1 /* 2 * Copyright (c) 2016-present, Yann Collet, Facebook, Inc. 3 * All rights reserved. 4 * 5 * This source code is licensed under both the BSD-style license (found in the 6 * LICENSE file in the root directory of this source tree) and the GPLv2 (found 7 * in the COPYING file in the root directory of this source tree). 8 * You may select, at your option, one of the above-listed licenses. 9 */ 10 #if defined (__cplusplus) 11 extern "C" { 12 #endif 13 14 #ifndef ZSTD_H_235446 15 #define ZSTD_H_235446 16 17 /* ====== Dependency ======*/ 18 #include <stddef.h> /* size_t */ 19 20 21 /* ===== ZSTDLIB_API : control library symbols visibility ===== */ 22 #ifndef ZSTDLIB_VISIBILITY 23 # if defined(__GNUC__) && (__GNUC__ >= 4) 24 # define ZSTDLIB_VISIBILITY __attribute__ ((visibility ("default"))) 25 # else 26 # define ZSTDLIB_VISIBILITY 27 # endif 28 #endif 29 #if defined(ZSTD_DLL_EXPORT) && (ZSTD_DLL_EXPORT==1) 30 # define ZSTDLIB_API __declspec(dllexport) ZSTDLIB_VISIBILITY 31 #elif defined(ZSTD_DLL_IMPORT) && (ZSTD_DLL_IMPORT==1) 32 # define ZSTDLIB_API __declspec(dllimport) ZSTDLIB_VISIBILITY /* It isn't required but allows to generate better code, saving a function pointer load from the IAT and an indirect jump.*/ 33 #else 34 # define ZSTDLIB_API ZSTDLIB_VISIBILITY 35 #endif 36 37 38 /******************************************************************************************************* 39 Introduction 40 41 zstd, short for Zstandard, is a fast lossless compression algorithm, 42 targeting real-time compression scenarios at zlib-level and better compression ratios. 43 The zstd compression library provides in-memory compression and decompression functions. 44 The library supports compression levels from 1 up to ZSTD_maxCLevel() which is currently 22. 45 Levels >= 20, labeled `--ultra`, should be used with caution, as they require more memory. 46 Compression can be done in: 47 - a single step (described as Simple API) 48 - a single step, reusing a context (described as Explicit context) 49 - unbounded multiple steps (described as Streaming compression) 50 The compression ratio achievable on small data can be highly improved using a dictionary in: 51 - a single step (described as Simple dictionary API) 52 - a single step, reusing a dictionary (described as Bulk-processing dictionary API) 53 54 Advanced experimental functions can be accessed using #define ZSTD_STATIC_LINKING_ONLY before including zstd.h. 55 Advanced experimental APIs shall never be used with a dynamic library. 56 They are not "stable", their definition may change in the future. Only static linking is allowed. 57 *********************************************************************************************************/ 58 59 /*------ Version ------*/ 60 #define ZSTD_VERSION_MAJOR 1 61 #define ZSTD_VERSION_MINOR 3 62 #define ZSTD_VERSION_RELEASE 4 63 64 #define ZSTD_VERSION_NUMBER (ZSTD_VERSION_MAJOR *100*100 + ZSTD_VERSION_MINOR *100 + ZSTD_VERSION_RELEASE) 65 ZSTDLIB_API unsigned ZSTD_versionNumber(void); /**< useful to check dll version */ 66 67 #define ZSTD_LIB_VERSION ZSTD_VERSION_MAJOR.ZSTD_VERSION_MINOR.ZSTD_VERSION_RELEASE 68 #define ZSTD_QUOTE(str) #str 69 #define ZSTD_EXPAND_AND_QUOTE(str) ZSTD_QUOTE(str) 70 #define ZSTD_VERSION_STRING ZSTD_EXPAND_AND_QUOTE(ZSTD_LIB_VERSION) 71 ZSTDLIB_API const char* ZSTD_versionString(void); /* added in v1.3.0 */ 72 73 74 /*************************************** 75 * Simple API 76 ***************************************/ 77 /*! ZSTD_compress() : 78 * Compresses `src` content as a single zstd compressed frame into already allocated `dst`. 79 * Hint : compression runs faster if `dstCapacity` >= `ZSTD_compressBound(srcSize)`. 80 * @return : compressed size written into `dst` (<= `dstCapacity), 81 * or an error code if it fails (which can be tested using ZSTD_isError()). */ 82 ZSTDLIB_API size_t ZSTD_compress( void* dst, size_t dstCapacity, 83 const void* src, size_t srcSize, 84 int compressionLevel); 85 86 /*! ZSTD_decompress() : 87 * `compressedSize` : must be the _exact_ size of some number of compressed and/or skippable frames. 88 * `dstCapacity` is an upper bound of originalSize to regenerate. 89 * If user cannot imply a maximum upper bound, it's better to use streaming mode to decompress data. 90 * @return : the number of bytes decompressed into `dst` (<= `dstCapacity`), 91 * or an errorCode if it fails (which can be tested using ZSTD_isError()). */ 92 ZSTDLIB_API size_t ZSTD_decompress( void* dst, size_t dstCapacity, 93 const void* src, size_t compressedSize); 94 95 /*! ZSTD_getFrameContentSize() : added in v1.3.0 96 * `src` should point to the start of a ZSTD encoded frame. 97 * `srcSize` must be at least as large as the frame header. 98 * hint : any size >= `ZSTD_frameHeaderSize_max` is large enough. 99 * @return : - decompressed size of the frame in `src`, if known 100 * - ZSTD_CONTENTSIZE_UNKNOWN if the size cannot be determined 101 * - ZSTD_CONTENTSIZE_ERROR if an error occurred (e.g. invalid magic number, srcSize too small) 102 * note 1 : a 0 return value means the frame is valid but "empty". 103 * note 2 : decompressed size is an optional field, it may not be present, typically in streaming mode. 104 * When `return==ZSTD_CONTENTSIZE_UNKNOWN`, data to decompress could be any size. 105 * In which case, it's necessary to use streaming mode to decompress data. 106 * Optionally, application can rely on some implicit limit, 107 * as ZSTD_decompress() only needs an upper bound of decompressed size. 108 * (For example, data could be necessarily cut into blocks <= 16 KB). 109 * note 3 : decompressed size is always present when compression is done with ZSTD_compress() 110 * note 4 : decompressed size can be very large (64-bits value), 111 * potentially larger than what local system can handle as a single memory segment. 112 * In which case, it's necessary to use streaming mode to decompress data. 113 * note 5 : If source is untrusted, decompressed size could be wrong or intentionally modified. 114 * Always ensure return value fits within application's authorized limits. 115 * Each application can set its own limits. 116 * note 6 : This function replaces ZSTD_getDecompressedSize() */ 117 #define ZSTD_CONTENTSIZE_UNKNOWN (0ULL - 1) 118 #define ZSTD_CONTENTSIZE_ERROR (0ULL - 2) 119 ZSTDLIB_API unsigned long long ZSTD_getFrameContentSize(const void *src, size_t srcSize); 120 121 /*! ZSTD_getDecompressedSize() : 122 * NOTE: This function is now obsolete, in favor of ZSTD_getFrameContentSize(). 123 * Both functions work the same way, but ZSTD_getDecompressedSize() blends 124 * "empty", "unknown" and "error" results to the same return value (0), 125 * while ZSTD_getFrameContentSize() gives them separate return values. 126 * `src` is the start of a zstd compressed frame. 127 * @return : content size to be decompressed, as a 64-bits value _if known and not empty_, 0 otherwise. */ 128 ZSTDLIB_API unsigned long long ZSTD_getDecompressedSize(const void* src, size_t srcSize); 129 130 131 /*====== Helper functions ======*/ 132 #define ZSTD_COMPRESSBOUND(srcSize) ((srcSize) + ((srcSize)>>8) + (((srcSize) < (128<<10)) ? (((128<<10) - (srcSize)) >> 11) /* margin, from 64 to 0 */ : 0)) /* this formula ensures that bound(A) + bound(B) <= bound(A+B) as long as A and B >= 128 KB */ 133 ZSTDLIB_API size_t ZSTD_compressBound(size_t srcSize); /*!< maximum compressed size in worst case single-pass scenario */ 134 ZSTDLIB_API unsigned ZSTD_isError(size_t code); /*!< tells if a `size_t` function result is an error code */ 135 ZSTDLIB_API const char* ZSTD_getErrorName(size_t code); /*!< provides readable string from an error code */ 136 ZSTDLIB_API int ZSTD_maxCLevel(void); /*!< maximum compression level available */ 137 138 139 /*************************************** 140 * Explicit context 141 ***************************************/ 142 /*= Compression context 143 * When compressing many times, 144 * it is recommended to allocate a context just once, and re-use it for each successive compression operation. 145 * This will make workload friendlier for system's memory. 146 * Use one context per thread for parallel execution in multi-threaded environments. */ 147 typedef struct ZSTD_CCtx_s ZSTD_CCtx; 148 ZSTDLIB_API ZSTD_CCtx* ZSTD_createCCtx(void); 149 ZSTDLIB_API size_t ZSTD_freeCCtx(ZSTD_CCtx* cctx); 150 151 /*! ZSTD_compressCCtx() : 152 * Same as ZSTD_compress(), requires an allocated ZSTD_CCtx (see ZSTD_createCCtx()). */ 153 ZSTDLIB_API size_t ZSTD_compressCCtx(ZSTD_CCtx* ctx, 154 void* dst, size_t dstCapacity, 155 const void* src, size_t srcSize, 156 int compressionLevel); 157 158 /*= Decompression context 159 * When decompressing many times, 160 * it is recommended to allocate a context only once, 161 * and re-use it for each successive compression operation. 162 * This will make workload friendlier for system's memory. 163 * Use one context per thread for parallel execution. */ 164 typedef struct ZSTD_DCtx_s ZSTD_DCtx; 165 ZSTDLIB_API ZSTD_DCtx* ZSTD_createDCtx(void); 166 ZSTDLIB_API size_t ZSTD_freeDCtx(ZSTD_DCtx* dctx); 167 168 /*! ZSTD_decompressDCtx() : 169 * Same as ZSTD_decompress(), requires an allocated ZSTD_DCtx (see ZSTD_createDCtx()) */ 170 ZSTDLIB_API size_t ZSTD_decompressDCtx(ZSTD_DCtx* ctx, 171 void* dst, size_t dstCapacity, 172 const void* src, size_t srcSize); 173 174 175 /************************** 176 * Simple dictionary API 177 ***************************/ 178 /*! ZSTD_compress_usingDict() : 179 * Compression using a predefined Dictionary (see dictBuilder/zdict.h). 180 * Note : This function loads the dictionary, resulting in significant startup delay. 181 * Note : When `dict == NULL || dictSize < 8` no dictionary is used. */ 182 ZSTDLIB_API size_t ZSTD_compress_usingDict(ZSTD_CCtx* ctx, 183 void* dst, size_t dstCapacity, 184 const void* src, size_t srcSize, 185 const void* dict,size_t dictSize, 186 int compressionLevel); 187 188 /*! ZSTD_decompress_usingDict() : 189 * Decompression using a predefined Dictionary (see dictBuilder/zdict.h). 190 * Dictionary must be identical to the one used during compression. 191 * Note : This function loads the dictionary, resulting in significant startup delay. 192 * Note : When `dict == NULL || dictSize < 8` no dictionary is used. */ 193 ZSTDLIB_API size_t ZSTD_decompress_usingDict(ZSTD_DCtx* dctx, 194 void* dst, size_t dstCapacity, 195 const void* src, size_t srcSize, 196 const void* dict,size_t dictSize); 197 198 199 /********************************** 200 * Bulk processing dictionary API 201 *********************************/ 202 typedef struct ZSTD_CDict_s ZSTD_CDict; 203 204 /*! ZSTD_createCDict() : 205 * When compressing multiple messages / blocks with the same dictionary, it's recommended to load it just once. 206 * ZSTD_createCDict() will create a digested dictionary, ready to start future compression operations without startup delay. 