1 // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0-only
2 /* ******************************************************************
3 * FSE : Finite State Entropy decoder
4 * Copyright (c) 2013-2020, Yann Collet, Facebook, Inc.
5 *
6 * You can contact the author at :
7 * - FSE source repository : https://github.com/Cyan4973/FiniteStateEntropy
8 * - Public forum : https://groups.google.com/forum/#!forum/lz4c
9 *
10 * This source code is licensed under both the BSD-style license (found in the
11 * LICENSE file in the root directory of this source tree) and the GPLv2 (found
12 * in the COPYING file in the root directory of this source tree).
13 * You may select, at your option, one of the above-listed licenses.
14 ****************************************************************** */
15
16
17 /* **************************************************************
18 * Includes
19 ****************************************************************/
20 #include <stdlib.h> /* malloc, free, qsort */
21 #include <string.h> /* memcpy, memset */
22 #include "bitstream.h"
23 #include "compiler.h"
24 #define FSE_STATIC_LINKING_ONLY
25 #include "fse.h"
26 #include "error_private.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 */
FSE_buildDTable(FSE_DTable * dt,const short * normalizedCounter,unsigned maxSymbolValue,unsigned tableLog)60 size_t FSE_buildDTable(FSE_DTable* dt, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog)
61 {
62 void* const tdPtr = dt+1; /* because *dt is unsigned, 32-bits aligned on 32-bits */
63 FSE_DECODE_TYPE* const tableDecode = (FSE_DECODE_TYPE*) (tdPtr);
64 U16 symbolNext[FSE_MAX_SYMBOL_VALUE+1];
65
66 U32 const maxSV1 = maxSymbolValue + 1;
67 U32 const tableSize = 1 << tableLog;
68 U32 highThreshold = tableSize-1;
69
70 /* Sanity Checks */
71 if (maxSymbolValue > FSE_MAX_SYMBOL_VALUE) return ERROR(maxSymbolValue_tooLarge);
72 if (tableLog > FSE_MAX_TABLELOG) return ERROR(tableLog_tooLarge);
73
74 /* Init, lay down lowprob symbols */
75 { FSE_DTableHeader DTableH;
76 DTableH.tableLog = (U16)tableLog;
77 DTableH.fastMode = 1;
78 { S16 const largeLimit= (S16)(1 << (tableLog-1));
79 U32 s;
80 for (s=0; s<maxSV1; s++) {
81 if (normalizedCounter[s]==-1) {
82 tableDecode[highThreshold--].symbol = (FSE_FUNCTION_TYPE)s;
83 symbolNext[s] = 1;
84 } else {
85 if (normalizedCounter[s] >= largeLimit) DTableH.fastMode=0;
86 symbolNext[s] = normalizedCounter[s];
87 } } }
88 memcpy(dt, &DTableH, sizeof(DTableH));
89 }
90
91 /* Spread symbols */
92 { U32 const tableMask = tableSize-1;
93 U32 const step = FSE_TABLESTEP(tableSize);
94 U32 s, position = 0;
95 for (s=0; s<maxSV1; s++) {
96 int i;
97 for (i=0; i<normalizedCounter[s]; i++) {
98 tableDecode[position].symbol = (FSE_FUNCTION_TYPE)s;
99 position = (position + step) & tableMask;
100 while (position > highThreshold) position = (position + step) & tableMask; /* lowprob area */
101 } }
102 if (position!=0) return ERROR(GENERIC); /* position must reach all cells once, otherwise normalizedCounter is incorrect */
103 }
104
105 /* Build Decoding table */
106 { U32 u;
107 for (u=0; u<tableSize; u++) {
