1 /* 2 LZ4 auto-framing library 3 Header File 4 Copyright (C) 2011-2020, Yann Collet. 5 BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php) 6 7 Redistribution and use in source and binary forms, with or without 8 modification, are permitted provided that the following conditions are 9 met: 10 11 * Redistributions of source code must retain the above copyright 12 notice, this list of conditions and the following disclaimer. 13 * Redistributions in binary form must reproduce the above 14 copyright notice, this list of conditions and the following disclaimer 15 in the documentation and/or other materials provided with the 16 distribution. 17 18 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 19 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 20 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 21 A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 22 OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 23 SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 24 LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 28 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 30 You can contact the author at : 31 - LZ4 source repository : https://github.com/lz4/lz4 32 - LZ4 public forum : https://groups.google.com/forum/#!forum/lz4c 33 */ 34 35 /* LZ4F is a stand-alone API able to create and decode LZ4 frames 36 * conformant with specification v1.6.1 in doc/lz4_Frame_format.md . 37 * Generated frames are compatible with `lz4` CLI. 38 * 39 * LZ4F also offers streaming capabilities. 40 * 41 * lz4.h is not required when using lz4frame.h, 42 * except to extract common constant such as LZ4_VERSION_NUMBER. 43 * */ 44 45 #ifndef LZ4F_H_09782039843 46 #define LZ4F_H_09782039843 47 48 #if defined (__cplusplus) 49 extern "C" { 50 #endif 51 52 /* --- Dependency --- */ 53 #include <stddef.h> /* size_t */ 54 55 56 /** 57 Introduction 58 59 lz4frame.h implements LZ4 frame specification (doc/lz4_Frame_format.md). 60 lz4frame.h provides frame compression functions that take care 61 of encoding standard metadata alongside LZ4-compressed blocks. 62 */ 63 64 /*-*************************************************************** 65 * Compiler specifics 66 *****************************************************************/ 67 /* LZ4_DLL_EXPORT : 68 * Enable exporting of functions when building a Windows DLL 69 * LZ4FLIB_VISIBILITY : 70 * Control library symbols visibility. 71 */ 72 #ifndef LZ4FLIB_VISIBILITY 73 # if defined(__GNUC__) && (__GNUC__ >= 4) 74 # define LZ4FLIB_VISIBILITY __attribute__ ((visibility ("default"))) 75 # else 76 # define LZ4FLIB_VISIBILITY 77 # endif 78 #endif 79 #if defined(LZ4_DLL_EXPORT) && (LZ4_DLL_EXPORT==1) 80 # define LZ4FLIB_API __declspec(dllexport) LZ4FLIB_VISIBILITY 81 #elif defined(LZ4_DLL_IMPORT) && (LZ4_DLL_IMPORT==1) 82 # define LZ4FLIB_API __declspec(dllimport) LZ4FLIB_VISIBILITY 83 #else 84 # define LZ4FLIB_API LZ4FLIB_VISIBILITY 85 #endif 86 87 #ifdef LZ4F_DISABLE_DEPRECATE_WARNINGS 88 # define LZ4F_DEPRECATE(x) x 89 #else 90 # if defined(_MSC_VER) 91 # define LZ4F_DEPRECATE(x) x /* __declspec(deprecated) x - only works with C++ */ 92 # elif defined(__clang__) || (defined(__GNUC__) && (__GNUC__ >= 6)) 93 # define LZ4F_DEPRECATE(x) x __attribute__((deprecated)) 94 # else 95 # define LZ4F_DEPRECATE(x) x /* no deprecation warning for this compiler */ 96 # endif 97 #endif 98 99 100 /*-************************************ 101 * Error management 102 **************************************/ 103 typedef size_t LZ4F_errorCode_t; 104 105 LZ4FLIB_API unsigned LZ4F_isError(LZ4F_errorCode_t code); /**< tells when a function result is an error code */ 106 LZ4FLIB_API const char* LZ4F_getErrorName(LZ4F_errorCode_t code); /**< return error code string; for debugging */ 107 108 109 /*-************************************ 110 * Frame compression types 111 ************************************* */ 112 /* #define LZ4F_ENABLE_OBSOLETE_ENUMS // uncomment to enable obsolete enums */ 113 #ifdef LZ4F_ENABLE_OBSOLETE_ENUMS 114 # define LZ4F_OBSOLETE_ENUM(x) , LZ4F_DEPRECATE(x) = LZ4F_##x 115 #else 116 # define LZ4F_OBSOLETE_ENUM(x) 117 #endif 118 119 /* The larger the block size, the (slightly) better the compression ratio, 120 * though there are diminishing returns. 121 * Larger blocks also increase memory usage on both compression and decompression sides. 122 */ 123 typedef enum { 124 LZ4F_default=0, 125 LZ4F_max64KB=4, 126 LZ4F_max256KB=5, 127 LZ4F_max1MB=6, 128 LZ4F_max4MB=7 129 LZ4F_OBSOLETE_ENUM(max64KB) 130 LZ4F_OBSOLETE_ENUM(max256KB) 131 LZ4F_OBSOLETE_ENUM(max1MB) 132 LZ4F_OBSOLETE_ENUM(max4MB) 133 } LZ4F_blockSizeID_t; 134 135 /* Linked blocks sharply reduce inefficiencies when using small blocks, 136 * they compress better. 137 * However, some LZ4 decoders are only compatible with independent blocks */ 138 typedef enum { 139 LZ4F_blockLinked=0, 140 LZ4F_blockIndependent 141 LZ4F_OBSOLETE_ENUM(blockLinked) 142 LZ4F_OBSOLETE_ENUM(blockIndependent) 143 } LZ4F_blockMode_t; 144 145 typedef enum { 146 LZ4F_noContentChecksum=0, 147 LZ4F_contentChecksumEnabled 148 LZ4F_OBSOLETE_ENUM(noContentChecksum) 149 LZ4F_OBSOLETE_ENUM(contentChecksumEnabled) 150 } LZ4F_contentChecksum_t; 151 152 typedef enum { 153 LZ4F_noBlockChecksum=0, 154 LZ4F_blockChecksumEnabled 155 } LZ4F_blockChecksum_t; 156 157 typedef enum { 158 LZ4F_frame=0, 159 LZ4F_skippableFrame 160 LZ4F_OBSOLETE_ENUM(skippableFrame) 161 } LZ4F_frameType_t; 162 163 #ifdef LZ4F_ENABLE_OBSOLETE_ENUMS 164 typedef LZ4F_blockSizeID_t blockSizeID_t; 165 typedef LZ4F_blockMode_t blockMode_t; 166 typedef LZ4F_frameType_t frameType_t; 167 typedef LZ4F_contentChecksum_t contentChecksum_t; 168 #endif 169 170 /*! LZ4F_frameInfo_t : 171 * makes it possible to set or read frame parameters. 172 * Structure must be first init to 0, using memset() or LZ4F_INIT_FRAMEINFO, 173 * setting all parameters to default. 174 * It's then possible to update selectively some parameters */ 175 typedef struct { 176 LZ4F_blockSizeID_t blockSizeID; /* max64KB, max256KB, max1MB, max4MB; 0 == default */ 177 LZ4F_blockMode_t blockMode; /* LZ4F_blockLinked, LZ4F_blockIndependent; 0 == default */ 178 LZ4F_contentChecksum_t contentChecksumFlag; /* 1: frame terminated with 32-bit checksum of decompressed data; 0: disabled (default) */ 179 LZ4F_frameType_t frameType; /* read-only field : LZ4F_frame or LZ4F_skippableFrame */ 180 unsigned long long contentSize; /* Size of uncompressed content ; 0 == unknown */ 181 unsigned dictID; /* Dictionary ID, sent by compressor to help decoder select correct dictionary; 0 == no dictID provided */ 182 LZ4F_blockChecksum_t blockChecksumFlag; /* 1: each block followed by a checksum of block's compressed data; 0: disabled (default) */ 183 } LZ4F_frameInfo_t; 184 185 #define LZ4F_INIT_FRAMEINFO { LZ4F_default, LZ4F_blockLinked, LZ4F_noContentChecksum, LZ4F_frame, 0ULL, 0U, LZ4F_noBlockChecksum } /* v1.8.3+ */ 186 187 /*! LZ4F_preferences_t : 188 * makes it possible to supply advanced compression instructions to streaming interface. 189 * Structure must be first init to 0, using memset() or LZ4F_INIT_PREFERENCES, 190 * setting all parameters to default. 