1 /* ****************************************************************** 2 * FSE : Finite State Entropy codec 3 * Public Prototypes declaration 4 * Copyright (c) 2013-2020, Yann Collet, Facebook, Inc. 5 * 6 * You can contact the author at : 7 * - Source repository : https://github.com/Cyan4973/FiniteStateEntropy 8 * 9 * This source code is licensed under both the BSD-style license (found in the 10 * LICENSE file in the root directory of this source tree) and the GPLv2 (found 11 * in the COPYING file in the root directory of this source tree). 12 * You may select, at your option, one of the above-listed licenses. 13 ****************************************************************** */ 14 15 #if defined (__cplusplus) 16 extern "C" { 17 #endif 18 19 #ifndef FSE_H 20 #define FSE_H 21 22 23 /*-***************************************** 24 * Dependencies 25 ******************************************/ 26 #include <stddef.h> /* size_t, ptrdiff_t */ 27 28 29 /*-***************************************** 30 * FSE_PUBLIC_API : control library symbols visibility 31 ******************************************/ 32 #if defined(FSE_DLL_EXPORT) && (FSE_DLL_EXPORT==1) && defined(__GNUC__) && (__GNUC__ >= 4) 33 # define FSE_PUBLIC_API __attribute__ ((visibility ("default"))) 34 #elif defined(FSE_DLL_EXPORT) && (FSE_DLL_EXPORT==1) /* Visual expected */ 35 # define FSE_PUBLIC_API __declspec(dllexport) 36 #elif defined(FSE_DLL_IMPORT) && (FSE_DLL_IMPORT==1) 37 # define FSE_PUBLIC_API __declspec(dllimport) /* It isn't required but allows to generate better code, saving a function pointer load from the IAT and an indirect jump.*/ 38 #else 39 # define FSE_PUBLIC_API 40 #endif 41 42 /*------ Version ------*/ 43 #define FSE_VERSION_MAJOR 0 44 #define FSE_VERSION_MINOR 9 45 #define FSE_VERSION_RELEASE 0 46 47 #define FSE_LIB_VERSION FSE_VERSION_MAJOR.FSE_VERSION_MINOR.FSE_VERSION_RELEASE 48 #define FSE_QUOTE(str) #str 49 #define FSE_EXPAND_AND_QUOTE(str) FSE_QUOTE(str) 50 #define FSE_VERSION_STRING FSE_EXPAND_AND_QUOTE(FSE_LIB_VERSION) 51 52 #define FSE_VERSION_NUMBER (FSE_VERSION_MAJOR *100*100 + FSE_VERSION_MINOR *100 + FSE_VERSION_RELEASE) 53 FSE_PUBLIC_API unsigned FSE_versionNumber(void); /**< library version number; to be used when checking dll version */ 54 55 56 /*-**************************************** 57 * FSE simple functions 58 ******************************************/ 59 /*! FSE_compress() : 60 Compress content of buffer 'src', of size 'srcSize', into destination buffer 'dst'. 61 'dst' buffer must be already allocated. Compression runs faster is dstCapacity >= FSE_compressBound(srcSize). 62 @return : size of compressed data (<= dstCapacity). 63 Special values : if return == 0, srcData is not compressible => Nothing is stored within dst !!! 64 if return == 1, srcData is a single byte symbol * srcSize times. Use RLE compression instead. 65 if FSE_isError(return), compression failed (more details using FSE_getErrorName()) 66 */ 67 FSE_PUBLIC_API size_t FSE_compress(void* dst, size_t dstCapacity, 68 const void* src, size_t srcSize); 69 70 /*! FSE_decompress(): 71 Decompress FSE data from buffer 'cSrc', of size 'cSrcSize', 72 into already allocated destination buffer 'dst', of size 'dstCapacity'. 73 @return : size of regenerated data (<= maxDstSize), 74 or an error code, which can be tested using FSE_isError() . 75 76 ** Important ** : FSE_decompress() does not decompress non-compressible nor RLE data !!! 77 Why ? : making this distinction requires a header. 78 Header management is intentionally delegated to the user layer, which can better manage special cases. 79 */ 80 FSE_PUBLIC_API size_t FSE_decompress(void* dst, size_t dstCapacity, 81 const void* cSrc, size_t cSrcSize); 82 83 84 /*-***************************************** 85 * Tool functions 86 ******************************************/ 87 FSE_PUBLIC_API size_t FSE_compressBound(size_t size); /* maximum compressed size */ 88 89 /* Error Management */ 90 FSE_PUBLIC_API unsigned FSE_isError(size_t code); /* tells if a return value is an error code */ 91 FSE_PUBLIC_API const char* FSE_getErrorName(size_t code); /* provides error code string (useful for debugging) */ 92 93 94 /*-***************************************** 95 * FSE advanced functions 96 ******************************************/ 97 /*! FSE_compress2() : 98 Same as FSE_compress(), but allows the selection of 'maxSymbolValue' and 'tableLog' 99 Both parameters can be defined as '0' to mean : use default value 100 @return : size of compressed data 101 Special values : if return == 0, srcData is not compressible => Nothing is stored within cSrc !!! 