207 * ZSTD_CDict can be created once and shared by multiple threads concurrently, since its usage is read-only. 208 * `dictBuffer` can be released after ZSTD_CDict creation, since its content is copied within CDict */ 209 ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict(const void* dictBuffer, size_t dictSize, 210 int compressionLevel); 211 212 /*! ZSTD_freeCDict() : 213 * Function frees memory allocated by ZSTD_createCDict(). */ 214 ZSTDLIB_API size_t ZSTD_freeCDict(ZSTD_CDict* CDict); 215 216 /*! ZSTD_compress_usingCDict() : 217 * Compression using a digested Dictionary. 218 * Faster startup than ZSTD_compress_usingDict(), recommended when same dictionary is used multiple times. 219 * Note that compression level is decided during dictionary creation. 220 * Frame parameters are hardcoded (dictID=yes, contentSize=yes, checksum=no) */ 221 ZSTDLIB_API size_t ZSTD_compress_usingCDict(ZSTD_CCtx* cctx, 222 void* dst, size_t dstCapacity, 223 const void* src, size_t srcSize, 224 const ZSTD_CDict* cdict); 225 226 227 typedef struct ZSTD_DDict_s ZSTD_DDict; 228 229 /*! ZSTD_createDDict() : 230 * Create a digested dictionary, ready to start decompression operation without startup delay. 231 * dictBuffer can be released after DDict creation, as its content is copied inside DDict */ 232 ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict(const void* dictBuffer, size_t dictSize); 233 234 /*! ZSTD_freeDDict() : 235 * Function frees memory allocated with ZSTD_createDDict() */ 236 ZSTDLIB_API size_t ZSTD_freeDDict(ZSTD_DDict* ddict); 237 238 /*! ZSTD_decompress_usingDDict() : 239 * Decompression using a digested Dictionary. 240 * Faster startup than ZSTD_decompress_usingDict(), recommended when same dictionary is used multiple times. */ 241 ZSTDLIB_API size_t ZSTD_decompress_usingDDict(ZSTD_DCtx* dctx, 242 void* dst, size_t dstCapacity, 243 const void* src, size_t srcSize, 244 const ZSTD_DDict* ddict); 245 246 247 /**************************** 248 * Streaming 249 ****************************/ 250 251 typedef struct ZSTD_inBuffer_s { 252 const void* src; /**< start of input buffer */ 253 size_t size; /**< size of input buffer */ 254 size_t pos; /**< position where reading stopped. Will be updated. Necessarily 0 <= pos <= size */ 255 } ZSTD_inBuffer; 256 257 typedef struct ZSTD_outBuffer_s { 258 void* dst; /**< start of output buffer */ 259 size_t size; /**< size of output buffer */ 260 size_t pos; /**< position where writing stopped. Will be updated. Necessarily 0 <= pos <= size */ 261 } ZSTD_outBuffer; 262 263 264 265 /*-*********************************************************************** 266 * Streaming compression - HowTo 267 * 268 * A ZSTD_CStream object is required to track streaming operation. 269 * Use ZSTD_createCStream() and ZSTD_freeCStream() to create/release resources. 270 * ZSTD_CStream objects can be reused multiple times on consecutive compression operations. 271 * It is recommended to re-use ZSTD_CStream in situations where many streaming operations will be achieved consecutively, 272 * since it will play nicer with system's memory, by re-using already allocated memory. 273 * Use one separate ZSTD_CStream per thread for parallel execution. 274 * 275 * Start a new compression by initializing ZSTD_CStream. 276 * Use ZSTD_initCStream() to start a new compression operation. 277 * Use ZSTD_initCStream_usingDict() or ZSTD_initCStream_usingCDict() for a compression which requires a dictionary (experimental section) 278 * 279 * Use ZSTD_compressStream() repetitively to consume input stream. 280 * The function will automatically update both `pos` fields. 281 * Note that it may not consume the entire input, in which case `pos < size`, 282 * and it's up to the caller to present again remaining data. 283 * @return : a size hint, preferred nb of bytes to use as input for next function call 284 * or an error code, which can be tested using ZSTD_isError(). 285 * Note 1 : it's just a hint, to help latency a little, any other value will work fine. 286 * Note 2 : size hint is guaranteed to be <= ZSTD_CStreamInSize() 287 * 288 * At any moment, it's possible to flush whatever data remains within internal buffer, using ZSTD_flushStream(). 289 * `output->pos` will be updated. 290 * Note that some content might still be left within internal buffer if `output->size` is too small. 291 * @return : nb of bytes still present within internal buffer (0 if it's empty) 292 * or an error code, which can be tested using ZSTD_isError(). 293 * 294 * ZSTD_endStream() instructs to finish a frame. 295 * It will perform a flush and write frame epilogue. 296 * The epilogue is required for decoders to consider a frame completed. 297 * ZSTD_endStream() may not be able to flush full data if `output->size` is too small. 298 * In which case, call again ZSTD_endStream() to complete the flush. 299 * @return : 0 if frame fully completed and fully flushed, 300 or >0 if some data is still present within internal buffer 301 (value is minimum size estimation for remaining data to flush, but it could be more) 302 * or an error code, which can be tested using ZSTD_isError(). 303 * 304 * *******************************************************************/ 305 306 typedef ZSTD_CCtx ZSTD_CStream; /**< CCtx and CStream are now effectively same object (>= v1.3.0) */ 307 /* Continue to distinguish them for compatibility with versions <= v1.2.0 */ 308 /*===== ZSTD_CStream management functions =====*/ 309 ZSTDLIB_API ZSTD_CStream* ZSTD_createCStream(void); 310 ZSTDLIB_API size_t ZSTD_freeCStream(ZSTD_CStream* zcs); 311 312 /*===== Streaming compression functions =====*/ 313 ZSTDLIB_API size_t ZSTD_initCStream(ZSTD_CStream* zcs, int compressionLevel); 314 ZSTDLIB_API size_t ZSTD_compressStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output, ZSTD_inBuffer* input); 315 ZSTDLIB_API size_t ZSTD_flushStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output); 316 ZSTDLIB_API size_t ZSTD_endStream(ZSTD_CStream* zcs, ZSTD_outBuffer* output); 317 318 ZSTDLIB_API size_t ZSTD_CStreamInSize(void); /**< recommended size for input buffer */ 319 ZSTDLIB_API size_t ZSTD_CStreamOutSize(void); /**< recommended size for output buffer. Guarantee to successfully flush at least one complete compressed block in all circumstances. */ 320 321 322 323 /*-*************************************************************************** 324 * Streaming decompression - HowTo 325 * 326 * A ZSTD_DStream object is required to track streaming operations. 327 * Use ZSTD_createDStream() and ZSTD_freeDStream() to create/release resources. 328 * ZSTD_DStream objects can be re-used multiple times. 329 * 330 * Use ZSTD_initDStream() to start a new decompression operation, 331 * or ZSTD_initDStream_usingDict() if decompression requires a dictionary. 332 * @return : recommended first input size 333 * 334 * Use ZSTD_decompressStream() repetitively to consume your input. 335 * The function will update both `pos` fields. 336 * If `input.pos < input.size`, some input has not been consumed. 337 * It's up to the caller to present again remaining data. 338 * If `output.pos < output.size`, decoder has flushed everything it could. 339 * @return : 0 when a frame is completely decoded and fully flushed, 340 * an error code, which can be tested using ZSTD_isError(), 341 * any other value > 0, which means there is still some decoding to do to complete current frame. 342 * The return value is a suggested next input size (a hint to improve latency) that will never load more than the current frame. 343 * *******************************************************************************/ 344 345 typedef ZSTD_DCtx ZSTD_DStream; /**< DCtx and DStream are now effectively same object (>= v1.3.0) */ 346 /* For compatibility with versions <= v1.2.0, continue to consider them separated. */ 347 /*===== ZSTD_DStream management functions =====*/ 348 ZSTDLIB_API ZSTD_DStream* ZSTD_createDStream(void); 349 ZSTDLIB_API size_t ZSTD_freeDStream(ZSTD_DStream* zds); 350 351 /*===== Streaming decompression functions =====*/ 352 ZSTDLIB_API size_t ZSTD_initDStream(ZSTD_DStream* zds); 353 ZSTDLIB_API size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inBuffer* input); 354 355 ZSTDLIB_API size_t ZSTD_DStreamInSize(void); /*!< recommended size for input buffer */ 356 ZSTDLIB_API size_t ZSTD_DStreamOutSize(void); /*!< recommended size for output buffer. Guarantee to successfully flush at least one complete block in all circumstances. */ 357 358 #endif /* ZSTD_H_235446 */ 359 360 361 362 /**************************************************************************************** 363 * START OF ADVANCED AND EXPERIMENTAL FUNCTIONS 364 * The definitions in this section are considered experimental. 365 * They should never be used with a dynamic library, as prototypes may change in the future. 366 * They are provided for advanced scenarios. 367 * Use them only in association with static linking. 