source: thirdparty/blosc/internal-complibs/zstd-0.7.4/common/fse.h @ 8ebc79b

Revision 8ebc79b, 27.8 KB checked in by Hal Finkel <hfinkel@…>, 8 years ago (diff)

Add the other internal compression libraries from blocs

  • Property mode set to 100644
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1/* ******************************************************************
2   FSE : Finite State Entropy codec
3   Public Prototypes declaration
4   Copyright (C) 2013-2016, Yann Collet.
5
6   BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
7
8   Redistribution and use in source and binary forms, with or without
9   modification, are permitted provided that the following conditions are
10   met:
11
12       * Redistributions of source code must retain the above copyright
13   notice, this list of conditions and the following disclaimer.
14       * Redistributions in binary form must reproduce the above
15   copyright notice, this list of conditions and the following disclaimer
16   in the documentation and/or other materials provided with the
17   distribution.
18
19   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
23   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
25   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
29   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30
31   You can contact the author at :
32   - Source repository : https://github.com/Cyan4973/FiniteStateEntropy
33****************************************************************** */
34#ifndef FSE_H
35#define FSE_H
36
37#if defined (__cplusplus)
38extern "C" {
39#endif
40
41
42/*-*****************************************
43*  Dependencies
44******************************************/
45#include <stddef.h>    /* size_t, ptrdiff_t */
46
47
48/*-****************************************
49*  FSE simple functions
50******************************************/
51/*! FSE_compress() :
52    Compress content of buffer 'src', of size 'srcSize', into destination buffer 'dst'.
53    'dst' buffer must be already allocated. Compression runs faster is dstCapacity >= FSE_compressBound(srcSize).
54    @return : size of compressed data (<= dstCapacity).
55    Special values : if return == 0, srcData is not compressible => Nothing is stored within dst !!!
56                     if return == 1, srcData is a single byte symbol * srcSize times. Use RLE compression instead.
57                     if FSE_isError(return), compression failed (more details using FSE_getErrorName())
58*/
59size_t FSE_compress(void* dst, size_t dstCapacity,
60              const void* src, size_t srcSize);
61
62/*! FSE_decompress():
63    Decompress FSE data from buffer 'cSrc', of size 'cSrcSize',
64    into already allocated destination buffer 'dst', of size 'dstCapacity'.
65    @return : size of regenerated data (<= maxDstSize),
66              or an error code, which can be tested using FSE_isError() .
67
68    ** Important ** : FSE_decompress() does not decompress non-compressible nor RLE data !!!
69    Why ? : making this distinction requires a header.
70    Header management is intentionally delegated to the user layer, which can better manage special cases.
71*/
72size_t FSE_decompress(void* dst,  size_t dstCapacity,
73                const void* cSrc, size_t cSrcSize);
74
75
76/*-*****************************************
77*  Tool functions
78******************************************/
79size_t FSE_compressBound(size_t size);       /* maximum compressed size */
80
81/* Error Management */
82unsigned    FSE_isError(size_t code);        /* tells if a return value is an error code */
83const char* FSE_getErrorName(size_t code);   /* provides error code string (useful for debugging) */
84
85
86/*-*****************************************
87*  FSE advanced functions
88******************************************/
89/*! FSE_compress2() :
90    Same as FSE_compress(), but allows the selection of 'maxSymbolValue' and 'tableLog'
91    Both parameters can be defined as '0' to mean : use default value
92    @return : size of compressed data
93    Special values : if return == 0, srcData is not compressible => Nothing is stored within cSrc !!!
94                     if return == 1, srcData is a single byte symbol * srcSize times. Use RLE compression.
95                     if FSE_isError(return), it's an error code.
96*/
97size_t FSE_compress2 (void* dst, size_t dstSize, const void* src, size_t srcSize, unsigned maxSymbolValue, unsigned tableLog);
98
99
100/*-*****************************************
101*  FSE detailed API
102******************************************/
103/*!
104FSE_compress() does the following:
1051. count symbol occurrence from source[] into table count[]
1062. normalize counters so that sum(count[]) == Power_of_2 (2^tableLog)
1073. save normalized counters to memory buffer using writeNCount()
1084. build encoding table 'CTable' from normalized counters
1095. encode the data stream using encoding table 'CTable'
110
111FSE_decompress() does the following:
1121. read normalized counters with readNCount()
1132. build decoding table 'DTable' from normalized counters
1143. decode the data stream using decoding table 'DTable'
115
116The following API allows targeting specific sub-functions for advanced tasks.