102 if return == 1, srcData is a single byte symbol * srcSize times. Use RLE compression. 103 if FSE_isError(return), it's an error code. 104 */ 105 FSE_PUBLIC_API size_t FSE_compress2 (void* dst, size_t dstSize, const void* src, size_t srcSize, unsigned maxSymbolValue, unsigned tableLog); 106 107 108 /*-***************************************** 109 * FSE detailed API 110 ******************************************/ 111 /*! 112 FSE_compress() does the following: 113 1. count symbol occurrence from source[] into table count[] (see hist.h) 114 2. normalize counters so that sum(count[]) == Power_of_2 (2^tableLog) 115 3. save normalized counters to memory buffer using writeNCount() 116 4. build encoding table 'CTable' from normalized counters 117 5. encode the data stream using encoding table 'CTable' 118 119 FSE_decompress() does the following: 120 1. read normalized counters with readNCount() 121 2. build decoding table 'DTable' from normalized counters 122 3. decode the data stream using decoding table 'DTable' 123 124 The following API allows targeting specific sub-functions for advanced tasks. 125 For example, it's possible to compress several blocks using the same 'CTable', 126 or to save and provide normalized distribution using external method. 127 */ 128 129 /* *** COMPRESSION *** */ 130 131 /*! FSE_optimalTableLog(): 132 dynamically downsize 'tableLog' when conditions are met. 133 It saves CPU time, by using smaller tables, while preserving or even improving compression ratio. 134 @return : recommended tableLog (necessarily <= 'maxTableLog') */ 135 FSE_PUBLIC_API unsigned FSE_optimalTableLog(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue); 136 137 /*! FSE_normalizeCount(): 138 normalize counts so that sum(count[]) == Power_of_2 (2^tableLog) 139 'normalizedCounter' is a table of short, of minimum size (maxSymbolValue+1). 140 @return : tableLog, 141 or an errorCode, which can be tested using FSE_isError() */ 142 FSE_PUBLIC_API size_t FSE_normalizeCount(short* normalizedCounter, unsigned tableLog, 143 const unsigned* count, size_t srcSize, unsigned maxSymbolValue); 144 145 /*! FSE_NCountWriteBound(): 146 Provides the maximum possible size of an FSE normalized table, given 'maxSymbolValue' and 'tableLog'. 147 Typically useful for allocation purpose. */ 148 FSE_PUBLIC_API size_t FSE_NCountWriteBound(unsigned maxSymbolValue, unsigned tableLog); 149 150 /*! FSE_writeNCount(): 151 Compactly save 'normalizedCounter' into 'buffer'. 152 @return : size of the compressed table, 153 or an errorCode, which can be tested using FSE_isError(). */ 154 FSE_PUBLIC_API size_t FSE_writeNCount (void* buffer, size_t bufferSize, 155 const short* normalizedCounter, 156 unsigned maxSymbolValue, unsigned tableLog); 157 158 /*! Constructor and Destructor of FSE_CTable. 159 Note that FSE_CTable size depends on 'tableLog' and 'maxSymbolValue' */ 160 typedef unsigned FSE_CTable; /* don't allocate that. It's only meant to be more restrictive than void* */ 161 FSE_PUBLIC_API FSE_CTable* FSE_createCTable (unsigned maxSymbolValue, unsigned tableLog); 162 FSE_PUBLIC_API void FSE_freeCTable (FSE_CTable* ct); 163 164 /*! FSE_buildCTable(): 165 Builds `ct`, which must be already allocated, using FSE_createCTable(). 166 @return : 0, or an errorCode, which can be tested using FSE_isError() */ 167 FSE_PUBLIC_API size_t FSE_buildCTable(FSE_CTable* ct, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog); 168 169 /*! FSE_compress_usingCTable(): 170 Compress `src` using `ct` into `dst` which must be already allocated. 