1 /* ******************************************************************
2 * FSE : Finite State Entropy codec
3 * Public Prototypes declaration
4 * Copyright (c) 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 "zstd_deps.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 useLowProbCount is a boolean parameter which trades off compressed size for
141 faster header decoding. When it is set to 1, the compressed data will be slightly
142 smaller. And when it is set to 0, FSE_readNCount() and FSE_buildDTable() will be
143 faster. If you are compressing a small amount of data (< 2 KB) then useLowProbCount=0
144 is a good default, since header deserialization makes a big speed difference.
145 Otherwise, useLowProbCount=1 is a good default, since the speed difference is small.
146 @return : tableLog,
147 or an errorCode, which can be tested using FSE_isError() */
148 FSE_PUBLIC_API size_t FSE_normalizeCount(short* normalizedCounter, unsigned tableLog,
149 const unsigned* count, size_t srcSize, unsigned maxSymbolValue, unsigned useLowProbCount);
150
151 /*! FSE_NCountWriteBound():
152 Provides the maximum possible size of an FSE normalized table, given 'maxSymbolValue' and 'tableLog'.
153 Typically useful for allocation purpose. */
154 FSE_PUBLIC_API size_t FSE_NCountWriteBound(unsigned maxSymbolValue, unsigned tableLog);
155
156 /*! FSE_writeNCount():
157 Compactly save 'normalizedCounter' into 'buffer'.
158 @return : size of the compressed table,
159 or an errorCode, which can be tested using FSE_isError(). */
160 FSE_PUBLIC_API size_t FSE_writeNCount (void* buffer, size_t bufferSize,
161 const short* normalizedCounter,
162 unsigned maxSymbolValue, unsigned tableLog);
163
164 /*! Constructor and Destructor of FSE_CTable.
165 Note that FSE_CTable size depends on 'tableLog' and 'maxSymbolValue' */
166 typedef unsigned FSE_CTable; /* don't allocate that. It's only meant to be more restrictive than void* */
167 FSE_PUBLIC_API FSE_CTable* FSE_createCTable (unsigned maxSymbolValue, unsigned tableLog);
168 FSE_PUBLIC_API void FSE_freeCTable (FSE_CTable* ct);
169
170 /*! FSE_buildCTable():
171 Builds `ct`, which must be already allocated, using FSE_createCTable().
172 @return : 0, or an errorCode, which can be tested using FSE_isError() */
173 FSE_PUBLIC_API size_t FSE_buildCTable(FSE_CTable* ct, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog);
174
175 /*! FSE_compress_usingCTable():
176 Compress `src` using `ct` into `dst` which must be already allocated.
177 @return : size of compressed data (<= `dstCapacity`),
178 or 0 if compressed data could not fit into `dst`,
179 or an errorCode, which can be tested using FSE_isError() */
180 FSE_PUBLIC_API size_t FSE_compress_usingCTable (void* dst, size_t dstCapacity, const void* src, size_t srcSize, const FSE_CTable* ct);
181
182 /*!
183 Tutorial :
184 ----------
185 The first step is to count all symbols. FSE_count() does this job very fast.
186 Result will be saved into 'count', a table of unsigned int, which must be already allocated, and have 'maxSymbolValuePtr[0]+1' cells.
187 'src' is a table of bytes of size 'srcSize'. All values within 'src' MUST be <= maxSymbolValuePtr[0]
188 maxSymbolValuePtr[0] will be updated, with its real value (necessarily <= original value)
189 FSE_count() will return the number of occurrence of the most frequent symbol.
190 This can be used to know if there is a single symbol within 'src', and to quickly evaluate its compressibility.
191 If there is an error, the function will return an ErrorCode (which can be tested using FSE_isError()).
192
193 The next step is to normalize the frequencies.
194 FSE_normalizeCount() will ensure that sum of frequencies is == 2 ^'tableLog'.
195 It also guarantees a minimum of 1 to any Symbol with frequency >= 1.
196 You can use 'tableLog'==0 to mean "use default tableLog value".
197 If you are unsure of which tableLog value to use, you can ask FSE_optimalTableLog(),
198 which will provide the optimal valid tableLog given sourceSize, maxSymbolValue, and a user-defined maximum (0 means "default").
199
200 The result of FSE_normalizeCount() will be saved into a table,
201 called 'normalizedCounter', which is a table of signed short.