191 * All reserved fields must be set to zero. */ 192 typedef struct { 193 LZ4F_frameInfo_t frameInfo; 194 int compressionLevel; /* 0: default (fast mode); values > LZ4HC_CLEVEL_MAX count as LZ4HC_CLEVEL_MAX; values < 0 trigger "fast acceleration" */ 195 unsigned autoFlush; /* 1: always flush; reduces usage of internal buffers */ 196 unsigned favorDecSpeed; /* 1: parser favors decompression speed vs compression ratio. Only works for high compression modes (>= LZ4HC_CLEVEL_OPT_MIN) */ /* v1.8.2+ */ 197 unsigned reserved[3]; /* must be zero for forward compatibility */ 198 } LZ4F_preferences_t; 199 200 #define LZ4F_INIT_PREFERENCES { LZ4F_INIT_FRAMEINFO, 0, 0u, 0u, { 0u, 0u, 0u } } /* v1.8.3+ */ 201 202 203 /*-********************************* 204 * Simple compression function 205 ***********************************/ 206 207 LZ4FLIB_API int LZ4F_compressionLevel_max(void); /* v1.8.0+ */ 208 209 /*! LZ4F_compressFrameBound() : 210 * Returns the maximum possible compressed size with LZ4F_compressFrame() given srcSize and preferences. 211 * `preferencesPtr` is optional. It can be replaced by NULL, in which case, the function will assume default preferences. 212 * Note : this result is only usable with LZ4F_compressFrame(). 213 * It may also be used with LZ4F_compressUpdate() _if no flush() operation_ is performed. 214 */ 215 LZ4FLIB_API size_t LZ4F_compressFrameBound(size_t srcSize, const LZ4F_preferences_t* preferencesPtr); 216 217 /*! LZ4F_compressFrame() : 218 * Compress an entire srcBuffer into a valid LZ4 frame. 219 * dstCapacity MUST be >= LZ4F_compressFrameBound(srcSize, preferencesPtr). 220 * The LZ4F_preferences_t structure is optional : you can provide NULL as argument. All preferences will be set to default. 221 * @return : number of bytes written into dstBuffer. 222 * or an error code if it fails (can be tested using LZ4F_isError()) 223 */ 224 LZ4FLIB_API size_t LZ4F_compressFrame(void* dstBuffer, size_t dstCapacity, 225 const void* srcBuffer, size_t srcSize, 226 const LZ4F_preferences_t* preferencesPtr); 227 228 229 /*-*********************************** 230 * Advanced compression functions 231 *************************************/ 232 typedef struct LZ4F_cctx_s LZ4F_cctx; /* incomplete type */ 233 typedef LZ4F_cctx* LZ4F_compressionContext_t; /* for compatibility with previous API version */ 234 235 typedef struct { 236 unsigned stableSrc; /* 1 == src content will remain present on future calls to LZ4F_compress(); skip copying src content within tmp buffer */ 237 unsigned reserved[3]; 238 } LZ4F_compressOptions_t; 239 240 /*--- Resource Management ---*/ 241 242 #define LZ4F_VERSION 100 /* This number can be used to check for an incompatible API breaking change */ 243 LZ4FLIB_API unsigned LZ4F_getVersion(void); 244 245 /*! LZ4F_createCompressionContext() : 246 * The first thing to do is to create a compressionContext object, which will be used in all compression operations. 247 * This is achieved using LZ4F_createCompressionContext(), which takes as argument a version. 248 * The version provided MUST be LZ4F_VERSION. It is intended to track potential version mismatch, notably when using DLL. 249 * The function will provide a pointer to a fully allocated LZ4F_cctx object. 250 * If @return != zero, there was an error during context creation. 251 * Object can release its memory using LZ4F_freeCompressionContext(); 252 */ 253 LZ4FLIB_API LZ4F_errorCode_t LZ4F_createCompressionContext(LZ4F_cctx** cctxPtr, unsigned version); 254 LZ4FLIB_API LZ4F_errorCode_t LZ4F_freeCompressionContext(LZ4F_cctx* cctx); 255 256 257 /*---- Compression ----*/ 258 259 #define LZ4F_HEADER_SIZE_MIN 7 /* LZ4 Frame header size can vary, depending on selected paramaters */ 260 #define LZ4F_HEADER_SIZE_MAX 19 261 262 /* Size in bytes of a block header in little-endian format. Highest bit indicates if block data is uncompressed */ 263 #define LZ4F_BLOCK_HEADER_SIZE 4 264 265 /* Size in bytes of a block checksum footer in little-endian format. */ 266 #define LZ4F_BLOCK_CHECKSUM_SIZE 4 267 268 /* Size in bytes of the content checksum. */ 269 #define LZ4F_CONTENT_CHECKSUM_SIZE 4 270 271 /*! LZ4F_compressBegin() : 272 * will write the frame header into dstBuffer. 