171 @return : size of compressed data (<= `dstCapacity`), 172 or 0 if compressed data could not fit into `dst`, 173 or an errorCode, which can be tested using FSE_isError() */ 174 FSE_PUBLIC_API size_t FSE_compress_usingCTable (void* dst, size_t dstCapacity, const void* src, size_t srcSize, const FSE_CTable* ct); 175 176 /*! 177 Tutorial : 178 ---------- 179 The first step is to count all symbols. FSE_count() does this job very fast. 180 Result will be saved into 'count', a table of unsigned int, which must be already allocated, and have 'maxSymbolValuePtr[0]+1' cells. 181 'src' is a table of bytes of size 'srcSize'. All values within 'src' MUST be <= maxSymbolValuePtr[0] 182 maxSymbolValuePtr[0] will be updated, with its real value (necessarily <= original value) 183 FSE_count() will return the number of occurrence of the most frequent symbol. 184 This can be used to know if there is a single symbol within 'src', and to quickly evaluate its compressibility. 185 If there is an error, the function will return an ErrorCode (which can be tested using FSE_isError()). 186 187 The next step is to normalize the frequencies. 188 FSE_normalizeCount() will ensure that sum of frequencies is == 2 ^'tableLog'. 189 It also guarantees a minimum of 1 to any Symbol with frequency >= 1. 190 You can use 'tableLog'==0 to mean "use default tableLog value". 191 If you are unsure of which tableLog value to use, you can ask FSE_optimalTableLog(), 192 which will provide the optimal valid tableLog given sourceSize, maxSymbolValue, and a user-defined maximum (0 means "default"). 193 194 The result of FSE_normalizeCount() will be saved into a table, 195 called 'normalizedCounter', which is a table of signed short. 196 'normalizedCounter' must be already allocated, and have at least 'maxSymbolValue+1' cells. 197 The return value is tableLog if everything proceeded as expected. 198 It is 0 if there is a single symbol within distribution. 199 If there is an error (ex: invalid tableLog value), the function will return an ErrorCode (which can be tested using FSE_isError()). 200 201 'normalizedCounter' can be saved in a compact manner to a memory area using FSE_writeNCount(). 202 'buffer' must be already allocated. 203 For guaranteed success, buffer size must be at least FSE_headerBound(). 204 The result of the function is the number of bytes written into 'buffer'. 205 If there is an error, the function will return an ErrorCode (which can be tested using FSE_isError(); ex : buffer size too small). 206 207 'normalizedCounter' can then be used to create the compression table 'CTable'. 208 The space required by 'CTable' must be already allocated, using FSE_createCTable(). 209 You can then use FSE_buildCTable() to fill 'CTable'. 210 If there is an error, both functions will return an ErrorCode (which can be tested using FSE_isError()). 211 212 'CTable' can then be used to compress 'src', with FSE_compress_usingCTable(). 213 Similar to FSE_count(), the convention is that 'src' is assumed to be a table of char of size 'srcSize' 214 The function returns the size of compressed data (without header), necessarily <= `dstCapacity`. 215 If it returns '0', compressed data could not fit into 'dst'. 216 If there is an error, the function will return an ErrorCode (which can be tested using FSE_isError()). 217 */ 218 219 220 /* *** DECOMPRESSION *** */ 221 222 /*! FSE_readNCount(): 223 Read compactly saved 'normalizedCounter' from 'rBuffer'. 224 @return : size read from 'rBuffer', 225 or an errorCode, which can be tested using FSE_isError(). 226 maxSymbolValuePtr[0] and tableLogPtr[0] will also be updated with their respective values */ 227 FSE_PUBLIC_API size_t FSE_readNCount (short* normalizedCounter, 228 unsigned* maxSymbolValuePtr, unsigned* tableLogPtr, 229 const void* rBuffer, size_t rBuffSize); 230 231 /*! Constructor and Destructor of FSE_DTable. 232 Note that its size depends on 'tableLog' */ 233 typedef unsigned FSE_DTable; /* don't allocate that. It's just a way to be more restrictive than void* */ 234 FSE_PUBLIC_API FSE_DTable* FSE_createDTable(unsigned tableLog); 235 FSE_PUBLIC_API void FSE_freeDTable(FSE_DTable* dt); 236 237 /*! FSE_buildDTable(): 238 Builds 'dt', which must be already allocated, using FSE_createDTable(). 