1 /* ******************************************************************
2  * FSE : Finite State Entropy decoder
3  * Copyright (c) 2013-2020, 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 <stdlib.h>     /* malloc, free, qsort */
20 #include <string.h>     /* memcpy, memset */
21 #include "bitstream.h"
22 #include "compiler.h"
23 #define FSE_STATIC_LINKING_ONLY
24 #include "fse.h"
25 #include "error_private.h"
26 
27 
28 /* **************************************************************
29 *  Error Management
30 ****************************************************************/
31 #define FSE_isError ERR_isError
32 #define FSE_STATIC_ASSERT(c) DEBUG_STATIC_ASSERT(c)   /* use only *after* variable declarations */
33 
34 
35 /* **************************************************************
36 *  Templates
37 ****************************************************************/
38 /*
39   designed to be included
40   for type-specific functions (template emulation in C)
41   Objective is to write these functions only once, for improved maintenance
42 */
43 
44 /* safety checks */
45 #ifndef FSE_FUNCTION_EXTENSION
46 #  error "FSE_FUNCTION_EXTENSION must be defined"
47 #endif
48 #ifndef FSE_FUNCTION_TYPE
49 #  error "FSE_FUNCTION_TYPE must be defined"
50 #endif
51 
52 /* Function names */
53 #define FSE_CAT(X,Y) X##Y
54 #define FSE_FUNCTION_NAME(X,Y) FSE_CAT(X,Y)
55 #define FSE_TYPE_NAME(X,Y) FSE_CAT(X,Y)
56 
57 
58 /* Function templates */
59 size_t FSE_buildDTable(FSE_DTable* dt, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog)
60 {
61     void* const tdPtr = dt+1;   /* because *dt is unsigned, 32-bits aligned on 32-bits */
62     FSE_DECODE_TYPE* const tableDecode = (FSE_DECODE_TYPE*) (tdPtr);
63     U16 symbolNext[FSE_MAX_SYMBOL_VALUE+1];
64 
65     U32 const maxSV1 = maxSymbolValue + 1;
66     U32 const tableSize = 1 << tableLog;
67     U32 highThreshold = tableSize-1;
68 
69     /* Sanity Checks */
70     if (maxSymbolValue > FSE_MAX_SYMBOL_VALUE) return ERROR(maxSymbolValue_tooLarge);
71     if (tableLog > FSE_MAX_TABLELOG) return ERROR(tableLog_tooLarge);
72 
73     /* Init, lay down lowprob symbols */
74     {   FSE_DTableHeader DTableH;
75         DTableH.tableLog = (U16)tableLog;
76         DTableH.fastMode = 1;
77         {   S16 const largeLimit= (S16)(1 << (tableLog-1));
78             U32 s;
79             for (s=0; s<maxSV1; s++) {
80                 if (normalizedCounter[s]==-1) {
81                     tableDecode[highThreshold--].symbol = (FSE_FUNCTION_TYPE)s;
82                     symbolNext[s] = 1;
83                 } else {
84                     if (normalizedCounter[s] >= largeLimit) DTableH.fastMode=0;
85                     symbolNext[s] = normalizedCounter[s];
86         }   }   }
87         memcpy(dt, &DTableH, sizeof(DTableH));
88     }
89 
90     /* Spread symbols */
91     {   U32 const tableMask = tableSize-1;
92         U32 const step = FSE_TABLESTEP(tableSize);
93         U32 s, position = 0;
94         for (s=0; s<maxSV1; s++) {
95             int i;
96             for (i=0; i<normalizedCounter[s]; i++) {
97                 tableDecode[position].symbol = (FSE_FUNCTION_TYPE)s;
98                 position = (position + step) & tableMask;
99                 while (position > highThreshold) position = (position + step) & tableMask;   /* lowprob area */