368 * ***************************************************************************************/ 369 370 #if defined(ZSTD_STATIC_LINKING_ONLY) && !defined(ZSTD_H_ZSTD_STATIC_LINKING_ONLY) 371 #define ZSTD_H_ZSTD_STATIC_LINKING_ONLY 372 373 /* --- Constants ---*/ 374 #define ZSTD_MAGICNUMBER 0xFD2FB528 /* >= v0.8.0 */ 375 #define ZSTD_MAGIC_SKIPPABLE_START 0x184D2A50U 376 #define ZSTD_MAGIC_DICTIONARY 0xEC30A437 /* >= v0.7.0 */ 377 378 #define ZSTD_WINDOWLOG_MAX_32 30 379 #define ZSTD_WINDOWLOG_MAX_64 31 380 #define ZSTD_WINDOWLOG_MAX ((unsigned)(sizeof(size_t) == 4 ? ZSTD_WINDOWLOG_MAX_32 : ZSTD_WINDOWLOG_MAX_64)) 381 #define ZSTD_WINDOWLOG_MIN 10 382 #define ZSTD_HASHLOG_MAX ((ZSTD_WINDOWLOG_MAX < 30) ? ZSTD_WINDOWLOG_MAX : 30) 383 #define ZSTD_HASHLOG_MIN 6 384 #define ZSTD_CHAINLOG_MAX_32 29 385 #define ZSTD_CHAINLOG_MAX_64 30 386 #define ZSTD_CHAINLOG_MAX ((unsigned)(sizeof(size_t) == 4 ? ZSTD_CHAINLOG_MAX_32 : ZSTD_CHAINLOG_MAX_64)) 387 #define ZSTD_CHAINLOG_MIN ZSTD_HASHLOG_MIN 388 #define ZSTD_HASHLOG3_MAX 17 389 #define ZSTD_SEARCHLOG_MAX (ZSTD_WINDOWLOG_MAX-1) 390 #define ZSTD_SEARCHLOG_MIN 1 391 #define ZSTD_SEARCHLENGTH_MAX 7 /* only for ZSTD_fast, other strategies are limited to 6 */ 392 #define ZSTD_SEARCHLENGTH_MIN 3 /* only for ZSTD_btopt, other strategies are limited to 4 */ 393 #define ZSTD_TARGETLENGTH_MIN 1 /* only used by btopt, btultra and btfast */ 394 #define ZSTD_LDM_MINMATCH_MIN 4 395 #define ZSTD_LDM_MINMATCH_MAX 4096 396 #define ZSTD_LDM_BUCKETSIZELOG_MAX 8 397 398 #define ZSTD_FRAMEHEADERSIZE_PREFIX 5 /* minimum input size to know frame header size */ 399 #define ZSTD_FRAMEHEADERSIZE_MIN 6 400 #define ZSTD_FRAMEHEADERSIZE_MAX 18 /* for static allocation */ 401 static const size_t ZSTD_frameHeaderSize_prefix = ZSTD_FRAMEHEADERSIZE_PREFIX; 402 static const size_t ZSTD_frameHeaderSize_min = ZSTD_FRAMEHEADERSIZE_MIN; 403 static const size_t ZSTD_frameHeaderSize_max = ZSTD_FRAMEHEADERSIZE_MAX; 404 static const size_t ZSTD_skippableHeaderSize = 8; /* magic number + skippable frame length */ 405 406 407 /*--- Advanced types ---*/ 408 typedef enum { ZSTD_fast=1, ZSTD_dfast, ZSTD_greedy, ZSTD_lazy, ZSTD_lazy2, 409 ZSTD_btlazy2, ZSTD_btopt, ZSTD_btultra } ZSTD_strategy; /* from faster to stronger */ 410 411 typedef struct { 412 unsigned windowLog; /**< largest match distance : larger == more compression, more memory needed during decompression */ 413 unsigned chainLog; /**< fully searched segment : larger == more compression, slower, more memory (useless for fast) */ 414 unsigned hashLog; /**< dispatch table : larger == faster, more memory */ 415 unsigned searchLog; /**< nb of searches : larger == more compression, slower */ 416 unsigned searchLength; /**< match length searched : larger == faster decompression, sometimes less compression */ 417 unsigned targetLength; /**< acceptable match size for optimal parser (only) : larger == more compression, slower */ 418 ZSTD_strategy strategy; 419 } ZSTD_compressionParameters; 420 421 typedef struct { 422 unsigned contentSizeFlag; /**< 1: content size will be in frame header (when known) */ 423 unsigned checksumFlag; /**< 1: generate a 32-bits checksum at end of frame, for error detection */ 424 unsigned noDictIDFlag; /**< 1: no dictID will be saved into frame header (if dictionary compression) */ 425 } ZSTD_frameParameters; 426 427 typedef struct { 428 ZSTD_compressionParameters cParams; 429 ZSTD_frameParameters fParams; 430 } ZSTD_parameters; 431 432 typedef struct ZSTD_CCtx_params_s ZSTD_CCtx_params; 433 434 typedef enum { 435 ZSTD_dct_auto=0, /* dictionary is "full" when starting with ZSTD_MAGIC_DICTIONARY, otherwise it is "rawContent" */ 436 ZSTD_dct_rawContent, /* ensures dictionary is always loaded as rawContent, even if it starts with ZSTD_MAGIC_DICTIONARY */ 437 ZSTD_dct_fullDict /* refuses to load a dictionary if it does not respect Zstandard's specification */ 438 } ZSTD_dictContentType_e; 439 440 typedef enum { 441 ZSTD_dlm_byCopy = 0, /**< Copy dictionary content internally */ 442 ZSTD_dlm_byRef, /**< Reference dictionary content -- the dictionary buffer must outlive its users. */ 443 } ZSTD_dictLoadMethod_e; 444 445 446 447 /*************************************** 448 * Frame size functions 449 ***************************************/ 450 451 /*! ZSTD_findFrameCompressedSize() : 452 * `src` should point to the start of a ZSTD encoded frame or skippable frame 453 * `srcSize` must be >= first frame size 454 * @return : the compressed size of the first frame starting at `src`, 455 * suitable to pass to `ZSTD_decompress` or similar, 456 * or an error code if input is invalid */ 457 ZSTDLIB_API size_t ZSTD_findFrameCompressedSize(const void* src, size_t srcSize); 458 459 /*! ZSTD_findDecompressedSize() : 460 * `src` should point the start of a series of ZSTD encoded and/or skippable frames 461 * `srcSize` must be the _exact_ size of this series 462 * (i.e. there should be a frame boundary exactly at `srcSize` bytes after `src`) 463 * @return : - decompressed size of all data in all successive frames 464 * - if the decompressed size cannot be determined: ZSTD_CONTENTSIZE_UNKNOWN 465 * - if an error occurred: ZSTD_CONTENTSIZE_ERROR 466 * 467 * note 1 : decompressed size is an optional field, that may not be present, especially in streaming mode. 468 * When `return==ZSTD_CONTENTSIZE_UNKNOWN`, data to decompress could be any size. 469 * In which case, it's necessary to use streaming mode to decompress data. 470 * note 2 : decompressed size is always present when compression is done with ZSTD_compress() 471 * note 3 : decompressed size can be very large (64-bits value), 472 * potentially larger than what local system can handle as a single memory segment. 473 * In which case, it's necessary to use streaming mode to decompress data. 474 * note 4 : If source is untrusted, decompressed size could be wrong or intentionally modified. 475 * Always ensure result fits within application's authorized limits. 476 * Each application can set its own limits. 477 * note 5 : ZSTD_findDecompressedSize handles multiple frames, and so it must traverse the input to 478 * read each contained frame header. This is fast as most of the data is skipped, 479 * however it does mean that all frame data must be present and valid. */ 480 ZSTDLIB_API unsigned long long ZSTD_findDecompressedSize(const void* src, size_t srcSize); 481 482 /*! ZSTD_frameHeaderSize() : 483 * `src` should point to the start of a ZSTD frame 484 * `srcSize` must be >= ZSTD_frameHeaderSize_prefix. 485 * @return : size of the Frame Header */ 486 ZSTDLIB_API size_t ZSTD_frameHeaderSize(const void* src, size_t srcSize); 487 488 489 /*************************************** 490 * Memory management 491 ***************************************/ 492 493 /*! ZSTD_sizeof_*() : 494 * These functions give the current memory usage of selected object. 495 * Object memory usage can evolve when re-used. */ 496 ZSTDLIB_API size_t ZSTD_sizeof_CCtx(const ZSTD_CCtx* cctx); 497 ZSTDLIB_API size_t ZSTD_sizeof_DCtx(const ZSTD_DCtx* dctx); 498 ZSTDLIB_API size_t ZSTD_sizeof_CStream(const ZSTD_CStream* zcs); 499 ZSTDLIB_API size_t ZSTD_sizeof_DStream(const ZSTD_DStream* zds); 500 ZSTDLIB_API size_t ZSTD_sizeof_CDict(const ZSTD_CDict* cdict); 501 ZSTDLIB_API size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict); 502 503 /*! ZSTD_estimate*() : 504 * These functions make it possible to estimate memory usage 505 * of a future {D,C}Ctx, before its creation. 506 * ZSTD_estimateCCtxSize() will provide a budget large enough for any compression level up to selected one. 507 * It will also consider src size to be arbitrarily "large", which is worst case. 508 * If srcSize is known to always be small, ZSTD_estimateCCtxSize_usingCParams() can provide a tighter estimation. 509 * ZSTD_estimateCCtxSize_usingCParams() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel. 510 * ZSTD_estimateCCtxSize_usingCCtxParams() can be used in tandem with ZSTD_CCtxParam_setParameter(). Only single-threaded compression is supported. This function will return an error code if ZSTD_p_nbWorkers is >= 1. 511 * Note : CCtx size estimation is only correct for single-threaded compression. */ 512 ZSTDLIB_API size_t ZSTD_estimateCCtxSize(int compressionLevel); 513 ZSTDLIB_API size_t ZSTD_estimateCCtxSize_usingCParams(ZSTD_compressionParameters cParams); 514 ZSTDLIB_API size_t ZSTD_estimateCCtxSize_usingCCtxParams(const ZSTD_CCtx_params* params); 515 ZSTDLIB_API size_t ZSTD_estimateDCtxSize(void); 516 517 /*! ZSTD_estimateCStreamSize() : 518 * ZSTD_estimateCStreamSize() will provide a budget large enough for any compression level up to selected one. 519 * It will also consider src size to be arbitrarily "large", which is worst case. 520 * If srcSize is known to always be small, ZSTD_estimateCStreamSize_usingCParams() can provide a tighter estimation. 521 * ZSTD_estimateCStreamSize_usingCParams() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel. 522 * ZSTD_estimateCStreamSize_usingCCtxParams() can be used in tandem with ZSTD_CCtxParam_setParameter(). Only single-threaded compression is supported. This function will return an error code if ZSTD_p_nbWorkers is >= 1. 523 * Note : CStream size estimation is only correct for single-threaded compression. 524 * ZSTD_DStream memory budget depends on window Size. 525 * This information can be passed manually, using ZSTD_estimateDStreamSize, 526 * or deducted from a valid frame Header, using ZSTD_estimateDStreamSize_fromFrame(); 527 * Note : if streaming is init with function ZSTD_init?Stream_usingDict(), 528 * an internal ?Dict will be created, which additional size is not estimated here. 529 * In this case, get total size by adding ZSTD_estimate?DictSize */ 530 ZSTDLIB_API size_t ZSTD_estimateCStreamSize(int compressionLevel); 531 ZSTDLIB_API size_t ZSTD_estimateCStreamSize_usingCParams(ZSTD_compressionParameters cParams); 532 ZSTDLIB_API size_t ZSTD_estimateCStreamSize_usingCCtxParams(const ZSTD_CCtx_params* params); 533 ZSTDLIB_API size_t ZSTD_estimateDStreamSize(size_t windowSize); 534 ZSTDLIB_API size_t ZSTD_estimateDStreamSize_fromFrame(const void* src, size_t srcSize); 535 536 /*! ZSTD_estimate?DictSize() : 537 * ZSTD_estimateCDictSize() will bet that src size is relatively "small", and content is copied, like ZSTD_createCDict(). 538 * ZSTD_estimateCDictSize_advanced() makes it possible to control compression parameters precisely, like ZSTD_createCDict_advanced(). 539 * Note : dictionaries created by reference (`ZSTD_dlm_byRef`) are logically smaller. 540 */ 541 ZSTDLIB_API size_t ZSTD_estimateCDictSize(size_t dictSize, int compressionLevel); 542 ZSTDLIB_API size_t ZSTD_estimateCDictSize_advanced(size_t dictSize, ZSTD_compressionParameters cParams, ZSTD_dictLoadMethod_e dictLoadMethod); 543 ZSTDLIB_API size_t ZSTD_estimateDDictSize(size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod); 544 545 /*! ZSTD_initStatic*() : 546 * Initialize an object using a pre-allocated fixed-size buffer. 547 * workspace: The memory area to emplace the object into. 548 * Provided pointer *must be 8-bytes aligned*. 549 * Buffer must outlive object. 550 * workspaceSize: Use ZSTD_estimate*Size() to determine 551 * how large workspace must be to support target scenario. 552 * @return : pointer to object (same address as workspace, just different type), 553 * or NULL if error (size too small, incorrect alignment, etc.) 554 * Note : zstd will never resize nor malloc() when using a static buffer. 555 * If the object requires more memory than available, 556 * zstd will just error out (typically ZSTD_error_memory_allocation). 557 * Note 2 : there is no corresponding "free" function. 558 * Since workspace is allocated externally, it must be freed externally too. 559 * Note 3 : cParams : use ZSTD_getCParams() to convert a compression level 560 * into its associated cParams. 