239 return : 0, or an errorCode, which can be tested using FSE_isError() */ 240 FSE_PUBLIC_API size_t FSE_buildDTable (FSE_DTable* dt, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog); 241 242 /*! FSE_decompress_usingDTable(): 243 Decompress compressed source `cSrc` of size `cSrcSize` using `dt` 244 into `dst` which must be already allocated. 245 @return : size of regenerated data (necessarily <= `dstCapacity`), 246 or an errorCode, which can be tested using FSE_isError() */ 247 FSE_PUBLIC_API size_t FSE_decompress_usingDTable(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize, const FSE_DTable* dt); 248 249 /*! 250 Tutorial : 251 ---------- 252 (Note : these functions only decompress FSE-compressed blocks. 253 If block is uncompressed, use memcpy() instead 254 If block is a single repeated byte, use memset() instead ) 255 256 The first step is to obtain the normalized frequencies of symbols. 257 This can be performed by FSE_readNCount() if it was saved using FSE_writeNCount(). 258 'normalizedCounter' must be already allocated, and have at least 'maxSymbolValuePtr[0]+1' cells of signed short. 259 In practice, that means it's necessary to know 'maxSymbolValue' beforehand, 260 or size the table to handle worst case situations (typically 256). 261 FSE_readNCount() will provide 'tableLog' and 'maxSymbolValue'. 262 The result of FSE_readNCount() is the number of bytes read from 'rBuffer'. 263 Note that 'rBufferSize' must be at least 4 bytes, even if useful information is less than that. 264 If there is an error, the function will return an error code, which can be tested using FSE_isError(). 265 266 The next step is to build the decompression tables 'FSE_DTable' from 'normalizedCounter'. 267 This is performed by the function FSE_buildDTable(). 268 The space required by 'FSE_DTable' must be already allocated using FSE_createDTable(). 269 If there is an error, the function will return an error code, which can be tested using FSE_isError(). 270 271 `FSE_DTable` can then be used to decompress `cSrc`, with FSE_decompress_usingDTable(). 272 `cSrcSize` must be strictly correct, otherwise decompression will fail. 273 FSE_decompress_usingDTable() result will tell how many bytes were regenerated (<=`dstCapacity`). 274 If there is an error, the function will return an error code, which can be tested using FSE_isError(). (ex: dst buffer too small) 275 */ 276 277 #endif /* FSE_H */ 278 279 #if defined(FSE_STATIC_LINKING_ONLY) && !defined(FSE_H_FSE_STATIC_LINKING_ONLY) 280 #define FSE_H_FSE_STATIC_LINKING_ONLY 281 282 /* *** Dependency *** */ 283 #include "bitstream.h" 284 285 286 /* ***************************************** 287 * Static allocation 288 *******************************************/ 289 /* FSE buffer bounds */ 290 #define FSE_NCOUNTBOUND 512 291 #define FSE_BLOCKBOUND(size) (size + (size>>7) + 4 /* fse states */ + sizeof(size_t) /* bitContainer */) 292 #define FSE_COMPRESSBOUND(size) (FSE_NCOUNTBOUND + FSE_BLOCKBOUND(size)) /* Macro version, useful for static allocation */ 293 294 /* It is possible to statically allocate FSE CTable/DTable as a table of FSE_CTable/FSE_DTable using below macros */ 295 #define FSE_CTABLE_SIZE_U32(maxTableLog, maxSymbolValue) (1 + (1<<(maxTableLog-1)) + ((maxSymbolValue+1)*2)) 296 #define FSE_DTABLE_SIZE_U32(maxTableLog) (1 + (1<<maxTableLog)) 297 298 /* or use the size to malloc() space directly. Pay attention to alignment restrictions though */ 299 #define FSE_CTABLE_SIZE(maxTableLog, maxSymbolValue) (FSE_CTABLE_SIZE_U32(maxTableLog, maxSymbolValue) * sizeof(FSE_CTable)) 300 #define FSE_DTABLE_SIZE(maxTableLog) (FSE_DTABLE_SIZE_U32(maxTableLog) * sizeof(FSE_DTable)) 301 302 303 /* ***************************************** 304 * FSE advanced API 305 ***************************************** */ 306 307 unsigned FSE_optimalTableLog_internal(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue, unsigned minus); 308 /**< same as FSE_optimalTableLog(), which used `minus==2` */ 309 310 /* FSE_compress_wksp() : 311 * Same as FSE_compress2(), but using an externally allocated scratch buffer (`workSpace`). 