273 * dstCapacity must be >= LZ4F_HEADER_SIZE_MAX bytes. 274 * `prefsPtr` is optional : you can provide NULL as argument, all preferences will then be set to default. 275 * @return : number of bytes written into dstBuffer for the header 276 * or an error code (which can be tested using LZ4F_isError()) 277 */ 278 LZ4FLIB_API size_t LZ4F_compressBegin(LZ4F_cctx* cctx, 279 void* dstBuffer, size_t dstCapacity, 280 const LZ4F_preferences_t* prefsPtr); 281 282 /*! LZ4F_compressBound() : 283 * Provides minimum dstCapacity required to guarantee success of 284 * LZ4F_compressUpdate(), given a srcSize and preferences, for a worst case scenario. 285 * When srcSize==0, LZ4F_compressBound() provides an upper bound for LZ4F_flush() and LZ4F_compressEnd() instead. 286 * Note that the result is only valid for a single invocation of LZ4F_compressUpdate(). 287 * When invoking LZ4F_compressUpdate() multiple times, 288 * if the output buffer is gradually filled up instead of emptied and re-used from its start, 289 * one must check if there is enough remaining capacity before each invocation, using LZ4F_compressBound(). 290 * @return is always the same for a srcSize and prefsPtr. 291 * prefsPtr is optional : when NULL is provided, preferences will be set to cover worst case scenario. 292 * tech details : 293 * @return if automatic flushing is not enabled, includes the possibility that internal buffer might already be filled by up to (blockSize-1) bytes. 294 * It also includes frame footer (ending + checksum), since it might be generated by LZ4F_compressEnd(). 295 * @return doesn't include frame header, as it was already generated by LZ4F_compressBegin(). 296 */ 297 LZ4FLIB_API size_t LZ4F_compressBound(size_t srcSize, const LZ4F_preferences_t* prefsPtr); 298 299 /*! LZ4F_compressUpdate() : 300 * LZ4F_compressUpdate() can be called repetitively to compress as much data as necessary. 301 * Important rule: dstCapacity MUST be large enough to ensure operation success even in worst case situations. 302 * This value is provided by LZ4F_compressBound(). 303 * If this condition is not respected, LZ4F_compress() will fail (result is an errorCode). 304 * LZ4F_compressUpdate() doesn't guarantee error recovery. 305 * When an error occurs, compression context must be freed or resized. 306 * `cOptPtr` is optional : NULL can be provided, in which case all options are set to default. 307 * @return : number of bytes written into `dstBuffer` (it can be zero, meaning input data was just buffered). 308 * or an error code if it fails (which can be tested using LZ4F_isError()) 309 */ 310 LZ4FLIB_API size_t LZ4F_compressUpdate(LZ4F_cctx* cctx, 311 void* dstBuffer, size_t dstCapacity, 312 const void* srcBuffer, size_t srcSize, 313 const LZ4F_compressOptions_t* cOptPtr); 314 315 /*! LZ4F_flush() : 316 * When data must be generated and sent immediately, without waiting for a block to be completely filled, 317 * it's possible to call LZ4_flush(). It will immediately compress any data buffered within cctx. 318 * `dstCapacity` must be large enough to ensure the operation will be successful. 319 * `cOptPtr` is optional : it's possible to provide NULL, all options will be set to default. 