1 /* ******************************************************************
2 * FSE : Finite State Entropy encoder
3 * Copyright (c) Yann Collet, Facebook, Inc.
4 *
5 * You can contact the author at :
6 * - FSE source repository : https://github.com/Cyan4973/FiniteStateEntropy
7 * - Public forum : https://groups.google.com/forum/#!forum/lz4c
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 /* **************************************************************
16 * Includes
17 ****************************************************************/
18 #include "../common/compiler.h"
19 #include "../common/mem.h" /* U32, U16, etc. */
20 #include "../common/debug.h" /* assert, DEBUGLOG */
21 #include "hist.h" /* HIST_count_wksp */
22 #include "../common/bitstream.h"
23 #define FSE_STATIC_LINKING_ONLY
24 #include "../common/fse.h"
25 #include "../common/error_private.h"
26 #define ZSTD_DEPS_NEED_MALLOC
27 #define ZSTD_DEPS_NEED_MATH64
28 #include "../common/zstd_deps.h" /* ZSTD_malloc, ZSTD_free, ZSTD_memcpy, ZSTD_memset */
29
30
31 /* **************************************************************
32 * Error Management
33 ****************************************************************/
34 #define FSE_isError ERR_isError
35
36
37 /* **************************************************************
38 * Templates
39 ****************************************************************/
40 /*
41 designed to be included
42 for type-specific functions (template emulation in C)
43 Objective is to write these functions only once, for improved maintenance
44 */
45
46 /* safety checks */
47 #ifndef FSE_FUNCTION_EXTENSION
48 # error "FSE_FUNCTION_EXTENSION must be defined"
49 #endif
50 #ifndef FSE_FUNCTION_TYPE
51 # error "FSE_FUNCTION_TYPE must be defined"
52 #endif
53
54 /* Function names */
55 #define FSE_CAT(X,Y) X##Y
56 #define FSE_FUNCTION_NAME(X,Y) FSE_CAT(X,Y)
57 #define FSE_TYPE_NAME(X,Y) FSE_CAT(X,Y)
58
59
60 /* Function templates */
61
62 /* FSE_buildCTable_wksp() :
63 * Same as FSE_buildCTable(), but using an externally allocated scratch buffer (`workSpace`).
64 * wkspSize should be sized to handle worst case situation, which is `1<<max_tableLog * sizeof(FSE_FUNCTION_TYPE)`
65 * workSpace must also be properly aligned with FSE_FUNCTION_TYPE requirements
66 */
FSE_buildCTable_wksp(FSE_CTable * ct,const short * normalizedCounter,unsigned maxSymbolValue,unsigned tableLog,void * workSpace,size_t wkspSize)67 size_t FSE_buildCTable_wksp(FSE_CTable* ct,
68 const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog,
69 void* workSpace, size_t wkspSize)
70 {
71 U32 const tableSize = 1 << tableLog;
72 U32 const tableMask = tableSize - 1;
73 void* const ptr = ct;
74 U16* const tableU16 = ( (U16*) ptr) + 2;
75 void* const FSCT = ((U32*)ptr) + 1 /* header */ + (tableLog ? tableSize>>1 : 1) ;
76 FSE_symbolCompressionTransform* const symbolTT = (FSE_symbolCompressionTransform*) (FSCT);
77 U32 const step = FSE_TABLESTEP(tableSize);
78
79 U32* cumul = (U32*)workSpace;
80 FSE_FUNCTION_TYPE* tableSymbol = (FSE_FUNCTION_TYPE*)(cumul + (maxSymbolValue + 2));
81
82 U32 highThreshold = tableSize-1;
83
84 if ((size_t)workSpace & 3) return ERROR(GENERIC); /* Must be 4 byte aligned */
