/* ****************************************************************** * FSE : Finite State Entropy decoder * Copyright (c) Yann Collet, Facebook, Inc. * * You can contact the author at : * - FSE source repository : https://github.com/Cyan4973/FiniteStateEntropy * - Public forum : https://groups.google.com/forum/#!forum/lz4c * * This source code is licensed under both the BSD-style license (found in the * LICENSE file in the root directory of this source tree) and the GPLv2 (found * in the COPYING file in the root directory of this source tree). * You may select, at your option, one of the above-listed licenses. ****************************************************************** */ /* ************************************************************** * Includes ****************************************************************/ #include "debug.h" /* assert */ #include "bitstream.h" #include "compiler.h" #define FSE_STATIC_LINKING_ONLY #include "fse.h" #include "error_private.h" #define ZSTD_DEPS_NEED_MALLOC #include "zstd_deps.h" /* ************************************************************** * Error Management ****************************************************************/ #define FSE_isError ERR_isError #define FSE_STATIC_ASSERT(c) DEBUG_STATIC_ASSERT(c) /* use only *after* variable declarations */ /* ************************************************************** * Templates ****************************************************************/ /* designed to be included for type-specific functions (template emulation in C) Objective is to write these functions only once, for improved maintenance */ /* safety checks */ #ifndef FSE_FUNCTION_EXTENSION # error "FSE_FUNCTION_EXTENSION must be defined" #endif #ifndef FSE_FUNCTION_TYPE # error "FSE_FUNCTION_TYPE must be defined" #endif /* Function names */ #define FSE_CAT(X,Y) X##Y #define FSE_FUNCTION_NAME(X,Y) FSE_CAT(X,Y) #define FSE_TYPE_NAME(X,Y) FSE_CAT(X,Y) /* Function templates */ FSE_DTable* FSE_createDTable (unsigned tableLog) { if (tableLog > FSE_TABLELOG_ABSOLUTE_MAX) tableLog = FSE_TABLELOG_ABSOLUTE_MAX; return (FSE_DTable*)ZSTD_malloc( FSE_DTABLE_SIZE_U32(tableLog) * sizeof (U32) ); } void FSE_freeDTable (FSE_DTable* dt) { ZSTD_free(dt); } static size_t FSE_buildDTable_internal(FSE_DTable* dt, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void* workSpace, size_t wkspSize) { void* const tdPtr = dt+1; /* because *dt is unsigned, 32-bits aligned on 32-bits */ FSE_DECODE_TYPE* const tableDecode = (FSE_DECODE_TYPE*) (tdPtr); U16* symbolNext = (U16*)workSpace; BYTE* spread = (BYTE*)(symbolNext + maxSymbolValue + 1); U32 const maxSV1 = maxSymbolValue + 1; U32 const tableSize = 1 << tableLog; U32 highThreshold = tableSize-1; /* Sanity Checks */ if (FSE_BUILD_DTABLE_WKSP_SIZE(tableLog, maxSymbolValue) > wkspSize) return ERROR(maxSymbolValue_tooLarge); if (maxSymbolValue > FSE_MAX_SYMBOL_VALUE) return ERROR(maxSymbolValue_tooLarge); if (tableLog > FSE_MAX_TABLELOG) return ERROR(tableLog_tooLarge); /* Init, lay down lowprob symbols */ { FSE_DTableHeader DTableH; DTableH.tableLog = (U16)tableLog; DTableH.fastMode = 1; { S16 const largeLimit= (S16)(1 << (tableLog-1)); U32 s; for (s=0; s<maxSV1; s++) { if (normalizedCounter[s]==-1) { tableDecode[highThreshold--].symbol = (FSE_FUNCTION_TYPE)s; symbolNext[s] = 1; } else { if (normalizedCounter[s] >= largeLimit) DTableH.fastMode=0; symbolNext[s] = normalizedCounter[s]; } } } ZSTD_memcpy(dt, &DTableH, sizeof(DTableH)); } /* Spread symbols */ if (highThreshold == tableSize - 1) { size_t const tableMask = tableSize-1; size_t const step = FSE_TABLESTEP(tableSize); /* First lay down the symbols in order. * We use a uint64_t to lay down 8 bytes at a time. This reduces branch * misses since small blocks generally have small table logs, so nearly * all symbols have counts <= 8. We ensure we have 8 bytes at the end of * our buffer to handle the over-write. */ { U64 const add = 0x0101010101010101ull; size_t pos = 0; U64 sv = 0; U32 s; for (s=0; s<maxSV1; ++s, sv += add) { int i; int const n = normalizedCounter[s]; MEM_write64(spread + pos, sv); for (i = 8; i < n; i += 8) { MEM_write64(spread + pos + i, sv); } pos += n; } } /* Now we spread those positions across the table. * The benefit of doing it in two stages is that we avoid the the * variable size inner loop, which caused lots of branch misses. * Now we can run through all the positions without any branch misses. * We unroll the loop twice, since that is what emperically worked best. */ { size_t position = 0; size_t s; size_t const unroll = 2; assert(tableSize % unroll == 0); /* FSE_MIN_TABLELOG is 5 */ for (s = 0; s < (size_t)tableSize; s += unroll) { size_t u; for (u = 0; u < unroll; ++u) { size_t const uPosition = (position + (u * step)) & tableMask; tableDecode[uPosition].symbol = spread[s + u]; } position = (position + (unroll * step)) & tableMask; } assert(position == 0); } } else { U32 const tableMask = tableSize-1; U32 const step = FSE_TABLESTEP(tableSize); U32 s, position = 0; for (s=0; s<maxSV1; s++) { int i; for (i=0; i<normalizedCounter[s]; i++) { tableDecode[position].symbol = (FSE_FUNCTION_TYPE)s; position = (position + step) & tableMask; while (position > highThreshold) position = (position + step) & tableMask; /* lowprob area */ } } if (position!=0) return ERROR(GENERIC); /* position must reach all cells once, otherwise normalizedCounter is incorrect */ } /* Build Decoding table */ { U32 u; for (u=0; u<tableSize; u++) { FSE_FUNCTION_TYPE const symbol = (FSE_FUNCTION_TYPE)(tableDecode[u].symbol); U32 const nextState = symbolNext[symbol]++; tableDecode[u].nbBits = (BYTE) (tableLog - BIT_highbit32(nextState) ); tableDecode[u].newState = (U16) ( (nextState << tableDecode[u].nbBits) - tableSize); } } return 0; } size_t FSE_buildDTable_wksp(FSE_DTable* dt, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, void* workSpace, size_t wkspSize) { return FSE_buildDTable_internal(dt, normalizedCounter, maxSymbolValue, tableLog, workSpace, wkspSize); } #ifndef FSE_COMMONDEFS_ONLY /*-******************************************************* * Decompression (Byte symbols) *********************************************************/ size_t FSE_buildDTable_rle (FSE_DTable* dt, BYTE symbolValue) { void* ptr = dt; FSE_DTableHeader* const DTableH = (FSE_DTableHeader*)ptr; void* dPtr = dt + 1; FSE_decode_t* const cell = (FSE_decode_t*)dPtr; DTableH->tableLog = 0; DTableH->fastMode = 0; cell->newState = 0; cell->symbol = symbolValue; cell->nbBits = 0; return 0; } size_t FSE_buildDTable_raw (FSE_DTable* dt, unsigned nbBits) { void* ptr = dt; FSE_DTableHeader* const DTableH = (FSE_DTableHeader*)ptr; void* dPtr = dt + 1; FSE_decode_t* const dinfo = (FSE_decode_t*)dPtr; const unsigned tableSize = 1 << nbBits; const unsigned tableMask = tableSize - 1; const unsigned maxSV1 = tableMask+1; unsigned s; /* Sanity checks */ if (nbBits < 1) return ERROR(GENERIC); /* min size */ /* Build Decoding Table */ DTableH->tableLog = (U16)nbBits; DTableH->fastMode = 1; for (s=0; s<maxSV1; s++) { dinfo[s].newState = 0; dinfo[s].symbol = (BYTE)s; dinfo[s].nbBits = (BYTE)nbBits; } return 0; } FORCE_INLINE_TEMPLATE size_t FSE_decompress_usingDTable_generic( void* dst, size_t maxDstSize, const void* cSrc, size_t cSrcSize, const FSE_DTable* dt, const unsigned fast) { BYTE* const ostart = (BYTE*) dst; BYTE* op = ostart; BYTE* const omax = op + maxDstSize; BYTE* const olimit = omax-3; BIT_DStream_t bitD; FSE_DState_t state1; FSE_DState_t state2; /* Init */ CHECK_F(BIT_initDStream(&bitD, cSrc, cSrcSize)); FSE_initDState(&state1, &bitD, dt); FSE_initDState(&state2, &bitD, dt); #define FSE_GETSYMBOL(statePtr) fast ? FSE_decodeSymbolFast(statePtr, &bitD) : FSE_decodeSymbol(statePtr, &bitD) /* 4 symbols per loop */ for ( ; (BIT_reloadDStream(&bitD)==BIT_DStream_unfinished) & (op<olimit) ; op+=4) { op[0] = FSE_GETSYMBOL(&state1); if (FSE_MAX_TABLELOG*2+7 > sizeof(bitD.bitContainer)*8) /* This test must be static */ BIT_reloadDStream(&bitD); op[1] = FSE_GETSYMBOL(&state2); if (FSE_MAX_TABLELOG*4+7 > sizeof(bitD.bitContainer)*8) /* This test must be static */ { if (BIT_reloadDStream(&bitD) > BIT_DStream_unfinished) { op+=2; break; } } op[2] = FSE_GETSYMBOL(&state1); if (FSE_MAX_TABLELOG*2+7 > sizeof(bitD.bitContainer)*8) /* This test must be static */ BIT_reloadDStream(&bitD); op[3] = FSE_GETSYMBOL(&state2); } /* tail */ /* note : BIT_reloadDStream(&bitD) >= FSE_DStream_partiallyFilled; Ends at exactly BIT_DStream_completed */ while (1) { if (op>(omax-2)) return ERROR(dstSize_tooSmall); *op++ = FSE_GETSYMBOL(&state1); if (BIT_reloadDStream(&bitD)==BIT_DStream_overflow) { *op++ = FSE_GETSYMBOL(&state2); break; } if (op>(omax-2)) return ERROR(dstSize_tooSmall); *op++ = FSE_GETSYMBOL(&state2); if (BIT_reloadDStream(&bitD)==BIT_DStream_overflow) { *op++ = FSE_GETSYMBOL(&state1); break; } } return op-ostart; } size_t FSE_decompress_usingDTable(void* dst, size_t originalSize, const void* cSrc, size_t cSrcSize, const FSE_DTable* dt) { const void* ptr = dt; const FSE_DTableHeader* DTableH = (const FSE_DTableHeader*)ptr; const U32 fastMode = DTableH->fastMode; /* select fast mode (static) */ if (fastMode) return FSE_decompress_usingDTable_generic(dst, originalSize, cSrc, cSrcSize, dt, 1); return FSE_decompress_usingDTable_generic(dst, originalSize, cSrc, cSrcSize, dt, 0); } size_t FSE_decompress_wksp(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize, unsigned maxLog, void* workSpace, size_t wkspSize) { return FSE_decompress_wksp_bmi2(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize, /* bmi2 */ 