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 */
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 U32 const maxSV1 = maxSymbolValue+1;
79
80 U16* cumul = (U16*)workSpace; /* size = maxSV1 */
81 FSE_FUNCTION_TYPE* const tableSymbol = (FSE_FUNCTION_TYPE*)(cumul + (maxSV1+1)); /* size = tableSize */
82
83 U32 highThreshold = tableSize-1;
84
85 assert(((size_t)workSpace & 1) == 0); /* Must be 2 bytes-aligned */
86 if (FSE_BUILD_CTABLE_WORKSPACE_SIZE(maxSymbolValue, tableLog) > wkspSize) return ERROR(tableLog_tooLarge);
87 /* CTable header */
88 tableU16[-2] = (U16) tableLog;
89 tableU16[-1] = (U16) maxSymbolValue;
90 assert(tableLog < 16); /* required for threshold strategy to work */
91
92 /* For explanations on how to distribute symbol values over the table :
93 * http://fastcompression.blogspot.fr/2014/02/fse-distributing-symbol-values.html */
94
95 #ifdef __clang_analyzer__
96 ZSTD_memset(tableSymbol, 0, sizeof(*tableSymbol) * tableSize); /* useless initialization, just to keep scan-build happy */
97 #endif
98
99 /* symbol start positions */
100 { U32 u;
101 cumul[0] = 0;
102 for (u=1; u <= maxSV1; u++) {
103 if (normalizedCounter[u-1]==-1) { /* Low proba symbol */
104 cumul[u] = cumul[u-1] + 1;
105 tableSymbol[highThreshold--] = (FSE_FUNCTION_TYPE)(u-1);
106 } else {
107 assert(normalizedCounter[u-1] >= 0);
108 cumul[u] = cumul[u-1] + (U16)normalizedCounter[u-1];
109 assert(cumul[u] >= cumul[u-1]); /* no overflow */
110 } }
111 cumul[maxSV1] = (U16)(tableSize+1);
112 }
113
114 /* Spread symbols */
115 if (highThreshold == tableSize - 1) {
116 /* Case for no low prob count symbols. Lay down 8 bytes at a time
117 * to reduce branch misses since we are operating on a small block
118 */
119 BYTE* const spread = tableSymbol + tableSize; /* size = tableSize + 8 (may write beyond tableSize) */
120 { U64 const add = 0x0101010101010101ull;
121 size_t pos = 0;
122 U64 sv = 0;
123 U32 s;
124 for (s=0; s<maxSV1; ++s, sv += add) {
125 int i;
126 int const n = normalizedCounter[s];
127 MEM_write64(spread + pos, sv);
128 for (i = 8; i < n; i += 8) {
129 MEM_write64(spread + pos + i, sv);
130 }
131 assert(n>=0);
132 pos += (size_t)n;
133 }
134 }
135 /* Spread symbols across the table. Lack of lowprob symbols means that
136 * we don't need variable sized inner loop, so we can unroll the loop and
137 * reduce branch misses.
138 */
139 { size_t position = 0;
140 size_t s;
141 size_t const unroll = 2; /* Experimentally determined optimal unroll */
142 assert(tableSize % unroll == 0); /* FSE_MIN_TABLELOG is 5 */
143 for (s = 0; s < (size_t)tableSize; s += unroll) {
144 size_t u;
145 for (u = 0; u < unroll; ++u) {
146 size_t const uPosition = (position + (u * step)) & tableMask;
147 tableSymbol[uPosition] = spread[s + u];
148 }
149 position = (position + (unroll * step)) & tableMask;
150 }
151 assert(position == 0); /* Must have initialized all positions */
152 }
153 } else {
154 U32 position = 0;
155 U32 symbol;
156 for (symbol=0; symbol<maxSV1; symbol++) {
157 int nbOccurrences;
158 int const freq = normalizedCounter[symbol];
159 for (nbOccurrences=0; nbOccurrences<freq; nbOccurrences++) {
160 tableSymbol[position] = (FSE_FUNCTION_TYPE)symbol;
161 position = (position + step) & tableMask;
162 while (position > highThreshold)
163 position = (position + step) & tableMask; /* Low proba area */
164 } }
165 assert(position==0); /* Must have initialized all positions */
166 }
167
168 /* Build table */
169 { U32 u; for (u=0; u<tableSize; u++) {
170 FSE_FUNCTION_TYPE s = tableSymbol[u]; /* note : static analyzer may not understand tableSymbol is properly initialized */
171 tableU16[cumul[s]++] = (U16) (tableSize+u); /* TableU16 : sorted by symbol order; gives next state value */
172 } }
173
174 /* Build Symbol Transformation Table */
