1 /* ******************************************************************
2 * FSE : Finite State Entropy decoder
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 /* **************************************************************
17 * Includes
18 ****************************************************************/
19 #include "debug.h" /* assert */
20 #include "bitstream.h"
21 #include "compiler.h"
22 #define FSE_STATIC_LINKING_ONLY
23 #include "fse.h"
24 #include "error_private.h"
25 #define ZSTD_DEPS_NEED_MALLOC
26 #include "zstd_deps.h"
27
28
29 /* **************************************************************
30 * Error Management
31 ****************************************************************/
32 #define FSE_isError ERR_isError
33 #define FSE_STATIC_ASSERT(c) DEBUG_STATIC_ASSERT(c) /* use only *after* variable declarations */
34
35
36 /* **************************************************************
37 * Templates
38 ****************************************************************/
39 /*
40 designed to be included
41 for type-specific functions (template emulation in C)
42 Objective is to write these functions only once, for improved maintenance
43 */
44
45 /* safety checks */
46 #ifndef FSE_FUNCTION_EXTENSION
47 # error "FSE_FUNCTION_EXTENSION must be defined"
48 #endif
49 #ifndef FSE_FUNCTION_TYPE
50 # error "FSE_FUNCTION_TYPE must be defined"
51 #endif
52
53 /* Function names */
54 #define FSE_CAT(X,Y) X##Y
55 #define FSE_FUNCTION_NAME(X,Y) FSE_CAT(X,Y)
56 #define FSE_TYPE_NAME(X,Y) FSE_CAT(X,Y)
57
58
59 /* Function templates */
60 FSE_DTable* FSE_createDTable (unsigned tableLog)
61 {
62 if (tableLog > FSE_TABLELOG_ABSOLUTE_MAX) tableLog = FSE_TABLELOG_ABSOLUTE_MAX;
63 return (FSE_DTable*)ZSTD_malloc( FSE_DTABLE_SIZE_U32(tableLog) * sizeof (U32) );
64 }
65
66 void FSE_freeDTable (FSE_DTable* dt)
67 {
68 ZSTD_free(dt);
69 }
70
71 static size_t FSE_buildDTable_internal(FSE_DTable* dt, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void* workSpace, size_t wkspSize)
72 {
73 void* const tdPtr = dt+1; /* because *dt is unsigned, 32-bits aligned on 32-bits */
74 FSE_DECODE_TYPE* const tableDecode = (FSE_DECODE_TYPE*) (tdPtr);
75 U16* symbolNext = (U16*)workSpace;
76 BYTE* spread = (BYTE*)(symbolNext + maxSymbolValue + 1);
77
78 U32 const maxSV1 = maxSymbolValue + 1;
79 U32 const tableSize = 1 << tableLog;
80 U32 highThreshold = tableSize-1;
81
82 /* Sanity Checks */
83 if (FSE_BUILD_DTABLE_WKSP_SIZE(tableLog, maxSymbolValue) > wkspSize) return ERROR(maxSymbolValue_tooLarge);
84 if (maxSymbolValue > FSE_MAX_SYMBOL_VALUE) return ERROR(maxSymbolValue_tooLarge);
85 if (tableLog > FSE_MAX_TABLELOG) return ERROR(tableLog_tooLarge);
86
87 /* Init, lay down lowprob symbols */
88 { FSE_DTableHeader DTableH;
89 DTableH.tableLog = (U16)tableLog;
90 DTableH.fastMode = 1;
91 { S16 const largeLimit= (S16)(1 << (tableLog-1));
92 U32 s;
93 for (s=0; s<maxSV1; s++) {
94 if (normalizedCounter[s]==-1) {
95 tableDecode[highThreshold--].symbol = (FSE_FUNCTION_TYPE)s;
96 symbolNext[s] = 1;
97 } else {
98 if (normalizedCounter[s] >= largeLimit) DTableH.fastMode=0;
99 symbolNext[s] = normalizedCounter[s];
100 } } }
101 ZSTD_memcpy(dt, &DTableH, sizeof(DTableH));
102 }
103
104 /* Spread symbols */
105 if (highThreshold == tableSize - 1) {
106 size_t const tableMask = tableSize-1;
107 size_t const step = FSE_TABLESTEP(tableSize);
108 /* First lay down the symbols in order.