561 * Limitation 1 : currently not compatible with internal dictionary creation, triggered by 562 * ZSTD_CCtx_loadDictionary(), ZSTD_initCStream_usingDict() or ZSTD_initDStream_usingDict(). 563 * Limitation 2 : static cctx currently not compatible with multi-threading. 564 * Limitation 3 : static dctx is incompatible with legacy support. 565 */ 566 ZSTDLIB_API ZSTD_CCtx* ZSTD_initStaticCCtx(void* workspace, size_t workspaceSize); 567 ZSTDLIB_API ZSTD_CStream* ZSTD_initStaticCStream(void* workspace, size_t workspaceSize); /**< same as ZSTD_initStaticCCtx() */ 568 569 ZSTDLIB_API ZSTD_DCtx* ZSTD_initStaticDCtx(void* workspace, size_t workspaceSize); 570 ZSTDLIB_API ZSTD_DStream* ZSTD_initStaticDStream(void* workspace, size_t workspaceSize); /**< same as ZSTD_initStaticDCtx() */ 571 572 ZSTDLIB_API const ZSTD_CDict* ZSTD_initStaticCDict( 573 void* workspace, size_t workspaceSize, 574 const void* dict, size_t dictSize, 575 ZSTD_dictLoadMethod_e dictLoadMethod, 576 ZSTD_dictContentType_e dictContentType, 577 ZSTD_compressionParameters cParams); 578 579 ZSTDLIB_API const ZSTD_DDict* ZSTD_initStaticDDict( 580 void* workspace, size_t workspaceSize, 581 const void* dict, size_t dictSize, 582 ZSTD_dictLoadMethod_e dictLoadMethod, 583 ZSTD_dictContentType_e dictContentType); 584 585 /*! Custom memory allocation : 586 * These prototypes make it possible to pass your own allocation/free functions. 587 * ZSTD_customMem is provided at creation time, using ZSTD_create*_advanced() variants listed below. 588 * All allocation/free operations will be completed using these custom variants instead of regular <stdlib.h> ones. 589 */ 590 typedef void* (*ZSTD_allocFunction) (void* opaque, size_t size); 591 typedef void (*ZSTD_freeFunction) (void* opaque, void* address); 592 typedef struct { ZSTD_allocFunction customAlloc; ZSTD_freeFunction customFree; void* opaque; } ZSTD_customMem; 593 static ZSTD_customMem const ZSTD_defaultCMem = { NULL, NULL, NULL }; /**< this constant defers to stdlib's functions */ 594 595 ZSTDLIB_API ZSTD_CCtx* ZSTD_createCCtx_advanced(ZSTD_customMem customMem); 596 ZSTDLIB_API ZSTD_CStream* ZSTD_createCStream_advanced(ZSTD_customMem customMem); 597 ZSTDLIB_API ZSTD_DCtx* ZSTD_createDCtx_advanced(ZSTD_customMem customMem); 598 ZSTDLIB_API ZSTD_DStream* ZSTD_createDStream_advanced(ZSTD_customMem customMem); 599 600 ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict_advanced(const void* dict, size_t dictSize, 601 ZSTD_dictLoadMethod_e dictLoadMethod, 602 ZSTD_dictContentType_e dictContentType, 603 ZSTD_compressionParameters cParams, 604 ZSTD_customMem customMem); 605 606 ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict_advanced(const void* dict, size_t dictSize, 607 ZSTD_dictLoadMethod_e dictLoadMethod, 608 ZSTD_dictContentType_e dictContentType, 609 ZSTD_customMem customMem); 610 611 612 613 /*************************************** 614 * Advanced compression functions 615 ***************************************/ 616 617 /*! ZSTD_createCDict_byReference() : 618 * Create a digested dictionary for compression 619 * Dictionary content is simply referenced, and therefore stays in dictBuffer. 620 * It is important that dictBuffer outlives CDict, it must remain read accessible throughout the lifetime of CDict */ 621 ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict_byReference(const void* dictBuffer, size_t dictSize, int compressionLevel); 622 623 /*! ZSTD_getCParams() : 624 * @return ZSTD_compressionParameters structure for a selected compression level and estimated srcSize. 625 * `estimatedSrcSize` value is optional, select 0 if not known */ 626 ZSTDLIB_API ZSTD_compressionParameters ZSTD_getCParams(int compressionLevel, unsigned long long estimatedSrcSize, size_t dictSize); 627 628 /*! ZSTD_getParams() : 629 * same as ZSTD_getCParams(), but @return a full `ZSTD_parameters` object instead of sub-component `ZSTD_compressionParameters`. 630 * All fields of `ZSTD_frameParameters` are set to default : contentSize=1, checksum=0, noDictID=0 */ 631 ZSTDLIB_API ZSTD_parameters ZSTD_getParams(int compressionLevel, unsigned long long estimatedSrcSize, size_t dictSize); 632 633 /*! ZSTD_checkCParams() : 634 * Ensure param values remain within authorized range */ 635 ZSTDLIB_API size_t ZSTD_checkCParams(ZSTD_compressionParameters params); 636 637 /*! ZSTD_adjustCParams() : 638 * optimize params for a given `srcSize` and `dictSize`. 639 * both values are optional, select `0` if unknown. */ 640 ZSTDLIB_API ZSTD_compressionParameters ZSTD_adjustCParams(ZSTD_compressionParameters cPar, unsigned long long srcSize, size_t dictSize); 641 642 /*! ZSTD_compress_advanced() : 643 * Same as ZSTD_compress_usingDict(), with fine-tune control over each compression parameter */ 644 ZSTDLIB_API size_t ZSTD_compress_advanced (ZSTD_CCtx* cctx, 645 void* dst, size_t dstCapacity, 646 const void* src, size_t srcSize, 647 const void* dict,size_t dictSize, 648 ZSTD_parameters params); 649 650 /*! ZSTD_compress_usingCDict_advanced() : 651 * Same as ZSTD_compress_usingCDict(), with fine-tune control over frame parameters */ 652 ZSTDLIB_API size_t ZSTD_compress_usingCDict_advanced(ZSTD_CCtx* cctx, 653 void* dst, size_t dstCapacity, 654 const void* src, size_t srcSize, 655 const ZSTD_CDict* cdict, ZSTD_frameParameters fParams); 656 657 658 /*--- Advanced decompression functions ---*/ 659 660 /*! ZSTD_isFrame() : 661 * Tells if the content of `buffer` starts with a valid Frame Identifier. 662 * Note : Frame Identifier is 4 bytes. If `size < 4`, @return will always be 0. 663 * Note 2 : Legacy Frame Identifiers are considered valid only if Legacy Support is enabled. 664 * Note 3 : Skippable Frame Identifiers are considered valid. */ 665 ZSTDLIB_API unsigned ZSTD_isFrame(const void* buffer, size_t size); 666 667 /*! ZSTD_createDDict_byReference() : 668 * Create a digested dictionary, ready to start decompression operation without startup delay. 669 * Dictionary content is referenced, and therefore stays in dictBuffer. 670 * It is important that dictBuffer outlives DDict, 671 * it must remain read accessible throughout the lifetime of DDict */ 672 ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict_byReference(const void* dictBuffer, size_t dictSize); 673 674 675 /*! ZSTD_getDictID_fromDict() : 676 * Provides the dictID stored within dictionary. 677 * if @return == 0, the dictionary is not conformant with Zstandard specification. 678 * It can still be loaded, but as a content-only dictionary. */ 679 ZSTDLIB_API unsigned ZSTD_getDictID_fromDict(const void* dict, size_t dictSize); 680 681 /*! ZSTD_getDictID_fromDDict() : 682 * Provides the dictID of the dictionary loaded into `ddict`. 683 * If @return == 0, the dictionary is not conformant to Zstandard specification, or empty. 684 * Non-conformant dictionaries can still be loaded, but as content-only dictionaries. */ 685 ZSTDLIB_API unsigned ZSTD_getDictID_fromDDict(const ZSTD_DDict* ddict); 686 687 /*! ZSTD_getDictID_fromFrame() : 688 * Provides the dictID required to decompressed the frame stored within `src`. 689 * If @return == 0, the dictID could not be decoded. 690 * This could for one of the following reasons : 691 * - The frame does not require a dictionary to be decoded (most common case). 692 * - The frame was built with dictID intentionally removed. Whatever dictionary is necessary is a hidden information. 693 * Note : this use case also happens when using a non-conformant dictionary. 694 * - `srcSize` is too small, and as a result, the frame header could not be decoded (only possible if `srcSize < ZSTD_FRAMEHEADERSIZE_MAX`). 695 * - This is not a Zstandard frame. 696 * When identifying the exact failure cause, it's possible to use ZSTD_getFrameHeader(), which will provide a more precise error code. */ 697 ZSTDLIB_API unsigned ZSTD_getDictID_fromFrame(const void* src, size_t srcSize); 698 699 700 /******************************************************************** 701 * Advanced streaming functions 702 ********************************************************************/ 703 704 /*===== Advanced Streaming compression functions =====*/ 705 ZSTDLIB_API size_t ZSTD_initCStream_srcSize(ZSTD_CStream* zcs, int compressionLevel, unsigned long long pledgedSrcSize); /**< pledgedSrcSize must be correct. If it is not known at init time, use ZSTD_CONTENTSIZE_UNKNOWN. Note that, for compatibility with older programs, "0" also disables frame content size field. It may be enabled in the future. */ 706 ZSTDLIB_API size_t ZSTD_initCStream_usingDict(ZSTD_CStream* zcs, const void* dict, size_t dictSize, int compressionLevel); /**< creates of an internal CDict (incompatible with static CCtx), except if dict == NULL or dictSize < 8, in which case no dict is used. Note: dict is loaded with ZSTD_dm_auto (treated as a full zstd dictionary if it begins with ZSTD_MAGIC_DICTIONARY, else as raw content) and ZSTD_dlm_byCopy.*/ 707 ZSTDLIB_API size_t ZSTD_initCStream_advanced(ZSTD_CStream* zcs, const void* dict, size_t dictSize, 708 ZSTD_parameters params, unsigned long long pledgedSrcSize); /**< pledgedSrcSize must be correct. If srcSize is not known at init time, use value ZSTD_CONTENTSIZE_UNKNOWN. dict is loaded with ZSTD_dm_auto and ZSTD_dlm_byCopy. */ 709 ZSTDLIB_API size_t ZSTD_initCStream_usingCDict(ZSTD_CStream* zcs, const ZSTD_CDict* cdict); /**< note : cdict will just be referenced, and must outlive compression session */ 710 ZSTDLIB_API size_t ZSTD_initCStream_usingCDict_advanced(ZSTD_CStream* zcs, const ZSTD_CDict* cdict, ZSTD_frameParameters fParams, unsigned long long pledgedSrcSize); /**< same as ZSTD_initCStream_usingCDict(), with control over frame parameters. pledgedSrcSize must be correct. If srcSize is not known at init time, use value ZSTD_CONTENTSIZE_UNKNOWN. */ 711 712 /*! ZSTD_resetCStream() : 713 * start a new compression job, using same parameters from previous job. 714 * This is typically useful to skip dictionary loading stage, since it will re-use it in-place.. 715 * Note that zcs must be init at least once before using ZSTD_resetCStream(). 716 * If pledgedSrcSize is not known at reset time, use macro ZSTD_CONTENTSIZE_UNKNOWN. 717 * If pledgedSrcSize > 0, its value must be correct, as it will be written in header, and controlled at the end. 718 * For the time being, pledgedSrcSize==0 is interpreted as "srcSize unknown" for compatibility with older programs, 719 * but it will change to mean "empty" in future version, so use macro ZSTD_CONTENTSIZE_UNKNOWN instead. 