardless 2540 * of whether checksumming was specified during compression. This offers some 2541 * slight performance benefits, and may be useful for debugging. 2542 * Param has values of type ZSTD_forceIgnoreChecksum_e 2543 */ 2544 #define ZSTD_d_forceIgnoreChecksum ZSTD_d_experimentalParam3 2545 2546 /* ZSTD_d_refMultipleDDicts 2547 * Experimental parameter. 2548 * Default is 0 == disabled. Set to 1 to enable 2549 * 2550 * If enabled and dctx is allocated on the heap, then additional memory will be allocated 2551 * to store references to multiple ZSTD_DDict. That is, multiple calls of ZSTD_refDDict() 2552 * using a given ZSTD_DCtx, rather than overwriting the previous DDict reference, will instead 2553 * store all references. At decompression time, the appropriate dictID is selected 2554 * from the set of DDicts based on the dictID in the frame. 2555 * 2556 * Usage is simply calling ZSTD_refDDict() on multiple dict buffers. 2557 * 2558 * Param has values of byte ZSTD_refMultipleDDicts_e 2559 * 2560 * WARNING: Enabling this parameter and calling ZSTD_DCtx_refDDict(), will trigger memory 2561 * allocation for the hash table. ZSTD_freeDCtx() also frees this memory. 2562 * Memory is allocated as per ZSTD_DCtx::customMem. 2563 * 2564 * Although this function allocates memory for the table, the user is still responsible for 2565 * memory management of the underlying ZSTD_DDict* themselves. 2566 */ 2567 #define ZSTD_d_refMultipleDDicts ZSTD_d_experimentalParam4 2568 2569 /* ZSTD_d_disableHuffmanAssembly 2570 * Set to 1 to disable the Huffman assembly implementation. 2571 * The default value is 0, which allows zstd to use the Huffman assembly 2572 * implementation if available. 2573 * 2574 * This parameter can be used to disable Huffman assembly at runtime. 2575 * If you want to disable it at compile time you can define the macro 2576 * ZSTD_DISABLE_ASM. 2577 */ 2578 #define ZSTD_d_disableHuffmanAssembly ZSTD_d_experimentalParam5 2579 2580 /* ZSTD_d_maxBlockSize 2581 * Allowed values are between 1KB and ZSTD_BLOCKSIZE_MAX (128KB). 2582 * The default is ZSTD_BLOCKSIZE_MAX, and setting to 0 will set to the default. 2583 * 2584 * Forces the decompressor to reject blocks whose content size is 2585 * larger than the configured maxBlockSize. When maxBlockSize is 2586 * larger than the windowSize, the windowSize is used instead. 2587 * This saves memory on the decoder when you know all blocks are small. 2588 * 2589 * This option is typically used in conjunction with ZSTD_c_maxBlockSize. 2590 * 2591 * WARNING: This causes the decoder to reject otherwise valid frames 2592 * that have block sizes larger than the configured maxBlockSize. 2593 */ 2594 #define ZSTD_d_maxBlockSize ZSTD_d_experimentalParam6 2595 2596 2597 /*! ZSTD_DCtx_setFormat() : 2598 * This function is REDUNDANT. Prefer ZSTD_DCtx_setParameter(). 2599 * Instruct the decoder context about what kind of data to decode next. 2600 * This instruction is mandatory to decode data without a fully-formed header, 2601 * such ZSTD_f_zstd1_magicless for example. 2602 * @return : 0, or an error code (which can be tested using ZSTD_isError()). */ 2603 ZSTD_DEPRECATED("use ZSTD_DCtx_setParameter() instead") 2604 ZSTDLIB_STATIC_API 2605 size_t ZSTD_DCtx_setFormat(ZSTD_DCtx* dctx, ZSTD_format_e format); 2606 2607 /*! ZSTD_decompressStream_simpleArgs() : 2608 * Same as ZSTD_decompressStream(), 2609 * but using only integral types as arguments. 2610 * This can be helpful for binders from dynamic languages 2611 * which have troubles handling structures containing memory pointers. 2612 */ 2613 ZSTDLIB_STATIC_API size_t ZSTD_decompressStream_simpleArgs ( 2614 ZSTD_DCtx* dctx, 2615 void* dst, size_t dstCapacity, size_t* dstPos, 2616 const void* src, size_t srcSize, size_t* srcPos); 2617 2618 2619 /******************************************************************** 2620 * Advanced streaming functions 2621 * Warning : most of these functions are now redundant with the Advanced API. 2622 * Once Advanced API reaches "stable" status, 2623 * redundant functions will be deprecated, and then at some point removed. 2624 ********************************************************************/ 2625 2626 /*===== Advanced Streaming compression functions =====*/ 2627 2628 /*! ZSTD_initCStream_srcSize() : 2629 * This function is DEPRECATED, and equivalent to: 2630 * ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only); 2631 * ZSTD_CCtx_refCDict(zcs, NULL); // clear the dictionary (if any) 2632 * ZSTD_CCtx_setParameter(zcs, ZSTD_c_compressionLevel, compressionLevel); 2633 * ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize); 2634 * 2635 * pledgedSrcSize must be correct. If it is not known at init time, use 2636 * ZSTD_CONTENTSIZE_UNKNOWN. Note that, for compatibility with older programs, 2637 * "0" also disables frame content size field. It may be enabled in the future. 