85 if (FSE_BUILD_CTABLE_WORKSPACE_SIZE(maxSymbolValue, tableLog) > wkspSize) return ERROR(tableLog_tooLarge);
86 /* CTable header */
87 tableU16[-2] = (U16) tableLog;
88 tableU16[-1] = (U16) maxSymbolValue;
89 assert(tableLog < 16); /* required for threshold strategy to work */
90
91 /* For explanations on how to distribute symbol values over the table :
92 * http://fastcompression.blogspot.fr/2014/02/fse-distributing-symbol-values.html */
93
94 #ifdef __clang_analyzer__
95 ZSTD_memset(tableSymbol, 0, sizeof(*tableSymbol) * tableSize); /* useless initialization, just to keep scan-build happy */
96 #endif
97
98 /* symbol start positions */
99 { U32 u;
100 cumul[0] = 0;
101 for (u=1; u <= maxSymbolValue+1; u++) {
102 if (normalizedCounter[u-1]==-1) { /* Low proba symbol */
103 cumul[u] = cumul[u-1] + 1;
104 tableSymbol[highThreshold--] = (FSE_FUNCTION_TYPE)(u-1);
105 } else {
106 cumul[u] = cumul[u-1] + normalizedCounter[u-1];
107 } }
108 cumul[maxSymbolValue+1] = tableSize+1;
109 }
110
111 /* Spread symbols */
112 { U32 position = 0;
113 U32 symbol;
114 for (symbol=0; symbol<=maxSymbolValue; symbol++) {
115 int nbOccurrences;
116 int const freq = normalizedCounter[symbol];
117 for (nbOccurrences=0; nbOccurrences<freq; nbOccurrences++) {
118 tableSymbol[position] = (FSE_FUNCTION_TYPE)symbol;
119 position = (position + step) & tableMask;
120 while (position > highThreshold)
121 position = (position + step) & tableMask; /* Low proba area */
122 } }
123
124 assert(position==0); /* Must have initialized all positions */
125 }
126
127 /* Build table */
128 { U32 u; for (u=0; u<tableSize; u++) {
129 FSE_FUNCTION_TYPE s = tableSymbol[u]; /* note : static analyzer may not understand tableSymbol is properly initialized */
130 tableU16[cumul[s]++] = (U16) (tableSize+u); /* TableU16 : sorted by symbol order; gives next state value */
131 } }
132
133 /* Build Symbol Transformation Table */
134 { unsigned total = 0;
135 unsigned s;
136 for (s=0; s<=maxSymbolValue; s++) {
137 switch (normalizedCounter[s])
138 {
139 case 0:
140 /* filling nonetheless, for compatibility with FSE_getMaxNbBits() */
141 symbolTT[s].deltaNbBits = ((tableLog+1) << 16) - (1<<tableLog);
142 break;
143
144 case -1:
145 case 1:
146 symbolTT[s].deltaNbBits = (tableLog << 16) - (1<<tableLog);
147 symbolTT[s].deltaFindState = total - 1;
148 total ++;
149 break;
150 default :
151 {
152 U32 const maxBitsOut = tableLog - BIT_highbit32 (normalizedCounter[s]-1);
153 U32 const minStatePlus = normalizedCounter[s] << maxBitsOut;
154 symbolTT[s].deltaNbBits = (maxBitsOut << 16) - minStatePlus;
155 symbolTT[s].deltaFindState = total - normalizedCounter[s];
156 total += normalizedCounter[s];
157 } } } }
158
159 #if 0 /* debug : symbol costs */
160 DEBUGLOG(5, "\n --- table statistics : ");
161 { U32 symbol;
162 for (symbol=0; symbol<=maxSymbolValue; symbol++) {
163 DEBUGLOG(5, "%3u: w=%3i, maxBits=%u, fracBits=%.2f",
164 symbol, normalizedCounter[symbol],
165 FSE_getMaxNbBits(symbolTT, symbol),
166 (double)FSE_bitCost(symbolTT, tableLog, symbol, 8) / 256);
167 }
168 }
169 #endif
170
171 return 0;
172 }
173
174
175
176
177 #ifndef FSE_COMMONDEFS_ONLY
178
179
180 /*-**************************************************************
181 * FSE NCount encoding
182 ****************************************************************/
