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 */