202 'normalizedCounter' must be already allocated, and have at least 'maxSymbolValue+1' cells.
203 The return value is tableLog if everything proceeded as expected.
204 It is 0 if there is a single symbol within distribution.
205 If there is an error (ex: invalid tableLog value), the function will return an ErrorCode (which can be tested using FSE_isError()).
206
207 'normalizedCounter' can be saved in a compact manner to a memory area using FSE_writeNCount().
208 'buffer' must be already allocated.
209 For guaranteed success, buffer size must be at least FSE_headerBound().
210 The result of the function is the number of bytes written into 'buffer'.
211 If there is an error, the function will return an ErrorCode (which can be tested using FSE_isError(); ex : buffer size too small).
212
213 'normalizedCounter' can then be used to create the compression table 'CTable'.
214 The space required by 'CTable' must be already allocated, using FSE_createCTable().
215 You can then use FSE_buildCTable() to fill 'CTable'.
216 If there is an error, both functions will return an ErrorCode (which can be tested using FSE_isError()).
217
218 'CTable' can then be used to compress 'src', with FSE_compress_usingCTable().
219 Similar to FSE_count(), the convention is that 'src' is assumed to be a table of char of size 'srcSize'
220 The function returns the size of compressed data (without header), necessarily <= `dstCapacity`.
221 If it returns '0', compressed data could not fit into 'dst'.
222 If there is an error, the function will return an ErrorCode (which can be tested using FSE_isError()).
223 */
224
225
226 /* *** DECOMPRESSION *** */
227
228 /*! FSE_readNCount():
229 Read compactly saved 'normalizedCounter' from 'rBuffer'.
230 @return : size read from 'rBuffer',
231 or an errorCode, which can be tested using FSE_isError().
232 maxSymbolValuePtr[0] and tableLogPtr[0] will also be updated with their respective values */
233 FSE_PUBLIC_API size_t FSE_readNCount (short* normalizedCounter,
234 unsigned* maxSymbolValuePtr, unsigned* tableLogPtr,
235 const void* rBuffer, size_t rBuffSize);
236
237 /*! FSE_readNCount_bmi2():
238 * Same as FSE_readNCount() but pass bmi2=1 when your CPU supports BMI2 and 0 otherwise.
239 */
240 FSE_PUBLIC_API size_t FSE_readNCount_bmi2(short* normalizedCounter,
241 unsigned* maxSymbolValuePtr, unsigned* tableLogPtr,
242 const void* rBuffer, size_t rBuffSize, int bmi2);
243
244 /*! Constructor and Destructor of FSE_DTable.
245 Note that its size depends on 'tableLog' */
246 typedef unsigned FSE_DTable; /* don't allocate that. It's just a way to be more restrictive than void* */
247 FSE_PUBLIC_API FSE_DTable* FSE_createDTable(unsigned tableLog);
248 FSE_PUBLIC_API void FSE_freeDTable(FSE_DTable* dt);
249
250 /*! FSE_buildDTable():
251 Builds 'dt', which must be already allocated, using FSE_createDTable().
252 return : 0, or an errorCode, which can be tested using FSE_isError() */
253 FSE_PUBLIC_API size_t FSE_buildDTable (FSE_DTable* dt, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog);
254
255 /*! FSE_decompress_usingDTable():
256 Decompress compressed source `cSrc` of size `cSrcSize` using `dt`
257 into `dst` which must be already allocated.
258 @return : size of regenerated data (necessarily <= `dstCapacity`),
259 or an errorCode, which can be tested using FSE_isError() */
260 FSE_PUBLIC_API size_t FSE_decompress_usingDTable(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize, const FSE_DTable* dt);
261
262 /*!
263 Tutorial :
264 ----------
265 (Note : these functions only decompress FSE-compressed blocks.
266 If block is uncompressed, use memcpy() instead
267 If block is a single repeated byte, use memset() instead )
268
269 The first step is to obtain the normalized frequencies of symbols.
270 This can be performed by FSE_readNCount() if it was saved using FSE_writeNCount().
271 'normalizedCounter' must be already allocated, and have at least 'maxSymbolValuePtr[0]+1' cells of signed short.
272 In practice, that means it's necessary to know 'maxSymbolValue' beforehand,
273 or size the table to handle worst case situations (typically 256).