312 * FSE_WKSP_SIZE_U32() provides the minimum size required for `workSpace` as a table of FSE_CTable. 313 */ 314 #define FSE_WKSP_SIZE_U32(maxTableLog, maxSymbolValue) ( FSE_CTABLE_SIZE_U32(maxTableLog, maxSymbolValue) + ((maxTableLog > 12) ? (1 << (maxTableLog - 2)) : 1024) ) 315 size_t FSE_compress_wksp (void* dst, size_t dstSize, const void* src, size_t srcSize, unsigned maxSymbolValue, unsigned tableLog, void* workSpace, size_t wkspSize); 316 317 size_t FSE_buildCTable_raw (FSE_CTable* ct, unsigned nbBits); 318 /**< build a fake FSE_CTable, designed for a flat distribution, where each symbol uses nbBits */ 319 320 size_t FSE_buildCTable_rle (FSE_CTable* ct, unsigned char symbolValue); 321 /**< build a fake FSE_CTable, designed to compress always the same symbolValue */ 322 323 /* FSE_buildCTable_wksp() : 324 * Same as FSE_buildCTable(), but using an externally allocated scratch buffer (`workSpace`). 325 * `wkspSize` must be >= `(1<<tableLog)`. 326 */ 327 size_t FSE_buildCTable_wksp(FSE_CTable* ct, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void* workSpace, size_t wkspSize); 328 329 size_t FSE_buildDTable_raw (FSE_DTable* dt, unsigned nbBits); 330 /**< build a fake FSE_DTable, designed to read a flat distribution where each symbol uses nbBits */ 331 332 size_t FSE_buildDTable_rle (FSE_DTable* dt, unsigned char symbolValue); 333 /**< build a fake FSE_DTable, designed to always generate the same symbolValue */ 334 335 size_t FSE_decompress_wksp(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize, FSE_DTable* workSpace, unsigned maxLog); 336 /**< same as FSE_decompress(), using an externally allocated `workSpace` produced with `FSE_DTABLE_SIZE_U32(maxLog)` */ 337 338 typedef enum { 339 FSE_repeat_none, /**< Cannot use the previous table */ 340 FSE_repeat_check, /**< Can use the previous table but it must be checked */ 341 FSE_repeat_valid /**< Can use the previous table and it is assumed to be valid */ 342 } FSE_repeat; 343 344 /* ***************************************** 345 * FSE symbol compression API 346 *******************************************/ 347 /*! 348 This API consists of small unitary functions, which highly benefit from being inlined. 349 Hence their body are included in next section. 350 */ 351 typedef struct { 352 ptrdiff_t value; 353 const void* stateTable; 354 const void* symbolTT; 355 unsigned stateLog; 356 } FSE_CState_t; 357 358 static void FSE_initCState(FSE_CState_t* CStatePtr, const FSE_CTable* ct); 359 360 static void FSE_encodeSymbol(BIT_CStream_t* bitC, FSE_CState_t* CStatePtr, unsigned symbol); 361 362 static void FSE_flushCState(BIT_CStream_t* bitC, const FSE_CState_t* CStatePtr); 363 364 /**< 365 These functions are inner components of FSE_compress_usingCTable(). 366 They allow the creation of custom streams, mixing multiple tables and bit sources. 367 368 A key property to keep in mind is that encoding and decoding are done **in reverse direction**. 369 So the first symbol you will encode is the last you will decode, like a LIFO stack. 370 371 You will need a few variables to track your CStream. They are : 372 373 FSE_CTable ct; // Provided by FSE_buildCTable() 374 BIT_CStream_t bitStream; // bitStream tracking structure 375 FSE_CState_t state; // State tracking structure (can have several) 376 377 378 The first thing to do is to init bitStream and state. 379 size_t errorCode = BIT_initCStream(&bitStream, dstBuffer, maxDstSize); 380 FSE_initCState(&state, ct); 381 382 Note that BIT_initCStream() can produce an error code, so its result should be tested, using FSE_isError(); 383 You can then encode your input data, byte after byte. 384 FSE_encodeSymbol() outputs a maximum of 'tableLog' bits at a time. 385 Remember decoding will be done in reverse direction. 386 FSE_encodeByte(&bitStream, &state, symbol); 387 388 At any time, you can also add any bit sequence. 389 Note : maximum allowed nbBits is 25, for compatibility with 32-bits decoders 390 BIT_addBits(&bitStream, bitField, nbBits); 391 392 The above methods don't commit data to memory, they just store it into local register, for speed. 393 Local register size is 64-bits on 64-bits systems, 32-bits on 32-bits systems (size_t). 