1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> 4<title>1.9.4 Manual</title> 5</head> 6<body> 7<h1>1.9.4 Manual</h1> 8<hr> 9<a name="Contents"></a><h2>Contents</h2> 10<ol> 11<li><a href="#Chapter1">Introduction</a></li> 12<li><a href="#Chapter2">Compiler specifics</a></li> 13<li><a href="#Chapter3">Error management</a></li> 14<li><a href="#Chapter4">Frame compression types</a></li> 15<li><a href="#Chapter5">Simple compression function</a></li> 16<li><a href="#Chapter6">Advanced compression functions</a></li> 17<li><a href="#Chapter7">Resource Management</a></li> 18<li><a href="#Chapter8">Compression</a></li> 19<li><a href="#Chapter9">Decompression functions</a></li> 20<li><a href="#Chapter10">Streaming decompression functions</a></li> 21<li><a href="#Chapter11">Bulk processing dictionary API</a></li> 22</ol> 23<hr> 24<a name="Chapter1"></a><h2>Introduction</h2><pre> 25 lz4frame.h implements LZ4 frame specification: see doc/lz4_Frame_format.md . 26 LZ4 Frames are compatible with `lz4` CLI, 27 and designed to be interoperable with any system. 28<BR></pre> 29 30<a name="Chapter2"></a><h2>Compiler specifics</h2><pre></pre> 31 32<a name="Chapter3"></a><h2>Error management</h2><pre></pre> 33 34<pre><b>unsigned LZ4F_isError(LZ4F_errorCode_t code); </b>/**< tells when a function result is an error code */<b> 35</b></pre><BR> 36<pre><b>const char* LZ4F_getErrorName(LZ4F_errorCode_t code); </b>/**< return error code string; for debugging */<b> 37</b></pre><BR> 38<a name="Chapter4"></a><h2>Frame compression types</h2><pre> 39<BR></pre> 40 41<pre><b>typedef enum { 42 LZ4F_default=0, 43 LZ4F_max64KB=4, 44 LZ4F_max256KB=5, 45 LZ4F_max1MB=6, 46 LZ4F_max4MB=7 47 LZ4F_OBSOLETE_ENUM(max64KB) 48 LZ4F_OBSOLETE_ENUM(max256KB) 49 LZ4F_OBSOLETE_ENUM(max1MB) 50 LZ4F_OBSOLETE_ENUM(max4MB) 51} LZ4F_blockSizeID_t; 52</b></pre><BR> 53<pre><b>typedef enum { 54 LZ4F_blockLinked=0, 55 LZ4F_blockIndependent 56 LZ4F_OBSOLETE_ENUM(blockLinked) 57 LZ4F_OBSOLETE_ENUM(blockIndependent) 58} LZ4F_blockMode_t; 59</b></pre><BR> 60<pre><b>typedef enum { 61 LZ4F_noContentChecksum=0, 62 LZ4F_contentChecksumEnabled 63 LZ4F_OBSOLETE_ENUM(noContentChecksum) 64 LZ4F_OBSOLETE_ENUM(contentChecksumEnabled) 65} LZ4F_contentChecksum_t; 66</b></pre><BR> 67<pre><b>typedef enum { 68 LZ4F_noBlockChecksum=0, 69 LZ4F_blockChecksumEnabled 70} LZ4F_blockChecksum_t; 71</b></pre><BR> 72<pre><b>typedef enum { 73 LZ4F_frame=0, 74 LZ4F_skippableFrame 75 LZ4F_OBSOLETE_ENUM(skippableFrame) 76} LZ4F_frameType_t; 77</b></pre><BR> 78<pre><b>typedef struct { 79 LZ4F_blockSizeID_t blockSizeID; </b>/* max64KB, max256KB, max1MB, max4MB; 0 == default */<b> 80 LZ4F_blockMode_t blockMode; </b>/* LZ4F_blockLinked, LZ4F_blockIndependent; 0 == default */<b> 81 LZ4F_contentChecksum_t contentChecksumFlag; </b>/* 1: frame terminated with 32-bit checksum of decompressed data; 0: disabled (default) */<b> 82 LZ4F_frameType_t frameType; </b>/* read-only field : LZ4F_frame or LZ4F_skippableFrame */<b> 83 unsigned long long contentSize; </b>/* Size of uncompressed content ; 0 == unknown */<b> 84 unsigned dictID; </b>/* Dictionary ID, sent by compressor to help decoder select correct dictionary; 0 == no dictID provided */<b> 85 LZ4F_blockChecksum_t blockChecksumFlag; </b>/* 1: each block followed by a checksum of block's compressed data; 0: disabled (default) */<b> 86} LZ4F_frameInfo_t; 87</b><p> makes it possible to set or read frame parameters. 88 Structure must be first init to 0, using memset() or LZ4F_INIT_FRAMEINFO, 89 setting all parameters to default. 90 It's then possible to update selectively some parameters 91</p></pre><BR> 92 93<pre><b>typedef struct { 94 LZ4F_frameInfo_t frameInfo; 95 int compressionLevel; </b>/* 0: default (fast mode); values > LZ4HC_CLEVEL_MAX count as LZ4HC_CLEVEL_MAX; values < 0 trigger "fast acceleration" */<b> 96 unsigned autoFlush; </b>/* 1: always flush; reduces usage of internal buffers */<b> 97 unsigned favorDecSpeed; </b>/* 1: parser favors decompression speed vs compression ratio. Only works for high compression modes (>= LZ4HC_CLEVEL_OPT_MIN) */ /* v1.8.2+ */<b> 98 unsigned reserved[3]; </b>/* must be zero for forward compatibility */<b> 99} LZ4F_preferences_t; 100</b><p> makes it possible to supply advanced compression instructions to streaming interface. 