2638 * This prototype will generate compilation warnings. 2639 */ 2640 ZSTD_DEPRECATED("use ZSTD_CCtx_reset, see zstd.h for detailed instructions") 2641 ZSTDLIB_STATIC_API 2642 size_t ZSTD_initCStream_srcSize(ZSTD_CStream* zcs, 2643 int compressionLevel, 2644 unsigned long long pledgedSrcSize); 2645 2646 /*! ZSTD_initCStream_usingDict() : 2647 * This function is DEPRECATED, and is equivalent to: 2648 * ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only); 2649 * ZSTD_CCtx_setParameter(zcs, ZSTD_c_compressionLevel, compressionLevel); 2650 * ZSTD_CCtx_loadDictionary(zcs, dict, dictSize); 2651 * 2652 * Creates of an internal CDict (incompatible with static CCtx), except if 2653 * dict == NULL or dictSize < 8, in which case no dict is used. 2654 * Note: dict is loaded with ZSTD_dct_auto (treated as a full zstd dictionary if 2655 * it begins with ZSTD_MAGIC_DICTIONARY, else as raw content) and ZSTD_dlm_byCopy. 2656 * This prototype will generate compilation warnings. 2657 */ 2658 ZSTD_DEPRECATED("use ZSTD_CCtx_reset, see zstd.h for detailed instructions") 2659 ZSTDLIB_STATIC_API 2660 size_t ZSTD_initCStream_usingDict(ZSTD_CStream* zcs, 2661 const void* dict, size_t dictSize, 2662 int compressionLevel); 2663 2664 /*! ZSTD_initCStream_advanced() : 2665 * This function is DEPRECATED, and is equivalent to: 2666 * ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only); 2667 * ZSTD_CCtx_setParams(zcs, params); 2668 * ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize); 2669 * ZSTD_CCtx_loadDictionary(zcs, dict, dictSize); 2670 * 2671 * dict is loaded with ZSTD_dct_auto and ZSTD_dlm_byCopy. 2672 * pledgedSrcSize must be correct. 2673 * If srcSize is not known at init time, use value ZSTD_CONTENTSIZE_UNKNOWN. 2674 * This prototype will generate compilation warnings. 2675 */ 2676 ZSTD_DEPRECATED("use ZSTD_CCtx_reset, see zstd.h for detailed instructions") 2677 ZSTDLIB_STATIC_API 2678 size_t ZSTD_initCStream_advanced(ZSTD_CStream* zcs, 2679 const void* dict, size_t dictSize, 2680 ZSTD_parameters params, 2681 unsigned long long pledgedSrcSize); 2682 2683 /*! ZSTD_initCStream_usingCDict() : 2684 * This function is DEPRECATED, and equivalent to: 2685 * ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only); 2686 * ZSTD_CCtx_refCDict(zcs, cdict); 2687 * 2688 * note : cdict will just be referenced, and must outlive compression session 2689 * This prototype will generate compilation warnings. 2690 */ 2691 ZSTD_DEPRECATED("use ZSTD_CCtx_reset and ZSTD_CCtx_refCDict, see zstd.h for detailed instructions") 2692 ZSTDLIB_STATIC_API 2693 size_t ZSTD_initCStream_usingCDict(ZSTD_CStream* zcs, const ZSTD_CDict* cdict); 2694 2695 /*! ZSTD_initCStream_usingCDict_advanced() : 2696 * This function is DEPRECATED, and is equivalent to: 2697 * ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only); 2698 * ZSTD_CCtx_setFParams(zcs, fParams); 2699 * ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize); 2700 * ZSTD_CCtx_refCDict(zcs, cdict); 2701 * 2702 * same as ZSTD_initCStream_usingCDict(), with control over frame parameters. 2703 * pledgedSrcSize must be correct. If srcSize is not known at init time, use 2704 * value ZSTD_CONTENTSIZE_UNKNOWN. 2705 * This prototype will generate compilation warnings. 2706 */ 2707 ZSTD_DEPRECATED("use ZSTD_CCtx_reset and ZSTD_CCtx_refCDict, see zstd.h for detailed instructions") 2708 ZSTDLIB_STATIC_API 2709 size_t ZSTD_initCStream_usingCDict_advanced(ZSTD_CStream* zcs, 2710 const ZSTD_CDict* cdict, 2711 ZSTD_frameParameters fParams, 2712 unsigned long long pledgedSrcSize); 2713 2714 /*! ZSTD_resetCStream() : 2715 * This function is DEPRECATED, and is equivalent to: 2716 * ZSTD_CCtx_reset(zcs, ZSTD_reset_session_only); 2717 * ZSTD_CCtx_setPledgedSrcSize(zcs, pledgedSrcSize); 2718 * Note: ZSTD_resetCStream() interprets pledgedSrcSize == 0 as ZSTD_CONTENTSIZE_UNKNOWN, but 2719 * ZSTD_CCtx_setPledgedSrcSize() does not do the same, so ZSTD_CONTENTSIZE_UNKNOWN must be 2720 * explicitly specified. 2721 * 2722 * start a new frame, using same parameters from previous frame. 2723 * This is typically useful to skip dictionary loading stage, since it will reuse it in-place. 2724 * Note that zcs must be init at least once before using ZSTD_resetCStream(). 2725 * If pledgedSrcSize is not known at reset time, use macro ZSTD_CONTENTSIZE_UNKNOWN. 