/*
 * Copyright (c) 2018-present, Facebook, Inc.
 * All rights reserved.
 *
 * 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.
 */

#ifndef FUNCTION
#  error "FUNCTION(name) must be defined"
#endif

#ifndef TARGET
#  error "TARGET must be defined"
#endif


static TARGET BYTE FUNCTION(HUF_decodeSymbolX2)(BIT_DStream_t* Dstream, const HUF_DEltX2* dt, const U32 dtLog)
{
    size_t const val = BIT_lookBitsFast(Dstream, dtLog); /* note : dtLog >= 1 */
    BYTE const c = dt[val].byte;
    BIT_skipBits(Dstream, dt[val].nbBits);
    return c;
}

#define HUF_DECODE_SYMBOLX2_0(ptr, DStreamPtr) \
    *ptr++ = FUNCTION(HUF_decodeSymbolX2)(DStreamPtr, dt, dtLog)

#define HUF_DECODE_SYMBOLX2_1(ptr, DStreamPtr) \
    if (MEM_64bits() || (HUF_TABLELOG_MAX<=12)) \
        HUF_DECODE_SYMBOLX2_0(ptr, DStreamPtr)

#define HUF_DECODE_SYMBOLX2_2(ptr, DStreamPtr) \
    if (MEM_64bits()) \
        HUF_DECODE_SYMBOLX2_0(ptr, DStreamPtr)

HINT_INLINE TARGET size_t FUNCTION(HUF_decodeStreamX2)(BYTE* p, BIT_DStream_t* const bitDPtr, BYTE* const pEnd, const HUF_DEltX2* const dt, const U32 dtLog)
{
    BYTE* const pStart = p;

    /* up to 4 symbols at a time */
    while ((BIT_reloadDStream(bitDPtr) == BIT_DStream_unfinished) && (p <= pEnd-4)) {
        HUF_DECODE_SYMBOLX2_2(p, bitDPtr);
        HUF_DECODE_SYMBOLX2_1(p, bitDPtr);
        HUF_DECODE_SYMBOLX2_2(p, bitDPtr);
        HUF_DECODE_SYMBOLX2_0(p, bitDPtr);
    }

    /* closer to the end */
    while ((BIT_reloadDStream(bitDPtr) == BIT_DStream_unfinished) && (p < pEnd))
        HUF_DECODE_SYMBOLX2_0(p, bitDPtr);

    /* no more data to retrieve from bitstream, hence no need to reload */
    while (p < pEnd)
        HUF_DECODE_SYMBOLX2_0(p, bitDPtr);

    return pEnd-pStart;
}

static TARGET size_t FUNCTION(HUF_decompress1X2_usingDTable_internal)(
          void* dst,  size_t dstSize,
    const void* cSrc, size_t cSrcSize,
    const HUF_DTable* DTable)
{
    BYTE* op = (BYTE*)dst;
    BYTE* const oend = op + dstSize;
    const void* dtPtr = DTable + 1;
    const HUF_DEltX2* const dt = (const HUF_DEltX2*)dtPtr;
    BIT_DStream_t bitD;
    DTableDesc const dtd = HUF_getDTableDesc(DTable);
    U32 const dtLog = dtd.tableLog;

    { size_t const errorCode = BIT_initDStream(&bitD, cSrc, cSrcSize);
      if (HUF_isError(errorCode)) return errorCode; }

    FUNCTION(HUF_decodeStreamX2)(op, &bitD, oend, dt, dtLog);

    /* check */
    if (!BIT_endOfDStream(&bitD)) return ERROR(corruption_detected);

    return dstSize;
}

static TARGET size_t
FUNCTION(HUF_decompress4X2_usingDTable_internal)(
          void* dst,  size_t dstSize,
    const void* cSrc, size_t cSrcSize,
    const HUF_DTable* DTable)
{
    /* Check */
    if (cSrcSize < 10) return ERROR(corruption_detected);  /* strict minimum : jump table + 1 byte per stream */

    {   const BYTE* const istart = (const BYTE*) cSrc;
        BYTE* const ostart = (BYTE*) dst;
        BYTE* const oend = ostart + dstSize;
        const void* const dtPtr = DTable + 1;
        const HUF_DEltX2* const dt = (const HUF_DEltX2*)dtPtr;

