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 #include <ntifs.h>
27 #include <ntddk.h>
28 
29 
30 /* **************************************************************
31 *  Error Management
32 ****************************************************************/
33 #define FSE_isError ERR_isError
34 #define FSE_STATIC_ASSERT(c) DEBUG_STATIC_ASSERT(c)   /* use only *after* variable declarations */
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 #define FSED_ALLOC_TAG 0x64455346 // "FSEd"
60 
61 /* Function templates */
62 FSE_DTable* FSE_createDTable (unsigned tableLog)
63 {
64     if (tableLog > FSE_TABLELOG_ABSOLUTE_MAX) tableLog = FSE_TABLELOG_ABSOLUTE_MAX;
65     return (FSE_DTable*)ExAllocatePoolWithTag(PagedPool, FSE_DTABLE_SIZE_U32(tableLog) * sizeof (U32), FSED_ALLOC_TAG);
66 }
67 
68 void FSE_freeDTable (FSE_DTable* dt)
69 {
70     ExFreePool(dt);
71 }
72 
73 size_t FSE_buildDTable(FSE_DTable* dt, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog)
74 {
75     void* const tdPtr = dt+1;   /* because *dt is unsigned, 32-bits aligned on 32-bits */
76     FSE_DECODE_TYPE* const tableDecode = (FSE_DECODE_TYPE*) (tdPtr);
77     U16 symbolNext[FSE_MAX_SYMBOL_VALUE+1];
78 
79     U32 const maxSV1 = maxSymbolValue + 1;
80     U32 const tableSize = 1 << tableLog;
81     U32 highThreshold = tableSize-1;
82 
83     /* Sanity Checks */
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         memcpy(dt, &DTableH, sizeof(DTableH));
102     }
103 
104     /* Spread symbols */
105     {   U32 const tableMask = tableSize-1;
106         U32 const step = FSE_TABLESTEP(tableSize);
107         U32 s, position = 0;
108         for (s=0; s<maxSV1; s++) {
109             int i;
110             for (i=0; i<normalizedCounter[s]; i++) {
111                 tableDecode[position].symbol = (FSE_FUNCTION_TYPE)s;
112                 position = (position + step) & tableMask;
113                 while (position > highThreshold) position = (position + step) & tableMask;   /* lowprob area */
114         }   }
115         if (position!=0) return ERROR(GENERIC);   /* position must reach all cells once, otherwise normalizedCounter is incorrect */
116     }
117 
118     /* Build Decoding table */
119     {   U32 u;
120         for (u=0; u<tableSize; u++) {
121             FSE_FUNCTION_TYPE const symbol = (FSE_FUNCTION_TYPE)(tableDecode[u].symbol);
122             U32 const nextState = symbolNext[symbol]++;
123             tableDecode[u].nbBits = (BYTE) (tableLog - BIT_highbit32(nextState) );
124             tableDecode[u].newState = (U16) ( (nextState << tableDecode[u].nbBits) - tableSize);
125     }   }
126 
127     return 0;
128 }
129 
130 
131 #ifndef FSE_COMMONDEFS_ONLY
132 
133 /*-*******************************************************
134 *  Decompression (Byte symbols)
135 *********************************************************/
136 size_t FSE_buildDTable_rle (FSE_DTable* dt, BYTE symbolValue)
137 {
138     void* ptr = dt;
139     FSE_DTableHeader* const DTableH = (FSE_DTableHeader*)ptr;
140     void* dPtr = dt + 1;
141     FSE_decode_t* const cell = (FSE_decode_t*)dPtr;
142 
143     DTableH->tableLog = 0;
144     DTableH->fastMode = 0;
145 
146     cell->newState = 0;
147     cell->symbol = symbolValue;
148     cell->nbBits = 0;
149 
150     return 0;
151 }
152 
153 
154 size_t FSE_buildDTable_raw (FSE_DTable* dt, unsigned nbBits)
155 {
156     void* ptr = dt;
157     FSE_DTableHeader* const DTableH = (FSE_DTableHeader*)ptr;
158     void* dPtr = dt + 1;
159     FSE_decode_t* const dinfo = (FSE_decode_t*)dPtr;
160     const unsigned tableSize = 1 << nbBits;
161     const unsigned tableMask = tableSize - 1;
162     const unsigned maxSV1 = tableMask+1;
163     unsigned s;
164 
165     /* Sanity checks */
166     if (nbBits < 1) return ERROR(GENERIC);         /* min size */
167 
168     /* Build Decoding Table */
169     DTableH->tableLog = (U16)nbBits;
170     DTableH->fastMode = 1;
171     for (s=0; s<maxSV1; s++) {
172         dinfo[s].newState = 0;
173         dinfo[s].symbol = (BYTE)s;
174         dinfo[s].nbBits = (BYTE)nbBits;
175     }
176 
177     return 0;
178 }
179 
180 FORCE_INLINE_TEMPLATE size_t FSE_decompress_usingDTable_generic(
181           void* dst, size_t maxDstSize,
182     const void* cSrc, size_t cSrcSize,