274 FSE_readNCount() will provide 'tableLog' and 'maxSymbolValue'.
275 The result of FSE_readNCount() is the number of bytes read from 'rBuffer'.
276 Note that 'rBufferSize' must be at least 4 bytes, even if useful information is less than that.
277 If there is an error, the function will return an error code, which can be tested using FSE_isError().
278
279 The next step is to build the decompression tables 'FSE_DTable' from 'normalizedCounter'.
280 This is performed by the function FSE_buildDTable().
281 The space required by 'FSE_DTable' must be already allocated using FSE_createDTable().
282 If there is an error, the function will return an error code, which can be tested using FSE_isError().
283
284 `FSE_DTable` can then be used to decompress `cSrc`, with FSE_decompress_usingDTable().
285 `cSrcSize` must be strictly correct, otherwise decompression will fail.
286 FSE_decompress_usingDTable() result will tell how many bytes were regenerated (<=`dstCapacity`).
287 If there is an error, the function will return an error code, which can be tested using FSE_isError(). (ex: dst buffer too small)
288 */
289
290 #endif /* FSE_H */
291
292 #if defined(FSE_STATIC_LINKING_ONLY) && !defined(FSE_H_FSE_STATIC_LINKING_ONLY)
293 #define FSE_H_FSE_STATIC_LINKING_ONLY
294
295 /* *** Dependency *** */
296 #include "bitstream.h"
297
298
299 /* *****************************************
300 * Static allocation
301 *******************************************/
302 /* FSE buffer bounds */
303 #define FSE_NCOUNTBOUND 512
304 #define FSE_BLOCKBOUND(size) ((size) + ((size)>>7) + 4 /* fse states */ + sizeof(size_t) /* bitContainer */)
305 #define FSE_COMPRESSBOUND(size) (FSE_NCOUNTBOUND + FSE_BLOCKBOUND(size)) /* Macro version, useful for static allocation */
306
307 /* It is possible to statically allocate FSE CTable/DTable as a table of FSE_CTable/FSE_DTable using below macros */
308 #define FSE_CTABLE_SIZE_U32(maxTableLog, maxSymbolValue) (1 + (1<<((maxTableLog)-1)) + (((maxSymbolValue)+1)*2))
309 #define FSE_DTABLE_SIZE_U32(maxTableLog) (1 + (1<<(maxTableLog)))
310
311 /* or use the size to malloc() space directly. Pay attention to alignment restrictions though */
312 #define FSE_CTABLE_SIZE(maxTableLog, maxSymbolValue) (FSE_CTABLE_SIZE_U32(maxTableLog, maxSymbolValue) * sizeof(FSE_CTable))
313 #define FSE_DTABLE_SIZE(maxTableLog) (FSE_DTABLE_SIZE_U32(maxTableLog) * sizeof(FSE_DTable))
314
315
316 /* *****************************************
317 * FSE advanced API
318 ***************************************** */
319
320 unsigned FSE_optimalTableLog_internal(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue, unsigned minus);
321 /**< same as FSE_optimalTableLog(), which used `minus==2` */
322
323 /* FSE_compress_wksp() :
324 * Same as FSE_compress2(), but using an externally allocated scratch buffer (`workSpace`).
325 * FSE_COMPRESS_WKSP_SIZE_U32() provides the minimum size required for `workSpace` as a table of FSE_CTable.
326 */
327 #define FSE_COMPRESS_WKSP_SIZE_U32(maxTableLog, maxSymbolValue) ( FSE_CTABLE_SIZE_U32(maxTableLog, maxSymbolValue) + ((maxTableLog > 12) ? (1 << (maxTableLog - 2)) : 1024) )
328 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);
329
330 size_t FSE_buildCTable_raw (FSE_CTable* ct, unsigned nbBits);
331 /**< build a fake FSE_CTable, designed for a flat distribution, where each symbol uses nbBits */
332
333 size_t FSE_buildCTable_rle (FSE_CTable* ct, unsigned char symbolValue);
334 /**< build a fake FSE_CTable, designed to compress always the same symbolValue */
335
336 /* FSE_buildCTable_wksp() :
337 * Same as FSE_buildCTable(), but using an externally allocated scratch buffer (`workSpace`).
338 * `wkspSize` must be >= `FSE_BUILD_CTABLE_WORKSPACE_SIZE_U32(maxSymbolValue, tableLog)` of `unsigned`.
339 * See FSE_buildCTable_wksp() for breakdown of workspace usage.