FSE_NCountWriteBound(unsigned maxSymbolValue,unsigned tableLog)183 size_t FSE_NCountWriteBound(unsigned maxSymbolValue, unsigned tableLog)
184 {
185 size_t const maxHeaderSize = (((maxSymbolValue+1) * tableLog) >> 3) + 3;
186 return maxSymbolValue ? maxHeaderSize : FSE_NCOUNTBOUND; /* maxSymbolValue==0 ? use default */
187 }
188
189 static size_t
FSE_writeNCount_generic(void * header,size_t headerBufferSize,const short * normalizedCounter,unsigned maxSymbolValue,unsigned tableLog,unsigned writeIsSafe)190 FSE_writeNCount_generic (void* header, size_t headerBufferSize,
191 const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog,
192 unsigned writeIsSafe)
193 {
194 BYTE* const ostart = (BYTE*) header;
195 BYTE* out = ostart;
196 BYTE* const oend = ostart + headerBufferSize;
197 int nbBits;
198 const int tableSize = 1 << tableLog;
199 int remaining;
200 int threshold;
201 U32 bitStream = 0;
202 int bitCount = 0;
203 unsigned symbol = 0;
204 unsigned const alphabetSize = maxSymbolValue + 1;
205 int previousIs0 = 0;
206
207 /* Table Size */
208 bitStream += (tableLog-FSE_MIN_TABLELOG) << bitCount;
209 bitCount += 4;
210
211 /* Init */
212 remaining = tableSize+1; /* +1 for extra accuracy */
213 threshold = tableSize;
214 nbBits = tableLog+1;
215
216 while ((symbol < alphabetSize) && (remaining>1)) { /* stops at 1 */
217 if (previousIs0) {
218 unsigned start = symbol;
219 while ((symbol < alphabetSize) && !normalizedCounter[symbol]) symbol++;
220 if (symbol == alphabetSize) break; /* incorrect distribution */
221 while (symbol >= start+24) {
222 start+=24;
223 bitStream += 0xFFFFU << bitCount;
224 if ((!writeIsSafe) && (out > oend-2))
225 return ERROR(dstSize_tooSmall); /* Buffer overflow */
226 out[0] = (BYTE) bitStream;
227 out[1] = (BYTE)(bitStream>>8);
228 out+=2;
229 bitStream>>=16;
230 }
231 while (symbol >= start+3) {
232 start+=3;
233 bitStream += 3 << bitCount;
234 bitCount += 2;
235 }
236 bitStream += (symbol-start) << bitCount;
237 bitCount += 2;
238 if (bitCount>16) {
239 if ((!writeIsSafe) && (out > oend - 2))
240 return ERROR(dstSize_tooSmall); /* Buffer overflow */
241 out[0] = (BYTE)bitStream;
242 out[1] = (BYTE)(bitStream>>8);
243 out += 2;
244 bitStream >>= 16;
245 bitCount -= 16;
246 } }
247 { int count = normalizedCounter[symbol++];
248 int const max = (2*threshold-1) - remaining;
249 remaining -= count < 0 ? -count : count;
250 count++; /* +1 for extra accuracy */
251 if (count>=threshold)
252 count += max; /* [0..max[ [max..threshold[ (...) [threshold+max 2*threshold[ */
253 bitStream += count << bitCount;
254 bitCount += nbBits;
255 bitCount -= (count<max);
256 previousIs0 = (count==1);
257 if (remaining<1) return ERROR(GENERIC);
258 while (remaining<threshold) { nbBits--; threshold>>=1; }
259 }
260 if (bitCount>16) {
261 if ((!writeIsSafe) && (out > oend - 2))
262 return ERROR(dstSize_tooSmall); /* Buffer overflow */
263 out[0] = (BYTE)bitStream;
264 out[1] = (BYTE)(bitStream>>8);
265 out += 2;
266 bitStream >>= 16;
267 bitCount -= 16;
268 } }
269
270 if (remaining != 1)
271 return ERROR(GENERIC); /* incorrect normalized distribution */
272 assert(symbol <= alphabetSize);
273
274 /* flush remaining bitStream */
275 if ((!writeIsSafe) && (out > oend - 2))
