2 * FSE : Finite State Entropy decoder
3 * Copyright (C) 2013-2015, Yann Collet.
5 * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions are
11 * * Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * * Redistributions in binary form must reproduce the above
14 * copyright notice, this list of conditions and the following disclaimer
15 * in the documentation and/or other materials provided with the
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 * This program is free software; you can redistribute it and/or modify it under
31 * the terms of the GNU General Public License version 2 as published by the
32 * Free Software Foundation. This program is dual-licensed; you may select
33 * either version 2 of the GNU General Public License ("GPL") or BSD license
36 * You can contact the author at :
37 * - Source repository : https://github.com/Cyan4973/FiniteStateEntropy
40 /* **************************************************************
42 ****************************************************************/
43 #define FORCE_INLINE static __always_inline
45 /* **************************************************************
47 ****************************************************************/
48 #include "bitstream.h"
50 #include "zstd_internal.h"
51 #include <linux/compiler.h>
52 #include <linux/kernel.h>
53 #include <linux/string.h> /* memcpy, memset */
55 /* **************************************************************
57 ****************************************************************/
58 #define FSE_isError ERR_isError
59 #define FSE_STATIC_ASSERT(c) \
61 enum { FSE_static_assert = 1 / (int)(!!(c)) }; \
62 } /* use only *after* variable declarations */
64 /* **************************************************************
66 ****************************************************************/
68 designed to be included
69 for type-specific functions (template emulation in C)
70 Objective is to write these functions only once, for improved maintenance
74 #ifndef FSE_FUNCTION_EXTENSION
75 #error "FSE_FUNCTION_EXTENSION must be defined"
77 #ifndef FSE_FUNCTION_TYPE
78 #error "FSE_FUNCTION_TYPE must be defined"
82 #define FSE_CAT(X, Y) X##Y
83 #define FSE_FUNCTION_NAME(X, Y) FSE_CAT(X, Y)
84 #define FSE_TYPE_NAME(X, Y) FSE_CAT(X, Y)
86 /* Function templates */
88 size_t FSE_buildDTable_wksp(FSE_DTable *dt, const short *normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void *workspace, size_t workspaceSize)
90 void *const tdPtr = dt + 1; /* because *dt is unsigned, 32-bits aligned on 32-bits */
91 FSE_DECODE_TYPE *const tableDecode = (FSE_DECODE_TYPE *)(tdPtr);
92 U16 *symbolNext = (U16 *)workspace;
94 U32 const maxSV1 = maxSymbolValue + 1;
95 U32 const tableSize = 1 << tableLog;
96 U32 highThreshold = tableSize - 1;
99 if (workspaceSize < sizeof(U16) * (FSE_MAX_SYMBOL_VALUE + 1))
100 return ERROR(tableLog_tooLarge);
101 if (maxSymbolValue > FSE_MAX_SYMBOL_VALUE)
102 return ERROR(maxSymbolValue_tooLarge);
103 if (tableLog > FSE_MAX_TABLELOG)
104 return ERROR(tableLog_tooLarge);
106 /* Init, lay down lowprob symbols */
108 FSE_DTableHeader DTableH;
109 DTableH.tableLog = (U16)tableLog;
110 DTableH.fastMode = 1;
112 S16 const largeLimit = (S16)(1 << (tableLog - 1));
114 for (s = 0; s < maxSV1; s++) {
115 if (normalizedCounter[s] == -1) {
116 tableDecode[highThreshold--].symbol = (FSE_FUNCTION_TYPE)s;
119 if (normalizedCounter[s] >= largeLimit)
120 DTableH.fastMode = 0;
121 symbolNext[s] = normalizedCounter[s];
125 memcpy(dt, &DTableH, sizeof(DTableH));
130 U32 const tableMask = tableSize - 1;
131 U32 const step = FSE_TABLESTEP(tableSize);
133 for (s = 0; s < maxSV1; s++) {
135 for (i = 0; i < normalizedCounter[s]; i++) {
136 tableDecode[position].symbol = (FSE_FUNCTION_TYPE)s;
137 position = (position + step) & tableMask;
138 while (position > highThreshold)
139 position = (position + step) & tableMask; /* lowprob area */
143 return ERROR(GENERIC); /* position must reach all cells once, otherwise normalizedCounter is incorrect */
146 /* Build Decoding table */
149 for (u = 0; u < tableSize; u++) {
150 FSE_FUNCTION_TYPE const symbol = (FSE_FUNCTION_TYPE)(tableDecode[u].symbol);
151 U16 nextState = symbolNext[symbol]++;
152 tableDecode[u].nbBits = (BYTE)(tableLog - BIT_highbit32((U32)nextState));
153 tableDecode[u].newState = (U16)((nextState << tableDecode[u].nbBits) - tableSize);
160 /*-*******************************************************
161 * Decompression (Byte symbols)