101 Structure must be first init to 0, using memset() or LZ4F_INIT_PREFERENCES, 102 setting all parameters to default. 103 All reserved fields must be set to zero. 104</p></pre><BR> 105 106<a name="Chapter5"></a><h2>Simple compression function</h2><pre></pre> 107 108<pre><b>size_t LZ4F_compressFrameBound(size_t srcSize, const LZ4F_preferences_t* preferencesPtr); 109</b><p> Returns the maximum possible compressed size with LZ4F_compressFrame() given srcSize and preferences. 110 `preferencesPtr` is optional. It can be replaced by NULL, in which case, the function will assume default preferences. 111 Note : this result is only usable with LZ4F_compressFrame(). 112 It may also be relevant to LZ4F_compressUpdate() _only if_ no flush() operation is ever performed. 113 114</p></pre><BR> 115 116<pre><b>size_t LZ4F_compressFrame(void* dstBuffer, size_t dstCapacity, 117 const void* srcBuffer, size_t srcSize, 118 const LZ4F_preferences_t* preferencesPtr); 119</b><p> Compress an entire srcBuffer into a valid LZ4 frame. 120 dstCapacity MUST be >= LZ4F_compressFrameBound(srcSize, preferencesPtr). 121 The LZ4F_preferences_t structure is optional : you can provide NULL as argument. All preferences will be set to default. 122 @return : number of bytes written into dstBuffer. 123 or an error code if it fails (can be tested using LZ4F_isError()) 124 125</p></pre><BR> 126 127<a name="Chapter6"></a><h2>Advanced compression functions</h2><pre></pre> 128 129<pre><b>typedef struct { 130 unsigned stableSrc; </b>/* 1 == src content will remain present on future calls to LZ4F_compress(); skip copying src content within tmp buffer */<b> 131 unsigned reserved[3]; 132} LZ4F_compressOptions_t; 133</b></pre><BR> 134<a name="Chapter7"></a><h2>Resource Management</h2><pre></pre> 135 136<pre><b>LZ4F_errorCode_t LZ4F_createCompressionContext(LZ4F_cctx** cctxPtr, unsigned version); 137LZ4F_errorCode_t LZ4F_freeCompressionContext(LZ4F_cctx* cctx); 138</b><p> The first thing to do is to create a compressionContext object, 139 which will keep track of operation state during streaming compression. 140 This is achieved using LZ4F_createCompressionContext(), which takes as argument a version, 141 and a pointer to LZ4F_cctx*, to write the resulting pointer into. 142 @version provided MUST be LZ4F_VERSION. It is intended to track potential version mismatch, notably when using DLL. 143 The function provides a pointer to a fully allocated LZ4F_cctx object. 144 @cctxPtr MUST be != NULL. 145 If @return != zero, context creation failed. 146 A created compression context can be employed multiple times for consecutive streaming operations. 147 Once all streaming compression jobs are completed, 148 the state object can be released using LZ4F_freeCompressionContext(). 149 Note1 : LZ4F_freeCompressionContext() is always successful. Its return value can be ignored. 150 Note2 : LZ4F_freeCompressionContext() works fine with NULL input pointers (do nothing). 151</p></pre><BR> 152 153<a name="Chapter8"></a><h2>Compression</h2><pre></pre> 154 155<pre><b>size_t LZ4F_compressBegin(LZ4F_cctx* cctx, 156 void* dstBuffer, size_t dstCapacity, 157 const LZ4F_preferences_t* prefsPtr); 158</b><p> will write the frame header into dstBuffer. 159 dstCapacity must be >= LZ4F_HEADER_SIZE_MAX bytes. 160 `prefsPtr` is optional : you can provide NULL as argument, all preferences will then be set to default. 161 @return : number of bytes written into dstBuffer for the header 162 or an error code (which can be tested using LZ4F_isError()) 163 164</p></pre><BR> 165 166<pre><b>size_t LZ4F_compressBound(size_t srcSize, const LZ4F_preferences_t* prefsPtr); 167</b><p> Provides minimum dstCapacity required to guarantee success of 168 LZ4F_compressUpdate(), given a srcSize and preferences, for a worst case scenario. 