175 { unsigned total = 0;
176 unsigned s;
177 for (s=0; s<=maxSymbolValue; s++) {
178 switch (normalizedCounter[s])
179 {
180 case 0:
181 /* filling nonetheless, for compatibility with FSE_getMaxNbBits() */
182 symbolTT[s].deltaNbBits = ((tableLog+1) << 16) - (1<<tableLog);
183 break;
184
185 case -1:
186 case 1:
187 symbolTT[s].deltaNbBits = (tableLog << 16) - (1<<tableLog);
188 assert(total <= INT_MAX);
189 symbolTT[s].deltaFindState = (int)(total - 1);
190 total ++;
191 break;
192 default :
193 assert(normalizedCounter[s] > 1);
194 { U32 const maxBitsOut = tableLog - BIT_highbit32 ((U32)normalizedCounter[s]-1);
195 U32 const minStatePlus = (U32)normalizedCounter[s] << maxBitsOut;
196 symbolTT[s].deltaNbBits = (maxBitsOut << 16) - minStatePlus;
197 symbolTT[s].deltaFindState = (int)(total - (unsigned)normalizedCounter[s]);
198 total += (unsigned)normalizedCounter[s];
199 } } } }
200
201 #if 0 /* debug : symbol costs */
202 DEBUGLOG(5, "\n --- table statistics : ");
203 { U32 symbol;
204 for (symbol=0; symbol<=maxSymbolValue; symbol++) {
205 DEBUGLOG(5, "%3u: w=%3i, maxBits=%u, fracBits=%.2f",
206 symbol, normalizedCounter[symbol],
207 FSE_getMaxNbBits(symbolTT, symbol),
208 (double)FSE_bitCost(symbolTT, tableLog, symbol, 8) / 256);
209 } }
210 #endif
211
212 return 0;
213 }
214
215
216
217 #ifndef FSE_COMMONDEFS_ONLY
218
219 /*-**************************************************************
220 * FSE NCount encoding
221 ****************************************************************/
222 size_t FSE_NCountWriteBound(unsigned maxSymbolValue, unsigned tableLog)
223 {
224 size_t const maxHeaderSize = (((maxSymbolValue+1) * tableLog
225 + 4 /* bitCount initialized at 4 */
226 + 2 /* first two symbols may use one additional bit each */) / 8)
227 + 1 /* round up to whole nb bytes */
228 + 2 /* additional two bytes for bitstream flush */;
229 return maxSymbolValue ? maxHeaderSize : FSE_NCOUNTBOUND; /* maxSymbolValue==0 ? use default */
230 }
231
232 static size_t
233 FSE_writeNCount_generic (void* header, size_t headerBufferSize,
234 const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog,
235 unsigned writeIsSafe)
236 {
237 BYTE* const ostart = (BYTE*) header;
238 BYTE* out = ostart;
239 BYTE* const oend = ostart + headerBufferSize;
240 int nbBits;
241 const int tableSize = 1 << tableLog;
242 int remaining;
243 int threshold;
244 U32 bitStream = 0;
245 int bitCount = 0;
246 unsigned symbol = 0;
247 unsigned const alphabetSize = maxSymbolValue + 1;
248 int previousIs0 = 0;
249
250 /* Table Size */
251 bitStream += (tableLog-FSE_MIN_TABLELOG) << bitCount;
252 bitCount += 4;
253
254 /* Init */
255 remaining = tableSize+1; /* +1 for extra accuracy */
256 threshold = tableSize;
257 nbBits = tableLog+1;
258
259 while ((symbol < alphabetSize) && (remaining>1)) { /* stops at 1 */
260 if (previousIs0) {
261 unsigned start = symbol;
262 while ((symbol < alphabetSize) && !normalizedCounter[symbol]) symbol++;
263 if (symbol == alphabetSize) break; /* incorrect distribution */
264 while (symbol >= start+24) {
265 start+=24;
266 bitStream += 0xFFFFU << bitCount;
267 if ((!writeIsSafe) && (out > oend-2))
268 return ERROR(dstSize_tooSmall); /* Buffer overflow */
269 out[0] = (BYTE) bitStream;
270 out[1] = (BYTE)(bitStream>>8);
271 out+=2;
272 bitStream>>=16;
273 }
274 while (symbol >= start+3) {
275 start+=3;
276 bitStream += 3 << bitCount;
277 bitCount += 2;
278 }
279 bitStream += (symbol-start) << bitCount;
280 bitCount += 2;
281 if (bitCount>16) {
282 if ((!writeIsSafe) && (out > oend - 2))
283 return ERROR(dstSize_tooSmall); /* Buffer overflow */
284 out[0] = (BYTE)bitStream;
285 out[1] = (BYTE)(bitStream>>8);
286 out += 2;
287 bitStream >>= 16;
288 bitCount -= 16;
289 } }
290 { int count = normalizedCounter[symbol++];