720 * @return : 0, or an error code (which can be tested using ZSTD_isError()) */ 721 ZSTDLIB_API size_t ZSTD_resetCStream(ZSTD_CStream* zcs, unsigned long long pledgedSrcSize); 722 723 724 typedef struct { 725 unsigned long long ingested; 726 unsigned long long consumed; 727 unsigned long long produced; 728 } ZSTD_frameProgression; 729 730 /* ZSTD_getFrameProgression(): 731 * tells how much data has been ingested (read from input) 732 * consumed (input actually compressed) and produced (output) for current frame. 733 * Therefore, (ingested - consumed) is amount of input data buffered internally, not yet compressed. 734 * Can report progression inside worker threads (multi-threading and non-blocking mode). 735 */ 736 ZSTD_frameProgression ZSTD_getFrameProgression(const ZSTD_CCtx* cctx); 737 738 739 740 /*===== Advanced Streaming decompression functions =====*/ 741 typedef enum { DStream_p_maxWindowSize } ZSTD_DStreamParameter_e; 742 ZSTDLIB_API size_t ZSTD_setDStreamParameter(ZSTD_DStream* zds, ZSTD_DStreamParameter_e paramType, unsigned paramValue); /* obsolete : this API will be removed in a future version */ 743 ZSTDLIB_API size_t ZSTD_initDStream_usingDict(ZSTD_DStream* zds, const void* dict, size_t dictSize); /**< note: no dictionary will be used if dict == NULL or dictSize < 8 */ 744 ZSTDLIB_API size_t ZSTD_initDStream_usingDDict(ZSTD_DStream* zds, const ZSTD_DDict* ddict); /**< note : ddict is referenced, it must outlive decompression session */ 745 ZSTDLIB_API size_t ZSTD_resetDStream(ZSTD_DStream* zds); /**< re-use decompression parameters from previous init; saves dictionary loading */ 746 747 748 /********************************************************************* 749 * Buffer-less and synchronous inner streaming functions 750 * 751 * This is an advanced API, giving full control over buffer management, for users which need direct control over memory. 752 * But it's also a complex one, with several restrictions, documented below. 753 * Prefer normal streaming API for an easier experience. 754 ********************************************************************* */ 755 756 /** 757 Buffer-less streaming compression (synchronous mode) 758 759 A ZSTD_CCtx object is required to track streaming operations. 760 Use ZSTD_createCCtx() / ZSTD_freeCCtx() to manage resource. 761 ZSTD_CCtx object can be re-used multiple times within successive compression operations. 762 763 Start by initializing a context. 764 Use ZSTD_compressBegin(), or ZSTD_compressBegin_usingDict() for dictionary compression, 765 or ZSTD_compressBegin_advanced(), for finer parameter control. 766 It's also possible to duplicate a reference context which has already been initialized, using ZSTD_copyCCtx() 767 768 Then, consume your input using ZSTD_compressContinue(). 769 There are some important considerations to keep in mind when using this advanced function : 770 - ZSTD_compressContinue() has no internal buffer. It uses externally provided buffers only. 771 - Interface is synchronous : input is consumed entirely and produces 1+ compressed blocks. 772 - Caller must ensure there is enough space in `dst` to store compressed data under worst case scenario. 773 Worst case evaluation is provided by ZSTD_compressBound(). 774 ZSTD_compressContinue() doesn't guarantee recover after a failed compression. 775 - ZSTD_compressContinue() presumes prior input ***is still accessible and unmodified*** (up to maximum distance size, see WindowLog). 776 It remembers all previous contiguous blocks, plus one separated memory segment (which can itself consists of multiple contiguous blocks) 777 - ZSTD_compressContinue() detects that prior input has been overwritten when `src` buffer overlaps. 778 In which case, it will "discard" the relevant memory section from its history. 779 780 Finish a frame with ZSTD_compressEnd(), which will write the last block(s) and optional checksum. 781 It's possible to use srcSize==0, in which case, it will write a final empty block to end the frame. 782 Without last block mark, frames are considered unfinished (hence corrupted) by compliant decoders. 783 784 `ZSTD_CCtx` object can be re-used (ZSTD_compressBegin()) to compress again. 785 */ 786 787 /*===== Buffer-less streaming compression functions =====*/ 788 ZSTDLIB_API size_t ZSTD_compressBegin(ZSTD_CCtx* cctx, int compressionLevel); 789 ZSTDLIB_API size_t ZSTD_compressBegin_usingDict(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, int compressionLevel); 790 ZSTDLIB_API size_t ZSTD_compressBegin_advanced(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, ZSTD_parameters params, unsigned long long pledgedSrcSize); /**< pledgedSrcSize : If srcSize is not known at init time, use ZSTD_CONTENTSIZE_UNKNOWN */ 791 ZSTDLIB_API size_t ZSTD_compressBegin_usingCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict); /**< note: fails if cdict==NULL */ 792 ZSTDLIB_API size_t ZSTD_compressBegin_usingCDict_advanced(ZSTD_CCtx* const cctx, const ZSTD_CDict* const cdict, ZSTD_frameParameters const fParams, unsigned long long const pledgedSrcSize); /* compression parameters are already set within cdict. pledgedSrcSize must be correct. If srcSize is not known, use macro ZSTD_CONTENTSIZE_UNKNOWN */ 793 ZSTDLIB_API size_t ZSTD_copyCCtx(ZSTD_CCtx* cctx, const ZSTD_CCtx* preparedCCtx, unsigned long long pledgedSrcSize); /**< note: if pledgedSrcSize is not known, use ZSTD_CONTENTSIZE_UNKNOWN */ 794 795 ZSTDLIB_API size_t ZSTD_compressContinue(ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize); 796 ZSTDLIB_API size_t ZSTD_compressEnd(ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize); 797 798 799 /*- 800 Buffer-less streaming decompression (synchronous mode) 801 802 A ZSTD_DCtx object is required to track streaming operations. 803 Use ZSTD_createDCtx() / ZSTD_freeDCtx() to manage it. 804 A ZSTD_DCtx object can be re-used multiple times. 805 806 First typical operation is to retrieve frame parameters, using ZSTD_getFrameHeader(). 807 Frame header is extracted from the beginning of compressed frame, so providing only the frame's beginning is enough. 808 Data fragment must be large enough to ensure successful decoding. 809 `ZSTD_frameHeaderSize_max` bytes is guaranteed to always be large enough. 810 @result : 0 : successful decoding, the `ZSTD_frameHeader` structure is correctly filled. 811 >0 : `srcSize` is too small, please provide at least @result bytes on next attempt. 812 errorCode, which can be tested using ZSTD_isError(). 813 814 It fills a ZSTD_frameHeader structure with important information to correctly decode the frame, 815 such as the dictionary ID, content size, or maximum back-reference distance (`windowSize`). 816 Note that these values could be wrong, either because of data corruption, or because a 3rd party deliberately spoofs false information. 817 As a consequence, check that values remain within valid application range. 818 For example, do not allocate memory blindly, check that `windowSize` is within expectation. 819 Each application can set its own limits, depending on local restrictions. 820 For extended interoperability, it is recommended to support `windowSize` of at least 8 MB. 821 822 ZSTD_decompressContinue() needs previous data blocks during decompression, up to `windowSize` bytes. 823 ZSTD_decompressContinue() is very sensitive to contiguity, 824 if 2 blocks don't follow each other, make sure that either the compressor breaks contiguity at the same place, 825 or that previous contiguous segment is large enough to properly handle maximum back-reference distance. 826 There are multiple ways to guarantee this condition. 827 828 The most memory efficient way is to use a round buffer of sufficient size. 829 Sufficient size is determined by invoking ZSTD_decodingBufferSize_min(), 830 which can @return an error code if required value is too large for current system (in 32-bits mode). 831 In a round buffer methodology, ZSTD_decompressContinue() decompresses each block next to previous one, 832 up to the moment there is not enough room left in the buffer to guarantee decoding another full block, 833 which maximum size is provided in `ZSTD_frameHeader` structure, field `blockSizeMax`. 834 At which point, decoding can resume from the beginning of the buffer. 835 Note that already decoded data stored in the buffer should be flushed before being overwritten. 836 837 There are alternatives possible, for example using two or more buffers of size `windowSize` each, though they consume more memory. 838 839 Finally, if you control the compression process, you can also ignore all buffer size rules, 840 as long as the encoder and decoder progress in "lock-step", 841 aka use exactly the same buffer sizes, break contiguity at the same place, etc. 842 843 Once buffers are setup, start decompression, with ZSTD_decompressBegin(). 844 If decompression requires a dictionary, use ZSTD_decompressBegin_usingDict() or ZSTD_decompressBegin_usingDDict(). 845 846 Then use ZSTD_nextSrcSizeToDecompress() and ZSTD_decompressContinue() alternatively. 847 ZSTD_nextSrcSizeToDecompress() tells how many bytes to provide as 'srcSize' to ZSTD_decompressContinue(). 848 ZSTD_decompressContinue() requires this _exact_ amount of bytes, or it will fail. 849 850 @result of ZSTD_decompressContinue() is the number of bytes regenerated within 'dst' (necessarily <= dstCapacity). 851 It can be zero : it just means ZSTD_decompressContinue() has decoded some metadata item. 852 It can also be an error code, which can be tested with ZSTD_isError(). 853 854 A frame is fully decoded when ZSTD_nextSrcSizeToDecompress() returns zero. 855 Context can then be reset to start a new decompression. 856 857 Note : it's possible to know if next input to present is a header or a block, using ZSTD_nextInputType(). 858 This information is not required to properly decode a frame. 859 860 == Special case : skippable frames == 861 862 Skippable frames allow integration of user-defined data into a flow of concatenated frames. 863 Skippable frames will be ignored (skipped) by decompressor. 864 The format of skippable frames is as follows : 865 a) Skippable frame ID - 4 Bytes, Little endian format, any value from 0x184D2A50 to 0x184D2A5F 866 b) Frame Size - 4 Bytes, Little endian format, unsigned 32-bits 867 c) Frame Content - any content (User Data) of length equal to Frame Size 868 For skippable frames ZSTD_getFrameHeader() returns zfhPtr->frameType==ZSTD_skippableFrame. 869 For skippable frames ZSTD_decompressContinue() always returns 0 : it only skips the content. 870 */ 871 872 /*===== Buffer-less streaming decompression functions =====*/ 873 typedef enum { ZSTD_frame, ZSTD_skippableFrame } ZSTD_frameType_e; 874 typedef struct { 875 unsigned long long frameContentSize; /* if == ZSTD_CONTENTSIZE_UNKNOWN, it means this field is not available. 