394 Writing data to memory is a manual operation, performed by the flushBits function. 395 BIT_flushBits(&bitStream); 396 397 Your last FSE encoding operation shall be to flush your last state value(s). 398 FSE_flushState(&bitStream, &state); 399 400 Finally, you must close the bitStream. 401 The function returns the size of CStream in bytes. 402 If data couldn't fit into dstBuffer, it will return a 0 ( == not compressible) 403 If there is an error, it returns an errorCode (which can be tested using FSE_isError()). 404 size_t size = BIT_closeCStream(&bitStream); 405 */ 406 407 408 /* ***************************************** 409 * FSE symbol decompression API 410 *******************************************/ 411 typedef struct { 412 size_t state; 413 const void* table; /* precise table may vary, depending on U16 */ 414 } FSE_DState_t; 415 416 417 static void FSE_initDState(FSE_DState_t* DStatePtr, BIT_DStream_t* bitD, const FSE_DTable* dt); 418 419 static unsigned char FSE_decodeSymbol(FSE_DState_t* DStatePtr, BIT_DStream_t* bitD); 420 421 static unsigned FSE_endOfDState(const FSE_DState_t* DStatePtr); 422 423 /**< 424 Let's now decompose FSE_decompress_usingDTable() into its unitary components. 425 You will decode FSE-encoded symbols from the bitStream, 426 and also any other bitFields you put in, **in reverse order**. 427 428 You will need a few variables to track your bitStream. They are : 429 430 BIT_DStream_t DStream; // Stream context 431 FSE_DState_t DState; // State context. Multiple ones are possible 432 FSE_DTable* DTablePtr; // Decoding table, provided by FSE_buildDTable() 433 434 The first thing to do is to init the bitStream. 435 errorCode = BIT_initDStream(&DStream, srcBuffer, srcSize); 436 437 You should then retrieve your initial state(s) 438 (in reverse flushing order if you have several ones) : 439 errorCode = FSE_initDState(&DState, &DStream, DTablePtr); 440 441 You can then decode your data, symbol after symbol. 442 For information the maximum number of bits read by FSE_decodeSymbol() is 'tableLog'. 443 Keep in mind that symbols are decoded in reverse order, like a LIFO stack (last in, first out). 444 unsigned char symbol = FSE_decodeSymbol(&DState, &DStream); 445 446 You can retrieve any bitfield you eventually stored into the bitStream (in reverse order) 447 Note : maximum allowed nbBits is 25, for 32-bits compatibility 448 size_t bitField = BIT_readBits(&DStream, nbBits); 449 450 All above operations only read from local register (which size depends on size_t). 451 Refueling the register from memory is manually performed by the reload method. 452 endSignal = FSE_reloadDStream(&DStream); 453 454 BIT_reloadDStream() result tells if there is still some more data to read from DStream. 455 BIT_DStream_unfinished : there is still some data left into the DStream. 456 BIT_DStream_endOfBuffer : Dstream reached end of buffer. Its container may no longer be completely filled. 457 BIT_DStream_completed : Dstream reached its exact end, corresponding in general to decompression completed. 458 BIT_DStream_tooFar : Dstream went too far. Decompression result is corrupted. 459 460 When reaching end of buffer (BIT_DStream_endOfBuffer), progress slowly, notably if you decode multiple symbols per loop, 461 to properly detect the exact end of stream. 462 After each decoded symbol, check if DStream is fully consumed using this simple test : 463 BIT_reloadDStream(&DStream) >= BIT_DStream_completed 464 465 When it's done, verify decompression is fully completed, by checking both DStream and the relevant states. 466 Checking if DStream has reached its end is performed by : 467 BIT_endOfDStream(&DStream); 468 Check also the states. There might be some symbols left there, if some high probability ones (>50%) are possible. 