340 */
341 #define FSE_BUILD_CTABLE_WORKSPACE_SIZE_U32(maxSymbolValue, tableLog) (((maxSymbolValue + 2) + (1ull << (tableLog)))/2 + sizeof(U64)/sizeof(U32) /* additional 8 bytes for potential table overwrite */)
342 #define FSE_BUILD_CTABLE_WORKSPACE_SIZE(maxSymbolValue, tableLog) (sizeof(unsigned) * FSE_BUILD_CTABLE_WORKSPACE_SIZE_U32(maxSymbolValue, tableLog))
343 size_t FSE_buildCTable_wksp(FSE_CTable* ct, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void* workSpace, size_t wkspSize);
344
345 #define FSE_BUILD_DTABLE_WKSP_SIZE(maxTableLog, maxSymbolValue) (sizeof(short) * (maxSymbolValue + 1) + (1ULL << maxTableLog) + 8)
346 #define FSE_BUILD_DTABLE_WKSP_SIZE_U32(maxTableLog, maxSymbolValue) ((FSE_BUILD_DTABLE_WKSP_SIZE(maxTableLog, maxSymbolValue) + sizeof(unsigned) - 1) / sizeof(unsigned))
347 FSE_PUBLIC_API size_t FSE_buildDTable_wksp(FSE_DTable* dt, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void* workSpace, size_t wkspSize);
348 /**< Same as FSE_buildDTable(), using an externally allocated `workspace` produced with `FSE_BUILD_DTABLE_WKSP_SIZE_U32(maxSymbolValue)` */
349
350 size_t FSE_buildDTable_raw (FSE_DTable* dt, unsigned nbBits);
351 /**< build a fake FSE_DTable, designed to read a flat distribution where each symbol uses nbBits */
352
353 size_t FSE_buildDTable_rle (FSE_DTable* dt, unsigned char symbolValue);
354 /**< build a fake FSE_DTable, designed to always generate the same symbolValue */
355
356 #define FSE_DECOMPRESS_WKSP_SIZE_U32(maxTableLog, maxSymbolValue) (FSE_DTABLE_SIZE_U32(maxTableLog) + FSE_BUILD_DTABLE_WKSP_SIZE_U32(maxTableLog, maxSymbolValue) + (FSE_MAX_SYMBOL_VALUE + 1) / 2 + 1)
357 #define FSE_DECOMPRESS_WKSP_SIZE(maxTableLog, maxSymbolValue) (FSE_DECOMPRESS_WKSP_SIZE_U32(maxTableLog, maxSymbolValue) * sizeof(unsigned))
358 size_t FSE_decompress_wksp(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize, unsigned maxLog, void* workSpace, size_t wkspSize);
359 /**< same as FSE_decompress(), using an externally allocated `workSpace` produced with `FSE_DECOMPRESS_WKSP_SIZE_U32(maxLog, maxSymbolValue)` */
360
361 size_t FSE_decompress_wksp_bmi2(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize, unsigned maxLog, void* workSpace, size_t wkspSize, int bmi2);
362 /**< Same as FSE_decompress_wksp() but with dynamic BMI2 support. Pass 1 if your CPU supports BMI2 or 0 if it doesn't. */
363
364 typedef enum {
365 FSE_repeat_none, /**< Cannot use the previous table */
366 FSE_repeat_check, /**< Can use the previous table but it must be checked */
367 FSE_repeat_valid /**< Can use the previous table and it is assumed to be valid */
368 } FSE_repeat;
369
370 /* *****************************************
371 * FSE symbol compression API
372 *******************************************/
373 /*!
374 This API consists of small unitary functions, which highly benefit from being inlined.
375 Hence their body are included in next section.
376 */
377 typedef struct {
378 ptrdiff_t value;
379 const void* stateTable;
380 const void* symbolTT;
381 unsigned stateLog;
382 } FSE_CState_t;
383
384 static void FSE_initCState(FSE_CState_t* CStatePtr, const FSE_CTable* ct);
385
386 static void FSE_encodeSymbol(BIT_CStream_t* bitC, FSE_CState_t* CStatePtr, unsigned symbol);
387
388 static void FSE_flushCState(BIT_CStream_t* bitC, const FSE_CState_t* CStatePtr);
