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1/* ******************************************************************2 * FSE : Finite State Entropy decoder3 * Copyright (c) Yann Collet, Facebook, Inc.4 *5 * You can contact the author at :6 * - FSE source repository : https://github.com/Cyan4973/FiniteStateEntropy7 * - Public forum : https://groups.google.com/forum/#!forum/lz4c8 *9 * This source code is licensed under both the BSD-style license (found in the10 * LICENSE file in the root directory of this source tree) and the GPLv2 (found11 * 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* Includes18****************************************************************/19#include "debug.h" /* assert */20#include "bitstream.h"21#include "compiler.h"22#define FSE_STATIC_LINKING_ONLY23#include "fse.h"24#include "error_private.h"25#define ZSTD_DEPS_NEED_MALLOC26#include "zstd_deps.h"27 28 29/* **************************************************************30* Error Management31****************************************************************/32#define FSE_isError ERR_isError33#define FSE_STATIC_ASSERT(c) DEBUG_STATIC_ASSERT(c) /* use only *after* variable declarations */34 35 36/* **************************************************************37* Templates38****************************************************************/39/*40 designed to be included41 for type-specific functions (template emulation in C)42 Objective is to write these functions only once, for improved maintenance43*/44 45/* safety checks */46#ifndef FSE_FUNCTION_EXTENSION47# error "FSE_FUNCTION_EXTENSION must be defined"48#endif49#ifndef FSE_FUNCTION_TYPE50# error "FSE_FUNCTION_TYPE must be defined"51#endif52 53/* Function names */54#define FSE_CAT(X,Y) X##Y55#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 */60FSE_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 66void FSE_freeDTable (FSE_DTable* dt)67{68 ZSTD_free(dt);69}70 71static 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 branch110 * misses since small blocks generally have small table logs, so nearly111 * all symbols have counts <= 8. We ensure we have 8 bytes at the end of112 * 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 the131 * 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 176size_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_ONLY183 184/*-*******************************************************185* Decompression (Byte symbols)186*********************************************************/187size_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 205size_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 231FORCE_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 294size_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 308size_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 313typedef struct {314 short ncount[FSE_MAX_SYMBOL_VALUE + 1];315 FSE_DTable dtable[]; /* Dynamically sized */316} FSE_DecompressWksp;317 318 319FORCE_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. */362static 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_BMI2368BMI2_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#endif373 374size_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_BMI2377 if (bmi2) {378 return FSE_decompress_wksp_body_bmi2(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize);379 }380#endif381 (void)bmi2;382 return FSE_decompress_wksp_body_default(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize);383}384 385 386typedef FSE_DTable DTable_max_t[FSE_DTABLE_SIZE_U32(FSE_MAX_TABLELOG)];387 388 389 390#endif /* FSE_COMMONDEFS_ONLY */391