320 * @return : nb of bytes written into dstBuffer (can be zero, when there is no data stored within cctx) 321 * or an error code if it fails (which can be tested using LZ4F_isError()) 322 * Note : LZ4F_flush() is guaranteed to be successful when dstCapacity >= LZ4F_compressBound(0, prefsPtr). 323 */ 324 LZ4FLIB_API size_t LZ4F_flush(LZ4F_cctx* cctx, 325 void* dstBuffer, size_t dstCapacity, 326 const LZ4F_compressOptions_t* cOptPtr); 327 328 /*! LZ4F_compressEnd() : 329 * To properly finish an LZ4 frame, invoke LZ4F_compressEnd(). 330 * It will flush whatever data remained within `cctx` (like LZ4_flush()) 331 * and properly finalize the frame, with an endMark and a checksum. 332 * `cOptPtr` is optional : NULL can be provided, in which case all options will be set to default. 333 * @return : nb of bytes written into dstBuffer, necessarily >= 4 (endMark), 334 * or an error code if it fails (which can be tested using LZ4F_isError()) 335 * Note : LZ4F_compressEnd() is guaranteed to be successful when dstCapacity >= LZ4F_compressBound(0, prefsPtr). 336 * A successful call to LZ4F_compressEnd() makes `cctx` available again for another compression task. 337 */ 338 LZ4FLIB_API size_t LZ4F_compressEnd(LZ4F_cctx* cctx, 339 void* dstBuffer, size_t dstCapacity, 340 const LZ4F_compressOptions_t* cOptPtr); 341 342 343 /*-********************************* 344 * Decompression functions 345 ***********************************/ 346 typedef struct LZ4F_dctx_s LZ4F_dctx; /* incomplete type */ 347 typedef LZ4F_dctx* LZ4F_decompressionContext_t; /* compatibility with previous API versions */ 348 349 typedef struct { 350 unsigned stableDst; /* pledges that last 64KB decompressed data will remain available unmodified. This optimization skips storage operations in tmp buffers. */ 351 unsigned reserved[3]; /* must be set to zero for forward compatibility */ 352 } LZ4F_decompressOptions_t; 353 354 355 /* Resource management */ 356 357 /*! LZ4F_createDecompressionContext() : 358 * Create an LZ4F_dctx object, to track all decompression operations. 359 * The version provided MUST be LZ4F_VERSION. 360 * The function provides a pointer to an allocated and initialized LZ4F_dctx object. 361 * The result is an errorCode, which can be tested using LZ4F_isError(). 362 * dctx memory can be released using LZ4F_freeDecompressionContext(); 363 * Result of LZ4F_freeDecompressionContext() indicates current state of decompressionContext when being released. 364 * That is, it should be == 0 if decompression has been completed fully and correctly. 365 */ 366 LZ4FLIB_API LZ4F_errorCode_t LZ4F_createDecompressionContext(LZ4F_dctx** dctxPtr, unsigned version); 367 LZ4FLIB_API LZ4F_errorCode_t LZ4F_freeDecompressionContext(LZ4F_dctx* dctx); 368 369 370 /*-*********************************** 371 * Streaming decompression functions 372 *************************************/ 373 374 #define LZ4F_MIN_SIZE_TO_KNOW_HEADER_LENGTH 5 375 376 /*! LZ4F_headerSize() : v1.9.0+ 377 * Provide the header size of a frame starting at `src`. 378 * `srcSize` must be >= LZ4F_MIN_SIZE_TO_KNOW_HEADER_LENGTH, 379 * which is enough to decode the header length. 380 * @return : size of frame header 381 * or an error code, which can be tested using LZ4F_isError() 382 * note : Frame header size is variable, but is guaranteed to be 383 * >= LZ4F_HEADER_SIZE_MIN bytes, and <= LZ4F_HEADER_SIZE_MAX bytes. 384 */ 385 LZ4FLIB_API size_t LZ4F_headerSize(const void* src, size_t srcSize); 386 387 /*! LZ4F_getFrameInfo() : 388 * This function extracts frame parameters (max blockSize, dictID, etc.). 389 * Its usage is optional: user can call LZ4F_decompress() directly. 