169 When srcSize==0, LZ4F_compressBound() provides an upper bound for LZ4F_flush() and LZ4F_compressEnd() instead. 170 Note that the result is only valid for a single invocation of LZ4F_compressUpdate(). 171 When invoking LZ4F_compressUpdate() multiple times, 172 if the output buffer is gradually filled up instead of emptied and re-used from its start, 173 one must check if there is enough remaining capacity before each invocation, using LZ4F_compressBound(). 174 @return is always the same for a srcSize and prefsPtr. 175 prefsPtr is optional : when NULL is provided, preferences will be set to cover worst case scenario. 176 tech details : 177 @return if automatic flushing is not enabled, includes the possibility that internal buffer might already be filled by up to (blockSize-1) bytes. 178 It also includes frame footer (ending + checksum), since it might be generated by LZ4F_compressEnd(). 179 @return doesn't include frame header, as it was already generated by LZ4F_compressBegin(). 180 181</p></pre><BR> 182 183<pre><b>size_t LZ4F_compressUpdate(LZ4F_cctx* cctx, 184 void* dstBuffer, size_t dstCapacity, 185 const void* srcBuffer, size_t srcSize, 186 const LZ4F_compressOptions_t* cOptPtr); 187</b><p> LZ4F_compressUpdate() can be called repetitively to compress as much data as necessary. 188 Important rule: dstCapacity MUST be large enough to ensure operation success even in worst case situations. 189 This value is provided by LZ4F_compressBound(). 190 If this condition is not respected, LZ4F_compress() will fail (result is an errorCode). 191 After an error, the state is left in a UB state, and must be re-initialized or freed. 192 If previously an uncompressed block was written, buffered data is flushed 193 before appending compressed data is continued. 194 `cOptPtr` is optional : NULL can be provided, in which case all options are set to default. 195 @return : number of bytes written into `dstBuffer` (it can be zero, meaning input data was just buffered). 196 or an error code if it fails (which can be tested using LZ4F_isError()) 197 198</p></pre><BR> 199 200<pre><b>size_t LZ4F_flush(LZ4F_cctx* cctx, 201 void* dstBuffer, size_t dstCapacity, 202 const LZ4F_compressOptions_t* cOptPtr); 203</b><p> When data must be generated and sent immediately, without waiting for a block to be completely filled, 204 it's possible to call LZ4_flush(). It will immediately compress any data buffered within cctx. 205 `dstCapacity` must be large enough to ensure the operation will be successful. 206 `cOptPtr` is optional : it's possible to provide NULL, all options will be set to default. 207 @return : nb of bytes written into dstBuffer (can be zero, when there is no data stored within cctx) 208 or an error code if it fails (which can be tested using LZ4F_isError()) 209 Note : LZ4F_flush() is guaranteed to be successful when dstCapacity >= LZ4F_compressBound(0, prefsPtr). 210 211</p></pre><BR> 212 213<pre><b>size_t LZ4F_compressEnd(LZ4F_cctx* cctx, 214 void* dstBuffer, size_t dstCapacity, 215 const LZ4F_compressOptions_t* cOptPtr); 216</b><p> To properly finish an LZ4 frame, invoke LZ4F_compressEnd(). 217 It will flush whatever data remained within `cctx` (like LZ4_flush()) 218 and properly finalize the frame, with an endMark and a checksum. 219 `cOptPtr` is optional : NULL can be provided, in which case all options will be set to default. 220 @return : nb of bytes written into dstBuffer, necessarily >= 4 (endMark), 221 or an error code if it fails (which can be tested using LZ4F_isError()) 222 Note : LZ4F_compressEnd() is guaranteed to be successful when dstCapacity >= LZ4F_compressBound(0, prefsPtr). 223 A successful call to LZ4F_compressEnd() makes `cctx` available again for another compression task. 224 225</p></pre><BR> 226 227<a name="Chapter9"></a><h2>Decompression functions</h2><pre></pre> 228 229<pre><b>typedef struct { 230 unsigned stableDst; /* pledges that last 64KB decompressed data will remain available unmodified between invocations. 