117For example, it's possible to compress several blocks using the same 'CTable',
118or to save and provide normalized distribution using external method.
119*/
120
121/* *** COMPRESSION *** */
122
123/*! FSE_count():
124    Provides the precise count of each byte within a table 'count'.
125    'count' is a table of unsigned int, of minimum size (*maxSymbolValuePtr+1).
126    *maxSymbolValuePtr will be updated if detected smaller than initial value.
127    @return : the count of the most frequent symbol (which is not identified).
128              if return == srcSize, there is only one symbol.
129              Can also return an error code, which can be tested with FSE_isError(). */
130size_t FSE_count(unsigned* count, unsigned* maxSymbolValuePtr, const void* src, size_t srcSize);
131
132/*! FSE_optimalTableLog():
133    dynamically downsize 'tableLog' when conditions are met.
134    It saves CPU time, by using smaller tables, while preserving or even improving compression ratio.
135    @return : recommended tableLog (necessarily <= 'maxTableLog') */
136unsigned FSE_optimalTableLog(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue);
137
138/*! FSE_normalizeCount():
139    normalize counts so that sum(count[]) == Power_of_2 (2^tableLog)
140    'normalizedCounter' is a table of short, of minimum size (maxSymbolValue+1).
141    @return : tableLog,
142              or an errorCode, which can be tested using FSE_isError() */
143size_t FSE_normalizeCount(short* normalizedCounter, unsigned tableLog, 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. */
148size_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(). */
154size_t FSE_writeNCount (void* buffer, size_t bufferSize, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog);
155
156
157/*! Constructor and Destructor of FSE_CTable.
158    Note that FSE_CTable size depends on 'tableLog' and 'maxSymbolValue' */
159typedef unsigned FSE_CTable;   /* don't allocate that. It's only meant to be more restrictive than void* */
160FSE_CTable* FSE_createCTable (unsigned tableLog, unsigned maxSymbolValue);
161void        FSE_freeCTable (FSE_CTable* ct);
162
163/*! FSE_buildCTable():
164    Builds `ct`, which must be already allocated, using FSE_createCTable().
165    @return : 0, or an errorCode, which can be tested using FSE_isError() */
166size_t FSE_buildCTable(FSE_CTable* ct, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog);
167
168/*! FSE_compress_usingCTable():
169    Compress `src` using `ct` into `dst` which must be already allocated.
170    @return : size of compressed data (<= `dstCapacity`),
171              or 0 if compressed data could not fit into `dst`,
172              or an errorCode, which can be tested using FSE_isError() */
173size_t FSE_compress_usingCTable (void* dst, size_t dstCapacity, const void* src, size_t srcSize, const FSE_CTable* ct);
174
175/*!
176Tutorial :
177----------
178The first step is to count all symbols. FSE_count() does this job very fast.
179Result will be saved into 'count', a table of unsigned int, which must be already allocated, and have 'maxSymbolValuePtr[0]+1' cells.
180'src' is a table of bytes of size 'srcSize'. All values within 'src' MUST be <= maxSymbolValuePtr[0]
181maxSymbolValuePtr[0] will be updated, with its real value (necessarily <= original value)
182FSE_count() will return the number of occurrence of the most frequent symbol.
183This can be used to know if there is a single symbol within 'src', and to quickly evaluate its compressibility.
184If there is an error, the function will return an ErrorCode (which can be tested using FSE_isError()).
185
186The next step is to normalize the frequencies.
187FSE_normalizeCount() will ensure that sum of frequencies is == 2 ^'tableLog'.
188It also guarantees a minimum of 1 to any Symbol with frequency >= 1.
189You can use 'tableLog'==0 to mean "use default tableLog value".
190If you are unsure of which tableLog value to use, you can ask FSE_optimalTableLog(),
191which will provide the optimal valid tableLog given sourceSize, maxSymbolValue, and a user-defined maximum (0 means "default").
192
193The result of FSE_normalizeCount() will be saved into a table,
194called 'normalizedCounter', which is a table of signed short.