2726 * If pledgedSrcSize > 0, its value must be correct, as it will be written in header, and controlled at the end. 2727 * For the time being, pledgedSrcSize==0 is interpreted as "srcSize unknown" for compatibility with older programs, 2728 * but it will change to mean "empty" in future version, so use macro ZSTD_CONTENTSIZE_UNKNOWN instead. 2729 * @return : 0, or an error code (which can be tested using ZSTD_isError()) 2730 * This prototype will generate compilation warnings. 2731 */ 2732 ZSTD_DEPRECATED("use ZSTD_CCtx_reset, see zstd.h for detailed instructions") 2733 ZSTDLIB_STATIC_API 2734 size_t ZSTD_resetCStream(ZSTD_CStream* zcs, unsigned long long pledgedSrcSize); 2735 2736 2737 typedef struct { 2738 unsigned long long ingested; /* nb input bytes read and buffered */ 2739 unsigned long long consumed; /* nb input bytes actually compressed */ 2740 unsigned long long produced; /* nb of compressed bytes generated and buffered */ 2741 unsigned long long flushed; /* nb of compressed bytes flushed : not provided; can be tracked from caller side */ 2742 unsigned currentJobID; /* MT only : latest started job nb */ 2743 unsigned nbActiveWorkers; /* MT only : nb of workers actively compressing at probe time */ 2744 } ZSTD_frameProgression; 2745 2746 /* ZSTD_getFrameProgression() : 2747 * tells how much data has been ingested (read from input) 2748 * consumed (input actually compressed) and produced (output) for current frame. 2749 * Note : (ingested - consumed) is amount of input data buffered internally, not yet compressed. 2750 * Aggregates progression inside active worker threads. 2751 */ 2752 ZSTDLIB_STATIC_API ZSTD_frameProgression ZSTD_getFrameProgression(const ZSTD_CCtx* cctx); 2753 2754 /*! ZSTD_toFlushNow() : 2755 * Tell how many bytes are ready to be flushed immediately. 2756 * Useful for multithreading scenarios (nbWorkers >= 1). 2757 * Probe the oldest active job, defined as oldest job not yet entirely flushed, 2758 * and check its output buffer. 2759 * @return : amount of data stored in oldest job and ready to be flushed immediately. 2760 * if @return == 0, it means either : 2761 * + there is no active job (could be checked with ZSTD_frameProgression()), or 2762 * + oldest job is still actively compressing data, 2763 * but everything it has produced has also been flushed so far, 2764 * therefore flush speed is limited by production speed of oldest job 2765 * irrespective of the speed of concurrent (and newer) jobs. 2766 */ 2767 ZSTDLIB_STATIC_API size_t ZSTD_toFlushNow(ZSTD_CCtx* cctx); 2768 2769 2770 /*===== Advanced Streaming decompression functions =====*/ 2771 2772 /*! 2773 * This function is deprecated, and is equivalent to: 2774 * 2775 * ZSTD_DCtx_reset(zds, ZSTD_reset_session_only); 2776 * ZSTD_DCtx_loadDictionary(zds, dict, dictSize); 2777 * 2778 * note: no dictionary will be used if dict == NULL or dictSize < 8 2779 */ 2780 ZSTD_DEPRECATED("use ZSTD_DCtx_reset + ZSTD_DCtx_loadDictionary, see zstd.h for detailed instructions") 2781 ZSTDLIB_STATIC_API size_t ZSTD_initDStream_usingDict(ZSTD_DStream* zds, const void* dict, size_t dictSize); 2782 2783 /*! 2784 * This function is deprecated, and is equivalent to: 2785 * 2786 * ZSTD_DCtx_reset(zds, ZSTD_reset_session_only); 2787 * ZSTD_DCtx_refDDict(zds, ddict); 2788 * 2789 * note : ddict is referenced, it must outlive decompression session 2790 */ 2791 ZSTD_DEPRECATED("use ZSTD_DCtx_reset + ZSTD_DCtx_refDDict, see zstd.h for detailed instructions") 2792 ZSTDLIB_STATIC_API size_t ZSTD_initDStream_usingDDict(ZSTD_DStream* zds, const ZSTD_DDict* ddict); 2793 2794 /*! 2795 * This function is deprecated, and is equivalent to: 2796 * 2797 * ZSTD_DCtx_reset(zds, ZSTD_reset_session_only); 2798 * 2799 * reuse decompression parameters from previous init; saves dictionary loading 2800 */ 2801 ZSTD_DEPRECATED("use ZSTD_DCtx_reset, see zstd.h for detailed instructions") 2802 ZSTDLIB_STATIC_API size_t ZSTD_resetDStream(ZSTD_DStream* zds); 2803 2804 2805 /* ********************* BLOCK-LEVEL SEQUENCE PRODUCER API ********************* 2806 * 2807 * *** OVERVIEW *** 2808 * The Block-Level Sequence Producer API allows users to provide their own custom 2809 * sequence producer which libzstd invokes to process each block. The produced list 2810 * of sequences (literals and matches) is then post-processed by libzstd to produce 2811 * valid compressed blocks. 