291 int const max = (2*threshold-1) - remaining;
292 remaining -= count < 0 ? -count : count;
293 count++; /* +1 for extra accuracy */
294 if (count>=threshold)
295 count += max; /* [0..max[ [max..threshold[ (...) [threshold+max 2*threshold[ */
296 bitStream += count << bitCount;
297 bitCount += nbBits;
298 bitCount -= (count<max);
299 previousIs0 = (count==1);
300 if (remaining<1) return ERROR(GENERIC);
301 while (remaining<threshold) { nbBits--; threshold>>=1; }
302 }
303 if (bitCount>16) {
304 if ((!writeIsSafe) && (out > oend - 2))
305 return ERROR(dstSize_tooSmall); /* Buffer overflow */
306 out[0] = (BYTE)bitStream;
307 out[1] = (BYTE)(bitStream>>8);
308 out += 2;
309 bitStream >>= 16;
310 bitCount -= 16;
311 } }
312
313 if (remaining != 1)
314 return ERROR(GENERIC); /* incorrect normalized distribution */
315 assert(symbol <= alphabetSize);
316
317 /* flush remaining bitStream */
318 if ((!writeIsSafe) && (out > oend - 2))
319 return ERROR(dstSize_tooSmall); /* Buffer overflow */
320 out[0] = (BYTE)bitStream;
321 out[1] = (BYTE)(bitStream>>8);
322 out+= (bitCount+7) /8;
323
324 return (out-ostart);
325 }
326
327
328 size_t FSE_writeNCount (void* buffer, size_t bufferSize,
329 const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog)
330 {
331 if (tableLog > FSE_MAX_TABLELOG) return ERROR(tableLog_tooLarge); /* Unsupported */
332 if (tableLog < FSE_MIN_TABLELOG) return ERROR(GENERIC); /* Unsupported */
333
334 if (bufferSize < FSE_NCountWriteBound(maxSymbolValue, tableLog))
335 return FSE_writeNCount_generic(buffer, bufferSize, normalizedCounter, maxSymbolValue, tableLog, 0);
336
337 return FSE_writeNCount_generic(buffer, bufferSize, normalizedCounter, maxSymbolValue, tableLog, 1 /* write in buffer is safe */);
338 }
339
340
341 /*-**************************************************************
342 * FSE Compression Code
343 ****************************************************************/
344
345 FSE_CTable* FSE_createCTable (unsigned maxSymbolValue, unsigned tableLog)
346 {
347 size_t size;
348 if (tableLog > FSE_TABLELOG_ABSOLUTE_MAX) tableLog = FSE_TABLELOG_ABSOLUTE_MAX;
349 size = FSE_CTABLE_SIZE_U32 (tableLog, maxSymbolValue) * sizeof(U32);
350 return (FSE_CTable*)ZSTD_malloc(size);
351 }
352
353 void FSE_freeCTable (FSE_CTable* ct) { ZSTD_free(ct); }
354
355 /* provides the minimum logSize to safely represent a distribution */
356 static unsigned FSE_minTableLog(size_t srcSize, unsigned maxSymbolValue)
357 {
358 U32 minBitsSrc = BIT_highbit32((U32)(srcSize)) + 1;
359 U32 minBitsSymbols = BIT_highbit32(maxSymbolValue) + 2;
360 U32 minBits = minBitsSrc < minBitsSymbols ? minBitsSrc : minBitsSymbols;
361 assert(srcSize > 1); /* Not supported, RLE should be used instead */
362 return minBits;
363 }
364
365 unsigned FSE_optimalTableLog_internal(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue, unsigned minus)
366 {
367 U32 maxBitsSrc = BIT_highbit32((U32)(srcSize - 1)) - minus;
368 U32 tableLog = maxTableLog;
369 U32 minBits = FSE_minTableLog(srcSize, maxSymbolValue);
370 assert(srcSize > 1); /* Not supported, RLE should be used instead */
371 if (tableLog==0) tableLog = FSE_DEFAULT_TABLELOG;
372 if (maxBitsSrc < tableLog) tableLog = maxBitsSrc; /* Accuracy can be reduced */
373 if (minBits > tableLog) tableLog = minBits; /* Need a minimum to safely represent all symbol values */
374 if (tableLog < FSE_MIN_TABLELOG) tableLog = FSE_MIN_TABLELOG;
375 if (tableLog > FSE_MAX_TABLELOG) tableLog = FSE_MAX_TABLELOG;
376 return tableLog;
377 }
378
379 unsigned FSE_optimalTableLog(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue)
380 {
381 return FSE_optimalTableLog_internal(maxTableLog, srcSize, maxSymbolValue, 2);
382 }
383
384 /* Secondary normalization method.