108 FSE_FUNCTION_TYPE const symbol = (FSE_FUNCTION_TYPE)(tableDecode[u].symbol);
109 U32 const nextState = symbolNext[symbol]++;
110 tableDecode[u].nbBits = (BYTE) (tableLog - BIT_highbit32(nextState) );
111 tableDecode[u].newState = (U16) ( (nextState << tableDecode[u].nbBits) - tableSize);
112 } }
113
114 return 0;
115 }
116
117
118 #ifndef FSE_COMMONDEFS_ONLY
119
120 /*-*******************************************************
121 * Decompression (Byte symbols)
122 *********************************************************/
FSE_buildDTable_rle(FSE_DTable * dt,BYTE symbolValue)123 size_t FSE_buildDTable_rle (FSE_DTable* dt, BYTE symbolValue)
124 {
125 void* ptr = dt;
126 FSE_DTableHeader* const DTableH = (FSE_DTableHeader*)ptr;
127 void* dPtr = dt + 1;
128 FSE_decode_t* const cell = (FSE_decode_t*)dPtr;
129
130 DTableH->tableLog = 0;
131 DTableH->fastMode = 0;
132
133 cell->newState = 0;
134 cell->symbol = symbolValue;
135 cell->nbBits = 0;
136
137 return 0;
138 }
139
140
FSE_buildDTable_raw(FSE_DTable * dt,unsigned nbBits)141 size_t FSE_buildDTable_raw (FSE_DTable* dt, unsigned nbBits)
142 {
143 void* ptr = dt;
144 FSE_DTableHeader* const DTableH = (FSE_DTableHeader*)ptr;
145 void* dPtr = dt + 1;
146 FSE_decode_t* const dinfo = (FSE_decode_t*)dPtr;
147 const unsigned tableSize = 1 << nbBits;
148 const unsigned tableMask = tableSize - 1;
149 const unsigned maxSV1 = tableMask+1;
150 unsigned s;
151
152 /* Sanity checks */
153 if (nbBits < 1) return ERROR(GENERIC); /* min size */
154
155 /* Build Decoding Table */
156 DTableH->tableLog = (U16)nbBits;
157 DTableH->fastMode = 1;
158 for (s=0; s<maxSV1; s++) {
159 dinfo[s].newState = 0;
160 dinfo[s].symbol = (BYTE)s;
161 dinfo[s].nbBits = (BYTE)nbBits;
162 }
163
164 return 0;
165 }
166
FSE_decompress_usingDTable_generic(void * dst,size_t maxDstSize,const void * cSrc,size_t cSrcSize,const FSE_DTable * dt,const unsigned fast)167 FORCE_INLINE_TEMPLATE size_t FSE_decompress_usingDTable_generic(
168 void* dst, size_t maxDstSize,
169 const void* cSrc, size_t cSrcSize,
170 const FSE_DTable* dt, const unsigned fast)
171 {
172 BYTE* const ostart = (BYTE*) dst;
173 BYTE* op = ostart;
174 BYTE* const omax = op + maxDstSize;
175 BYTE* const olimit = omax-3;
176
177 BIT_DStream_t bitD;
178 FSE_DState_t state1;
179 FSE_DState_t state2;
180
181 /* Init */
182 CHECK_F(BIT_initDStream(&bitD, cSrc, cSrcSize));
183
184 FSE_initDState(&state1, &bitD, dt);
185 FSE_initDState(&state2, &bitD, dt);
186
187 #define FSE_GETSYMBOL(statePtr) fast ? FSE_decodeSymbolFast(statePtr, &bitD) : FSE_decodeSymbol(statePtr, &bitD)
188
189 /* 4 symbols per loop */
190 for ( ; (BIT_reloadDStream(&bitD)==BIT_DStream_unfinished) & (op<olimit) ; op+=4) {
191 op[0] = FSE_GETSYMBOL(&state1);
192
193 if (FSE_MAX_TABLELOG*2+7 > sizeof(bitD.bitContainer)*8) /* This test must be static */
194 BIT_reloadDStream(&bitD);
195
196 op[1] = FSE_GETSYMBOL(&state2);
197
198 if (FSE_MAX_TABLELOG*4+7 > sizeof(bitD.bitContainer)*8) /* This test must be static */
199 { if (BIT_reloadDStream(&bitD) > BIT_DStream_unfinished) { op+=2; break; } }
200
201 op[2] = FSE_GETSYMBOL(&state1);