0 means "empty" */ 876 unsigned long long windowSize; /* can be very large, up to <= frameContentSize */ 877 unsigned blockSizeMax; 878 ZSTD_frameType_e frameType; /* if == ZSTD_skippableFrame, frameContentSize is the size of skippable content */ 879 unsigned headerSize; 880 unsigned dictID; 881 unsigned checksumFlag; 882 } ZSTD_frameHeader; 883 ZSTDLIB_API size_t ZSTD_getFrameHeader(ZSTD_frameHeader* zfhPtr, const void* src, size_t srcSize); /**< doesn't consume input */ 884 ZSTDLIB_API size_t ZSTD_decodingBufferSize_min(unsigned long long windowSize, unsigned long long frameContentSize); /**< when frame content size is not known, pass in frameContentSize == ZSTD_CONTENTSIZE_UNKNOWN */ 885 886 ZSTDLIB_API size_t ZSTD_decompressBegin(ZSTD_DCtx* dctx); 887 ZSTDLIB_API size_t ZSTD_decompressBegin_usingDict(ZSTD_DCtx* dctx, const void* dict, size_t dictSize); 888 ZSTDLIB_API size_t ZSTD_decompressBegin_usingDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict); 889 890 ZSTDLIB_API size_t ZSTD_nextSrcSizeToDecompress(ZSTD_DCtx* dctx); 891 ZSTDLIB_API size_t ZSTD_decompressContinue(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize); 892 893 /* misc */ 894 ZSTDLIB_API void ZSTD_copyDCtx(ZSTD_DCtx* dctx, const ZSTD_DCtx* preparedDCtx); 895 typedef enum { ZSTDnit_frameHeader, ZSTDnit_blockHeader, ZSTDnit_block, ZSTDnit_lastBlock, ZSTDnit_checksum, ZSTDnit_skippableFrame } ZSTD_nextInputType_e; 896 ZSTDLIB_API ZSTD_nextInputType_e ZSTD_nextInputType(ZSTD_DCtx* dctx); 897 898 899 900 /* ============================================ */ 901 /** New advanced API (experimental) */ 902 /* ============================================ */ 903 904 /* notes on API design : 905 * In this proposal, parameters are pushed one by one into an existing context, 906 * and then applied on all subsequent compression jobs. 907 * When no parameter is ever provided, CCtx is created with compression level ZSTD_CLEVEL_DEFAULT. 908 * 909 * This API is intended to replace all others advanced / experimental API entry points. 910 * But it stands a reasonable chance to become "stable", after a reasonable testing period. 911 */ 912 913 /* note on naming convention : 914 * Initially, the API favored names like ZSTD_setCCtxParameter() . 915 * In this proposal, convention is changed towards ZSTD_CCtx_setParameter() . 916 * The main driver is that it identifies more clearly the target object type. 917 * It feels clearer when considering multiple targets : 918 * ZSTD_CDict_setParameter() (rather than ZSTD_setCDictParameter()) 919 * ZSTD_CCtxParams_setParameter() (rather than ZSTD_setCCtxParamsParameter() ) 920 * etc... 921 */ 922 923 /* note on enum design : 924 * All enum will be pinned to explicit values before reaching "stable API" status */ 925 926 typedef enum { 927 /* Opened question : should we have a format ZSTD_f_auto ? 928 * Today, it would mean exactly the same as ZSTD_f_zstd1. 929 * But, in the future, should several formats become supported, 930 * on the compression side, it would mean "default format". 931 * On the decompression side, it would mean "automatic format detection", 932 * so that ZSTD_f_zstd1 would mean "accept *only* zstd frames". 933 * Since meaning is a little different, another option could be to define different enums for compression and decompression. 934 * This question could be kept for later, when there are actually multiple formats to support, 935 * but there is also the question of pinning enum values, and pinning value `0` is especially important */ 936 ZSTD_f_zstd1 = 0, /* zstd frame format, specified in zstd_compression_format.md (default) */ 937 ZSTD_f_zstd1_magicless, /* Variant of zstd frame format, without initial 4-bytes magic number. 938 * Useful to save 4 bytes per generated frame. 939 * Decoder cannot recognise automatically this format, requiring instructions. */ 940 } ZSTD_format_e; 941 942 typedef enum { 943 /* compression format */ 944 ZSTD_p_format = 10, /* See ZSTD_format_e enum definition. 945 * Cast selected format as unsigned for ZSTD_CCtx_setParameter() compatibility. */ 946 947 /* compression parameters */ 948 ZSTD_p_compressionLevel=100, /* Update all compression parameters according to pre-defined cLevel table 949 * Default level is ZSTD_CLEVEL_DEFAULT==3. 950 * Special: value 0 means "do not change cLevel". 951 * Note 1 : it's possible to pass a negative compression level by casting it to unsigned type. 952 * Note 2 : setting a level sets all default values of other compression parameters. 953 * Note 3 : setting compressionLevel automatically updates ZSTD_p_compressLiterals. */ 954 ZSTD_p_windowLog, /* Maximum allowed back-reference distance, expressed as power of 2. 955 * Must be clamped between ZSTD_WINDOWLOG_MIN and ZSTD_WINDOWLOG_MAX. 956 * Special: value 0 means "use default windowLog". 957 * Note: Using a window size greater than ZSTD_MAXWINDOWSIZE_DEFAULT (default: 2^27) 958 * requires explicitly allowing such window size during decompression stage. */ 959 ZSTD_p_hashLog, /* Size of the probe table, as a power of 2. 960 * Resulting table size is (1 << (hashLog+2)). 961 * Must be clamped between ZSTD_HASHLOG_MIN and ZSTD_HASHLOG_MAX. 962 * Larger tables improve compression ratio of strategies <= dFast, 963 * and improve speed of strategies > dFast. 964 * Special: value 0 means "use default hashLog". */ 965 ZSTD_p_chainLog, /* Size of the full-search table, as a power of 2. 966 * Resulting table size is (1 << (chainLog+2)). 967 * Larger tables result in better and slower compression. 968 * This parameter is useless when using "fast" strategy. 969 * Special: value 0 means "use default chainLog". */ 970 ZSTD_p_searchLog, /* Number of search attempts, as a power of 2. 971 * More attempts result in better and slower compression. 972 * This parameter is useless when using "fast" and "dFast" strategies. 973 * Special: value 0 means "use default searchLog". */ 974 ZSTD_p_minMatch, /* Minimum size of searched matches (note : repCode matches can be smaller). 975 * Larger values make faster compression and decompression, but decrease ratio. 976 * Must be clamped between ZSTD_SEARCHLENGTH_MIN and ZSTD_SEARCHLENGTH_MAX. 977 * Note that currently, for all strategies < btopt, effective minimum is 4. 978 * , for all strategies > fast, effective maximum is 6. 979 * Special: value 0 means "use default minMatchLength". */ 980 ZSTD_p_targetLength, /* Impact of this field depends on strategy. 981 * For strategies btopt & btultra: 982 * Length of Match considered "good enough" to stop search. 983 * Larger values make compression stronger, and slower. 984 * For strategy fast: 985 * Distance between match sampling. 986 * Larger values make compression faster, and weaker. 987 * Special: value 0 means "use default targetLength". */ 988 ZSTD_p_compressionStrategy, /* See ZSTD_strategy enum definition. 989 * Cast selected strategy as unsigned for ZSTD_CCtx_setParameter() compatibility. 990 * The higher the value of selected strategy, the more complex it is, 991 * resulting in stronger and slower compression. 992 * Special: value 0 means "use default strategy". */ 993 994 ZSTD_p_enableLongDistanceMatching=160, /* Enable long distance matching. 995 * This parameter is designed to improve compression ratio 996 * for large inputs, by finding large matches at long distance. 997 * It increases memory usage and window size. 998 * Note: enabling this parameter increases ZSTD_p_windowLog to 128 MB 999 * except when expressly set to a different value. */ 1000 ZSTD_p_ldmHashLog, /* Size of the table for long distance matching, as a power of 2. 1001 * Larger values increase memory usage and compression ratio, 1002 * but decrease compression speed. 1003 * Must be clamped between ZSTD_HASHLOG_MIN and ZSTD_HASHLOG_MAX 1004 * default: windowlog - 7. 1005 * Special: value 0 means "automatically determine hashlog". */ 1006 ZSTD_p_ldmMinMatch, /* Minimum match size for long distance matcher. 1007 * Larger/too small values usually decrease compression ratio. 1008 * Must be clamped between ZSTD_LDM_MINMATCH_MIN and ZSTD_LDM_MINMATCH_MAX. 1009 * Special: value 0 means "use default value" (default: 64). */ 1010 ZSTD_p_ldmBucketSizeLog, /* Log size of each bucket in the LDM hash table for collision resolution. 1011 * Larger values improve collision resolution but decrease compression speed. 1012 * The maximum value is ZSTD_LDM_BUCKETSIZELOG_MAX . 1013 * Special: value 0 means "use default value" (default: 3). */ 1014 ZSTD_p_ldmHashEveryLog, /* Frequency of inserting/looking up entries in the LDM hash table. 1015 * Must be clamped between 0 and (ZSTD_WINDOWLOG_MAX - ZSTD_HASHLOG_MIN). 1016 * Default is MAX(0, (windowLog - ldmHashLog)), optimizing hash table usage. 1017 * Larger values improve compression speed. 1018 * Deviating far from default value will likely result in a compression ratio decrease. 1019 * Special: value 0 means "automatically determine hashEveryLog". */ 1020 1021 /* frame parameters */ 1022 ZSTD_p_contentSizeFlag=200, /* Content size will be written into frame header _whenever known_ (default:1) 1023 * Content size must be known at the beginning of compression, 1024 * it is provided using ZSTD_CCtx_setPledgedSrcSize() */ 1025 ZSTD_p_checksumFlag, /* A 32-bits checksum of content is written at end of frame (default:0) */ 1026 ZSTD_p_dictIDFlag, /* When applicable, dictionary's ID is written into frame header (default:1) */ 1027 1028 /* multi-threading parameters */ 1029 /* These parameters are only useful if multi-threading is enabled (ZSTD_MULTITHREAD). 1030 * They return an error otherwise. */ 1031 ZSTD_p_nbWorkers=400, /* Select how many threads will be spawned to compress in parallel. 1032 * When nbWorkers >= 1, triggers asynchronous mode : 1033 * ZSTD_compress_generic() consumes some input, flush some output if possible, and immediately gives back control to caller, 1034 * while compression work is performed in parallel, within worker threads. 1035 * (note : a strong exception to this rule is when first invocation sets ZSTD_e_end : it becomes a blocking call). 1036 * More workers improve speed, but also increase memory usage. 1037 * Default value is `0`, aka "single-threaded mode" : no worker is spawned, compression is performed inside Caller's thread, all invocations are blocking */ 1038 ZSTD_p_jobSize, /* Size of a compression job. This value is enforced only in non-blocking mode. 1039 * Each compression job is completed in parallel, so this value indirectly controls the nb of active threads. 