385 To be used when primary method fails. */
386
387 static size_t FSE_normalizeM2(short* norm, U32 tableLog, const unsigned* count, size_t total, U32 maxSymbolValue, short lowProbCount)
388 {
389 short const NOT_YET_ASSIGNED = -2;
390 U32 s;
391 U32 distributed = 0;
392 U32 ToDistribute;
393
394 /* Init */
395 U32 const lowThreshold = (U32)(total >> tableLog);
396 U32 lowOne = (U32)((total * 3) >> (tableLog + 1));
397
398 for (s=0; s<=maxSymbolValue; s++) {
399 if (count[s] == 0) {
400 norm[s]=0;
401 continue;
402 }
403 if (count[s] <= lowThreshold) {
404 norm[s] = lowProbCount;
405 distributed++;
406 total -= count[s];
407 continue;
408 }
409 if (count[s] <= lowOne) {
410 norm[s] = 1;
411 distributed++;
412 total -= count[s];
413 continue;
414 }
415
416 norm[s]=NOT_YET_ASSIGNED;
417 }
418 ToDistribute = (1 << tableLog) - distributed;
419
420 if (ToDistribute == 0)
421 return 0;
422
423 if ((total / ToDistribute) > lowOne) {
424 /* risk of rounding to zero */
425 lowOne = (U32)((total * 3) / (ToDistribute * 2));
426 for (s=0; s<=maxSymbolValue; s++) {
427 if ((norm[s] == NOT_YET_ASSIGNED) && (count[s] <= lowOne)) {
428 norm[s] = 1;
429 distributed++;
430 total -= count[s];
431 continue;
432 } }
433 ToDistribute = (1 << tableLog) - distributed;
434 }
435
436 if (distributed == maxSymbolValue+1) {
437 /* all values are pretty poor;
438 probably incompressible data (should have already been detected);
439 find max, then give all remaining points to max */
440 U32 maxV = 0, maxC = 0;
441 for (s=0; s<=maxSymbolValue; s++)
442 if (count[s] > maxC) { maxV=s; maxC=count[s]; }
443 norm[maxV] += (short)ToDistribute;
444 return 0;
445 }
446
447 if (total == 0) {
448 /* all of the symbols were low enough for the lowOne or lowThreshold */
449 for (s=0; ToDistribute > 0; s = (s+1)%(maxSymbolValue+1))
450 if (norm[s] > 0) { ToDistribute--; norm[s]++; }
451 return 0;
452 }
453
454 { U64 const vStepLog = 62 - tableLog;
455 U64 const mid = (1ULL << (vStepLog-1)) - 1;
456 U64 const rStep = ZSTD_div64((((U64)1<<vStepLog) * ToDistribute) + mid, (U32)total); /* scale on remaining */
457 U64 tmpTotal = mid;
458 for (s=0; s<=maxSymbolValue; s++) {
459 if (norm[s]==NOT_YET_ASSIGNED) {
460 U64 const end = tmpTotal + (count[s] * rStep);
461 U32 const sStart = (U32)(tmpTotal >> vStepLog);
462 U32 const sEnd = (U32)(end >> vStepLog);
463 U32 const weight = sEnd - sStart;
464 if (weight < 1)
465 return ERROR(GENERIC);
466 norm[s] = (short)weight;
467 tmpTotal = end;
468 } } }
469
470 return 0;
471 }
472
473 size_t FSE_normalizeCount (short* normalizedCounter, unsigned tableLog,
474 const unsigned* count, size_t total,
475 unsigned maxSymbolValue, unsigned useLowProbCount)
476 {
477 /* Sanity checks */
478 if (tableLog==0) tableLog = FSE_DEFAULT_TABLELOG;
479 if (tableLog < FSE_MIN_TABLELOG) return ERROR(GENERIC); /* Unsupported size */
480 if (tableLog > FSE_MAX_TABLELOG) return ERROR(tableLog_tooLarge); /* Unsupported size */
481 if (tableLog < FSE_minTableLog(total, maxSymbolValue)) return ERROR(GENERIC); /* Too small tableLog, compression potentially impossible */