469 FSE_endOfDState(&DState); 470 */ 471 472 473 /* ***************************************** 474 * FSE unsafe API 475 *******************************************/ 476 static unsigned char FSE_decodeSymbolFast(FSE_DState_t* DStatePtr, BIT_DStream_t* bitD); 477 /* faster, but works only if nbBits is always >= 1 (otherwise, result will be corrupted) */ 478 479 480 /* ***************************************** 481 * Implementation of inlined functions 482 *******************************************/ 483 typedef struct { 484 int deltaFindState; 485 U32 deltaNbBits; 486 } FSE_symbolCompressionTransform; /* total 8 bytes */ 487 488 MEM_STATIC void FSE_initCState(FSE_CState_t* statePtr, const FSE_CTable* ct) 489 { 490 const void* ptr = ct; 491 const U16* u16ptr = (const U16*) ptr; 492 const U32 tableLog = MEM_read16(ptr); 493 statePtr->value = (ptrdiff_t)1<<tableLog; 494 statePtr->stateTable = u16ptr+2; 495 statePtr->symbolTT = ct + 1 + (tableLog ? (1<<(tableLog-1)) : 1); 496 statePtr->stateLog = tableLog; 497 } 498 499 500 /*! FSE_initCState2() : 501 * Same as FSE_initCState(), but the first symbol to include (which will be the last to be read) 502 * uses the smallest state value possible, saving the cost of this symbol */ 503 MEM_STATIC void FSE_initCState2(FSE_CState_t* statePtr, const FSE_CTable* ct, U32 symbol) 504 { 505 FSE_initCState(statePtr, ct); 506 { const FSE_symbolCompressionTransform symbolTT = ((const FSE_symbolCompressionTransform*)(statePtr->symbolTT))[symbol]; 507 const U16* stateTable = (const U16*)(statePtr->stateTable); 508 U32 nbBitsOut = (U32)((symbolTT.deltaNbBits + (1<<15)) >> 16); 509 statePtr->value = (nbBitsOut << 16) - symbolTT.deltaNbBits; 510 statePtr->value = stateTable[(statePtr->value >> nbBitsOut) + symbolTT.deltaFindState]; 511 } 512 } 513 514 MEM_STATIC void FSE_encodeSymbol(BIT_CStream_t* bitC, FSE_CState_t* statePtr, unsigned symbol) 515 { 516 FSE_symbolCompressionTransform const symbolTT = ((const FSE_symbolCompressionTransform*)(statePtr->symbolTT))[symbol]; 517 const U16* const stateTable = (const U16*)(statePtr->stateTable); 518 U32 const nbBitsOut = (U32)((statePtr->value + symbolTT.deltaNbBits) >> 16); 519 BIT_addBits(bitC, statePtr->value, nbBitsOut); 520 statePtr->value = stateTable[ (statePtr->value >> nbBitsOut) + symbolTT.deltaFindState]; 521 } 522 523 MEM_STATIC void FSE_flushCState(BIT_CStream_t* bitC, const FSE_CState_t* statePtr) 524 { 525 BIT_addBits(bitC, statePtr->value, statePtr->stateLog); 526 BIT_flushBits(bitC); 527 } 528 529 530 /* FSE_getMaxNbBits() : 531 * Approximate maximum cost of a symbol, in bits. 532 * Fractional get rounded up (i.e : a symbol with a normalized frequency of 3 gives the same result as a frequency of 2) 533 * note 1 : assume symbolValue is valid (<= maxSymbolValue) 534 * note 2 : if freq[symbolValue]==0, @return a fake cost of tableLog+1 bits */ 535 MEM_STATIC U32 FSE_getMaxNbBits(const void* symbolTTPtr, U32 symbolValue) 536 { 537 const FSE_symbolCompressionTransform* symbolTT = (const FSE_symbolCompressionTransform*) symbolTTPtr; 538 return (symbolTT[symbolValue].deltaNbBits + ((1<<16)-1)) >> 16; 539 } 540 541 /* FSE_bitCost() : 542 * Approximate symbol cost, as fractional value, using fixed-point format (accuracyLog fractional bits) 543 * note 1 : assume symbolValue is valid (<= maxSymbolValue) 544 * note 2 : if freq[symbolValue]==0, @return a fake cost of tableLog+1 bits */ 545 MEM_STATIC U32 FSE_bitCost(const void* symbolTTPtr, U32 tableLog, U32 symbolValue, U32 accuracyLog) 546 { 547 const FSE_symbolCompressionTransform* symbolTT = (const FSE_symbolCompressionTransform*) symbolTTPtr; 548 U32 const minNbBits = symbolTT[symbolValue].deltaNbBits >> 16; 549 U32 const threshold = (minNbBits+1) << 16; 550 assert(tableLog < 16); 551 assert(accuracyLog < 31-tableLog); /* ensure enough room for renormalization double shift */ 552 { U32 const tableSize = 1 << tableLog; 553 U32 const deltaFromThreshold = threshold - (symbolTT[symbolValue].deltaNbBits + tableSize); 554 U32 const normalizedDeltaFromThreshold = (deltaFromThreshold << accuracyLog) >> tableLog; /* linear interpolation (very approximate) */ 555 U32 const bitMultiplier = 1 << accuracyLog; 556 assert(symbolTT[symbolValue].deltaNbBits + tableSize <= threshold); 557 assert(normalizedDeltaFromThreshold <= bitMultiplier); 558 return (minNbBits+1)*bitMultiplier - normalizedDeltaFromThreshold; 559 } 560 } 561 562 563 /* ====== Decompression ====== */ 