1040 * 0 means default, which is dynamically determined based on compression parameters. 1041 * Job size must be a minimum of overlapSize, or 1 MB, whichever is largest. 1042 * The minimum size is automatically and transparently enforced */ 1043 ZSTD_p_overlapSizeLog, /* Size of previous input reloaded at the beginning of each job. 1044 * 0 => no overlap, 6(default) => use 1/8th of windowSize, >=9 => use full windowSize */ 1045 1046 /* =================================================================== */ 1047 /* experimental parameters - no stability guaranteed */ 1048 /* =================================================================== */ 1049 1050 ZSTD_p_compressLiterals=1000, /* control huffman compression of literals (enabled) by default. 1051 * disabling it improves speed and decreases compression ratio by a large amount. 1052 * note : this setting is automatically updated when changing compression level. 1053 * positive compression levels set ZSTD_p_compressLiterals to 1. 1054 * negative compression levels set ZSTD_p_compressLiterals to 0. */ 1055 1056 ZSTD_p_forceMaxWindow=1100, /* Force back-reference distances to remain < windowSize, 1057 * even when referencing into Dictionary content (default:0) */ 1058 1059 } ZSTD_cParameter; 1060 1061 1062 /*! ZSTD_CCtx_setParameter() : 1063 * Set one compression parameter, selected by enum ZSTD_cParameter. 1064 * Setting a parameter is generally only possible during frame initialization (before starting compression), 1065 * except for a few exceptions which can be updated during compression: compressionLevel, hashLog, chainLog, searchLog, minMatch, targetLength and strategy. 1066 * Note : when `value` is an enum, cast it to unsigned for proper type checking. 1067 * @result : informational value (typically, value being set clamped correctly), 1068 * or an error code (which can be tested with ZSTD_isError()). */ 1069 ZSTDLIB_API size_t ZSTD_CCtx_setParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, unsigned value); 1070 1071 /*! ZSTD_CCtx_setPledgedSrcSize() : 1072 * Total input data size to be compressed as a single frame. 1073 * This value will be controlled at the end, and result in error if not respected. 1074 * @result : 0, or an error code (which can be tested with ZSTD_isError()). 1075 * Note 1 : 0 means zero, empty. 1076 * In order to mean "unknown content size", pass constant ZSTD_CONTENTSIZE_UNKNOWN. 1077 * ZSTD_CONTENTSIZE_UNKNOWN is default value for any new compression job. 1078 * Note 2 : If all data is provided and consumed in a single round, 1079 * this value is overriden by srcSize instead. */ 1080 ZSTDLIB_API size_t ZSTD_CCtx_setPledgedSrcSize(ZSTD_CCtx* cctx, unsigned long long pledgedSrcSize); 1081 1082 /*! ZSTD_CCtx_loadDictionary() : 1083 * Create an internal CDict from `dict` buffer. 1084 * Decompression will have to use same dictionary. 1085 * @result : 0, or an error code (which can be tested with ZSTD_isError()). 1086 * Special: Adding a NULL (or 0-size) dictionary invalidates previous dictionary, 1087 * meaning "return to no-dictionary mode". 1088 * Note 1 : Dictionary will be used for all future compression jobs. 1089 * To return to "no-dictionary" situation, load a NULL dictionary 1090 * Note 2 : Loading a dictionary involves building tables, which are dependent on compression parameters. 1091 * For this reason, compression parameters cannot be changed anymore after loading a dictionary. 1092 * It's also a CPU consuming operation, with non-negligible impact on latency. 1093 * Note 3 :`dict` content will be copied internally. 1094 * Use ZSTD_CCtx_loadDictionary_byReference() to reference dictionary content instead. 1095 * In such a case, dictionary buffer must outlive its users. 1096 * Note 4 : Use ZSTD_CCtx_loadDictionary_advanced() 1097 * to precisely select how dictionary content must be interpreted. */ 1098 ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary(ZSTD_CCtx* cctx, const void* dict, size_t dictSize); 1099 ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary_byReference(ZSTD_CCtx* cctx, const void* dict, size_t dictSize); 1100 ZSTDLIB_API size_t ZSTD_CCtx_loadDictionary_advanced(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod, ZSTD_dictContentType_e dictContentType); 1101 1102 1103 /*! ZSTD_CCtx_refCDict() : 1104 * Reference a prepared dictionary, to be used for all next compression jobs. 1105 * Note that compression parameters are enforced from within CDict, 1106 * and supercede any compression parameter previously set within CCtx. 1107 * The dictionary will remain valid for future compression jobs using same CCtx. 1108 * @result : 0, or an error code (which can be tested with ZSTD_isError()). 1109 * Special : adding a NULL CDict means "return to no-dictionary mode". 1110 * Note 1 : Currently, only one dictionary can be managed. 1111 * Adding a new dictionary effectively "discards" any previous one. 1112 * Note 2 : CDict is just referenced, its lifetime must outlive CCtx. */ 1113 ZSTDLIB_API size_t ZSTD_CCtx_refCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict); 1114 1115 /*! ZSTD_CCtx_refPrefix() : 1116 * Reference a prefix (single-usage dictionary) for next compression job. 1117 * Decompression need same prefix to properly regenerate data. 1118 * Prefix is **only used once**. Tables are discarded at end of compression job. 1119 * Subsequent compression jobs will be done without prefix (if none is explicitly referenced). 1120 * If there is a need to use same prefix multiple times, consider embedding it into a ZSTD_CDict instead. 1121 * @result : 0, or an error code (which can be tested with ZSTD_isError()). 1122 * Special: Adding any prefix (including NULL) invalidates any previous prefix or dictionary 1123 * Note 1 : Prefix buffer is referenced. It must outlive compression job. 1124 * Note 2 : Referencing a prefix involves building tables, which are dependent on compression parameters. 1125 * It's a CPU consuming operation, with non-negligible impact on latency. 1126 * Note 3 : By default, the prefix is treated as raw content (ZSTD_dm_rawContent). 1127 * Use ZSTD_CCtx_refPrefix_advanced() to alter dictMode. */ 1128 ZSTDLIB_API size_t ZSTD_CCtx_refPrefix(ZSTD_CCtx* cctx, const void* prefix, size_t prefixSize); 1129 ZSTDLIB_API size_t ZSTD_CCtx_refPrefix_advanced(ZSTD_CCtx* cctx, const void* prefix, size_t prefixSize, ZSTD_dictContentType_e dictContentType); 1130 1131 /*! ZSTD_CCtx_reset() : 1132 * Return a CCtx to clean state. 1133 * Useful after an error, or to interrupt an ongoing compression job and start a new one. 1134 * Any internal data not yet flushed is cancelled. 1135 * Dictionary (if any) is dropped. 1136 * All parameters are back to default values. 1137 * It's possible to modify compression parameters after a reset. 1138 */ 1139 ZSTDLIB_API void ZSTD_CCtx_reset(ZSTD_CCtx* cctx); 1140 1141 1142 1143 typedef enum { 1144 ZSTD_e_continue=0, /* collect more data, encoder decides when to output compressed result, for optimal conditions */ 1145 ZSTD_e_flush, /* flush any data provided so far - frame will continue, future data can still reference previous data for better compression */ 1146 ZSTD_e_end /* flush any remaining data and close current frame. Any additional data starts a new frame. */ 1147 } ZSTD_EndDirective; 1148 1149 /*! ZSTD_compress_generic() : 1150 * Behave about the same as ZSTD_compressStream. To note : 1151 * - Compression parameters are pushed into CCtx before starting compression, using ZSTD_CCtx_setParameter() 1152 * - Compression parameters cannot be changed once compression is started. 1153 * - outpot->pos must be <= dstCapacity, input->pos must be <= srcSize 1154 * - outpot->pos and input->pos will be updated. They are guaranteed to remain below their respective limit. 1155 * - In single-thread mode (default), function is blocking : it completed its job before returning to caller. 1156 * - In multi-thread mode, function is non-blocking : it just acquires a copy of input, and distribute job to internal worker threads, 1157 * and then immediately returns, just indicating that there is some data remaining to be flushed. 1158 * The function nonetheless guarantees forward progress : it will return only after it reads or write at least 1+ byte. 1159 * - Exception : in multi-threading mode, if the first call requests a ZSTD_e_end directive, it is blocking : it will complete compression before giving back control to caller. 1160 * - @return provides a minimum amount of data remaining to be flushed from internal buffers 1161 * or an error code, which can be tested using ZSTD_isError(). 1162 * if @return != 0, flush is not fully completed, there is still some data left within internal buffers. 1163 * This is useful for ZSTD_e_flush, since in this case more flushes are necessary to empty all buffers. 1164 * For ZSTD_e_end, @return == 0 when internal buffers are fully flushed and frame is completed. 1165 * - after a ZSTD_e_end directive, if internal buffer is not fully flushed (@return != 0), 1166 * only ZSTD_e_end or ZSTD_e_flush operations are allowed. 1167 * Before starting a new compression job, or changing compression parameters, 1168 * it is required to fully flush internal buffers. 1169 */ 1170 ZSTDLIB_API size_t ZSTD_compress_generic (ZSTD_CCtx* cctx, 1171 ZSTD_outBuffer* output, 1172 ZSTD_inBuffer* input, 1173 ZSTD_EndDirective endOp); 1174 1175 1176 /*! ZSTD_compress_generic_simpleArgs() : 1177 * Same as ZSTD_compress_generic(), 1178 * but using only integral types as arguments. 1179 * Argument list is larger than ZSTD_{in,out}Buffer, 1180 * but can be helpful for binders from dynamic languages 1181 * which have troubles handling structures containing memory pointers. 1182 */ 1183 ZSTDLIB_API size_t ZSTD_compress_generic_simpleArgs ( 1184 ZSTD_CCtx* cctx, 1185 void* dst, size_t dstCapacity, size_t* dstPos, 1186 const void* src, size_t srcSize, size_t* srcPos, 1187 ZSTD_EndDirective endOp); 1188 1189 1190 /*! ZSTD_CCtx_params : 1191 * Quick howto : 1192 * - ZSTD_createCCtxParams() : Create a ZSTD_CCtx_params structure 1193 * - ZSTD_CCtxParam_setParameter() : Push parameters one by one into 1194 * an existing ZSTD_CCtx_params structure. 1195 * This is similar to 1196 * ZSTD_CCtx_setParameter(). 1197 * - ZSTD_CCtx_setParametersUsingCCtxParams() : Apply parameters to 1198 * an existing CCtx. 1199 * These parameters will be applied to 1200 * all subsequent compression jobs. 1201 * - ZSTD_compress_generic() : Do compression using the CCtx. 1202 * - ZSTD_freeCCtxParams() : Free the memory. 