231 * This optimization skips storage operations in tmp buffers. */ 232 unsigned skipChecksums; /* disable checksum calculation and verification, even when one is present in frame, to save CPU time. 233 * Setting this option to 1 once disables all checksums for the rest of the frame. */ 234 unsigned reserved1; </b>/* must be set to zero for forward compatibility */<b> 235 unsigned reserved0; </b>/* idem */<b> 236} LZ4F_decompressOptions_t; 237</b></pre><BR> 238<pre><b>LZ4F_errorCode_t LZ4F_createDecompressionContext(LZ4F_dctx** dctxPtr, unsigned version); 239LZ4F_errorCode_t LZ4F_freeDecompressionContext(LZ4F_dctx* dctx); 240</b><p> Create an LZ4F_dctx object, to track all decompression operations. 241 @version provided MUST be LZ4F_VERSION. 242 @dctxPtr MUST be valid. 243 The function fills @dctxPtr with the value of a pointer to an allocated and initialized LZ4F_dctx object. 244 The @return is an errorCode, which can be tested using LZ4F_isError(). 245 dctx memory can be released using LZ4F_freeDecompressionContext(); 246 Result of LZ4F_freeDecompressionContext() indicates current state of decompressionContext when being released. 247 That is, it should be == 0 if decompression has been completed fully and correctly. 248 249</p></pre><BR> 250 251<a name="Chapter10"></a><h2>Streaming decompression functions</h2><pre></pre> 252 253<pre><b>size_t LZ4F_headerSize(const void* src, size_t srcSize); 254</b><p> Provide the header size of a frame starting at `src`. 255 `srcSize` must be >= LZ4F_MIN_SIZE_TO_KNOW_HEADER_LENGTH, 256 which is enough to decode the header length. 257 @return : size of frame header 258 or an error code, which can be tested using LZ4F_isError() 259 note : Frame header size is variable, but is guaranteed to be 260 >= LZ4F_HEADER_SIZE_MIN bytes, and <= LZ4F_HEADER_SIZE_MAX bytes. 261 262</p></pre><BR> 263 264<pre><b>size_t 265LZ4F_getFrameInfo(LZ4F_dctx* dctx, 266 LZ4F_frameInfo_t* frameInfoPtr, 267 const void* srcBuffer, size_t* srcSizePtr); 268</b><p> This function extracts frame parameters (max blockSize, dictID, etc.). 269 Its usage is optional: user can also invoke LZ4F_decompress() directly. 270 271 Extracted information will fill an existing LZ4F_frameInfo_t structure. 272 This can be useful for allocation and dictionary identification purposes. 273 274 LZ4F_getFrameInfo() can work in the following situations : 275 276 1) At the beginning of a new frame, before any invocation of LZ4F_decompress(). 277 It will decode header from `srcBuffer`, 278 consuming the header and starting the decoding process. 279 280 Input size must be large enough to contain the full frame header. 281 Frame header size can be known beforehand by LZ4F_headerSize(). 282 Frame header size is variable, but is guaranteed to be >= LZ4F_HEADER_SIZE_MIN bytes, 283 and not more than <= LZ4F_HEADER_SIZE_MAX bytes. 284 Hence, blindly providing LZ4F_HEADER_SIZE_MAX bytes or more will always work. 285 It's allowed to provide more input data than the header size, 286 LZ4F_getFrameInfo() will only consume the header. 287 288 If input size is not large enough, 289 aka if it's smaller than header size, 290 function will fail and return an error code. 291 292 2) After decoding has been started, 293 it's possible to invoke LZ4F_getFrameInfo() anytime 294 to extract already decoded frame parameters stored within dctx. 295 296 Note that, if decoding has barely started, 297 and not yet read enough information to decode the header, 298 LZ4F_getFrameInfo() will fail. 299 300 The number of bytes consumed from srcBuffer will be updated in *srcSizePtr (necessarily <= original value). 301 LZ4F_getFrameInfo() only consumes bytes when decoding has not yet started, 302 and when decoding the header has been successful. 303 Decompression must then resume from (srcBuffer + *srcSizePtr). 