564 565 typedef struct { 566 U16 tableLog; 567 U16 fastMode; 568 } FSE_DTableHeader; /* sizeof U32 */ 569 570 typedef struct 571 { 572 unsigned short newState; 573 unsigned char symbol; 574 unsigned char nbBits; 575 } FSE_decode_t; /* size == U32 */ 576 577 MEM_STATIC void FSE_initDState(FSE_DState_t* DStatePtr, BIT_DStream_t* bitD, const FSE_DTable* dt) 578 { 579 const void* ptr = dt; 580 const FSE_DTableHeader* const DTableH = (const FSE_DTableHeader*)ptr; 581 DStatePtr->state = BIT_readBits(bitD, DTableH->tableLog); 582 BIT_reloadDStream(bitD); 583 DStatePtr->table = dt + 1; 584 } 585 586 MEM_STATIC BYTE FSE_peekSymbol(const FSE_DState_t* DStatePtr) 587 { 588 FSE_decode_t const DInfo = ((const FSE_decode_t*)(DStatePtr->table))[DStatePtr->state]; 589 return DInfo.symbol; 590 } 591 592 MEM_STATIC void FSE_updateState(FSE_DState_t* DStatePtr, BIT_DStream_t* bitD) 593 { 594 FSE_decode_t const DInfo = ((const FSE_decode_t*)(DStatePtr->table))[DStatePtr->state]; 595 U32 const nbBits = DInfo.nbBits; 596 size_t const lowBits = BIT_readBits(bitD, nbBits); 597 DStatePtr->state = DInfo.newState + lowBits; 598 } 599 600 MEM_STATIC BYTE FSE_decodeSymbol(FSE_DState_t* DStatePtr, BIT_DStream_t* bitD) 601 { 602 FSE_decode_t const DInfo = ((const FSE_decode_t*)(DStatePtr->table))[DStatePtr->state]; 603 U32 const nbBits = DInfo.nbBits; 604 BYTE const symbol = DInfo.symbol; 605 size_t const lowBits = BIT_readBits(bitD, nbBits); 606 607 DStatePtr->state = DInfo.newState + lowBits; 608 return symbol; 609 } 610 611 /*! FSE_decodeSymbolFast() : 612 unsafe, only works if no symbol has a probability > 50% */ 613 MEM_STATIC BYTE FSE_decodeSymbolFast(FSE_DState_t* DStatePtr, BIT_DStream_t* bitD) 614 { 615 FSE_decode_t const DInfo = ((const FSE_decode_t*)(DStatePtr->table))[DStatePtr->state]; 616 U32 const nbBits = DInfo.nbBits; 617 BYTE const symbol = DInfo.symbol; 618 size_t const lowBits = BIT_readBitsFast(bitD, nbBits); 619 620 DStatePtr->state = DInfo.newState + lowBits; 621 return symbol; 622 } 623 624 MEM_STATIC unsigned FSE_endOfDState(const FSE_DState_t* DStatePtr) 625 { 626 return DStatePtr->state == 0; 627 } 628 629 630 631 #ifndef FSE_COMMONDEFS_ONLY 632 633 /* ************************************************************** 634 * Tuning parameters 635 ****************************************************************/ 636 /*!MEMORY_USAGE : 637 * Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.) 638 * Increasing memory usage improves compression ratio 639 * Reduced memory usage can improve speed, due to cache effect 640 * Recommended max value is 14, for 16KB, which nicely fits into Intel x86 L1 cache */ 641 #ifndef FSE_MAX_MEMORY_USAGE 642 # define FSE_MAX_MEMORY_USAGE 14 643 #endif 644 #ifndef FSE_DEFAULT_MEMORY_USAGE 645 # define FSE_DEFAULT_MEMORY_USAGE 13 646 #endif 647 648 /*!FSE_MAX_SYMBOL_VALUE : 649 * Maximum symbol value authorized. 650 * Required for proper stack allocation */ 651 #ifndef FSE_MAX_SYMBOL_VALUE 652 # define FSE_MAX_SYMBOL_VALUE 255 653 #endif 654 655 /* ************************************************************** 656 * template functions type & suffix 657 ****************************************************************/ 658 #define FSE_FUNCTION_TYPE BYTE 659 #define FSE_FUNCTION_EXTENSION 660 #define FSE_DECODE_TYPE FSE_decode_t 661 662 663 #endif /* !FSE_COMMONDEFS_ONLY */ 664 665 666 /* *************************************************************** 667 * Constants 668 *****************************************************************/ 669 #define FSE_MAX_TABLELOG (FSE_MAX_MEMORY_USAGE-2) 670 #define FSE_MAX_TABLESIZE (1U<<FSE_MAX_TABLELOG) 671 #define FSE_MAXTABLESIZE_MASK (FSE_MAX_TABLESIZE-1) 672 #define FSE_DEFAULT_TABLELOG (FSE_DEFAULT_MEMORY_USAGE-2) 673 #define FSE_MIN_TABLELOG 5 674 675 #define FSE_TABLELOG_ABSOLUTE_MAX 15 676 #if FSE_MAX_TABLELOG > FSE_TABLELOG_ABSOLUTE_MAX 677 # error "FSE_MAX_TABLELOG > FSE_TABLELOG_ABSOLUTE_MAX is not supported" 678 #endif 679 680 #define FSE_TABLESTEP(tableSize) ((tableSize>>1) + (tableSize>>3) + 3) 681 682 683 #endif /* FSE_STATIC_LINKING_ONLY */ 684 685 686 #if defined (__cplusplus) 687 } 688 #endif 689