path: root/contrib/libs/zstd/lib/common/fse_decompress.c

/* ****************************************************************** 
 * 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
BMI2_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)
{
    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 */