100         }   }
101         if (position!=0) return ERROR(GENERIC);   /* position must reach all cells once, otherwise normalizedCounter is incorrect */
102     }
103 
104     /* Build Decoding table */
105     {   U32 u;
106         for (u=0; u<tableSize; u++) {
107             FSE_FUNCTION_TYPE const symbol = (FSE_FUNCTION_TYPE)(tableDecode[u].symbol);
108             U32 const nextState = symbolNext[symbol]++;
109             tableDecode[u].nbBits = (BYTE) (tableLog - BIT_highbit32(nextState) );
110             tableDecode[u].newState = (U16) ( (nextState << tableDecode[u].nbBits) - tableSize);
111     }   }
112 
113     return 0;
114 }
115 
116 
117 #ifndef FSE_COMMONDEFS_ONLY
118 
119 /*-*******************************************************
120 *  Decompression (Byte symbols)
121 *********************************************************/
122 size_t FSE_buildDTable_rle (FSE_DTable* dt, BYTE symbolValue)
123 {
124     void* ptr = dt;
125     FSE_DTableHeader* const DTableH = (FSE_DTableHeader*)ptr;
126     void* dPtr = dt + 1;
127     FSE_decode_t* const cell = (FSE_decode_t*)dPtr;
128 
129     DTableH->tableLog = 0;
130     DTableH->fastMode = 0;
131 
132     cell->newState = 0;
133     cell->symbol = symbolValue;
134     cell->nbBits = 0;
135 
136     return 0;
137 }
138 
139 
140 size_t FSE_buildDTable_raw (FSE_DTable* dt, unsigned nbBits)
141 {
142     void* ptr = dt;
143     FSE_DTableHeader* const DTableH = (FSE_DTableHeader*)ptr;
144     void* dPtr = dt + 1;
145     FSE_decode_t* const dinfo = (FSE_decode_t*)dPtr;
146     const unsigned tableSize = 1 << nbBits;
147     const unsigned tableMask = tableSize - 1;
148     const unsigned maxSV1 = tableMask+1;
149     unsigned s;
150 
151     /* Sanity checks */
152     if (nbBits < 1) return ERROR(GENERIC);         /* min size */
153 
154     /* Build Decoding Table */
155     DTableH->tableLog = (U16)nbBits;
156     DTableH->fastMode = 1;
157     for (s=0; s<maxSV1; s++) {
158         dinfo[s].newState = 0;
159         dinfo[s].symbol = (BYTE)s;
160         dinfo[s].nbBits = (BYTE)nbBits;
161     }
162 
163     return 0;
164 }
165 
166 FORCE_INLINE_TEMPLATE size_t FSE_decompress_usingDTable_generic(
167           void* dst, size_t maxDstSize,
168     const void* cSrc, size_t cSrcSize,
169     const FSE_DTable* dt, const unsigned fast)
170 {
171     BYTE* const ostart = (BYTE*) dst;
172     BYTE* op = ostart;
173     BYTE* const omax = op + maxDstSize;
174     BYTE* const olimit = omax-3;
175 
176     BIT_DStream_t bitD;
177     FSE_DState_t state1;
178     FSE_DState_t state2;
179 
180     /* Init */
181     CHECK_F(BIT_initDStream(&bitD, cSrc, cSrcSize));
182 
183     FSE_initDState(&state1, &bitD, dt);
184     FSE_initDState(&state2, &bitD, dt);
185 
186 #define FSE_GETSYMBOL(statePtr) fast ? FSE_decodeSymbolFast(statePtr, &bitD) : FSE_decodeSymbol(statePtr, &bitD)
187 
188     /* 4 symbols per loop */
189     for ( ; (BIT_reloadDStream(&bitD)==BIT_DStream_unfinished) & (op<olimit) ; op+=4) {
190         op[0] = FSE_GETSYMBOL(&state1);
191 
192         if (FSE_MAX_TABLELOG*2+7 > sizeof(bitD.bitContainer)*8)    /* This test must be static */
193             BIT_reloadDStream(&bitD);
194 
195         op[1] = FSE_GETSYMBOL(&state2);
196 