195'normalizedCounter' must be already allocated, and have at least 'maxSymbolValue+1' cells.
196The return value is tableLog if everything proceeded as expected.
197It is 0 if there is a single symbol within distribution.
198If there is an error (ex: invalid tableLog value), the function will return an ErrorCode (which can be tested using FSE_isError()).
199
200'normalizedCounter' can be saved in a compact manner to a memory area using FSE_writeNCount().
201'buffer' must be already allocated.
202For guaranteed success, buffer size must be at least FSE_headerBound().
203The result of the function is the number of bytes written into 'buffer'.
204If there is an error, the function will return an ErrorCode (which can be tested using FSE_isError(); ex : buffer size too small).
205
206'normalizedCounter' can then be used to create the compression table 'CTable'.
207The space required by 'CTable' must be already allocated, using FSE_createCTable().
208You can then use FSE_buildCTable() to fill 'CTable'.
209If there is an error, both functions will return an ErrorCode (which can be tested using FSE_isError()).
210
211'CTable' can then be used to compress 'src', with FSE_compress_usingCTable().
212Similar to FSE_count(), the convention is that 'src' is assumed to be a table of char of size 'srcSize'
213The function returns the size of compressed data (without header), necessarily <= `dstCapacity`.
214If it returns '0', compressed data could not fit into 'dst'.
215If there is an error, the function will return an ErrorCode (which can be tested using FSE_isError()).
216*/
217
218
219/* *** DECOMPRESSION *** */
220
221/*! FSE_readNCount():
222    Read compactly saved 'normalizedCounter' from 'rBuffer'.
223    @return : size read from 'rBuffer',
224              or an errorCode, which can be tested using FSE_isError().
225              maxSymbolValuePtr[0] and tableLogPtr[0] will also be updated with their respective values */
226size_t FSE_readNCount (short* normalizedCounter, unsigned* maxSymbolValuePtr, unsigned* tableLogPtr, const void* rBuffer, size_t rBuffSize);
227
228/*! Constructor and Destructor of FSE_DTable.
229    Note that its size depends on 'tableLog' */
230typedef unsigned FSE_DTable;   /* don't allocate that. It's just a way to be more restrictive than void* */
231FSE_DTable* FSE_createDTable(unsigned tableLog);
232void        FSE_freeDTable(FSE_DTable* dt);
233
234/*! FSE_buildDTable():
235    Builds 'dt', which must be already allocated, using FSE_createDTable().
236    return : 0, or an errorCode, which can be tested using FSE_isError() */
237size_t FSE_buildDTable (FSE_DTable* dt, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog);
238
239/*! FSE_decompress_usingDTable():
240    Decompress compressed source `cSrc` of size `cSrcSize` using `dt`
241    into `dst` which must be already allocated.
242    @return : size of regenerated data (necessarily <= `dstCapacity`),
243              or an errorCode, which can be tested using FSE_isError() */
244size_t FSE_decompress_usingDTable(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize, const FSE_DTable* dt);
245
246/*!
247Tutorial :
248----------
249(Note : these functions only decompress FSE-compressed blocks.
250 If block is uncompressed, use memcpy() instead
251 If block is a single repeated byte, use memset() instead )
252
253The first step is to obtain the normalized frequencies of symbols.
254This can be performed by FSE_readNCount() if it was saved using FSE_writeNCount().
255'normalizedCounter' must be already allocated, and have at least 'maxSymbolValuePtr[0]+1' cells of signed short.
256In practice, that means it's necessary to know 'maxSymbolValue' beforehand,
257or size the table to handle worst case situations (typically 256).
258FSE_readNCount() will provide 'tableLog' and 'maxSymbolValue'.
259The result of FSE_readNCount() is the number of bytes read from 'rBuffer'.
260Note that 'rBufferSize' must be at least 4 bytes, even if useful information is less than that.
261If there is an error, the function will return an error code, which can be tested using FSE_isError().
262
263The next step is to build the decompression tables 'FSE_DTable' from 'normalizedCounter'.
264This is performed by the function FSE_buildDTable().
265The space required by 'FSE_DTable' must be already allocated using FSE_createDTable().
266If there is an error, the function will return an error code, which can be tested using FSE_isError().
267
268`FSE_DTable` can then be used to decompress `cSrc`, with FSE_decompress_usingDTable().