276 return ERROR(dstSize_tooSmall); /* Buffer overflow */
277 out[0] = (BYTE)bitStream;
278 out[1] = (BYTE)(bitStream>>8);
279 out+= (bitCount+7) /8;
280
281 return (out-ostart);
282 }
283
284
FSE_writeNCount(void * buffer,size_t bufferSize,const short * normalizedCounter,unsigned maxSymbolValue,unsigned tableLog)285 size_t FSE_writeNCount (void* buffer, size_t bufferSize,
286 const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog)
287 {
288 if (tableLog > FSE_MAX_TABLELOG) return ERROR(tableLog_tooLarge); /* Unsupported */
289 if (tableLog < FSE_MIN_TABLELOG) return ERROR(GENERIC); /* Unsupported */
290
291 if (bufferSize < FSE_NCountWriteBound(maxSymbolValue, tableLog))
292 return FSE_writeNCount_generic(buffer, bufferSize, normalizedCounter, maxSymbolValue, tableLog, 0);
293
294 return FSE_writeNCount_generic(buffer, bufferSize, normalizedCounter, maxSymbolValue, tableLog, 1 /* write in buffer is safe */);
295 }
296
297
298 /*-**************************************************************
299 * FSE Compression Code
300 ****************************************************************/
301
FSE_createCTable(unsigned maxSymbolValue,unsigned tableLog)302 FSE_CTable* FSE_createCTable (unsigned maxSymbolValue, unsigned tableLog)
303 {
304 size_t size;
305 if (tableLog > FSE_TABLELOG_ABSOLUTE_MAX) tableLog = FSE_TABLELOG_ABSOLUTE_MAX;
306 size = FSE_CTABLE_SIZE_U32 (tableLog, maxSymbolValue) * sizeof(U32);
307 return (FSE_CTable*)ZSTD_malloc(size);
308 }
309
FSE_freeCTable(FSE_CTable * ct)310 void FSE_freeCTable (FSE_CTable* ct) { ZSTD_free(ct); }
311
312 /* provides the minimum logSize to safely represent a distribution */
FSE_minTableLog(size_t srcSize,unsigned maxSymbolValue)313 static unsigned FSE_minTableLog(size_t srcSize, unsigned maxSymbolValue)
314 {
315 U32 minBitsSrc = BIT_highbit32((U32)(srcSize)) + 1;
316 U32 minBitsSymbols = BIT_highbit32(maxSymbolValue) + 2;
317 U32 minBits = minBitsSrc < minBitsSymbols ? minBitsSrc : minBitsSymbols;
318 assert(srcSize > 1); /* Not supported, RLE should be used instead */
319 return minBits;
320 }
321
FSE_optimalTableLog_internal(unsigned maxTableLog,size_t srcSize,unsigned maxSymbolValue,unsigned minus)322 unsigned FSE_optimalTableLog_internal(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue, unsigned minus)
323 {
324 U32 maxBitsSrc = BIT_highbit32((U32)(srcSize - 1)) - minus;
325 U32 tableLog = maxTableLog;
326 U32 minBits = FSE_minTableLog(srcSize, maxSymbolValue);
327 assert(srcSize > 1); /* Not supported, RLE should be used instead */
328 if (tableLog==0) tableLog = FSE_DEFAULT_TABLELOG;
329 if (maxBitsSrc < tableLog) tableLog = maxBitsSrc; /* Accuracy can be reduced */
330 if (minBits > tableLog) tableLog = minBits; /* Need a minimum to safely represent all symbol values */
331 if (tableLog < FSE_MIN_TABLELOG) tableLog = FSE_MIN_TABLELOG;
332 if (tableLog > FSE_MAX_TABLELOG) tableLog = FSE_MAX_TABLELOG;
333 return tableLog;
334 }
335
FSE_optimalTableLog(unsigned maxTableLog,size_t srcSize,unsigned maxSymbolValue)336 unsigned FSE_optimalTableLog(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue)
337 {
338 return FSE_optimalTableLog_internal(maxTableLog, srcSize, maxSymbolValue, 2);
339 }
340
341 /* Secondary normalization method.