389
390 /**<
391 These functions are inner components of FSE_compress_usingCTable().
392 They allow the creation of custom streams, mixing multiple tables and bit sources.
393
394 A key property to keep in mind is that encoding and decoding are done **in reverse direction**.
395 So the first symbol you will encode is the last you will decode, like a LIFO stack.
396
397 You will need a few variables to track your CStream. They are :
398
399 FSE_CTable ct; // Provided by FSE_buildCTable()
400 BIT_CStream_t bitStream; // bitStream tracking structure
401 FSE_CState_t state; // State tracking structure (can have several)
402
403
404 The first thing to do is to init bitStream and state.
405 size_t errorCode = BIT_initCStream(&bitStream, dstBuffer, maxDstSize);
406 FSE_initCState(&state, ct);
407
408 Note that BIT_initCStream() can produce an error code, so its result should be tested, using FSE_isError();
409 You can then encode your input data, byte after byte.
410 FSE_encodeSymbol() outputs a maximum of 'tableLog' bits at a time.
411 Remember decoding will be done in reverse direction.
412 FSE_encodeByte(&bitStream, &state, symbol);
413
414 At any time, you can also add any bit sequence.
415 Note : maximum allowed nbBits is 25, for compatibility with 32-bits decoders
416 BIT_addBits(&bitStream, bitField, nbBits);
417
418 The above methods don't commit data to memory, they just store it into local register, for speed.
419 Local register size is 64-bits on 64-bits systems, 32-bits on 32-bits systems (size_t).
420 Writing data to memory is a manual operation, performed by the flushBits function.
421 BIT_flushBits(&bitStream);
422
423 Your last FSE encoding operation shall be to flush your last state value(s).
424 FSE_flushState(&bitStream, &state);
425
426 Finally, you must close the bitStream.
427 The function returns the size of CStream in bytes.
428 If data couldn't fit into dstBuffer, it will return a 0 ( == not compressible)
429 If there is an error, it returns an errorCode (which can be tested using FSE_isError()).
430 size_t size = BIT_closeCStream(&bitStream);
431 */
432
433
434 /* *****************************************
435 * FSE symbol decompression API
436 *******************************************/
437 typedef struct {
438 size_t state;
439 const void* table; /* precise table may vary, depending on U16 */
440 } FSE_DState_t;
441
442
443 static void FSE_initDState(FSE_DState_t* DStatePtr, BIT_DStream_t* bitD, const FSE_DTable* dt);
444
445 static unsigned char FSE_decodeSymbol(FSE_DState_t* DStatePtr, BIT_DStream_t* bitD);
446
447 static unsigned FSE_endOfDState(const FSE_DState_t* DStatePtr);
448
449 /**<
450 Let's now decompose FSE_decompress_usingDTable() into its unitary components.
451 You will decode FSE-encoded symbols from the bitStream,
452 and also any other bitFields you put in, **in reverse order**.
453
454 You will need a few variables to track your bitStream. They are :
455
456 BIT_DStream_t DStream; // Stream context
457 FSE_DState_t DState; // State context. Multiple ones are possible
458 FSE_DTable* DTablePtr; // Decoding table, provided by FSE_buildDTable()
459
460 The first thing to do is to init the bitStream.
461 errorCode = BIT_initDStream(&DStream, srcBuffer, srcSize);
462
463 You should then retrieve your initial state(s)
464 (in reverse flushing order if you have several ones) :
465 errorCode = FSE_initDState(&DState, &DStream, DTablePtr);
466
467 You can then decode your data, symbol after symbol.
468 For information the maximum number of bits read by FSE_decodeSymbol() is 'tableLog'.
469 Keep in mind that symbols are decoded in reverse order, like a LIFO stack (last in, first out).
470 unsigned char symbol = FSE_decodeSymbol(&DState, &DStream);
471
472 You can retrieve any bitfield you eventually stored into the bitStream (in reverse order)
473 Note : maximum allowed nbBits is 25, for 32-bits compatibility
474 size_t bitField = BIT_readBits(&DStream, nbBits);
475
476 All above operations only read from local register (which size depends on size_t).
477 Refueling the register from memory is manually performed by the reload method.
478 endSignal = FSE_reloadDStream(&DStream);
479
480 BIT_reloadDStream() result tells if there is still some more data to read from DStream.
481 BIT_DStream_unfinished : there is still some data left into the DStream.
482 BIT_DStream_endOfBuffer : Dstream reached end of buffer. Its container may no longer be completely filled.
483 BIT_DStream_completed : Dstream reached its exact end, corresponding in general to decompression completed.
484 BIT_DStream_tooFar : Dstream went too far. Decompression result is corrupted.
485
486 When reaching end of buffer (BIT_DStream_endOfBuffer), progress slowly, notably if you decode multiple symbols per loop,
487 to properly detect the exact end of stream.