269`cSrcSize` must be strictly correct, otherwise decompression will fail.
270FSE_decompress_usingDTable() result will tell how many bytes were regenerated (<=`dstCapacity`).
271If there is an error, the function will return an error code, which can be tested using FSE_isError(). (ex: dst buffer too small)
272*/
273
274
275#ifdef FSE_STATIC_LINKING_ONLY
276
277/* *** Dependency *** */
278#include "bitstream.h"
279
280
281/* *****************************************
282*  Static allocation
283*******************************************/
284/* FSE buffer bounds */
285#define FSE_NCOUNTBOUND 512
286#define FSE_BLOCKBOUND(size) (size + (size>>7))
287#define FSE_COMPRESSBOUND(size) (FSE_NCOUNTBOUND + FSE_BLOCKBOUND(size))   /* Macro version, useful for static allocation */
288
289/* It is possible to statically allocate FSE CTable/DTable as a table of unsigned using below macros */
290#define FSE_CTABLE_SIZE_U32(maxTableLog, maxSymbolValue)   (1 + (1<<(maxTableLog-1)) + ((maxSymbolValue+1)*2))
291#define FSE_DTABLE_SIZE_U32(maxTableLog)                   (1 + (1<<maxTableLog))
292
293
294/* *****************************************
295*  FSE advanced API
296*******************************************/
297size_t FSE_countFast(unsigned* count, unsigned* maxSymbolValuePtr, const void* src, size_t srcSize);
298/**< same as FSE_count(), but blindly trusts that all byte values within src are <= *maxSymbolValuePtr  */
299
300unsigned FSE_optimalTableLog_internal(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue, unsigned minus);
301/**< same as FSE_optimalTableLog(), which used `minus==2` */
302
303size_t FSE_buildCTable_raw (FSE_CTable* ct, unsigned nbBits);
304/**< build a fake FSE_CTable, designed to not compress an input, where each symbol uses nbBits */
305
306size_t FSE_buildCTable_rle (FSE_CTable* ct, unsigned char symbolValue);
307/**< build a fake FSE_CTable, designed to compress always the same symbolValue */
308
309size_t FSE_buildDTable_raw (FSE_DTable* dt, unsigned nbBits);
310/**< build a fake FSE_DTable, designed to read an uncompressed bitstream where each symbol uses nbBits */
311
312size_t FSE_buildDTable_rle (FSE_DTable* dt, unsigned char symbolValue);
313/**< build a fake FSE_DTable, designed to always generate the same symbolValue */
314
315
316/* *****************************************
317*  FSE symbol compression API
318*******************************************/
319/*!
320   This API consists of small unitary functions, which highly benefit from being inlined.
321   You will want to enable link-time-optimization to ensure these functions are properly inlined in your binary.
322   Visual seems to do it automatically.
323   For gcc or clang, you'll need to add -flto flag at compilation and linking stages.
324   If none of these solutions is applicable, include "fse.c" directly.
325*/
326typedef struct
327{
328    ptrdiff_t   value;
329    const void* stateTable;
330    const void* symbolTT;
331    unsigned    stateLog;
332} FSE_CState_t;
333
334static void FSE_initCState(FSE_CState_t* CStatePtr, const FSE_CTable* ct);
335
336static void FSE_encodeSymbol(BIT_CStream_t* bitC, FSE_CState_t* CStatePtr, unsigned symbol);
337
338static void FSE_flushCState(BIT_CStream_t* bitC, const FSE_CState_t* CStatePtr);
339
340/**<
341These functions are inner components of FSE_compress_usingCTable().
342They allow the creation of custom streams, mixing multiple tables and bit sources.
343
344A key property to keep in mind is that encoding and decoding are done **in reverse direction**.
345So the first symbol you will encode is the last you will decode, like a LIFO stack.
346
347You will need a few variables to track your CStream. They are :
348
349FSE_CTable    ct;         // Provided by FSE_buildCTable()
350BIT_CStream_t bitStream;  // bitStream tracking structure
351FSE_CState_t  state;      // State tracking structure (can have several)
352
353
354The first thing to do is to init bitStream and state.