342 To be used when primary method fails. */
343
FSE_normalizeM2(short * norm,U32 tableLog,const unsigned * count,size_t total,U32 maxSymbolValue,short lowProbCount)344 static size_t FSE_normalizeM2(short* norm, U32 tableLog, const unsigned* count, size_t total, U32 maxSymbolValue, short lowProbCount)
345 {
346 short const NOT_YET_ASSIGNED = -2;
347 U32 s;
348 U32 distributed = 0;
349 U32 ToDistribute;
350
351 /* Init */
352 U32 const lowThreshold = (U32)(total >> tableLog);
353 U32 lowOne = (U32)((total * 3) >> (tableLog + 1));
354
355 for (s=0; s<=maxSymbolValue; s++) {
356 if (count[s] == 0) {
357 norm[s]=0;
358 continue;
359 }
360 if (count[s] <= lowThreshold) {
361 norm[s] = lowProbCount;
362 distributed++;
363 total -= count[s];
364 continue;
365 }
366 if (count[s] <= lowOne) {
367 norm[s] = 1;
368 distributed++;
369 total -= count[s];
370 continue;
371 }
372
373 norm[s]=NOT_YET_ASSIGNED;
374 }
375 ToDistribute = (1 << tableLog) - distributed;
376
377 if (ToDistribute == 0)
378 return 0;
379
380 if ((total / ToDistribute) > lowOne) {
381 /* risk of rounding to zero */
382 lowOne = (U32)((total * 3) / (ToDistribute * 2));
383 for (s=0; s<=maxSymbolValue; s++) {
384 if ((norm[s] == NOT_YET_ASSIGNED) && (count[s] <= lowOne)) {
385 norm[s] = 1;
386 distributed++;
387 total -= count[s];
388 continue;
389 } }
390 ToDistribute = (1 << tableLog) - distributed;
391 }
392
393 if (distributed == maxSymbolValue+1) {
394 /* all values are pretty poor;
395 probably incompressible data (should have already been detected);
396 find max, then give all remaining points to max */
397 U32 maxV = 0, maxC = 0;
398 for (s=0; s<=maxSymbolValue; s++)
399 if (count[s] > maxC) { maxV=s; maxC=count[s]; }
400 norm[maxV] += (short)ToDistribute;
401 return 0;
402 }
403
404 if (total == 0) {
405 /* all of the symbols were low enough for the lowOne or lowThreshold */
406 for (s=0; ToDistribute > 0; s = (s+1)%(maxSymbolValue+1))
407 if (norm[s] > 0) { ToDistribute--; norm[s]++; }
408 return 0;
409 }
410
411 { U64 const vStepLog = 62 - tableLog;
412 U64 const mid = (1ULL << (vStepLog-1)) - 1;
413 U64 const rStep = ZSTD_div64((((U64)1<<vStepLog) * ToDistribute) + mid, (U32)total); /* scale on remaining */
414 U64 tmpTotal = mid;
415 for (s=0; s<=maxSymbolValue; s++) {
416 if (norm[s]==NOT_YET_ASSIGNED) {
417 U64 const end = tmpTotal + (count[s] * rStep);
418 U32 const sStart = (U32)(tmpTotal >> vStepLog);
419 U32 const sEnd = (U32)(end >> vStepLog);
420 U32 const weight = sEnd - sStart;
421 if (weight < 1)
422 return ERROR(GENERIC);
423 norm[s] = (short)weight;
424 tmpTotal = end;
425 } } }
426
427 return 0;
428 }
429
FSE_normalizeCount(short * normalizedCounter,unsigned tableLog,const unsigned * count,size_t total,unsigned maxSymbolValue,unsigned useLowProbCount)430 size_t FSE_normalizeCount (short* normalizedCounter, unsigned tableLog,
431 const unsigned* count, size_t total,
432 unsigned maxSymbolValue, unsigned useLowProbCount)
433 {
434 /* Sanity checks */
435 if (tableLog==0) tableLog = FSE_DEFAULT_TABLELOG;
436 if (tableLog < FSE_MIN_TABLELOG) return ERROR(GENERIC); /* Unsupported size */
437 if (tableLog > FSE_MAX_TABLELOG) return ERROR(tableLog_tooLarge); /* Unsupported size */