390 * 391 * Extracted information will fill an existing LZ4F_frameInfo_t structure. 392 * This can be useful for allocation and dictionary identification purposes. 393 * 394 * LZ4F_getFrameInfo() can work in the following situations : 395 * 396 * 1) At the beginning of a new frame, before any invocation of LZ4F_decompress(). 397 * It will decode header from `srcBuffer`, 398 * consuming the header and starting the decoding process. 399 * 400 * Input size must be large enough to contain the full frame header. 401 * Frame header size can be known beforehand by LZ4F_headerSize(). 402 * Frame header size is variable, but is guaranteed to be >= LZ4F_HEADER_SIZE_MIN bytes, 403 * and not more than <= LZ4F_HEADER_SIZE_MAX bytes. 404 * Hence, blindly providing LZ4F_HEADER_SIZE_MAX bytes or more will always work. 405 * It's allowed to provide more input data than the header size, 406 * LZ4F_getFrameInfo() will only consume the header. 407 * 408 * If input size is not large enough, 409 * aka if it's smaller than header size, 410 * function will fail and return an error code. 411 * 412 * 2) After decoding has been started, 413 * it's possible to invoke LZ4F_getFrameInfo() anytime 414 * to extract already decoded frame parameters stored within dctx. 415 * 416 * Note that, if decoding has barely started, 417 * and not yet read enough information to decode the header, 418 * LZ4F_getFrameInfo() will fail. 419 * 420 * The number of bytes consumed from srcBuffer will be updated in *srcSizePtr (necessarily <= original value). 421 * LZ4F_getFrameInfo() only consumes bytes when decoding has not yet started, 422 * and when decoding the header has been successful. 423 * Decompression must then resume from (srcBuffer + *srcSizePtr). 424 * 425 * @return : a hint about how many srcSize bytes LZ4F_decompress() expects for next call, 426 * or an error code which can be tested using LZ4F_isError(). 427 * note 1 : in case of error, dctx is not modified. Decoding operation can resume from beginning safely. 428 * note 2 : frame parameters are *copied into* an already allocated LZ4F_frameInfo_t structure. 429 */ 430 LZ4FLIB_API size_t LZ4F_getFrameInfo(LZ4F_dctx* dctx, 431 LZ4F_frameInfo_t* frameInfoPtr, 432 const void* srcBuffer, size_t* srcSizePtr); 433 434 /*! LZ4F_decompress() : 435 * Call this function repetitively to regenerate data compressed in `srcBuffer`. 436 * 437 * The function requires a valid dctx state. 438 * It will read up to *srcSizePtr bytes from srcBuffer, 439 * and decompress data into dstBuffer, of capacity *dstSizePtr. 440 * 441 * The nb of bytes consumed from srcBuffer will be written into *srcSizePtr (necessarily <= original value). 442 * The nb of bytes decompressed into dstBuffer will be written into *dstSizePtr (necessarily <= original value). 443 * 444 * The function does not necessarily read all input bytes, so always check value in *srcSizePtr. 445 * Unconsumed source data must be presented again in subsequent invocations. 446 * 447 * `dstBuffer` can freely change between each consecutive function invocation. 448 * `dstBuffer` content will be overwritten. 449 * 450 * @return : an hint of how many `srcSize` bytes LZ4F_decompress() expects for next call. 451 * Schematically, it's the size of the current (or remaining) compressed block + header of next block. 452 * Respecting the hint provides some small speed benefit, because it skips intermediate buffers. 453 * This is just a hint though, it's always possible to provide any srcSize. 454 * 455 * When a frame is fully decoded, @return will be 0 (no more data expected). 