355    size_t errorCode = BIT_initCStream(&bitStream, dstBuffer, maxDstSize);
356    FSE_initCState(&state, ct);
357
358Note that BIT_initCStream() can produce an error code, so its result should be tested, using FSE_isError();
359You can then encode your input data, byte after byte.
360FSE_encodeSymbol() outputs a maximum of 'tableLog' bits at a time.
361Remember decoding will be done in reverse direction.
362    FSE_encodeByte(&bitStream, &state, symbol);
363
364At any time, you can also add any bit sequence.
365Note : maximum allowed nbBits is 25, for compatibility with 32-bits decoders
366    BIT_addBits(&bitStream, bitField, nbBits);
367
368The above methods don't commit data to memory, they just store it into local register, for speed.
369Local register size is 64-bits on 64-bits systems, 32-bits on 32-bits systems (size_t).
370Writing data to memory is a manual operation, performed by the flushBits function.
371    BIT_flushBits(&bitStream);
372
373Your last FSE encoding operation shall be to flush your last state value(s).
374    FSE_flushState(&bitStream, &state);
375
376Finally, you must close the bitStream.
377The function returns the size of CStream in bytes.
378If data couldn't fit into dstBuffer, it will return a 0 ( == not compressible)
379If there is an error, it returns an errorCode (which can be tested using FSE_isError()).
380    size_t size = BIT_closeCStream(&bitStream);
381*/
382
383
384/* *****************************************
385*  FSE symbol decompression API
386*******************************************/
387typedef struct
388{
389    size_t      state;
390    const void* table;   /* precise table may vary, depending on U16 */
391} FSE_DState_t;
392
393
394static void     FSE_initDState(FSE_DState_t* DStatePtr, BIT_DStream_t* bitD, const FSE_DTable* dt);
395
396static unsigned char FSE_decodeSymbol(FSE_DState_t* DStatePtr, BIT_DStream_t* bitD);
397
398static unsigned FSE_endOfDState(const FSE_DState_t* DStatePtr);
399
400/**<
401Let's now decompose FSE_decompress_usingDTable() into its unitary components.
402You will decode FSE-encoded symbols from the bitStream,
403and also any other bitFields you put in, **in reverse order**.
404
405You will need a few variables to track your bitStream. They are :
406
407BIT_DStream_t DStream;    // Stream context
408FSE_DState_t  DState;     // State context. Multiple ones are possible
409FSE_DTable*   DTablePtr;  // Decoding table, provided by FSE_buildDTable()
410
411The first thing to do is to init the bitStream.
412    errorCode = BIT_initDStream(&DStream, srcBuffer, srcSize);
413
414You should then retrieve your initial state(s)
415(in reverse flushing order if you have several ones) :
416    errorCode = FSE_initDState(&DState, &DStream, DTablePtr);
417
418You can then decode your data, symbol after symbol.
419For information the maximum number of bits read by FSE_decodeSymbol() is 'tableLog'.
420Keep in mind that symbols are decoded in reverse order, like a LIFO stack (last in, first out).
421    unsigned char symbol = FSE_decodeSymbol(&DState, &DStream);
422
423You can retrieve any bitfield you eventually stored into the bitStream (in reverse order)
424Note : maximum allowed nbBits is 25, for 32-bits compatibility
425    size_t bitField = BIT_readBits(&DStream, nbBits);
426
427All above operations only read from local register (which size depends on size_t).
428Refueling the register from memory is manually performed by the reload method.
429    endSignal = FSE_reloadDStream(&DStream);
430
431BIT_reloadDStream() result tells if there is still some more data to read from DStream.
432BIT_DStream_unfinished : there is still some data left into the DStream.
433BIT_DStream_endOfBuffer : Dstream reached end of buffer. Its container may no longer be completely filled.
434BIT_DStream_completed : Dstream reached its exact end, corresponding in general to decompression completed.
435BIT_DStream_tooFar : Dstream went too far. Decompression result is corrupted.
436
437When reaching end of buffer (BIT_DStream_endOfBuffer), progress slowly, notably if you decode multiple symbols per loop,
438to properly detect the exact end of stream.
439After each decoded symbol, check if DStream is fully consumed using this simple test :
440    BIT_reloadDStream(&DStream) >= BIT_DStream_completed
441
442When it's done, verify decompression is fully completed, by checking both DStream and the relevant states.