        /* Init */
        BIT_DStream_t bitD1;
        BIT_DStream_t bitD2;
        BIT_DStream_t bitD3;
        BIT_DStream_t bitD4;
        size_t const length1 = MEM_readLE16(istart);
        size_t const length2 = MEM_readLE16(istart+2);
        size_t const length3 = MEM_readLE16(istart+4);
        size_t const length4 = cSrcSize - (length1 + length2 + length3 + 6);
        const BYTE* const istart1 = istart + 6;  /* jumpTable */
        const BYTE* const istart2 = istart1 + length1;
        const BYTE* const istart3 = istart2 + length2;
        const BYTE* const istart4 = istart3 + length3;
        const size_t segmentSize = (dstSize+3) / 4;
        BYTE* const opStart2 = ostart + segmentSize;
        BYTE* const opStart3 = opStart2 + segmentSize;
        BYTE* const opStart4 = opStart3 + segmentSize;
        BYTE* op1 = ostart;
        BYTE* op2 = opStart2;
        BYTE* op3 = opStart3;
        BYTE* op4 = opStart4;
        U32 endSignal;
        DTableDesc const dtd = HUF_getDTableDesc(DTable);
        U32 const dtLog = dtd.tableLog;

        if (length4 > cSrcSize) return ERROR(corruption_detected);   /* overflow */
        { size_t const errorCode = BIT_initDStream(&bitD1, istart1, length1);
          if (HUF_isError(errorCode)) return errorCode; }
        { size_t const errorCode = BIT_initDStream(&bitD2, istart2, length2);
          if (HUF_isError(errorCode)) return errorCode; }
        { size_t const errorCode = BIT_initDStream(&bitD3, istart3, length3);
          if (HUF_isError(errorCode)) return errorCode; }
        { size_t const errorCode = BIT_initDStream(&bitD4, istart4, length4);
          if (HUF_isError(errorCode)) return errorCode; }

        /* 16-32 symbols per loop (4-8 symbols per stream) */
        endSignal = BIT_reloadDStream(&bitD1) | BIT_reloadDStream(&bitD2) | BIT_reloadDStream(&bitD3) | BIT_reloadDStream(&bitD4);
        for ( ; (endSignal==BIT_DStream_unfinished) && (op4<(oend-7)) ; ) {
            HUF_DECODE_SYMBOLX2_2(op1, &bitD1);
            HUF_DECODE_SYMBOLX2_2(op2, &bitD2);
            HUF_DECODE_SYMBOLX2_2(op3, &bitD3);
            HUF_DECODE_SYMBOLX2_2(op4, &bitD4);
            HUF_DECODE_SYMBOLX2_1(op1, &bitD1);
            HUF_DECODE_SYMBOLX2_1(op2, &bitD2);
            HUF_DECODE_SYMBOLX2_1(op3, &bitD3);
            HUF_DECODE_SYMBOLX2_1(op4, &bitD4);
            HUF_DECODE_SYMBOLX2_2(op1, &bitD1);
            HUF_DECODE_SYMBOLX2_2(op2, &bitD2);
            HUF_DECODE_SYMBOLX2_2(op3, &bitD3);
            HUF_DECODE_SYMBOLX2_2(op4, &bitD4);
            HUF_DECODE_SYMBOLX2_0(op1, &bitD1);
            HUF_DECODE_SYMBOLX2_0(op2, &bitD2);
            HUF_DECODE_SYMBOLX2_0(op3, &bitD3);
            HUF_DECODE_SYMBOLX2_0(op4, &bitD4);
            endSignal = BIT_reloadDStream(&bitD1) | BIT_reloadDStream(&bitD2) | BIT_reloadDStream(&bitD3) | BIT_reloadDStream(&bitD4);
        }

        /* check corruption */
        if (op1 > opStart2) return ERROR(corruption_detected);
        if (op2 > opStart3) return ERROR(corruption_detected);
        if (op3 > opStart4) return ERROR(corruption_detected);
        /* note : op4 supposed already verified within main loop */

        /* finish bitStreams one by one */
        FUNCTION(HUF_decodeStreamX2)(op1, &bitD1, opStart2, dt, dtLog);
        FUNCTION(HUF_decodeStreamX2)(op2, &bitD2, opStart3, dt, dtLog);
        FUNCTION(HUF_decodeStreamX2)(op3, &bitD3, opStart4, dt, dtLog);
        FUNCTION(HUF_decodeStreamX2)(op4, &bitD4, oend,     dt, dtLog);

        /* check */
        endSignal = BIT_endOfDStream(&bitD1) & BIT_endOfDStream(&bitD2) & BIT_endOfDStream(&bitD3) & BIT_endOfDStream(&bitD4);
        if (!endSignal) return ERROR(corruption_detected);