488 After each decoded symbol, check if DStream is fully consumed using this simple test :
489 BIT_reloadDStream(&DStream) >= BIT_DStream_completed
490
491 When it's done, verify decompression is fully completed, by checking both DStream and the relevant states.
492 Checking if DStream has reached its end is performed by :
493 BIT_endOfDStream(&DStream);
494 Check also the states. There might be some symbols left there, if some high probability ones (>50%) are possible.
495 FSE_endOfDState(&DState);
496 */
497
498
499 /* *****************************************
500 * FSE unsafe API
501 *******************************************/
502 static unsigned char FSE_decodeSymbolFast(FSE_DState_t* DStatePtr, BIT_DStream_t* bitD);
503 /* faster, but works only if nbBits is always >= 1 (otherwise, result will be corrupted) */
504
505
506 /* *****************************************
507 * Implementation of inlined functions
508 *******************************************/
509 typedef struct {
510 int deltaFindState;
511 U32 deltaNbBits;
512 } FSE_symbolCompressionTransform; /* total 8 bytes */
513
FSE_initCState(FSE_CState_t * statePtr,const FSE_CTable * ct)514 MEM_STATIC void FSE_initCState(FSE_CState_t* statePtr, const FSE_CTable* ct)
515 {
516 const void* ptr = ct;
517 const U16* u16ptr = (const U16*) ptr;
518 const U32 tableLog = MEM_read16(ptr);
519 statePtr->value = (ptrdiff_t)1<<tableLog;
520 statePtr->stateTable = u16ptr+2;
521 statePtr->symbolTT = ct + 1 + (tableLog ? (1<<(tableLog-1)) : 1);
522 statePtr->stateLog = tableLog;
523 }
524
525
526 /*! FSE_initCState2() :
527 * Same as FSE_initCState(), but the first symbol to include (which will be the last to be read)
528 * uses the smallest state value possible, saving the cost of this symbol */
FSE_initCState2(FSE_CState_t * statePtr,const FSE_CTable * ct,U32 symbol)529 MEM_STATIC void FSE_initCState2(FSE_CState_t* statePtr, const FSE_CTable* ct, U32 symbol)
530 {
531 FSE_initCState(statePtr, ct);
532 { const FSE_symbolCompressionTransform symbolTT = ((const FSE_symbolCompressionTransform*)(statePtr->symbolTT))[symbol];
533 const U16* stateTable = (const U16*)(statePtr->stateTable);
534 U32 nbBitsOut = (U32)((symbolTT.deltaNbBits + (1<<15)) >> 16);
535 statePtr->value = (nbBitsOut << 16) - symbolTT.deltaNbBits;
536 statePtr->value = stateTable[(statePtr->value >> nbBitsOut) + symbolTT.deltaFindState];
537 }
538 }
539
FSE_encodeSymbol(BIT_CStream_t * bitC,FSE_CState_t * statePtr,unsigned symbol)540 MEM_STATIC void FSE_encodeSymbol(BIT_CStream_t* bitC, FSE_CState_t* statePtr, unsigned symbol)
541 {
542 FSE_symbolCompressionTransform const symbolTT = ((const FSE_symbolCompressionTransform*)(statePtr->symbolTT))[symbol];
543 const U16* const stateTable = (const U16*)(statePtr->stateTable);
544 U32 const nbBitsOut = (U32)((statePtr->value + symbolTT.deltaNbBits) >> 16);
545 BIT_addBits(bitC, statePtr->value, nbBitsOut);
546 statePtr->value = stateTable[ (statePtr->value >> nbBitsOut) + symbolTT.deltaFindState];
547 }
548
FSE_flushCState(BIT_CStream_t * bitC,const FSE_CState_t * statePtr)549 MEM_STATIC void FSE_flushCState(BIT_CStream_t* bitC, const FSE_CState_t* statePtr)
550 {
551 BIT_addBits(bitC, statePtr->value, statePtr->stateLog);
552 BIT_flushBits(bitC);
553 }
554
555
556 /* FSE_getMaxNbBits() :
557 * Approximate maximum cost of a symbol, in bits.