109 * We use a uint64_t to lay down 8 bytes at a time. This reduces branch
110 * misses since small blocks generally have small table logs, so nearly
111 * all symbols have counts <= 8. We ensure we have 8 bytes at the end of
112 * our buffer to handle the over-write.
113 */
114 {
115 U64 const add = 0x0101010101010101ull;
116 size_t pos = 0;
117 U64 sv = 0;
118 U32 s;
119 for (s=0; s<maxSV1; ++s, sv += add) {
120 int i;
121 int const n = normalizedCounter[s];
122 MEM_write64(spread + pos, sv);
123 for (i = 8; i < n; i += 8) {
124 MEM_write64(spread + pos + i, sv);
125 }
126 pos += n;
127 }
128 }
129 /* Now we spread those positions across the table.
130 * The benefit of doing it in two stages is that we avoid the the
131 * variable size inner loop, which caused lots of branch misses.
132 * Now we can run through all the positions without any branch misses.
133 * We unroll the loop twice, since that is what emperically worked best.
134 */
135 {
136 size_t position = 0;
137 size_t s;
138 size_t const unroll = 2;
139 assert(tableSize % unroll == 0); /* FSE_MIN_TABLELOG is 5 */
140 for (s = 0; s < (size_t)tableSize; s += unroll) {
141 size_t u;
142 for (u = 0; u < unroll; ++u) {
143 size_t const uPosition = (position + (u * step)) & tableMask;
144 tableDecode[uPosition].symbol = spread[s + u];
145 }
146 position = (position + (unroll * step)) & tableMask;
147 }
148 assert(position == 0);
149 }
150 } else {
151 U32 const tableMask = tableSize-1;
152 U32 const step = FSE_TABLESTEP(tableSize);
153 U32 s, position = 0;
154 for (s=0; s<maxSV1; s++) {
155 int i;
156 for (i=0; i<normalizedCounter[s]; i++) {
157 tableDecode[position].symbol = (FSE_FUNCTION_TYPE)s;
158 position = (position + step) & tableMask;
159 while (position > highThreshold) position = (position + step) & tableMask; /* lowprob area */
160 } }
161 if (position!=0) return ERROR(GENERIC); /* position must reach all cells once, otherwise normalizedCounter is incorrect */
162 }
163
164 /* Build Decoding table */
165 { U32 u;
166 for (u=0; u<tableSize; u++) {
167 FSE_FUNCTION_TYPE const symbol = (FSE_FUNCTION_TYPE)(tableDecode[u].symbol);
168 U32 const nextState = symbolNext[symbol]++;
169 tableDecode[u].nbBits = (BYTE) (tableLog - BIT_highbit32(nextState) );
170 tableDecode[u].newState = (U16) ( (nextState << tableDecode[u].nbBits) - tableSize);
171 } }
172
173 return 0;
174 }
175
176 size_t FSE_buildDTable_wksp(FSE_DTable* dt, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void* workSpace, size_t wkspSize)
177 {
178 return FSE_buildDTable_internal(dt, normalizedCounter, maxSymbolValue, tableLog, workSpace, wkspSize);
179 }
180
181
182 #ifndef FSE_COMMONDEFS_ONLY
183
184 /*-*******************************************************
185 * Decompression (Byte symbols)
186 *********************************************************/
187 size_t FSE_buildDTable_rle (FSE_DTable* dt, BYTE symbolValue)
188 {
189 void* ptr = dt;
190 FSE_DTableHeader* const DTableH = (FSE_DTableHeader*)ptr;
191 void* dPtr = dt + 1;
192 FSE_decode_t* const cell = (FSE_decode_t*)dPtr;
193
194 DTableH->tableLog = 0;
195 DTableH->fastMode = 0;
196
197 cell->newState = 0;
198 cell->symbol = symbolValue;
199 cell->nbBits = 0;
200
201 return 0;
202 }
203
204