443Checking if DStream has reached its end is performed by :
444    BIT_endOfDStream(&DStream);
445Check also the states. There might be some symbols left there, if some high probability ones (>50%) are possible.
446    FSE_endOfDState(&DState);
447*/
448
449
450/* *****************************************
451*  FSE unsafe API
452*******************************************/
453static unsigned char FSE_decodeSymbolFast(FSE_DState_t* DStatePtr, BIT_DStream_t* bitD);
454/* faster, but works only if nbBits is always >= 1 (otherwise, result will be corrupted) */
455
456
457/* *****************************************
458*  Implementation of inlined functions
459*******************************************/
460typedef struct {
461    int deltaFindState;
462    U32 deltaNbBits;
463} FSE_symbolCompressionTransform; /* total 8 bytes */
464
465MEM_STATIC void FSE_initCState(FSE_CState_t* statePtr, const FSE_CTable* ct)
466{
467    const void* ptr = ct;
468    const U16* u16ptr = (const U16*) ptr;
469    const U32 tableLog = MEM_read16(ptr);
470    statePtr->value = (ptrdiff_t)1<<tableLog;
471    statePtr->stateTable = u16ptr+2;
472    statePtr->symbolTT = ((const U32*)ct + 1 + (tableLog ? (1<<(tableLog-1)) : 1));
473    statePtr->stateLog = tableLog;
474}
475
476
477/*! FSE_initCState2() :
478*   Same as FSE_initCState(), but the first symbol to include (which will be the last to be read)
479*   uses the smallest state value possible, saving the cost of this symbol */
480MEM_STATIC void FSE_initCState2(FSE_CState_t* statePtr, const FSE_CTable* ct, U32 symbol)
481{
482    FSE_initCState(statePtr, ct);
483    {   const FSE_symbolCompressionTransform symbolTT = ((const FSE_symbolCompressionTransform*)(statePtr->symbolTT))[symbol];
484        const U16* stateTable = (const U16*)(statePtr->stateTable);
485        U32 nbBitsOut  = (U32)((symbolTT.deltaNbBits + (1<<15)) >> 16);
486        statePtr->value = (nbBitsOut << 16) - symbolTT.deltaNbBits;
487        statePtr->value = stateTable[(statePtr->value >> nbBitsOut) + symbolTT.deltaFindState];
488    }
489}
490
491MEM_STATIC void FSE_encodeSymbol(BIT_CStream_t* bitC, FSE_CState_t* statePtr, U32 symbol)
492{
493    const FSE_symbolCompressionTransform symbolTT = ((const FSE_symbolCompressionTransform*)(statePtr->symbolTT))[symbol];
494    const U16* const stateTable = (const U16*)(statePtr->stateTable);
495    U32 nbBitsOut  = (U32)((statePtr->value + symbolTT.deltaNbBits) >> 16);
496    BIT_addBits(bitC, statePtr->value, nbBitsOut);
497    statePtr->value = stateTable[ (statePtr->value >> nbBitsOut) + symbolTT.deltaFindState];
498}
499
500MEM_STATIC void FSE_flushCState(BIT_CStream_t* bitC, const FSE_CState_t* statePtr)
501{
502    BIT_addBits(bitC, statePtr->value, statePtr->stateLog);
503    BIT_flushBits(bitC);
504}
505
506/*<=====    Decompression    =====>*/
507
508typedef struct {
509    U16 tableLog;
510    U16 fastMode;
511} FSE_DTableHeader;   /* sizeof U32 */
512
513typedef struct
514{
515    unsigned short newState;
516    unsigned char  symbol;
517    unsigned char  nbBits;
518} FSE_decode_t;   /* size == U32 */
519
520MEM_STATIC void FSE_initDState(FSE_DState_t* DStatePtr, BIT_DStream_t* bitD, const FSE_DTable* dt)
521{
522    const void* ptr = dt;
523    const FSE_DTableHeader* const DTableH = (const FSE_DTableHeader*)ptr;
524    DStatePtr->state = BIT_readBits(bitD, DTableH->tableLog);
525    BIT_reloadDStream(bitD);
526    DStatePtr->table = dt + 1;
527}
528