558 * Fractional get rounded up (i.e : a symbol with a normalized frequency of 3 gives the same result as a frequency of 2)
559 * note 1 : assume symbolValue is valid (<= maxSymbolValue)
560 * note 2 : if freq[symbolValue]==0, @return a fake cost of tableLog+1 bits */
FSE_getMaxNbBits(const void * symbolTTPtr,U32 symbolValue)561 MEM_STATIC U32 FSE_getMaxNbBits(const void* symbolTTPtr, U32 symbolValue)
562 {
563 const FSE_symbolCompressionTransform* symbolTT = (const FSE_symbolCompressionTransform*) symbolTTPtr;
564 return (symbolTT[symbolValue].deltaNbBits + ((1<<16)-1)) >> 16;
565 }
566
567 /* FSE_bitCost() :
568 * Approximate symbol cost, as fractional value, using fixed-point format (accuracyLog fractional bits)
569 * note 1 : assume symbolValue is valid (<= maxSymbolValue)
570 * note 2 : if freq[symbolValue]==0, @return a fake cost of tableLog+1 bits */
FSE_bitCost(const void * symbolTTPtr,U32 tableLog,U32 symbolValue,U32 accuracyLog)571 MEM_STATIC U32 FSE_bitCost(const void* symbolTTPtr, U32 tableLog, U32 symbolValue, U32 accuracyLog)
572 {
573 const FSE_symbolCompressionTransform* symbolTT = (const FSE_symbolCompressionTransform*) symbolTTPtr;
574 U32 const minNbBits = symbolTT[symbolValue].deltaNbBits >> 16;
575 U32 const threshold = (minNbBits+1) << 16;
576 assert(tableLog < 16);
577 assert(accuracyLog < 31-tableLog); /* ensure enough room for renormalization double shift */
578 { U32 const tableSize = 1 << tableLog;
579 U32 const deltaFromThreshold = threshold - (symbolTT[symbolValue].deltaNbBits + tableSize);
580 U32 const normalizedDeltaFromThreshold = (deltaFromThreshold << accuracyLog) >> tableLog; /* linear interpolation (very approximate) */
581 U32 const bitMultiplier = 1 << accuracyLog;
582 assert(symbolTT[symbolValue].deltaNbBits + tableSize <= threshold);
583 assert(normalizedDeltaFromThreshold <= bitMultiplier);
584 return (minNbBits+1)*bitMultiplier - normalizedDeltaFromThreshold;
585 }
586 }
587
588
589 /* ====== Decompression ====== */
590
591 typedef struct {
592 U16 tableLog;
593 U16 fastMode;
594 } FSE_DTableHeader; /* sizeof U32 */
595
596 typedef struct
597 {
598 unsigned short newState;
599 unsigned char symbol;
600 unsigned char nbBits;
601 } FSE_decode_t; /* size == U32 */
602
FSE_initDState(FSE_DState_t * DStatePtr,BIT_DStream_t * bitD,const FSE_DTable * dt)603 MEM_STATIC void FSE_initDState(FSE_DState_t* DStatePtr, BIT_DStream_t* bitD, const FSE_DTable* dt)
604 {
605 const void* ptr = dt;
606 const FSE_DTableHeader* const DTableH = (const FSE_DTableHeader*)ptr;
607 DStatePtr->state = BIT_readBits(bitD, DTableH->tableLog);
608 BIT_reloadDStream(bitD);
609 DStatePtr->table = dt + 1;
610 }
611
FSE_peekSymbol(const FSE_DState_t * DStatePtr)612 MEM_STATIC BYTE FSE_peekSymbol(const FSE_DState_t* DStatePtr)
613 {
614 FSE_decode_t const DInfo = ((const FSE_decode_t*)(DStatePtr->table))[DStatePtr->state];
615 return DInfo.symbol;
616 }
617
FSE_updateState(FSE_DState_t * DStatePtr,BIT_DStream_t * bitD)618 MEM_STATIC void FSE_updateState(FSE_DState_t* DStatePtr, BIT_DStream_t* bitD)
619 {
620 FSE_decode_t const DInfo = ((const FSE_decode_t*)(DStatePtr->table))[DStatePtr->state];
621 U32 const nbBits = DInfo.nbBits;
622 size_t const lowBits = BIT_readBits(bitD, nbBits);
623 DStatePtr->state = DInfo.newState + lowBits;
624 }
625