482
483 { static U32 const rtbTable[] = { 0, 473195, 504333, 520860, 550000, 700000, 750000, 830000 };
484 short const lowProbCount = useLowProbCount ? -1 : 1;
485 U64 const scale = 62 - tableLog;
486 U64 const step = ZSTD_div64((U64)1<<62, (U32)total); /* <== here, one division ! */
487 U64 const vStep = 1ULL<<(scale-20);
488 int stillToDistribute = 1<<tableLog;
489 unsigned s;
490 unsigned largest=0;
491 short largestP=0;
492 U32 lowThreshold = (U32)(total >> tableLog);
493
494 for (s=0; s<=maxSymbolValue; s++) {
495 if (count[s] == total) return 0; /* rle special case */
496 if (count[s] == 0) { normalizedCounter[s]=0; continue; }
497 if (count[s] <= lowThreshold) {
498 normalizedCounter[s] = lowProbCount;
499 stillToDistribute--;
500 } else {
501 short proba = (short)((count[s]*step) >> scale);
502 if (proba<8) {
503 U64 restToBeat = vStep * rtbTable[proba];
504 proba += (count[s]*step) - ((U64)proba<<scale) > restToBeat;
505 }
506 if (proba > largestP) { largestP=proba; largest=s; }
507 normalizedCounter[s] = proba;
508 stillToDistribute -= proba;
509 } }
510 if (-stillToDistribute >= (normalizedCounter[largest] >> 1)) {
511 /* corner case, need another normalization method */
512 size_t const errorCode = FSE_normalizeM2(normalizedCounter, tableLog, count, total, maxSymbolValue, lowProbCount);
513 if (FSE_isError(errorCode)) return errorCode;
514 }
515 else normalizedCounter[largest] += (short)stillToDistribute;
516 }
517
518 #if 0
519 { /* Print Table (debug) */
520 U32 s;
521 U32 nTotal = 0;
522 for (s=0; s<=maxSymbolValue; s++)
523 RAWLOG(2, "%3i: %4i \n", s, normalizedCounter[s]);
524 for (s=0; s<=maxSymbolValue; s++)
525 nTotal += abs(normalizedCounter[s]);
526 if (nTotal != (1U<<tableLog))
527 RAWLOG(2, "Warning !!! Total == %u != %u !!!", nTotal, 1U<<tableLog);
528 getchar();
529 }
530 #endif
531
532 return tableLog;
533 }
534
535
536 /* fake FSE_CTable, for raw (uncompressed) input */
537 size_t FSE_buildCTable_raw (FSE_CTable* ct, unsigned nbBits)
538 {
539 const unsigned tableSize = 1 << nbBits;
540 const unsigned tableMask = tableSize - 1;
541 const unsigned maxSymbolValue = tableMask;
542 void* const ptr = ct;
543 U16* const tableU16 = ( (U16*) ptr) + 2;
544 void* const FSCT = ((U32*)ptr) + 1 /* header */ + (tableSize>>1); /* assumption : tableLog >= 1 */
545 FSE_symbolCompressionTransform* const symbolTT = (FSE_symbolCompressionTransform*) (FSCT);
546 unsigned s;
547
548 /* Sanity checks */
549 if (nbBits < 1) return ERROR(GENERIC); /* min size */
550
551 /* header */
552 tableU16[-2] = (U16) nbBits;
553 tableU16[-1] = (U16) maxSymbolValue;
554
555 /* Build table */
556 for (s=0; s<tableSize; s++)
557 tableU16[s] = (U16)(tableSize + s);
558
559 /* Build Symbol Transformation Table */
560 { const U32 deltaNbBits = (nbBits << 16) - (1 << nbBits);
561 for (s=0; s<=maxSymbolValue; s++) {
562 symbolTT[s].deltaNbBits = deltaNbBits;
563 symbolTT[s].deltaFindState = s-1;
564 } }
565
566 return 0;
567 }
568
569 /* fake FSE_CTable, for rle input (always same symbol) */