456 * When provided with more bytes than necessary to decode a frame, 457 * LZ4F_decompress() will stop reading exactly at end of current frame, and @return 0. 458 * 459 * If decompression failed, @return is an error code, which can be tested using LZ4F_isError(). 460 * After a decompression error, the `dctx` context is not resumable. 461 * Use LZ4F_resetDecompressionContext() to return to clean state. 462 * 463 * After a frame is fully decoded, dctx can be used again to decompress another frame. 464 */ 465 LZ4FLIB_API size_t LZ4F_decompress(LZ4F_dctx* dctx, 466 void* dstBuffer, size_t* dstSizePtr, 467 const void* srcBuffer, size_t* srcSizePtr, 468 const LZ4F_decompressOptions_t* dOptPtr); 469 470 471 /*! LZ4F_resetDecompressionContext() : added in v1.8.0 472 * In case of an error, the context is left in "undefined" state. 473 * In which case, it's necessary to reset it, before re-using it. 474 * This method can also be used to abruptly stop any unfinished decompression, 475 * and start a new one using same context resources. */ 476 LZ4FLIB_API void LZ4F_resetDecompressionContext(LZ4F_dctx* dctx); /* always successful */ 477 478 479 480 #if defined (__cplusplus) 481 } 482 #endif 483 484 #endif /* LZ4F_H_09782039843 */ 485 486 #if defined(LZ4F_STATIC_LINKING_ONLY) && !defined(LZ4F_H_STATIC_09782039843) 487 #define LZ4F_H_STATIC_09782039843 488 489 #if defined (__cplusplus) 490 extern "C" { 491 #endif 492 493 /* These declarations are not stable and may change in the future. 494 * They are therefore only safe to depend on 495 * when the caller is statically linked against the library. 496 * To access their declarations, define LZ4F_STATIC_LINKING_ONLY. 497 * 498 * By default, these symbols aren't published into shared/dynamic libraries. 499 * You can override this behavior and force them to be published 500 * by defining LZ4F_PUBLISH_STATIC_FUNCTIONS. 501 * Use at your own risk. 502 */ 503 #ifdef LZ4F_PUBLISH_STATIC_FUNCTIONS 504 # define LZ4FLIB_STATIC_API LZ4FLIB_API 505 #else 506 # define LZ4FLIB_STATIC_API 507 #endif 508 509 510 /* --- Error List --- */ 511 #define LZ4F_LIST_ERRORS(ITEM) \ 512 ITEM(OK_NoError) \ 513 ITEM(ERROR_GENERIC) \ 514 ITEM(ERROR_maxBlockSize_invalid) \ 515 ITEM(ERROR_blockMode_invalid) \ 516 ITEM(ERROR_contentChecksumFlag_invalid) \ 517 ITEM(ERROR_compressionLevel_invalid) \ 518 ITEM(ERROR_headerVersion_wrong) \ 519 ITEM(ERROR_blockChecksum_invalid) \ 520 ITEM(ERROR_reservedFlag_set) \ 521 ITEM(ERROR_allocation_failed) \ 522 ITEM(ERROR_srcSize_tooLarge) \ 523 ITEM(ERROR_dstMaxSize_tooSmall) \ 524 ITEM(ERROR_frameHeader_incomplete) \ 525 ITEM(ERROR_frameType_unknown) \ 526 ITEM(ERROR_frameSize_wrong) \ 527 ITEM(ERROR_srcPtr_wrong) \ 528 ITEM(ERROR_decompressionFailed) \ 529 ITEM(ERROR_headerChecksum_invalid) \ 530 ITEM(ERROR_contentChecksum_invalid) \ 531 ITEM(ERROR_frameDecoding_alreadyStarted) \ 532 ITEM(ERROR_maxCode) 533 534 #define LZ4F_GENERATE_ENUM(ENUM) LZ4F_##ENUM, 535 536 /* enum list is exposed, to handle specific errors */ 537 typedef enum { LZ4F_LIST_ERRORS(LZ4F_GENERATE_ENUM) 538 _LZ4F_dummy_error_enum_for_c89_never_used } LZ4F_errorCodes; 539 540 LZ4FLIB_STATIC_API LZ4F_errorCodes LZ4F_getErrorCode(size_t functionResult); 541 542 LZ4FLIB_STATIC_API size_t LZ4F_getBlockSize(unsigned); 543 544 /********************************** 545 * Bulk processing dictionary API 546 *********************************/ 547 548 /* A Dictionary is useful for the compression of small messages (KB range). 549 * It dramatically improves compression efficiency. 550 * 551 * LZ4 can ingest any input as dictionary, though only the last 64 KB are useful. 