304 305 @return : a hint about how many srcSize bytes LZ4F_decompress() expects for next call, 306 or an error code which can be tested using LZ4F_isError(). 307 note 1 : in case of error, dctx is not modified. Decoding operation can resume from beginning safely. 308 note 2 : frame parameters are *copied into* an already allocated LZ4F_frameInfo_t structure. 309 310</p></pre><BR> 311 312<pre><b>size_t 313LZ4F_decompress(LZ4F_dctx* dctx, 314 void* dstBuffer, size_t* dstSizePtr, 315 const void* srcBuffer, size_t* srcSizePtr, 316 const LZ4F_decompressOptions_t* dOptPtr); 317</b><p> Call this function repetitively to regenerate data compressed in `srcBuffer`. 318 319 The function requires a valid dctx state. 320 It will read up to *srcSizePtr bytes from srcBuffer, 321 and decompress data into dstBuffer, of capacity *dstSizePtr. 322 323 The nb of bytes consumed from srcBuffer will be written into *srcSizePtr (necessarily <= original value). 324 The nb of bytes decompressed into dstBuffer will be written into *dstSizePtr (necessarily <= original value). 325 326 The function does not necessarily read all input bytes, so always check value in *srcSizePtr. 327 Unconsumed source data must be presented again in subsequent invocations. 328 329 `dstBuffer` can freely change between each consecutive function invocation. 330 `dstBuffer` content will be overwritten. 331 332 @return : an hint of how many `srcSize` bytes LZ4F_decompress() expects for next call. 333 Schematically, it's the size of the current (or remaining) compressed block + header of next block. 334 Respecting the hint provides some small speed benefit, because it skips intermediate buffers. 335 This is just a hint though, it's always possible to provide any srcSize. 336 337 When a frame is fully decoded, @return will be 0 (no more data expected). 338 When provided with more bytes than necessary to decode a frame, 339 LZ4F_decompress() will stop reading exactly at end of current frame, and @return 0. 340 341 If decompression failed, @return is an error code, which can be tested using LZ4F_isError(). 342 After a decompression error, the `dctx` context is not resumable. 343 Use LZ4F_resetDecompressionContext() to return to clean state. 344 345 After a frame is fully decoded, dctx can be used again to decompress another frame. 346 347</p></pre><BR> 348 349<pre><b>void LZ4F_resetDecompressionContext(LZ4F_dctx* dctx); </b>/* always successful */<b> 350</b><p> In case of an error, the context is left in "undefined" state. 351 In which case, it's necessary to reset it, before re-using it. 352 This method can also be used to abruptly stop any unfinished decompression, 353 and start a new one using same context resources. 354</p></pre><BR> 355 356<pre><b>typedef enum { LZ4F_LIST_ERRORS(LZ4F_GENERATE_ENUM) 357 _LZ4F_dummy_error_enum_for_c89_never_used } LZ4F_errorCodes; 358</b></pre><BR> 359<pre><b>LZ4FLIB_STATIC_API size_t LZ4F_getBlockSize(LZ4F_blockSizeID_t blockSizeID); 360</b><p> Return, in scalar format (size_t), 361 the maximum block size associated with blockSizeID. 362</p></pre><BR> 363 364<pre><b>LZ4FLIB_STATIC_API size_t 365LZ4F_uncompressedUpdate(LZ4F_cctx* cctx, 366 void* dstBuffer, size_t dstCapacity, 367 const void* srcBuffer, size_t srcSize, 368 const LZ4F_compressOptions_t* cOptPtr); 369</b><p> LZ4F_uncompressedUpdate() can be called repetitively to add as much data uncompressed data as necessary. 370 Important rule: dstCapacity MUST be large enough to store the entire source buffer as 371 no compression is done for this operation 372 If this condition is not respected, LZ4F_uncompressedUpdate() will fail (result is an errorCode). 373 After an error, the state is left in a UB state, and must be re-initialized or freed. 374 If previously a compressed block was written, buffered data is flushed 375 before appending uncompressed data is continued. 376 This is only supported when LZ4F_blockIndependent is used 377 `cOptPtr` is optional : NULL can be provided, in which case all options are set to default. 