2812 * 2813 * This block-level offload API is a more granular complement of the existing 2814 * frame-level offload API compressSequences() (introduced in v1.5.1). It offers 2815 * an easier migration story for applications already integrated with libzstd: the 2816 * user application continues to invoke the same compression functions 2817 * ZSTD_compress2() or ZSTD_compressStream2() as usual, and transparently benefits 2818 * from the specific advantages of the external sequence producer. For example, 2819 * the sequence producer could be tuned to take advantage of known characteristics 2820 * of the input, to offer better speed / ratio, or could leverage hardware 2821 * acceleration not available within libzstd itself. 2822 * 2823 * See contrib/externalSequenceProducer for an example program employing the 2824 * Block-Level Sequence Producer API. 2825 * 2826 * *** USAGE *** 2827 * The user is responsible for implementing a function of type 2828 * ZSTD_sequenceProducer_F. For each block, zstd will pass the following 2829 * arguments to the user-provided function: 2830 * 2831 * - sequenceProducerState: a pointer to a user-managed state for the sequence 2832 * producer. 2833 * 2834 * - outSeqs, outSeqsCapacity: an output buffer for the sequence producer. 2835 * outSeqsCapacity is guaranteed >= ZSTD_sequenceBound(srcSize). The memory 2836 * backing outSeqs is managed by the CCtx. 2837 * 2838 * - src, srcSize: an input buffer for the sequence producer to parse. 2839 * srcSize is guaranteed to be <= ZSTD_BLOCKSIZE_MAX. 2840 * 2841 * - dict, dictSize: a history buffer, which may be empty, which the sequence 2842 * producer may reference as it parses the src buffer. Currently, zstd will 2843 * always pass dictSize == 0 into external sequence producers, but this will 2844 * change in the future. 2845 * 2846 * - compressionLevel: a signed integer representing the zstd compression level 2847 * set by the user for the current operation. The sequence producer may choose 2848 * to use this information to change its compression strategy and speed/ratio 2849 * tradeoff. Note: the compression level does not reflect zstd parameters set 2850 * through the advanced API. 2851 * 2852 * - windowSize: a size_t representing the maximum allowed offset for external 2853 * sequences. Note that sequence offsets are sometimes allowed to exceed the 2854 * windowSize if a dictionary is present, see doc/zstd_compression_format.md 2855 * for details. 2856 * 2857 * The user-provided function shall return a size_t representing the number of 2858 * sequences written to outSeqs. This return value will be treated as an error 2859 * code if it is greater than outSeqsCapacity. The return value must be non-zero 2860 * if srcSize is non-zero. The ZSTD_SEQUENCE_PRODUCER_ERROR macro is provided 2861 * for convenience, but any value greater than outSeqsCapacity will be treated as 2862 * an error code. 2863 * 2864 * If the user-provided function does not return an error code, the sequences 2865 * written to outSeqs must be a valid parse of the src buffer. Data corruption may 2866 * occur if the parse is not valid. A parse is defined to be valid if the 2867 * following conditions hold: 2868 * - The sum of matchLengths and literalLengths must equal srcSize. 2869 * - All sequences in the parse, except for the final sequence, must have 2870 * matchLength >= ZSTD_MINMATCH_MIN. The final sequence must have 2871 * matchLength >= ZSTD_MINMATCH_MIN or matchLength == 0. 2872 * - All offsets must respect the windowSize parameter as specified in 2873 * doc/zstd_compression_format.md. 2874 * - If the final sequence has matchLength == 0, it must also have offset == 0. 2875 * 2876 * zstd will only validate these conditions (and fail compression if they do not 2877 * hold) if the ZSTD_c_validateSequences cParam is enabled. Note that sequence 2878 * validation has a performance cost. 2879 * 2880 * If the user-provided function returns an error, zstd will either fall back 2881 * to an internal sequence producer or fail the compression operation. The user can 2882 * choose between the two behaviors by setting the ZSTD_c_enableSeqProducerFallback 2883 * cParam. Fallback compression will follow any other cParam settings, such as 2884 * compression level, the same as in a normal compression operation. 2885 * 2886 * The user shall instruct zstd to use a particular ZSTD_sequenceProducer_F 2887 * function by calling 2888 * ZSTD_registerSequenceProducer(cctx, 2889 * sequenceProducerState, 2890 * sequenceProducer) 2891 * This setting will persist until the next parameter reset of the CCtx. 2892 * 2893 * The sequenceProducerState must be initialized by the user before calling 2894 * ZSTD_registerSequenceProducer(). The user is responsible for destroying the 2895 * sequenceProducerState. 2896 * 2897 * *** LIMITATIONS *** 2898 * This API is compatible with all zstd compression APIs which respect advanced parameters. 