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