0); } typedef struct { short ncount[FSE_MAX_SYMBOL_VALUE + 1]; FSE_DTable dtable[1]; /* Dynamically sized */ } FSE_DecompressWksp; FORCE_INLINE_TEMPLATE size_t FSE_decompress_wksp_body( void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize, unsigned maxLog, void* workSpace, size_t wkspSize, int bmi2) { const BYTE* const istart = (const BYTE*)cSrc; const BYTE* ip = istart; unsigned tableLog; unsigned maxSymbolValue = FSE_MAX_SYMBOL_VALUE; FSE_DecompressWksp* const wksp = (FSE_DecompressWksp*)workSpace; DEBUG_STATIC_ASSERT((FSE_MAX_SYMBOL_VALUE + 1) % 2 == 0); if (wkspSize < sizeof(*wksp)) return ERROR(GENERIC); /* normal FSE decoding mode */ { size_t const NCountLength = FSE_readNCount_bmi2(wksp->ncount, &maxSymbolValue, &tableLog, istart, cSrcSize, bmi2); if (FSE_isError(NCountLength)) return NCountLength; if (tableLog > maxLog) return ERROR(tableLog_tooLarge); assert(NCountLength <= cSrcSize); ip += NCountLength; cSrcSize -= NCountLength; } if (FSE_DECOMPRESS_WKSP_SIZE(tableLog, maxSymbolValue) > wkspSize) return ERROR(tableLog_tooLarge); workSpace = wksp->dtable + FSE_DTABLE_SIZE_U32(tableLog); wkspSize -= sizeof(*wksp) + FSE_DTABLE_SIZE(tableLog); CHECK_F( FSE_buildDTable_internal(wksp->dtable, wksp->ncount, maxSymbolValue, tableLog, workSpace, wkspSize) ); { const void* ptr = wksp->dtable; const FSE_DTableHeader* DTableH = (const FSE_DTableHeader*)ptr; const U32 fastMode = DTableH->fastMode; /* select fast mode (static) */ if (fastMode) return FSE_decompress_usingDTable_generic(dst, dstCapacity, ip, cSrcSize, wksp->dtable, 1); return FSE_decompress_usingDTable_generic(dst, dstCapacity, ip, cSrcSize, wksp->dtable, 0); } } /* Avoids the FORCE_INLINE of the _body() function. */ static 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) { return FSE_decompress_wksp_body(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize, 0); } #if DYNAMIC_BMI2 TARGET_ATTRIBUTE("bmi2") 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) { return FSE_decompress_wksp_body(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize, 1); } #endif size_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) { #if DYNAMIC_BMI2 if (bmi2) { return FSE_decompress_wksp_body_bmi2(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize); } #endif (void)bmi2; return FSE_decompress_wksp_body_default(dst, dstCapacity, cSrc, cSrcSize, maxLog, workSpace, wkspSize); } typedef FSE_DTable DTable_max_t[FSE_DTABLE_SIZE_U32(FSE_MAX_TABLELOG)]; #ifndef ZSTD_NO_UNUSED_FUNCTIONS size_t FSE_buildDTable(FSE_DTable* dt, const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog) { U32 wksp[FSE_BUILD_DTABLE_WKSP_SIZE_U32(FSE_TABLELOG_ABSOLUTE_MAX, FSE_MAX_SYMBOL_VALUE)]; return FSE_buildDTable_wksp(dt, normalizedCounter, maxSymbolValue, tableLog, wksp, sizeof(wksp)); } size_t FSE_decompress(void* dst, size_t dstCapacity, const void* cSrc, size_t cSrcSize) { /* Static analyzer seems unable to understand this table will be properly initialized later */ U32 wksp[FSE_DECOMPRESS_WKSP_SIZE_U32(FSE_MAX_TABLELOG, FSE_MAX_SYMBOL_VALUE)]; return FSE_decompress_wksp(dst, dstCapacity, cSrc, cSrcSize, FSE_MAX_TABLELOG, wksp, sizeof(wksp)); } #endif #endif /* FSE_COMMONDEFS_ONLY */