552 * Best results are generally achieved by using Zstandard's Dictionary Builder 553 * to generate a high-quality dictionary from a set of samples. 554 * 555 * Loading a dictionary has a cost, since it involves construction of tables. 556 * The Bulk processing dictionary API makes it possible to share this cost 557 * over an arbitrary number of compression jobs, even concurrently, 558 * markedly improving compression latency for these cases. 559 * 560 * The same dictionary will have to be used on the decompression side 561 * for decoding to be successful. 562 * To help identify the correct dictionary at decoding stage, 563 * the frame header allows optional embedding of a dictID field. 564 */ 565 typedef struct LZ4F_CDict_s LZ4F_CDict; 566 567 /*! LZ4_createCDict() : 568 * When compressing multiple messages / blocks using the same dictionary, it's recommended to load it just once. 569 * LZ4_createCDict() will create a digested dictionary, ready to start future compression operations without startup delay. 570 * LZ4_CDict can be created once and shared by multiple threads concurrently, since its usage is read-only. 571 * `dictBuffer` can be released after LZ4_CDict creation, since its content is copied within CDict */ 572 LZ4FLIB_STATIC_API LZ4F_CDict* LZ4F_createCDict(const void* dictBuffer, size_t dictSize); 573 LZ4FLIB_STATIC_API void LZ4F_freeCDict(LZ4F_CDict* CDict); 574 575 576 /*! LZ4_compressFrame_usingCDict() : 577 * Compress an entire srcBuffer into a valid LZ4 frame using a digested Dictionary. 578 * cctx must point to a context created by LZ4F_createCompressionContext(). 579 * If cdict==NULL, compress without a dictionary. 580 * dstBuffer MUST be >= LZ4F_compressFrameBound(srcSize, preferencesPtr). 581 * If this condition is not respected, function will fail (@return an errorCode). 582 * The LZ4F_preferences_t structure is optional : you may provide NULL as argument, 583 * but it's not recommended, as it's the only way to provide dictID in the frame header. 584 * @return : number of bytes written into dstBuffer. 585 * or an error code if it fails (can be tested using LZ4F_isError()) */ 586 LZ4FLIB_STATIC_API size_t LZ4F_compressFrame_usingCDict( 587 LZ4F_cctx* cctx, 588 void* dst, size_t dstCapacity, 589 const void* src, size_t srcSize, 590 const LZ4F_CDict* cdict, 591 const LZ4F_preferences_t* preferencesPtr); 592 593 594 /*! LZ4F_compressBegin_usingCDict() : 595 * Inits streaming dictionary compression, and writes the frame header into dstBuffer. 596 * dstCapacity must be >= LZ4F_HEADER_SIZE_MAX bytes. 597 * `prefsPtr` is optional : you may provide NULL as argument, 598 * however, it's the only way to provide dictID in the frame header. 599 * @return : number of bytes written into dstBuffer for the header, 600 * or an error code (which can be tested using LZ4F_isError()) */ 601 LZ4FLIB_STATIC_API size_t LZ4F_compressBegin_usingCDict( 602 LZ4F_cctx* cctx, 603 void* dstBuffer, size_t dstCapacity, 604 const LZ4F_CDict* cdict, 605 const LZ4F_preferences_t* prefsPtr); 606 607 608 /*! LZ4F_decompress_usingDict() : 609 * Same as LZ4F_decompress(), using a predefined dictionary. 610 * Dictionary is used "in place", without any preprocessing. 611 * It must remain accessible throughout the entire frame decoding. */ 612 LZ4FLIB_STATIC_API size_t LZ4F_decompress_usingDict( 613 LZ4F_dctx* dctxPtr, 614 void* dstBuffer, size_t* dstSizePtr, 615 const void* srcBuffer, size_t* srcSizePtr, 616 const void* dict, size_t dictSize, 617 const LZ4F_decompressOptions_t* decompressOptionsPtr); 618 619 #if defined (__cplusplus) 620 } 621 #endif 622 623 #endif /* defined(LZ4F_STATIC_LINKING_ONLY) && !defined(LZ4F_H_STATIC_09782039843) */ 624