378 @return : number of bytes written into `dstBuffer` (it can be zero, meaning input data was just buffered). 379 or an error code if it fails (which can be tested using LZ4F_isError()) 380 381</p></pre><BR> 382 383<a name="Chapter11"></a><h2>Bulk processing dictionary API</h2><pre></pre> 384 385<pre><b>LZ4FLIB_STATIC_API LZ4F_CDict* LZ4F_createCDict(const void* dictBuffer, size_t dictSize); 386LZ4FLIB_STATIC_API void LZ4F_freeCDict(LZ4F_CDict* CDict); 387</b><p> When compressing multiple messages / blocks using the same dictionary, it's recommended to load it just once. 388 LZ4_createCDict() will create a digested dictionary, ready to start future compression operations without startup delay. 389 LZ4_CDict can be created once and shared by multiple threads concurrently, since its usage is read-only. 390 `dictBuffer` can be released after LZ4_CDict creation, since its content is copied within CDict 391</p></pre><BR> 392 393<pre><b>LZ4FLIB_STATIC_API size_t 394LZ4F_compressFrame_usingCDict(LZ4F_cctx* cctx, 395 void* dst, size_t dstCapacity, 396 const void* src, size_t srcSize, 397 const LZ4F_CDict* cdict, 398 const LZ4F_preferences_t* preferencesPtr); 399</b><p> Compress an entire srcBuffer into a valid LZ4 frame using a digested Dictionary. 400 cctx must point to a context created by LZ4F_createCompressionContext(). 401 If cdict==NULL, compress without a dictionary. 402 dstBuffer MUST be >= LZ4F_compressFrameBound(srcSize, preferencesPtr). 403 If this condition is not respected, function will fail (@return an errorCode). 404 The LZ4F_preferences_t structure is optional : you may provide NULL as argument, 405 but it's not recommended, as it's the only way to provide dictID in the frame header. 406 @return : number of bytes written into dstBuffer. 407 or an error code if it fails (can be tested using LZ4F_isError()) 408</p></pre><BR> 409 410<pre><b>LZ4FLIB_STATIC_API size_t 411LZ4F_compressBegin_usingCDict(LZ4F_cctx* cctx, 412 void* dstBuffer, size_t dstCapacity, 413 const LZ4F_CDict* cdict, 414 const LZ4F_preferences_t* prefsPtr); 415</b><p> Inits streaming dictionary compression, and writes the frame header into dstBuffer. 416 dstCapacity must be >= LZ4F_HEADER_SIZE_MAX bytes. 417 `prefsPtr` is optional : you may provide NULL as argument, 418 however, it's the only way to provide dictID in the frame header. 419 @return : number of bytes written into dstBuffer for the header, 420 or an error code (which can be tested using LZ4F_isError()) 421</p></pre><BR> 422 423<pre><b>LZ4FLIB_STATIC_API size_t 424LZ4F_decompress_usingDict(LZ4F_dctx* dctxPtr, 425 void* dstBuffer, size_t* dstSizePtr, 426 const void* srcBuffer, size_t* srcSizePtr, 427 const void* dict, size_t dictSize, 428 const LZ4F_decompressOptions_t* decompressOptionsPtr); 429</b><p> Same as LZ4F_decompress(), using a predefined dictionary. 430 Dictionary is used "in place", without any preprocessing. 431 It must remain accessible throughout the entire frame decoding. 432</p></pre><BR> 433 434<pre><b>typedef void* (*LZ4F_AllocFunction) (void* opaqueState, size_t size); 435typedef void* (*LZ4F_CallocFunction) (void* opaqueState, size_t size); 436typedef void (*LZ4F_FreeFunction) (void* opaqueState, void* address); 437typedef struct { 438 LZ4F_AllocFunction customAlloc; 439 LZ4F_CallocFunction customCalloc; </b>/* optional; when not defined, uses customAlloc + memset */<b> 440 LZ4F_FreeFunction customFree; 441 void* opaqueState; 442} LZ4F_CustomMem; 443static 444#ifdef __GNUC__ 445__attribute__((__unused__)) 446#endif 447LZ4F_CustomMem const LZ4F_defaultCMem = { NULL, NULL, NULL, NULL }; </b>/**< this constant defers to stdlib's functions */<b> 448</b><p> These prototypes make it possible to pass custom allocation/free functions. 449 LZ4F_customMem is provided at state creation time, using LZ4F_create*_advanced() listed below. 450 All allocation/free operations will be completed using these custom variants instead of regular <stdlib.h> ones. 451 452</p></pre><BR> 453 454</html> 455</body> 456