529MEM_STATIC BYTE FSE_peekSymbol(const FSE_DState_t* DStatePtr)
530{
531    FSE_decode_t const DInfo = ((const FSE_decode_t*)(DStatePtr->table))[DStatePtr->state];
532    return DInfo.symbol;
533}
534
535MEM_STATIC void FSE_updateState(FSE_DState_t* DStatePtr, BIT_DStream_t* bitD)
536{
537    FSE_decode_t const DInfo = ((const FSE_decode_t*)(DStatePtr->table))[DStatePtr->state];
538    U32 const nbBits = DInfo.nbBits;
539    size_t const lowBits = BIT_readBits(bitD, nbBits);
540    DStatePtr->state = DInfo.newState + lowBits;
541}
542
543MEM_STATIC BYTE FSE_decodeSymbol(FSE_DState_t* DStatePtr, BIT_DStream_t* bitD)
544{
545    FSE_decode_t const DInfo = ((const FSE_decode_t*)(DStatePtr->table))[DStatePtr->state];
546    U32 const nbBits = DInfo.nbBits;
547    BYTE const symbol = DInfo.symbol;
548    size_t const lowBits = BIT_readBits(bitD, nbBits);
549
550    DStatePtr->state = DInfo.newState + lowBits;
551    return symbol;
552}
553
554/*! FSE_decodeSymbolFast() :
555    unsafe, only works if no symbol has a probability > 50% */
556MEM_STATIC BYTE FSE_decodeSymbolFast(FSE_DState_t* DStatePtr, BIT_DStream_t* bitD)
557{
558    FSE_decode_t const DInfo = ((const FSE_decode_t*)(DStatePtr->table))[DStatePtr->state];
559    U32 const nbBits = DInfo.nbBits;
560    BYTE const symbol = DInfo.symbol;
561    size_t const lowBits = BIT_readBitsFast(bitD, nbBits);
562
563    DStatePtr->state = DInfo.newState + lowBits;
564    return symbol;
565}
566
567MEM_STATIC unsigned FSE_endOfDState(const FSE_DState_t* DStatePtr)
568{
569    return DStatePtr->state == 0;
570}
571
572
573
574#ifndef FSE_COMMONDEFS_ONLY
575
576/* **************************************************************
577*  Tuning parameters
578****************************************************************/
579/*!MEMORY_USAGE :
580*  Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
581*  Increasing memory usage improves compression ratio
582*  Reduced memory usage can improve speed, due to cache effect
583*  Recommended max value is 14, for 16KB, which nicely fits into Intel x86 L1 cache */
584#define FSE_MAX_MEMORY_USAGE 14
585#define FSE_DEFAULT_MEMORY_USAGE 13
586
587/*!FSE_MAX_SYMBOL_VALUE :
588*  Maximum symbol value authorized.
589*  Required for proper stack allocation */
590#define FSE_MAX_SYMBOL_VALUE 255
591
592
593/* **************************************************************
594*  template functions type & suffix
595****************************************************************/
596#define FSE_FUNCTION_TYPE BYTE
597#define FSE_FUNCTION_EXTENSION
598#define FSE_DECODE_TYPE FSE_decode_t
599
600
601#endif   /* !FSE_COMMONDEFS_ONLY */
602
603
604/* ***************************************************************
605*  Constants
606*****************************************************************/
607#define FSE_MAX_TABLELOG  (FSE_MAX_MEMORY_USAGE-2)
608#define FSE_MAX_TABLESIZE (1U<<FSE_MAX_TABLELOG)
609#define FSE_MAXTABLESIZE_MASK (FSE_MAX_TABLESIZE-1)
610#define FSE_DEFAULT_TABLELOG (FSE_DEFAULT_MEMORY_USAGE-2)
611#define FSE_MIN_TABLELOG 5
612
613#define FSE_TABLELOG_ABSOLUTE_MAX 15
614#if FSE_MAX_TABLELOG > FSE_TABLELOG_ABSOLUTE_MAX
615#  error "FSE_MAX_TABLELOG > FSE_TABLELOG_ABSOLUTE_MAX is not supported"
616#endif
617
618#define FSE_TABLESTEP(tableSize) ((tableSize>>1) + (tableSize>>3) + 3)
619
620
621#endif /* FSE_STATIC_LINKING_ONLY */
622
623
624#if defined (__cplusplus)
625}
626#endif
627
628#endif  /* FSE_H */
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