438 if (tableLog < FSE_minTableLog(total, maxSymbolValue)) return ERROR(GENERIC); /* Too small tableLog, compression potentially impossible */
439
440 { static U32 const rtbTable[] = { 0, 473195, 504333, 520860, 550000, 700000, 750000, 830000 };
441 short const lowProbCount = useLowProbCount ? -1 : 1;
442 U64 const scale = 62 - tableLog;
443 U64 const step = ZSTD_div64((U64)1<<62, (U32)total); /* <== here, one division ! */
444 U64 const vStep = 1ULL<<(scale-20);
445 int stillToDistribute = 1<<tableLog;
446 unsigned s;
447 unsigned largest=0;
448 short largestP=0;
449 U32 lowThreshold = (U32)(total >> tableLog);
450
451 for (s=0; s<=maxSymbolValue; s++) {
452 if (count[s] == total) return 0; /* rle special case */
453 if (count[s] == 0) { normalizedCounter[s]=0; continue; }
454 if (count[s] <= lowThreshold) {
455 normalizedCounter[s] = lowProbCount;
456 stillToDistribute--;
457 } else {
458 short proba = (short)((count[s]*step) >> scale);
459 if (proba<8) {
460 U64 restToBeat = vStep * rtbTable[proba];
461 proba += (count[s]*step) - ((U64)proba<<scale) > restToBeat;
462 }
463 if (proba > largestP) { largestP=proba; largest=s; }
464 normalizedCounter[s] = proba;
465 stillToDistribute -= proba;
466 } }
467 if (-stillToDistribute >= (normalizedCounter[largest] >> 1)) {
468 /* corner case, need another normalization method */
469 size_t const errorCode = FSE_normalizeM2(normalizedCounter, tableLog, count, total, maxSymbolValue, lowProbCount);
470 if (FSE_isError(errorCode)) return errorCode;
471 }
472 else normalizedCounter[largest] += (short)stillToDistribute;
473 }
474
475 #if 0
476 { /* Print Table (debug) */
477 U32 s;
478 U32 nTotal = 0;
479 for (s=0; s<=maxSymbolValue; s++)
480 RAWLOG(2, "%3i: %4i \n", s, normalizedCounter[s]);
481 for (s=0; s<=maxSymbolValue; s++)
482 nTotal += abs(normalizedCounter[s]);
483 if (nTotal != (1U<<tableLog))
484 RAWLOG(2, "Warning !!! Total == %u != %u !!!", nTotal, 1U<<tableLog);
485 getchar();
486 }
487 #endif
488
489 return tableLog;
490 }
491
492
493 /* fake FSE_CTable, for raw (uncompressed) input */
FSE_buildCTable_raw(FSE_CTable * ct,unsigned nbBits)494 size_t FSE_buildCTable_raw (FSE_CTable* ct, unsigned nbBits)
495 {
496 const unsigned tableSize = 1 << nbBits;
497 const unsigned tableMask = tableSize - 1;
498 const unsigned maxSymbolValue = tableMask;
499 void* const ptr = ct;
500 U16* const tableU16 = ( (U16*) ptr) + 2;
501 void* const FSCT = ((U32*)ptr) + 1 /* header */ + (tableSize>>1); /* assumption : tableLog >= 1 */
502 FSE_symbolCompressionTransform* const symbolTT = (FSE_symbolCompressionTransform*) (FSCT);
503 unsigned s;
504
505 /* Sanity checks */
506 if (nbBits < 1) return ERROR(GENERIC); /* min size */
507
508 /* header */
509 tableU16[-2] = (U16) nbBits;
510 tableU16[-1] = (U16) maxSymbolValue;
511
512 /* Build table */
513 for (s=0; s<tableSize; s++)
514 tableU16[s] = (U16)(tableSize + s);
515
516 /* Build Symbol Transformation Table */
517 { const U32 deltaNbBits = (nbBits << 16) - (1 << nbBits);
518 for (s=0; s<=maxSymbolValue; s++) {
519 symbolTT[s].deltaNbBits = deltaNbBits;
520 symbolTT[s].deltaFindState = s-1;
521 } }
522
523 return 0;
524 }
525
526 /* fake FSE_CTable, for rle input (always same symbol) */