183     const FSE_DTable* dt, const unsigned fast)
184 {
185     BYTE* const ostart = (BYTE*) dst;
186     BYTE* op = ostart;
187     BYTE* const omax = op + maxDstSize;
188     BYTE* const olimit = omax-3;
189 
190     BIT_DStream_t bitD;
191     FSE_DState_t state1;
192     FSE_DState_t state2;
193 
194     /* Init */
195     CHECK_F(BIT_initDStream(&bitD, cSrc, cSrcSize));
196 
197     FSE_initDState(&state1, &bitD, dt);
198     FSE_initDState(&state2, &bitD, dt);
199 
200 #define FSE_GETSYMBOL(statePtr) fast ? FSE_decodeSymbolFast(statePtr, &bitD) : FSE_decodeSymbol(statePtr, &bitD)
201 
202     /* 4 symbols per loop */
203     for ( ; (BIT_reloadDStream(&bitD)==BIT_DStream_unfinished) & (op<olimit) ; op+=4) {
204         op[0] = FSE_GETSYMBOL(&state1);
205 
206         if (FSE_MAX_TABLELOG*2+7 > sizeof(bitD.bitContainer)*8)    /* This test must be static */
207             BIT_reloadDStream(&bitD);
208 
209         op[1] = FSE_GETSYMBOL(&state2);
210 
211         if (FSE_MAX_TABLELOG*4+7 > sizeof(bitD.bitContainer)*8)    /* This test must be static */
212             { if (BIT_reloadDStream(&bitD) > BIT_DStream_unfinished) { op+=2; break; } }
213 
214         op[2] = FSE_GETSYMBOL(&state1);
215 
216         if (FSE_MAX_TABLELOG*2+7 > sizeof(bitD.bitContainer)*8)    /* This test must be static */
217             BIT_reloadDStream(&bitD);
218 
219         op[3] = FSE_GETSYMBOL(&state2);
220     }
221 
222     /* tail */
223     /* note : BIT_reloadDStream(&bitD) >= FSE_DStream_partiallyFilled; Ends at exactly BIT_DStream_completed */
224     while (1) {
225         if (op>(omax-2)) return ERROR(dstSize_tooSmall);
226         *op++ = FSE_GETSYMBOL(&state1);
227         if (BIT_reloadDStream(&bitD)==BIT_DStream_overflow) {
228             *op++ = FSE_GETSYMBOL(&state2);
229             break;
230         }
231 
232         if (op>(omax-2)) return ERROR(dstSize_tooSmall);
233         *op++ = FSE_GETSYMBOL(&state2);
234         if (BIT_reloadDStream(&bitD)==BIT_DStream_overflow) {
235             *op++ = FSE_GETSYMBOL(&state1);
236             break;
237     }   }
238 
239     return op-ostart;
240 }
241 
242 
243 size_t FSE_decompress_usingDTable(void* dst, size_t originalSize,
244                             const void* cSrc, size_t cSrcSize,
245                             const FSE_DTable* dt)
246 {
247     const void* ptr = dt;
248     const FSE_DTableHeader* DTableH = (const FSE_DTableHeader*)ptr;
249     const U32 fastMode = DTableH->fastMode;
250 
251     /* select fast mode (static) */
252     if (fastMode) return FSE_decompress_usingDTable_generic(dst, originalSize, cSrc, cSrcSize, dt, 1);
253     return FSE_decompress_usingDTable_generic(dst, originalSize, cSrc, cSrcSize, dt, 0);
254 }
255 
256 
257 size_t FSE_decompress_wksp(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize, FSE_DTable* workSpace, unsigned maxLog)
258 {
259     const BYTE* const istart = (const BYTE*)cSrc;
260     const BYTE* ip = istart;
261     short counting[FSE_MAX_SYMBOL_VALUE+1];
262     unsigned tableLog;
263     unsigned maxSymbolValue = FSE_MAX_SYMBOL_VALUE;
264 
265     /* normal FSE decoding mode */
266     size_t const NCountLength = FSE_readNCount (counting, &maxSymbolValue, &tableLog, istart, cSrcSize);
267     if (FSE_isError(NCountLength)) return NCountLength;
268     /* if (NCountLength >= cSrcSize) return ERROR(srcSize_wrong); */  /* too small input size; supposed to be already checked in NCountLength, only remaining case : NCountLength==cSrcSize */
269     if (tableLog > maxLog) return ERROR(tableLog_tooLarge);
270     ip += NCountLength;
271     cSrcSize -= NCountLength;
272 
273     CHECK_F( FSE_buildDTable (workSpace, counting, maxSymbolValue, tableLog) );
274 
275     return FSE_decompress_usingDTable (dst, dstCapacity, ip, cSrcSize, workSpace);   /* always return, even if it is an error code */
276 }
277 
278 
279 typedef FSE_DTable DTable_max_t[FSE_DTABLE_SIZE_U32(FSE_MAX_TABLELOG)];
280 
281 size_t FSE_decompress(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize)
282 {
283     DTable_max_t dt;   /* Static analyzer seems unable to understand this table will be properly initialized later */
284     return FSE_decompress_wksp(dst, dstCapacity, cSrc, cSrcSize, dt, FSE_MAX_TABLELOG);
285 }
286 
287 
288 
289 #endif   /* FSE_COMMONDEFS_ONLY */
290