570 size_t FSE_buildCTable_rle (FSE_CTable* ct, BYTE symbolValue)
571 {
572 void* ptr = ct;
573 U16* tableU16 = ( (U16*) ptr) + 2;
574 void* FSCTptr = (U32*)ptr + 2;
575 FSE_symbolCompressionTransform* symbolTT = (FSE_symbolCompressionTransform*) FSCTptr;
576
577 /* header */
578 tableU16[-2] = (U16) 0;
579 tableU16[-1] = (U16) symbolValue;
580
581 /* Build table */
582 tableU16[0] = 0;
583 tableU16[1] = 0; /* just in case */
584
585 /* Build Symbol Transformation Table */
586 symbolTT[symbolValue].deltaNbBits = 0;
587 symbolTT[symbolValue].deltaFindState = 0;
588
589 return 0;
590 }
591
592
593 static size_t FSE_compress_usingCTable_generic (void* dst, size_t dstSize,
594 const void* src, size_t srcSize,
595 const FSE_CTable* ct, const unsigned fast)
596 {
597 const BYTE* const istart = (const BYTE*) src;
598 const BYTE* const iend = istart + srcSize;
599 const BYTE* ip=iend;
600
601 BIT_CStream_t bitC;
602 FSE_CState_t CState1, CState2;
603
604 /* init */
605 if (srcSize <= 2) return 0;
606 { size_t const initError = BIT_initCStream(&bitC, dst, dstSize);
607 if (FSE_isError(initError)) return 0; /* not enough space available to write a bitstream */ }
608
609 #define FSE_FLUSHBITS(s) (fast ? BIT_flushBitsFast(s) : BIT_flushBits(s))
610
611 if (srcSize & 1) {
612 FSE_initCState2(&CState1, ct, *--ip);
613 FSE_initCState2(&CState2, ct, *--ip);
614 FSE_encodeSymbol(&bitC, &CState1, *--ip);
615 FSE_FLUSHBITS(&bitC);
616 } else {
617 FSE_initCState2(&CState2, ct, *--ip);
618 FSE_initCState2(&CState1, ct, *--ip);
619 }
620
621 /* join to mod 4 */
622 srcSize -= 2;
623 if ((sizeof(bitC.bitContainer)*8 > FSE_MAX_TABLELOG*4+7 ) && (srcSize & 2)) { /* test bit 2 */
624 FSE_encodeSymbol(&bitC, &CState2, *--ip);
625 FSE_encodeSymbol(&bitC, &CState1, *--ip);
626 FSE_FLUSHBITS(&bitC);
627 }
628
629 /* 2 or 4 encoding per loop */
630 while ( ip>istart ) {
631
632 FSE_encodeSymbol(&bitC, &CState2, *--ip);
633
634 if (sizeof(bitC.bitContainer)*8 < FSE_MAX_TABLELOG*2+7 ) /* this test must be static */
635 FSE_FLUSHBITS(&bitC);
636
637 FSE_encodeSymbol(&bitC, &CState1, *--ip);
638
639 if (sizeof(bitC.bitContainer)*8 > FSE_MAX_TABLELOG*4+7 ) { /* this test must be static */
640 FSE_encodeSymbol(&bitC, &CState2, *--ip);
641 FSE_encodeSymbol(&bitC, &CState1, *--ip);
642 }
643
644 FSE_FLUSHBITS(&bitC);
645 }
646
647 FSE_flushCState(&bitC, &CState2);
648 FSE_flushCState(&bitC, &CState1);
649 return BIT_closeCStream(&bitC);
650 }
651
652 size_t FSE_compress_usingCTable (void* dst, size_t dstSize,
653 const void* src, size_t srcSize,
654 const FSE_CTable* ct)
655 {
656 unsigned const fast = (dstSize >= FSE_BLOCKBOUND(srcSize));
657
658 if (fast)
659 return FSE_compress_usingCTable_generic(dst, dstSize, src, srcSize, ct, 1);
660 else
661 return FSE_compress_usingCTable_generic(dst, dstSize, src, srcSize, ct, 0);
662 }
663
664
665 size_t FSE_compressBound(size_t size) { return FSE_COMPRESSBOUND(size); }
666
667
668 #endif /* FSE_COMMONDEFS_ONLY */
669
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