162 *********************************************************/
163 size_t FSE_buildDTable_rle(FSE_DTable *dt, BYTE symbolValue)
166 FSE_DTableHeader *const DTableH = (FSE_DTableHeader *)ptr;
168 FSE_decode_t *const cell = (FSE_decode_t *)dPtr;
170 DTableH->tableLog = 0;
171 DTableH->fastMode = 0;
174 cell->symbol = symbolValue;
180 size_t FSE_buildDTable_raw(FSE_DTable *dt, unsigned nbBits)
183 FSE_DTableHeader *const DTableH = (FSE_DTableHeader *)ptr;
185 FSE_decode_t *const dinfo = (FSE_decode_t *)dPtr;
186 const unsigned tableSize = 1 << nbBits;
187 const unsigned tableMask = tableSize - 1;
188 const unsigned maxSV1 = tableMask + 1;
193 return ERROR(GENERIC); /* min size */
195 /* Build Decoding Table */
196 DTableH->tableLog = (U16)nbBits;
197 DTableH->fastMode = 1;
198 for (s = 0; s < maxSV1; s++) {
199 dinfo[s].newState = 0;
200 dinfo[s].symbol = (BYTE)s;
201 dinfo[s].nbBits = (BYTE)nbBits;
207 FORCE_INLINE size_t FSE_decompress_usingDTable_generic(void *dst, size_t maxDstSize, const void *cSrc, size_t cSrcSize, const FSE_DTable *dt,
210 BYTE *const ostart = (BYTE *)dst;
212 BYTE *const omax = op + maxDstSize;
213 BYTE *const olimit = omax - 3;
220 CHECK_F(BIT_initDStream(&bitD, cSrc, cSrcSize));
222 FSE_initDState(&state1, &bitD, dt);
223 FSE_initDState(&state2, &bitD, dt);
225 #define FSE_GETSYMBOL(statePtr) fast ? FSE_decodeSymbolFast(statePtr, &bitD) : FSE_decodeSymbol(statePtr, &bitD)
227 /* 4 symbols per loop */
228 for (; (BIT_reloadDStream(&bitD) == BIT_DStream_unfinished) & (op < olimit); op += 4) {
229 op[0] = FSE_GETSYMBOL(&state1);
231 if (FSE_MAX_TABLELOG * 2 + 7 > sizeof(bitD.bitContainer) * 8) /* This test must be static */
232 BIT_reloadDStream(&bitD);
234 op[1] = FSE_GETSYMBOL(&state2);
236 if (FSE_MAX_TABLELOG * 4 + 7 > sizeof(bitD.bitContainer) * 8) /* This test must be static */
238 if (BIT_reloadDStream(&bitD) > BIT_DStream_unfinished) {
244 op[2] = FSE_GETSYMBOL(&state1);
246 if (FSE_MAX_TABLELOG * 2 + 7 > sizeof(bitD.bitContainer) * 8) /* This test must be static */
247 BIT_reloadDStream(&bitD);
249 op[3] = FSE_GETSYMBOL(&state2);
253 /* note : BIT_reloadDStream(&bitD) >= FSE_DStream_partiallyFilled; Ends at exactly BIT_DStream_completed */
256 return ERROR(dstSize_tooSmall);
257 *op++ = FSE_GETSYMBOL(&state1);
258 if (BIT_reloadDStream(&bitD) == BIT_DStream_overflow) {
259 *op++ = FSE_GETSYMBOL(&state2);
264 return ERROR(dstSize_tooSmall);
265 *op++ = FSE_GETSYMBOL(&state2);
266 if (BIT_reloadDStream(&bitD) == BIT_DStream_overflow) {
267 *op++ = FSE_GETSYMBOL(&state1);
275 size_t FSE_decompress_usingDTable(void *dst, size_t originalSize, const void *cSrc, size_t cSrcSize, const FSE_DTable *dt)
277 const void *ptr = dt;
278 const FSE_DTableHeader *DTableH = (const FSE_DTableHeader *)ptr;
279 const U32 fastMode = DTableH->fastMode;
281 /* select fast mode (static) */
283 return FSE_decompress_usingDTable_generic(dst, originalSize, cSrc, cSrcSize, dt, 1);
284 return FSE_decompress_usingDTable_generic(dst, originalSize, cSrc, cSrcSize, dt, 0);
287 size_t FSE_decompress_wksp(void *dst, size_t dstCapacity, const void *cSrc, size_t cSrcSize, unsigned maxLog, void *workspace, size_t workspaceSize)
289 const BYTE *const istart = (const BYTE *)cSrc;
290 const BYTE *ip = istart;
292 unsigned maxSymbolValue = FSE_MAX_SYMBOL_VALUE;
297 size_t spaceUsed32 = 0;
299 FSE_STATIC_ASSERT(sizeof(FSE_DTable) == sizeof(U32));
301 dt = (FSE_DTable *)((U32 *)workspace + spaceUsed32);
302 spaceUsed32 += FSE_DTABLE_SIZE_U32(maxLog);
303 counting = (short *)((U32 *)workspace + spaceUsed32);
304 spaceUsed32 += ALIGN(sizeof(short) * (FSE_MAX_SYMBOL_VALUE + 1), sizeof(U32)) >> 2;
306 if ((spaceUsed32 << 2) > workspaceSize)
307 return ERROR(tableLog_tooLarge);
308 workspace = (U32 *)workspace + spaceUsed32;
309 workspaceSize -= (spaceUsed32 << 2);
311 /* normal FSE decoding mode */
312 NCountLength = FSE_readNCount(counting, &maxSymbolValue, &tableLog, istart, cSrcSize);
313 if (FSE_isError(NCountLength))
315 // if (NCountLength >= cSrcSize) return ERROR(srcSize_wrong); /* too small input size; supposed to be already checked in NCountLength, only remaining
316 // case : NCountLength==cSrcSize */
317 if (tableLog > maxLog)
318 return ERROR(tableLog_tooLarge);
320 cSrcSize -= NCountLength;
322 CHECK_F(FSE_buildDTable_wksp(dt, counting, maxSymbolValue, tableLog, workspace, workspaceSize));
324 return FSE_decompress_usingDTable(dst, dstCapacity, ip, cSrcSize, dt); /* always return, even if it is an error code */