FSE_decodeSymbol(FSE_DState_t * DStatePtr,BIT_DStream_t * bitD)626 MEM_STATIC BYTE FSE_decodeSymbol(FSE_DState_t* DStatePtr, BIT_DStream_t* bitD)
627 {
628 FSE_decode_t const DInfo = ((const FSE_decode_t*)(DStatePtr->table))[DStatePtr->state];
629 U32 const nbBits = DInfo.nbBits;
630 BYTE const symbol = DInfo.symbol;
631 size_t const lowBits = BIT_readBits(bitD, nbBits);
632
633 DStatePtr->state = DInfo.newState + lowBits;
634 return symbol;
635 }
636
637 /*! FSE_decodeSymbolFast() :
638 unsafe, only works if no symbol has a probability > 50% */
FSE_decodeSymbolFast(FSE_DState_t * DStatePtr,BIT_DStream_t * bitD)639 MEM_STATIC BYTE FSE_decodeSymbolFast(FSE_DState_t* DStatePtr, BIT_DStream_t* bitD)
640 {
641 FSE_decode_t const DInfo = ((const FSE_decode_t*)(DStatePtr->table))[DStatePtr->state];
642 U32 const nbBits = DInfo.nbBits;
643 BYTE const symbol = DInfo.symbol;
644 size_t const lowBits = BIT_readBitsFast(bitD, nbBits);
645
646 DStatePtr->state = DInfo.newState + lowBits;
647 return symbol;
648 }
649
FSE_endOfDState(const FSE_DState_t * DStatePtr)650 MEM_STATIC unsigned FSE_endOfDState(const FSE_DState_t* DStatePtr)
651 {
652 return DStatePtr->state == 0;
653 }
654
655
656
657 #ifndef FSE_COMMONDEFS_ONLY
658
659 /* **************************************************************
660 * Tuning parameters
661 ****************************************************************/
662 /*!MEMORY_USAGE :
663 * Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
664 * Increasing memory usage improves compression ratio
665 * Reduced memory usage can improve speed, due to cache effect
666 * Recommended max value is 14, for 16KB, which nicely fits into Intel x86 L1 cache */
667 #ifndef FSE_MAX_MEMORY_USAGE
668 # define FSE_MAX_MEMORY_USAGE 14
669 #endif
670 #ifndef FSE_DEFAULT_MEMORY_USAGE
671 # define FSE_DEFAULT_MEMORY_USAGE 13
672 #endif
673 #if (FSE_DEFAULT_MEMORY_USAGE > FSE_MAX_MEMORY_USAGE)
674 # error "FSE_DEFAULT_MEMORY_USAGE must be <= FSE_MAX_MEMORY_USAGE"
675 #endif
676
677 /*!FSE_MAX_SYMBOL_VALUE :
678 * Maximum symbol value authorized.
679 * Required for proper stack allocation */
680 #ifndef FSE_MAX_SYMBOL_VALUE
681 # define FSE_MAX_SYMBOL_VALUE 255
682 #endif
683
684 /* **************************************************************
685 * template functions type & suffix
686 ****************************************************************/
687 #define FSE_FUNCTION_TYPE BYTE
688 #define FSE_FUNCTION_EXTENSION
689 #define FSE_DECODE_TYPE FSE_decode_t
690
691
692 #endif /* !FSE_COMMONDEFS_ONLY */
693
694
695 /* ***************************************************************
696 * Constants
697 *****************************************************************/
698 #define FSE_MAX_TABLELOG (FSE_MAX_MEMORY_USAGE-2)
699 #define FSE_MAX_TABLESIZE (1U<<FSE_MAX_TABLELOG)
700 #define FSE_MAXTABLESIZE_MASK (FSE_MAX_TABLESIZE-1)
701 #define FSE_DEFAULT_TABLELOG (FSE_DEFAULT_MEMORY_USAGE-2)
702 #define FSE_MIN_TABLELOG 5
703
704 #define FSE_TABLELOG_ABSOLUTE_MAX 15
705 #if FSE_MAX_TABLELOG > FSE_TABLELOG_ABSOLUTE_MAX
706 # error "FSE_MAX_TABLELOG > FSE_TABLELOG_ABSOLUTE_MAX is not supported"
707 #endif
708
709 #define FSE_TABLESTEP(tableSize) (((tableSize)>>1) + ((tableSize)>>3) + 3)
710
711
712 #endif /* FSE_STATIC_LINKING_ONLY */
713
714
715 #if defined (__cplusplus)
716 }
717 #endif
718