2899 * However, there are three limitations: 2900 * 2901 * First, the ZSTD_c_enableLongDistanceMatching cParam is not currently supported. 2902 * COMPRESSION WILL FAIL if it is enabled and the user tries to compress with a block-level 2903 * external sequence producer. 2904 * - Note that ZSTD_c_enableLongDistanceMatching is auto-enabled by default in some 2905 * cases (see its documentation for details). Users must explicitly set 2906 * ZSTD_c_enableLongDistanceMatching to ZSTD_ps_disable in such cases if an external 2907 * sequence producer is registered. 2908 * - As of this writing, ZSTD_c_enableLongDistanceMatching is disabled by default 2909 * whenever ZSTD_c_windowLog < 128MB, but that's subject to change. Users should 2910 * check the docs on ZSTD_c_enableLongDistanceMatching whenever the Block-Level Sequence 2911 * Producer API is used in conjunction with advanced settings (like ZSTD_c_windowLog). 2912 * 2913 * Second, history buffers are not currently supported. Concretely, zstd will always pass 2914 * dictSize == 0 to the external sequence producer (for now). This has two implications: 2915 * - Dictionaries are not currently supported. Compression will *not* fail if the user 2916 * references a dictionary, but the dictionary won't have any effect. 2917 * - Stream history is not currently supported. All advanced compression APIs, including 2918 * streaming APIs, work with external sequence producers, but each block is treated as 2919 * an independent chunk without history from previous blocks. 2920 * 2921 * Third, multi-threading within a single compression is not currently supported. In other words, 2922 * COMPRESSION WILL FAIL if ZSTD_c_nbWorkers > 0 and an external sequence producer is registered. 2923 * Multi-threading across compressions is fine: simply create one CCtx per thread. 2924 * 2925 * Long-term, we plan to overcome all three limitations. There is no technical blocker to 2926 * overcoming them. It is purely a question of engineering effort. 2927 */ 2928 2929 #define ZSTD_SEQUENCE_PRODUCER_ERROR ((size_t)(-1)) 2930 2931 typedef size_t (*ZSTD_sequenceProducer_F) ( 2932 void* sequenceProducerState, 2933 ZSTD_Sequence* outSeqs, size_t outSeqsCapacity, 2934 const void* src, size_t srcSize, 2935 const void* dict, size_t dictSize, 2936 int compressionLevel, 2937 size_t windowSize 2938 ); 2939 2940 /*! ZSTD_registerSequenceProducer() : 2941 * Instruct zstd to use a block-level external sequence producer function. 2942 * 2943 * The sequenceProducerState must be initialized by the caller, and the caller is 2944 * responsible for managing its lifetime. This parameter is sticky across 2945 * compressions. It will remain set until the user explicitly resets compression 2946 * parameters. 2947 * 2948 * Sequence producer registration is considered to be an "advanced parameter", 2949 * part of the "advanced API". This means it will only have an effect on compression 2950 * APIs which respect advanced parameters, such as compress2() and compressStream2(). 2951 * Older compression APIs such as compressCCtx(), which predate the introduction of 2952 * "advanced parameters", will ignore any external sequence producer setting. 2953 * 2954 * The sequence producer can be "cleared" by registering a NULL function pointer. This 2955 * removes all limitations described above in the "LIMITATIONS" section of the API docs. 2956 * 2957 * The user is strongly encouraged to read the full API documentation (above) before 2958 * calling this function. */ 2959 ZSTDLIB_STATIC_API void 2960 ZSTD_registerSequenceProducer( 2961 ZSTD_CCtx* cctx, 2962 void* sequenceProducerState, 2963 ZSTD_sequenceProducer_F sequenceProducer 2964 ); 2965 2966 /*! ZSTD_CCtxParams_registerSequenceProducer() : 2967 * Same as ZSTD_registerSequenceProducer(), but operates on ZSTD_CCtx_params. 2968 * This is used for accurate size estimation with ZSTD_estimateCCtxSize_usingCCtxParams(), 2969 * which is needed when creating a ZSTD_CCtx with ZSTD_initStaticCCtx(). 2970 * 2971 * If you are using the external sequence producer API in a scenario where ZSTD_initStaticCCtx() 2972 * is required, then this function is for you. Otherwise, you probably don't need it. 2973 * 2974 * See tests/zstreamtest.c for example usage. */ 2975 ZSTDLIB_STATIC_API void 2976 ZSTD_CCtxParams_registerSequenceProducer( 2977 ZSTD_CCtx_params* params, 2978 void* sequenceProducerState, 2979 ZSTD_sequenceProducer_F sequenceProducer 2980 ); 2981 2982 2983 /********************************************************************* 2984 * Buffer-less and synchronous inner streaming functions (DEPRECATED) 2985 * 2986 * This API is deprecated, and will be removed in a future version. 