205 size_t FSE_buildDTable_raw (FSE_DTable* dt, unsigned nbBits)
206 {
207 void* ptr = dt;
208 FSE_DTableHeader* const DTableH = (FSE_DTableHeader*)ptr;
209 void* dPtr = dt + 1;
210 FSE_decode_t* const dinfo = (FSE_decode_t*)dPtr;
211 const unsigned tableSize = 1 << nbBits;
212 const unsigned tableMask = tableSize - 1;
213 const unsigned maxSV1 = tableMask+1;
214 unsigned s;
215
216 /* Sanity checks */
217 if (nbBits < 1) return ERROR(GENERIC); /* min size */
218
219 /* Build Decoding Table */
220 DTableH->tableLog = (U16)nbBits;
221 DTableH->fastMode = 1;
222 for (s=0; s<maxSV1; s++) {
223 dinfo[s].newState = 0;
224 dinfo[s].symbol = (BYTE)s;
225 dinfo[s].nbBits = (BYTE)nbBits;
226 }
227
228 return 0;
229 }
230
231 FORCE_INLINE_TEMPLATE size_t FSE_decompress_usingDTable_generic(
232 void* dst, size_t maxDstSize,
233 const void* cSrc, size_t cSrcSize,
234 const FSE_DTable* dt, const unsigned fast)
235 {
236 BYTE* const ostart = (BYTE*) dst;
237 BYTE* op = ostart;
238 BYTE* const omax = op + maxDstSize;
239 BYTE* const olimit = omax-3;
240
241 BIT_DStream_t bitD;
242 FSE_DState_t state1;
243 FSE_DState_t state2;
244
245 /* Init */
246 CHECK_F(BIT_initDStream(&bitD, cSrc, cSrcSize));
247
248 FSE_initDState(&state1, &bitD, dt);
249 FSE_initDState(&state2, &bitD, dt);
250
251 #define FSE_GETSYMBOL(statePtr) fast ? FSE_decodeSymbolFast(statePtr, &bitD) : FSE_decodeSymbol(statePtr, &bitD)
252
253 /* 4 symbols per loop */
254 for ( ; (BIT_reloadDStream(&bitD)==BIT_DStream_unfinished) & (op<olimit) ; op+=4) {
255 op[0] = FSE_GETSYMBOL(&state1);
256
257 if (FSE_MAX_TABLELOG*2+7 > sizeof(bitD.bitContainer)*8) /* This test must be static */
258 BIT_reloadDStream(&bitD);
259
260 op[1] = FSE_GETSYMBOL(&state2);
261
262 if (FSE_MAX_TABLELOG*4+7 > sizeof(bitD.bitContainer)*8) /* This test must be static */
263 { if (BIT_reloadDStream(&bitD) > BIT_DStream_unfinished) { op+=2; break; } }
264
265 op[2] = FSE_GETSYMBOL(&state1);
266
267 if (FSE_MAX_TABLELOG*2+7 > sizeof(bitD.bitContainer)*8) /* This test must be static */
268 BIT_reloadDStream(&bitD);
269
270 op[3] = FSE_GETSYMBOL(&state2);
271 }
272
273 /* tail */
274 /* note : BIT_reloadDStream(&bitD) >= FSE_DStream_partiallyFilled; Ends at exactly BIT_DStream_completed */
275 while (1) {
276 if (op>(omax-2)) return ERROR(dstSize_tooSmall);
277 *op++ = FSE_GETSYMBOL(&state1);
278 if (BIT_reloadDStream(&bitD)==BIT_DStream_overflow) {
279 *op++ = FSE_GETSYMBOL(&state2);
280 break;
281 }
282
283 if (op>(omax-2)) return ERROR(dstSize_tooSmall);
284 *op++ = FSE_GETSYMBOL(&state2);
285 if (BIT_reloadDStream(&bitD)==BIT_DStream_overflow) {
286 *op++ = FSE_GETSYMBOL(&state1);
287 break;
288 } }
289
290 return op-ostart;
291 }
292
293
294 size_t FSE_decompress_usingDTable(void* dst, size_t originalSize,
295 const void* cSrc, size_t cSrcSize,
296 const FSE_DTable* dt)
297 {
298 const void* ptr = dt;
299 const FSE_DTableHeader* DTableH = (const FSE_DTableHeader*)ptr;
300 const U32 fastMode = DTableH->fastMode;
301
302 /* select fast mode (static) */
303 if (fastMode) return FSE_decompress_usingDTable_generic(dst, originalSize, cSrc, cSrcSize, dt, 1);
304 return FSE_decompress_usingDTable_generic(dst, originalSize, cSrc, cSrcSize, dt, 0);
305 }
306
307