1203 * 1204 * This can be used with ZSTD_estimateCCtxSize_advanced_usingCCtxParams() 1205 * for static allocation for single-threaded compression. 1206 */ 1207 ZSTDLIB_API ZSTD_CCtx_params* ZSTD_createCCtxParams(void); 1208 ZSTDLIB_API size_t ZSTD_freeCCtxParams(ZSTD_CCtx_params* params); 1209 1210 1211 /*! ZSTD_CCtxParams_reset() : 1212 * Reset params to default values. 1213 */ 1214 ZSTDLIB_API size_t ZSTD_CCtxParams_reset(ZSTD_CCtx_params* params); 1215 1216 /*! ZSTD_CCtxParams_init() : 1217 * Initializes the compression parameters of cctxParams according to 1218 * compression level. All other parameters are reset to their default values. 1219 */ 1220 ZSTDLIB_API size_t ZSTD_CCtxParams_init(ZSTD_CCtx_params* cctxParams, int compressionLevel); 1221 1222 /*! ZSTD_CCtxParams_init_advanced() : 1223 * Initializes the compression and frame parameters of cctxParams according to 1224 * params. All other parameters are reset to their default values. 1225 */ 1226 ZSTDLIB_API size_t ZSTD_CCtxParams_init_advanced(ZSTD_CCtx_params* cctxParams, ZSTD_parameters params); 1227 1228 1229 /*! ZSTD_CCtxParam_setParameter() : 1230 * Similar to ZSTD_CCtx_setParameter. 1231 * Set one compression parameter, selected by enum ZSTD_cParameter. 1232 * Parameters must be applied to a ZSTD_CCtx using ZSTD_CCtx_setParametersUsingCCtxParams(). 1233 * Note : when `value` is an enum, cast it to unsigned for proper type checking. 1234 * @result : 0, or an error code (which can be tested with ZSTD_isError()). 1235 */ 1236 ZSTDLIB_API size_t ZSTD_CCtxParam_setParameter(ZSTD_CCtx_params* params, ZSTD_cParameter param, unsigned value); 1237 1238 /*! ZSTD_CCtx_setParametersUsingCCtxParams() : 1239 * Apply a set of ZSTD_CCtx_params to the compression context. 1240 * This can be done even after compression is started, 1241 * if nbWorkers==0, this will have no impact until a new compression is started. 1242 * if nbWorkers>=1, new parameters will be picked up at next job, 1243 * with a few restrictions (windowLog, pledgedSrcSize, nbWorkers, jobSize, and overlapLog are not updated). 1244 */ 1245 ZSTDLIB_API size_t ZSTD_CCtx_setParametersUsingCCtxParams( 1246 ZSTD_CCtx* cctx, const ZSTD_CCtx_params* params); 1247 1248 1249 /*=== Advanced parameters for decompression API ===*/ 1250 1251 /* The following parameters must be set after creating a ZSTD_DCtx* (or ZSTD_DStream*) object, 1252 * but before starting decompression of a frame. 1253 */ 1254 1255 /*! ZSTD_DCtx_loadDictionary() : 1256 * Create an internal DDict from dict buffer, 1257 * to be used to decompress next frames. 1258 * @result : 0, or an error code (which can be tested with ZSTD_isError()). 1259 * Special : Adding a NULL (or 0-size) dictionary invalidates any previous dictionary, 1260 * meaning "return to no-dictionary mode". 1261 * Note 1 : `dict` content will be copied internally. 1262 * Use ZSTD_DCtx_loadDictionary_byReference() 1263 * to reference dictionary content instead. 1264 * In which case, the dictionary buffer must outlive its users. 1265 * Note 2 : Loading a dictionary involves building tables, 1266 * which has a non-negligible impact on CPU usage and latency. 1267 * Note 3 : Use ZSTD_DCtx_loadDictionary_advanced() to select 1268 * how dictionary content will be interpreted and loaded. 1269 */ 1270 ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary(ZSTD_DCtx* dctx, const void* dict, size_t dictSize); 1271 ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary_byReference(ZSTD_DCtx* dctx, const void* dict, size_t dictSize); 1272 ZSTDLIB_API size_t ZSTD_DCtx_loadDictionary_advanced(ZSTD_DCtx* dctx, const void* dict, size_t dictSize, ZSTD_dictLoadMethod_e dictLoadMethod, ZSTD_dictContentType_e dictContentType); 1273 1274 1275 /*! ZSTD_DCtx_refDDict() : 1276 * Reference a prepared dictionary, to be used to decompress next frames. 1277 * The dictionary remains active for decompression of future frames using same DCtx. 1278 * @result : 0, or an error code (which can be tested with ZSTD_isError()). 1279 * Note 1 : Currently, only one dictionary can be managed. 1280 * Referencing a new dictionary effectively "discards" any previous one. 1281 * Special : adding a NULL DDict means "return to no-dictionary mode". 1282 * Note 2 : DDict is just referenced, its lifetime must outlive its usage from DCtx. 1283 */ 1284 ZSTDLIB_API size_t ZSTD_DCtx_refDDict(ZSTD_DCtx* dctx, const ZSTD_DDict* ddict); 1285 1286 1287 /*! ZSTD_DCtx_refPrefix() : 1288 * Reference a prefix (single-usage dictionary) for next compression job. 1289 * Prefix is **only used once**. It must be explicitly referenced before each frame. 1290 * If there is a need to use same prefix multiple times, consider embedding it into a ZSTD_DDict instead. 1291 * @result : 0, or an error code (which can be tested with ZSTD_isError()). 1292 * Note 1 : Adding any prefix (including NULL) invalidates any previously set prefix or dictionary 1293 * Note 2 : Prefix buffer is referenced. It must outlive compression job. 1294 * Note 3 : By default, the prefix is treated as raw content (ZSTD_dm_rawContent). 1295 * Use ZSTD_CCtx_refPrefix_advanced() to alter dictMode. 1296 * Note 4 : Referencing a raw content prefix has almost no cpu nor memory cost. 1297 */ 1298 ZSTDLIB_API size_t ZSTD_DCtx_refPrefix(ZSTD_DCtx* dctx, const void* prefix, size_t prefixSize); 1299 ZSTDLIB_API size_t ZSTD_DCtx_refPrefix_advanced(ZSTD_DCtx* dctx, const void* prefix, size_t prefixSize, ZSTD_dictContentType_e dictContentType); 1300 1301 1302 /*! ZSTD_DCtx_setMaxWindowSize() : 1303 * Refuses allocating internal buffers for frames requiring a window size larger than provided limit. 1304 * This is useful to prevent a decoder context from reserving too much memory for itself (potential attack scenario). 1305 * This parameter is only useful in streaming mode, since no internal buffer is allocated in direct mode. 1306 * By default, a decompression context accepts all window sizes <= (1 << ZSTD_WINDOWLOG_MAX) 1307 * @return : 0, or an error code (which can be tested using ZSTD_isError()). 1308 */ 1309 ZSTDLIB_API size_t ZSTD_DCtx_setMaxWindowSize(ZSTD_DCtx* dctx, size_t maxWindowSize); 1310 1311 1312 /*! ZSTD_DCtx_setFormat() : 1313 * Instruct the decoder context about what kind of data to decode next. 1314 * This instruction is mandatory to decode data without a fully-formed header, 1315 * such ZSTD_f_zstd1_magicless for example. 1316 * @return : 0, or an error code (which can be tested using ZSTD_isError()). 1317 */ 1318 ZSTDLIB_API size_t ZSTD_DCtx_setFormat(ZSTD_DCtx* dctx, ZSTD_format_e format); 1319 1320 1321 /*! ZSTD_decompress_generic() : 1322 * Behave the same as ZSTD_decompressStream. 1323 * Decompression parameters cannot be changed once decompression is started. 1324 * @return : an error code, which can be tested using ZSTD_isError() 1325 * if >0, a hint, nb of expected input bytes for next invocation. 1326 * `0` means : a frame has just been fully decoded and flushed. 1327 */ 1328 ZSTDLIB_API size_t ZSTD_decompress_generic(ZSTD_DCtx* dctx, 1329 ZSTD_outBuffer* output, 1330 ZSTD_inBuffer* input); 1331 1332 1333 /*! ZSTD_decompress_generic_simpleArgs() : 1334 * Same as ZSTD_decompress_generic(), 1335 * but using only integral types as arguments. 1336 * Argument list is larger than ZSTD_{in,out}Buffer, 1337 * but can be helpful for binders from dynamic languages 1338 * which have troubles handling structures containing memory pointers. 1339 */ 1340 ZSTDLIB_API size_t ZSTD_decompress_generic_simpleArgs ( 1341 ZSTD_DCtx* dctx, 1342 void* dst, size_t dstCapacity, size_t* dstPos, 1343 const void* src, size_t srcSize, size_t* srcPos); 1344 1345 1346 /*! ZSTD_DCtx_reset() : 1347 * Return a DCtx to clean state. 1348 * If a decompression was ongoing, any internal data not yet flushed is cancelled. 1349 * All parameters are back to default values, including sticky ones. 1350 * Dictionary (if any) is dropped. 1351 * Parameters can be modified again after a reset. 1352 */ 1353 ZSTDLIB_API void ZSTD_DCtx_reset(ZSTD_DCtx* dctx); 1354 1355 1356 1357 /* ============================ */ 1358 /** Block level API */ 1359 /* ============================ */ 1360 1361 /*! 1362 Block functions produce and decode raw zstd blocks, without frame metadata. 1363 Frame metadata cost is typically ~18 bytes, which can be non-negligible for very small blocks (< 100 bytes). 1364 User will have to take in charge required information to regenerate data, such as compressed and content sizes. 1365 1366 A few rules to respect : 1367 - Compressing and decompressing require a context structure 1368 + Use ZSTD_createCCtx() and ZSTD_createDCtx() 1369 - It is necessary to init context before starting 1370 + compression : any ZSTD_compressBegin*() variant, including with dictionary 1371 + decompression : any ZSTD_decompressBegin*() variant, including with dictionary 1372 + copyCCtx() and copyDCtx() can be used too 1373 - Block size is limited, it must be <= ZSTD_getBlockSize() <= ZSTD_BLOCKSIZE_MAX == 128 KB 1374 + If input is larger than a block size, it's necessary to split input data into multiple blocks 1375 + For inputs larger than a single block size, consider using the regular ZSTD_compress() instead. 1376 Frame metadata is not that costly, and quickly becomes negligible as source size grows larger. 1377 - When a block is considered not compressible enough, ZSTD_compressBlock() result will be zero. 1378 In which case, nothing is produced into `dst`. 1379 + User must test for such outcome and deal directly with uncompressed data 1380 + ZSTD_decompressBlock() doesn't accept uncompressed data as input !!! 1381 + In case of multiple successive blocks, should some of them be uncompressed, 1382 decoder must be informed of their existence in order to follow proper history. 1383 Use ZSTD_insertBlock() for such a case. 1384 */ 1385 1386 #define ZSTD_BLOCKSIZELOG_MAX 17 1387 #define ZSTD_BLOCKSIZE_MAX (1<<ZSTD_BLOCKSIZELOG_MAX) /* define, for static allocation */ 1388 /*===== Raw zstd block functions =====*/ 1389 ZSTDLIB_API size_t ZSTD_getBlockSize (const ZSTD_CCtx* cctx); 1390 ZSTDLIB_API size_t ZSTD_compressBlock (ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize); 1391 ZSTDLIB_API size_t ZSTD_decompressBlock(ZSTD_DCtx* dctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize); 1392 ZSTDLIB_API size_t ZSTD_insertBlock (ZSTD_DCtx* dctx, const void* blockStart, size_t blockSize); /**< insert uncompressed block into `dctx` history. Useful for multi-blocks decompression. */ 1393 1394 1395 #endif /* ZSTD_H_ZSTD_STATIC_LINKING_ONLY */ 1396 1397 #if defined (__cplusplus) 1398 } 1399 #endif 1400