202
203 if (FSE_MAX_TABLELOG*2+7 > sizeof(bitD.bitContainer)*8) /* This test must be static */
204 BIT_reloadDStream(&bitD);
205
206 op[3] = FSE_GETSYMBOL(&state2);
207 }
208
209 /* tail */
210 /* note : BIT_reloadDStream(&bitD) >= FSE_DStream_partiallyFilled; Ends at exactly BIT_DStream_completed */
211 while (1) {
212 if (op>(omax-2)) return ERROR(dstSize_tooSmall);
213 *op++ = FSE_GETSYMBOL(&state1);
214 if (BIT_reloadDStream(&bitD)==BIT_DStream_overflow) {
215 *op++ = FSE_GETSYMBOL(&state2);
216 break;
217 }
218
219 if (op>(omax-2)) return ERROR(dstSize_tooSmall);
220 *op++ = FSE_GETSYMBOL(&state2);
221 if (BIT_reloadDStream(&bitD)==BIT_DStream_overflow) {
222 *op++ = FSE_GETSYMBOL(&state1);
223 break;
224 } }
225
226 return op-ostart;
227 }
228
229
FSE_decompress_usingDTable(void * dst,size_t originalSize,const void * cSrc,size_t cSrcSize,const FSE_DTable * dt)230 size_t FSE_decompress_usingDTable(void* dst, size_t originalSize,
231 const void* cSrc, size_t cSrcSize,
232 const FSE_DTable* dt)
233 {
234 const void* ptr = dt;
235 const FSE_DTableHeader* DTableH = (const FSE_DTableHeader*)ptr;
236 const U32 fastMode = DTableH->fastMode;
237
238 /* select fast mode (static) */
239 if (fastMode) return FSE_decompress_usingDTable_generic(dst, originalSize, cSrc, cSrcSize, dt, 1);
240 return FSE_decompress_usingDTable_generic(dst, originalSize, cSrc, cSrcSize, dt, 0);
241 }
242
243
FSE_decompress_wksp(void * dst,size_t dstCapacity,const void * cSrc,size_t cSrcSize,FSE_DTable * workSpace,unsigned maxLog)244 size_t FSE_decompress_wksp(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize, FSE_DTable* workSpace, unsigned maxLog)
245 {
246 const BYTE* const istart = (const BYTE*)cSrc;
247 const BYTE* ip = istart;
248 short counting[FSE_MAX_SYMBOL_VALUE+1];
249 unsigned tableLog;
250 unsigned maxSymbolValue = FSE_MAX_SYMBOL_VALUE;
251
252 /* normal FSE decoding mode */
253 size_t const NCountLength = FSE_readNCount (counting, &maxSymbolValue, &tableLog, istart, cSrcSize);
254 if (FSE_isError(NCountLength)) return NCountLength;
255 /* if (NCountLength >= cSrcSize) return ERROR(srcSize_wrong); */ /* too small input size; supposed to be already checked in NCountLength, only remaining case : NCountLength==cSrcSize */
256 if (tableLog > maxLog) return ERROR(tableLog_tooLarge);
257 ip += NCountLength;
258 cSrcSize -= NCountLength;
259
260 CHECK_F( FSE_buildDTable (workSpace, counting, maxSymbolValue, tableLog) );
261
262 return FSE_decompress_usingDTable (dst, dstCapacity, ip, cSrcSize, workSpace); /* always return, even if it is an error code */
263 }
264
265
266 typedef FSE_DTable DTable_max_t[FSE_DTABLE_SIZE_U32(FSE_MAX_TABLELOG)];
267
FSE_decompress(void * dst,size_t dstCapacity,const void * cSrc,size_t cSrcSize)268 size_t FSE_decompress(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize)
269 {
270 DTable_max_t dt; /* Static analyzer seems unable to understand this table will be properly initialized later */
271 return FSE_decompress_wksp(dst, dstCapacity, cSrc, cSrcSize, dt, FSE_MAX_TABLELOG);
272 }
273
274
275
276 #endif /* FSE_COMMONDEFS_ONLY */
277