197         if (FSE_MAX_TABLELOG*4+7 > sizeof(bitD.bitContainer)*8)    /* This test must be static */
198             { if (BIT_reloadDStream(&bitD) > BIT_DStream_unfinished) { op+=2; break; } }
199 
200         op[2] = FSE_GETSYMBOL(&state1);
201 
202         if (FSE_MAX_TABLELOG*2+7 > sizeof(bitD.bitContainer)*8)    /* This test must be static */
203             BIT_reloadDStream(&bitD);
204 
205         op[3] = FSE_GETSYMBOL(&state2);
206     }
207 
208     /* tail */
209     /* note : BIT_reloadDStream(&bitD) >= FSE_DStream_partiallyFilled; Ends at exactly BIT_DStream_completed */
210     while (1) {
211         if (op>(omax-2)) return ERROR(dstSize_tooSmall);
212         *op++ = FSE_GETSYMBOL(&state1);
213         if (BIT_reloadDStream(&bitD)==BIT_DStream_overflow) {
214             *op++ = FSE_GETSYMBOL(&state2);
215             break;
216         }
217 
218         if (op>(omax-2)) return ERROR(dstSize_tooSmall);
219         *op++ = FSE_GETSYMBOL(&state2);
220         if (BIT_reloadDStream(&bitD)==BIT_DStream_overflow) {
221             *op++ = FSE_GETSYMBOL(&state1);
222             break;
223     }   }
224 
225     return op-ostart;
226 }
227 
228 
229 size_t FSE_decompress_usingDTable(void* dst, size_t originalSize,
230                             const void* cSrc, size_t cSrcSize,
231                             const FSE_DTable* dt)
232 {
233     const void* ptr = dt;
234     const FSE_DTableHeader* DTableH = (const FSE_DTableHeader*)ptr;
235     const U32 fastMode = DTableH->fastMode;
236 
237     /* select fast mode (static) */
238     if (fastMode) return FSE_decompress_usingDTable_generic(dst, originalSize, cSrc, cSrcSize, dt, 1);
239     return FSE_decompress_usingDTable_generic(dst, originalSize, cSrc, cSrcSize, dt, 0);
240 }
241 
242 
243 size_t FSE_decompress_wksp(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize, FSE_DTable* workSpace, unsigned maxLog)
244 {
245     const BYTE* const istart = (const BYTE*)cSrc;
246     const BYTE* ip = istart;
247     short counting[FSE_MAX_SYMBOL_VALUE+1];
248     unsigned tableLog;
249     unsigned maxSymbolValue = FSE_MAX_SYMBOL_VALUE;
250 
251     /* normal FSE decoding mode */
252     size_t const NCountLength = FSE_readNCount (counting, &maxSymbolValue, &tableLog, istart, cSrcSize);
253     if (FSE_isError(NCountLength)) return NCountLength;
254     /* if (NCountLength >= cSrcSize) return ERROR(srcSize_wrong); */  /* too small input size; supposed to be already checked in NCountLength, only remaining case : NCountLength==cSrcSize */
255     if (tableLog > maxLog) return ERROR(tableLog_tooLarge);
256     ip += NCountLength;
257     cSrcSize -= NCountLength;
258 
259     CHECK_F( FSE_buildDTable (workSpace, counting, maxSymbolValue, tableLog) );
260 
261     return FSE_decompress_usingDTable (dst, dstCapacity, ip, cSrcSize, workSpace);   /* always return, even if it is an error code */
262 }
263 
264 
265 typedef FSE_DTable DTable_max_t[FSE_DTABLE_SIZE_U32(FSE_MAX_TABLELOG)];
266 
267 size_t FSE_decompress(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize)
268 {
269     DTable_max_t dt;   /* Static analyzer seems unable to understand this table will be properly initialized later */
270     return FSE_decompress_wksp(dst, dstCapacity, cSrc, cSrcSize, dt, FSE_MAX_TABLELOG);
271 }
272 
273 
274 
275 #endif   /* FSE_COMMONDEFS_ONLY */
276