FSE_buildCTable_rle(FSE_CTable * ct,BYTE symbolValue)527 size_t FSE_buildCTable_rle (FSE_CTable* ct, BYTE symbolValue)
528 {
529 void* ptr = ct;
530 U16* tableU16 = ( (U16*) ptr) + 2;
531 void* FSCTptr = (U32*)ptr + 2;
532 FSE_symbolCompressionTransform* symbolTT = (FSE_symbolCompressionTransform*) FSCTptr;
533
534 /* header */
535 tableU16[-2] = (U16) 0;
536 tableU16[-1] = (U16) symbolValue;
537
538 /* Build table */
539 tableU16[0] = 0;
540 tableU16[1] = 0; /* just in case */
541
542 /* Build Symbol Transformation Table */
543 symbolTT[symbolValue].deltaNbBits = 0;
544 symbolTT[symbolValue].deltaFindState = 0;
545
546 return 0;
547 }
548
549
FSE_compress_usingCTable_generic(void * dst,size_t dstSize,const void * src,size_t srcSize,const FSE_CTable * ct,const unsigned fast)550 static size_t FSE_compress_usingCTable_generic (void* dst, size_t dstSize,
551 const void* src, size_t srcSize,
552 const FSE_CTable* ct, const unsigned fast)
553 {
554 const BYTE* const istart = (const BYTE*) src;
555 const BYTE* const iend = istart + srcSize;
556 const BYTE* ip=iend;
557
558 BIT_CStream_t bitC;
559 FSE_CState_t CState1, CState2;
560
561 /* init */
562 if (srcSize <= 2) return 0;
563 { size_t const initError = BIT_initCStream(&bitC, dst, dstSize);
564 if (FSE_isError(initError)) return 0; /* not enough space available to write a bitstream */ }
565
566 #define FSE_FLUSHBITS(s) (fast ? BIT_flushBitsFast(s) : BIT_flushBits(s))
567
568 if (srcSize & 1) {
569 FSE_initCState2(&CState1, ct, *--ip);
570 FSE_initCState2(&CState2, ct, *--ip);
571 FSE_encodeSymbol(&bitC, &CState1, *--ip);
572 FSE_FLUSHBITS(&bitC);
573 } else {
574 FSE_initCState2(&CState2, ct, *--ip);
575 FSE_initCState2(&CState1, ct, *--ip);
576 }
577
578 /* join to mod 4 */
579 srcSize -= 2;
580 if ((sizeof(bitC.bitContainer)*8 > FSE_MAX_TABLELOG*4+7 ) && (srcSize & 2)) { /* test bit 2 */
581 FSE_encodeSymbol(&bitC, &CState2, *--ip);
582 FSE_encodeSymbol(&bitC, &CState1, *--ip);
583 FSE_FLUSHBITS(&bitC);
584 }
585
586 /* 2 or 4 encoding per loop */
587 while ( ip>istart ) {
588
589 FSE_encodeSymbol(&bitC, &CState2, *--ip);
590
591 if (sizeof(bitC.bitContainer)*8 < FSE_MAX_TABLELOG*2+7 ) /* this test must be static */
592 FSE_FLUSHBITS(&bitC);
593
594 FSE_encodeSymbol(&bitC, &CState1, *--ip);
595
596 if (sizeof(bitC.bitContainer)*8 > FSE_MAX_TABLELOG*4+7 ) { /* this test must be static */
597 FSE_encodeSymbol(&bitC, &CState2, *--ip);
598 FSE_encodeSymbol(&bitC, &CState1, *--ip);
599 }
600
601 FSE_FLUSHBITS(&bitC);
602 }
603
604 FSE_flushCState(&bitC, &CState2);
605 FSE_flushCState(&bitC, &CState1);
606 return BIT_closeCStream(&bitC);
607 }
608
FSE_compress_usingCTable(void * dst,size_t dstSize,const void * src,size_t srcSize,const FSE_CTable * ct)609 size_t FSE_compress_usingCTable (void* dst, size_t dstSize,
610 const void* src, size_t srcSize,
611 const FSE_CTable* ct)
612 {
613 unsigned const fast = (dstSize >= FSE_BLOCKBOUND(srcSize));
614
615 if (fast)
616 return FSE_compress_usingCTable_generic(dst, dstSize, src, srcSize, ct, 1);
617 else
618 return FSE_compress_usingCTable_generic(dst, dstSize, src, srcSize, ct, 0);
619 }
620
621
FSE_compressBound(size_t size)622 size_t FSE_compressBound(size_t size) { return FSE_COMPRESSBOUND(size); }
623
624
625 #endif /* FSE_COMMONDEFS_ONLY */
626