2987 * It allows streaming (de)compression with user allocated buffers. 2988 * However, it is hard to use, and not as well tested as the rest of 2989 * our API. 2990 * 2991 * Please use the normal streaming API instead: ZSTD_compressStream2, 2992 * and ZSTD_decompressStream. 2993 * If there is functionality that you need, but it doesn't provide, 2994 * please open an issue on our GitHub. 2995 ********************************************************************* */ 2996 2997 /** 2998 Buffer-less streaming compression (synchronous mode) 2999 3000 A ZSTD_CCtx object is required to track streaming operations. 3001 Use ZSTD_createCCtx() / ZSTD_freeCCtx() to manage resource. 3002 ZSTD_CCtx object can be reused multiple times within successive compression operations. 3003 3004 Start by initializing a context. 3005 Use ZSTD_compressBegin(), or ZSTD_compressBegin_usingDict() for dictionary compression. 3006 3007 Then, consume your input using ZSTD_compressContinue(). 3008 There are some important considerations to keep in mind when using this advanced function : 3009 - ZSTD_compressContinue() has no internal buffer. It uses externally provided buffers only. 3010 - Interface is synchronous : input is consumed entirely and produces 1+ compressed blocks. 3011 - Caller must ensure there is enough space in `dst` to store compressed data under worst case scenario. 3012 Worst case evaluation is provided by ZSTD_compressBound(). 3013 ZSTD_compressContinue() doesn't guarantee recover after a failed compression. 3014 - ZSTD_compressContinue() presumes prior input ***is still accessible and unmodified*** (up to maximum distance size, see WindowLog). 3015 It remembers all previous contiguous blocks, plus one separated memory segment (which can itself consists of multiple contiguous blocks) 3016 - ZSTD_compressContinue() detects that prior input has been overwritten when `src` buffer overlaps. 3017 In which case, it will "discard" the relevant memory section from its history. 3018 3019 Finish a frame with ZSTD_compressEnd(), which will write the last block(s) and optional checksum. 3020 It's possible to use srcSize==0, in which case, it will write a final empty block to end the frame. 3021 Without last block mark, frames are considered unfinished (hence corrupted) by compliant decoders. 3022 3023 `ZSTD_CCtx` object can be reused (ZSTD_compressBegin()) to compress again. 3024 */ 3025 3026 /*===== Buffer-less streaming compression functions =====*/ 3027 ZSTD_DEPRECATED("The buffer-less API is deprecated in favor of the normal streaming API. See docs.") 3028 ZSTDLIB_STATIC_API size_t ZSTD_compressBegin(ZSTD_CCtx* cctx, int compressionLevel); 3029 ZSTD_DEPRECATED("The buffer-less API is deprecated in favor of the normal streaming API. See docs.") 3030 ZSTDLIB_STATIC_API size_t ZSTD_compressBegin_usingDict(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, int compressionLevel); 3031 ZSTD_DEPRECATED("The buffer-less API is deprecated in favor of the normal streaming API. See docs.") 3032 ZSTDLIB_STATIC_API size_t ZSTD_compressBegin_usingCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict); /**< note: fails if cdict==NULL */ 3033 3034 ZSTD_DEPRECATED("This function will likely be removed in a future release. It is misleading and has very limited utility.") 3035 ZSTDLIB_STATIC_API 3036 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 */ 3037 3038 ZSTD_DEPRECATED("The buffer-less API is deprecated in favor of the normal streaming API. See docs.") 3039 ZSTDLIB_STATIC_API size_t ZSTD_compressContinue(ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize); 3040 ZSTD_DEPRECATED("The buffer-less API is deprecated in favor of the normal streaming API. See docs.") 3041 ZSTDLIB_STATIC_API size_t ZSTD_compressEnd(ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize); 3042 3043 /* The ZSTD_compressBegin_advanced() and ZSTD_compressBegin_usingCDict_advanced() are now DEPRECATED and will generate a compiler warning */ 3044 ZSTD_DEPRECATED("use advanced API to access custom parameters") 3045 ZSTDLIB_STATIC_API 3046 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 */ 3047 ZSTD_DEPRECATED("use advanced API to access custom parameters") 3048 ZSTDLIB_STATIC_API 3049 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 */ 3050 /** 3051 Buffer-less streaming decompression (synchronous mode) 3052 3053 A ZSTD_DCtx object is required to track streaming operations. 3054 Use ZSTD_createDCtx() / ZSTD_freeDCtx() to manage it. 3055 A ZSTD_DCtx object can be reused multiple times. 3056 3057 First typical operation is to retrieve frame parameters, using ZSTD_getFrameHeader(). 