308 size_t FSE_decompress_wksp(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize, unsigned maxLog, void* workSpace, size_t wkspSize)
309 {
310 return FSE_decompress_wksp_bmi2(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize, /* bmi2 */ 0);
311 }
312
313 typedef struct {
314 short ncount[FSE_MAX_SYMBOL_VALUE + 1];
315 FSE_DTable dtable[]; /* Dynamically sized */
316 } FSE_DecompressWksp;
317
318
319 FORCE_INLINE_TEMPLATE size_t FSE_decompress_wksp_body(
320 void* dst, size_t dstCapacity,
321 const void* cSrc, size_t cSrcSize,
322 unsigned maxLog, void* workSpace, size_t wkspSize,
323 int bmi2)
324 {
325 const BYTE* const istart = (const BYTE*)cSrc;
326 const BYTE* ip = istart;
327 unsigned tableLog;
328 unsigned maxSymbolValue = FSE_MAX_SYMBOL_VALUE;
329 FSE_DecompressWksp* const wksp = (FSE_DecompressWksp*)workSpace;
330
331 DEBUG_STATIC_ASSERT((FSE_MAX_SYMBOL_VALUE + 1) % 2 == 0);
332 if (wkspSize < sizeof(*wksp)) return ERROR(GENERIC);
333
334 /* normal FSE decoding mode */
335 {
336 size_t const NCountLength = FSE_readNCount_bmi2(wksp->ncount, &maxSymbolValue, &tableLog, istart, cSrcSize, bmi2);
337 if (FSE_isError(NCountLength)) return NCountLength;
338 if (tableLog > maxLog) return ERROR(tableLog_tooLarge);
339 assert(NCountLength <= cSrcSize);
340 ip += NCountLength;
341 cSrcSize -= NCountLength;
342 }
343
344 if (FSE_DECOMPRESS_WKSP_SIZE(tableLog, maxSymbolValue) > wkspSize) return ERROR(tableLog_tooLarge);
345 workSpace = wksp->dtable + FSE_DTABLE_SIZE_U32(tableLog);
346 wkspSize -= sizeof(*wksp) + FSE_DTABLE_SIZE(tableLog);
347
348 CHECK_F( FSE_buildDTable_internal(wksp->dtable, wksp->ncount, maxSymbolValue, tableLog, workSpace, wkspSize) );
349
350 {
351 const void* ptr = wksp->dtable;
352 const FSE_DTableHeader* DTableH = (const FSE_DTableHeader*)ptr;
353 const U32 fastMode = DTableH->fastMode;
354
355 /* select fast mode (static) */
356 if (fastMode) return FSE_decompress_usingDTable_generic(dst, dstCapacity, ip, cSrcSize, wksp->dtable, 1);
357 return FSE_decompress_usingDTable_generic(dst, dstCapacity, ip, cSrcSize, wksp->dtable, 0);
358 }
359 }
360
361 /* Avoids the FORCE_INLINE of the _body() function. */
362 static size_t FSE_decompress_wksp_body_default(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize, unsigned maxLog, void* workSpace, size_t wkspSize)
363 {
364 return FSE_decompress_wksp_body(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize, 0);
365 }
366
367 #if DYNAMIC_BMI2
368 BMI2_TARGET_ATTRIBUTE static size_t FSE_decompress_wksp_body_bmi2(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize, unsigned maxLog, void* workSpace, size_t wkspSize)
369 {
370 return FSE_decompress_wksp_body(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize, 1);
371 }
372 #endif
373
374 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)
375 {
376 #if DYNAMIC_BMI2
377 if (bmi2) {
378 return FSE_decompress_wksp_body_bmi2(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize);
379 }
380 #endif
381 (void)bmi2;
382 return FSE_decompress_wksp_body_default(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize);
383 }
384
385
386 typedef FSE_DTable DTable_max_t[FSE_DTABLE_SIZE_U32(FSE_MAX_TABLELOG)];
387
388
389
390 #endif /* FSE_COMMONDEFS_ONLY */
391
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.