3058 Frame header is extracted from the beginning of compressed frame, so providing only the frame's beginning is enough. 3059 Data fragment must be large enough to ensure successful decoding. 3060 `ZSTD_frameHeaderSize_max` bytes is guaranteed to always be large enough. 3061 result : 0 : successful decoding, the `ZSTD_frameHeader` structure is correctly filled. 3062 >0 : `srcSize` is too small, please provide at least result bytes on next attempt. 3063 errorCode, which can be tested using ZSTD_isError(). 3064 3065 It fills a ZSTD_FrameHeader structure with important information to correctly decode the frame, 3066 such as the dictionary ID, content size, or maximum back-reference distance (`windowSize`). 3067 Note that these values could be wrong, either because of data corruption, or because a 3rd party deliberately spoofs false information. 3068 As a consequence, check that values remain within valid application range. 3069 For example, do not allocate memory blindly, check that `windowSize` is within expectation. 3070 Each application can set its own limits, depending on local restrictions. 3071 For extended interoperability, it is recommended to support `windowSize` of at least 8 MB. 3072 3073 ZSTD_decompressContinue() needs previous data blocks during decompression, up to `windowSize` bytes. 3074 ZSTD_decompressContinue() is very sensitive to contiguity, 3075 if 2 blocks don't follow each other, make sure that either the compressor breaks contiguity at the same place, 3076 or that previous contiguous segment is large enough to properly handle maximum back-reference distance. 3077 There are multiple ways to guarantee this condition. 3078 3079 The most memory efficient way is to use a round buffer of sufficient size. 3080 Sufficient size is determined by invoking ZSTD_decodingBufferSize_min(), 3081 which can return an error code if required value is too large for current system (in 32-bits mode). 3082 In a round buffer methodology, ZSTD_decompressContinue() decompresses each block next to previous one, 3083 up to the moment there is not enough room left in the buffer to guarantee decoding another full block, 3084 which maximum size is provided in `ZSTD_frameHeader` structure, field `blockSizeMax`. 3085 At which point, decoding can resume from the beginning of the buffer. 3086 Note that already decoded data stored in the buffer should be flushed before being overwritten. 3087 3088 There are alternatives possible, for example using two or more buffers of size `windowSize` each, though they consume more memory. 3089 3090 Finally, if you control the compression process, you can also ignore all buffer size rules, 3091 as long as the encoder and decoder progress in "lock-step", 3092 aka use exactly the same buffer sizes, break contiguity at the same place, etc. 3093 3094 Once buffers are setup, start decompression, with ZSTD_decompressBegin(). 3095 If decompression requires a dictionary, use ZSTD_decompressBegin_usingDict() or ZSTD_decompressBegin_usingDDict(). 3096 3097 Then use ZSTD_nextSrcSizeToDecompress() and ZSTD_decompressContinue() alternatively. 3098 ZSTD_nextSrcSizeToDecompress() tells how many bytes to provide as 'srcSize' to ZSTD_decompressContinue(). 3099 ZSTD_decompressContinue() requires this _exact_ amount of bytes, or it will fail. 3100 3101 result of ZSTD_decompressContinue() is the number of bytes regenerated within 'dst' (necessarily <= dstCapacity). 3102 It can be zero : it just means ZSTD_decompressContinue() has decoded some metadata item. 3103 It can also be an error code, which can be tested with ZSTD_isError(). 3104 3105 A frame is fully decoded when ZSTD_nextSrcSizeToDecompress() returns zero. 3106 Context can then be reset to start a new decompression. 3107 3108 Note : it's possible to know if next input to present is a header or a block, using ZSTD_nextInputType(). 3109 This information is not required to properly decode a frame. 3110 3111 == Special case : skippable frames == 3112 3113 Skippable frames allow integration of user-defined data into a flow of concatenated frames. 3114 Skippable frames will be ignored (skipped) by decompressor. 3115 The format of skippable frames is as follows : 3116 a) Skippable frame ID - 4 Bytes, Little endian format, any value from 0x184D2A50 to 0x184D2A5F 3117 b) Frame Size - 4 Bytes, Little endian format, unsigned 32-bits 3118 c) Frame Content - any content (User Data) of length equal to Frame Size 3119 For skippable frames ZSTD_getFrameHeader() returns zfhPtr->frameType==ZSTD_skippableFrame. 3120 For skippable frames ZSTD_decompressContinue() always returns 0 : it only skips the content. 3121 */ 3122 3123 /*===== Buffer-less streaming decompression functions =====*/ 3124 3125 ZSTDLIB_STATIC_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 */ 3126 3127 ZSTDLIB_STATIC_API size_t ZSTD_decompressBegin(ZSTD_DCtx* dctx); 3128 ZSTDLIB_STATIC_API size_t ZSTD_decompressBegin_usingDict(ZSTD_DCtx* dctx, const void* dict, size_t dictSize); 3129 ZSTDLIB_STATIC_API size_t ZSTD_decompressBegin_usingDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict); 3130 3131 ZSTDLIB_STATIC_API size_t ZSTD_nextSrcSizeToDecompress(ZSTD_DCtx* dctx); 3132 ZSTDLIB_STATIC_API size_t ZSTD_decompressContinue(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize); 3133 3134 /* misc */ 3135 ZSTD_DEPRECATED("This function will likely be removed in the next minor release. It is misleading and has very limited utility.") 3136 ZSTDLIB_STATIC_API void ZSTD_copyDCtx(ZSTD_DCtx* dctx, const ZSTD_DCtx* preparedDCtx); 3137 typedef enum { ZSTDnit_frameHeader, ZSTDnit_blockHeader, ZSTDnit_block, ZSTDnit_lastBlock, ZSTDnit_checksum, ZSTDnit_skippableFrame } ZSTD_nextInputType_e; 3138 ZSTDLIB_STATIC_API ZSTD_nextInputType_e ZSTD_nextInputType(ZSTD_DCtx* dctx); 3139 3140 3141 3142 3143 /* ========================================= */ 3144 /** Block level API (DEPRECATED) */ 3145 /* ========================================= */ 3146 3147 /*! 3148 3149 This API is deprecated in favor of the regular compression API. 3150 You can get the frame header down to 2 bytes by setting: 3151 - ZSTD_c_format = ZSTD_f_zstd1_magicless 3152 - ZSTD_c_contentSizeFlag = 0 3153 - ZSTD_c_checksumFlag = 0 3154 - ZSTD_c_dictIDFlag = 0 3155 3156 This API is not as well tested as our normal API, so we recommend not using it. 3157 We will be removing it in a future version. If the normal API doesn't provide 3158 the functionality you need, please open a GitHub issue. 3159 3160 Block functions produce and decode raw zstd blocks, without frame metadata. 3161 Frame metadata cost is typically ~12 bytes, which can be non-negligible for very small blocks (< 100 bytes). 3162 But users will have to take in charge needed metadata to regenerate data, such as compressed and content sizes. 3163 3164 A few rules to respect : 3165 - Compressing and decompressing require a context structure 3166 + Use ZSTD_createCCtx() and ZSTD_createDCtx() 3167 - It is necessary to init context before starting 3168 + compression : any ZSTD_compressBegin*() variant, including with dictionary 3169 + decompression : any ZSTD_decompressBegin*() variant, including with dictionary 3170 - Block size is limited, it must be <= ZSTD_getBlockSize() <= ZSTD_BLOCKSIZE_MAX == 128 KB 3171 + If input is larger than a block size, it's necessary to split input data into multiple blocks 3172 + For inputs larger than a single block, consider using regular ZSTD_compress() instead. 3173 Frame metadata is not that costly, and quickly becomes negligible as source size grows larger than a block. 3174 - When a block is considered not compressible enough, ZSTD_compressBlock() result will be 0 (zero) ! 3175 ===> In which case, nothing is produced into `dst` ! 3176 + User __must__ test for such outcome and deal directly with uncompressed data 3177 + A block cannot be declared incompressible if ZSTD_compressBlock() return value was != 0. 3178 Doing so would mess up with statistics history, leading to potential data corruption. 3179 + ZSTD_decompressBlock() _doesn't accept uncompressed data as input_ !! 3180 + In case of multiple successive blocks, should some of them be uncompressed, 3181 decoder must be informed of their existence in order to follow proper history. 3182 Use ZSTD_insertBlock() for such a case. 3183 */ 3184 3185 /*===== Raw zstd block functions =====*/ 3186 ZSTD_DEPRECATED("The block API is deprecated in favor of the normal compression API. See docs.") 3187 ZSTDLIB_STATIC_API size_t ZSTD_getBlockSize (const ZSTD_CCtx* cctx); 3188 ZSTD_DEPRECATED("The block API is deprecated in favor of the normal compression API. See docs.") 3189 ZSTDLIB_STATIC_API size_t ZSTD_compressBlock (ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize); 3190 ZSTD_DEPRECATED("The block API is deprecated in favor of the normal compression API. See docs.") 3191 ZSTDLIB_STATIC_API size_t ZSTD_decompressBlock(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize); 3192 ZSTD_DEPRECATED("The block API is deprecated in favor of the normal compression API. See docs.") 3193 ZSTDLIB_STATIC_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. */ 3194 3195 #if defined (__cplusplus) 3196 } 3197 #endif 3198 3199 #endif /* ZSTD_H_ZSTD_STATIC_LINKING_ONLY */ 3200