        /* decoded size */
        return dstSize;
    }
}

#undef HUF_DECODE_SYMBOLX2_0
#undef HUF_DECODE_SYMBOLX2_1
#undef HUF_DECODE_SYMBOLX2_2

static TARGET U32 FUNCTION(HUF_decodeSymbolX4)(void* op, BIT_DStream_t* DStream, const HUF_DEltX4* dt, const U32 dtLog)
{
    size_t const val = BIT_lookBitsFast(DStream, dtLog);   /* note : dtLog >= 1 */
    memcpy(op, dt+val, 2);
    BIT_skipBits(DStream, dt[val].nbBits);
    return dt[val].length;
}

static TARGET U32 FUNCTION(HUF_decodeLastSymbolX4)(void* op, BIT_DStream_t* DStream, const HUF_DEltX4* dt, const U32 dtLog)
{
    size_t const val = BIT_lookBitsFast(DStream, dtLog);   /* note : dtLog >= 1 */
    memcpy(op, dt+val, 1);
    if (dt[val].length==1) BIT_skipBits(DStream, dt[val].nbBits);
    else {
        if (DStream->bitsConsumed < (sizeof(DStream->bitContainer)*8)) {
            BIT_skipBits(DStream, dt[val].nbBits);
            if (DStream->bitsConsumed > (sizeof(DStream->bitContainer)*8))
                /* ugly hack; works only because it's the last symbol. Note : can't easily extract nbBits from just this symbol */
                DStream->bitsConsumed = (sizeof(DStream->bitContainer)*8);
    }   }
    return 1;
}


#define HUF_DECODE_SYMBOLX4_0(ptr, DStreamPtr) \
    ptr += FUNCTION(HUF_decodeSymbolX4)(ptr, DStreamPtr, dt, dtLog)

#define HUF_DECODE_SYMBOLX4_1(ptr, DStreamPtr) \
    if (MEM_64bits() || (HUF_TABLELOG_MAX<=12)) \
        ptr += FUNCTION(HUF_decodeSymbolX4)(ptr, DStreamPtr, dt, dtLog)

#define HUF_DECODE_SYMBOLX4_2(ptr, DStreamPtr) \
    if (MEM_64bits()) \
        ptr += FUNCTION(HUF_decodeSymbolX4)(ptr, DStreamPtr, dt, dtLog)

HINT_INLINE TARGET size_t FUNCTION(HUF_decodeStreamX4)(BYTE* p, BIT_DStream_t* bitDPtr, BYTE* const pEnd, const HUF_DEltX4* const dt, const U32 dtLog)
{
    BYTE* const pStart = p;

    /* up to 8 symbols at a time */
    while ((BIT_reloadDStream(bitDPtr) == BIT_DStream_unfinished) & (p < pEnd-(sizeof(bitDPtr->bitContainer)-1))) {
        HUF_DECODE_SYMBOLX4_2(p, bitDPtr);
        HUF_DECODE_SYMBOLX4_1(p, bitDPtr);
        HUF_DECODE_SYMBOLX4_2(p, bitDPtr);
        HUF_DECODE_SYMBOLX4_0(p, bitDPtr);
    }

    /* closer to end : up to 2 symbols at a time */
    while ((BIT_reloadDStream(bitDPtr) == BIT_DStream_unfinished) & (p <= pEnd-2))
        HUF_DECODE_SYMBOLX4_0(p, bitDPtr);

    while (p <= pEnd-2)
        HUF_DECODE_SYMBOLX4_0(p, bitDPtr);   /* no need to reload : reached the end of DStream */

    if (p < pEnd)
        p += FUNCTION(HUF_decodeLastSymbolX4)(p, bitDPtr, dt, dtLog);

    return p-pStart;
}

static TARGET size_t FUNCTION(HUF_decompress1X4_usingDTable_internal)(
          void* dst,  size_t dstSize,
    const void* cSrc, size_t cSrcSize,
    const HUF_DTable* DTable)
{
    BIT_DStream_t bitD;

    /* Init */
    {   size_t const errorCode = BIT_initDStream(&bitD, cSrc, cSrcSize);
        if (HUF_isError(errorCode)) return errorCode;
    }

    /* decode */
    {   BYTE* const ostart = (BYTE*) dst;
        BYTE* const oend = ostart + dstSize;
        const void* const dtPtr = DTable+1;   /* force compiler to not use strict-aliasing */
        const HUF_DEltX4* const dt = (const HUF_DEltX4*)dtPtr;
        DTableDesc const dtd = HUF_getDTableDesc(DTable);
        FUNCTION(HUF_decodeStreamX4)(ostart, &bitD, oend, dt, dtd.tableLog);
    }

    /* check */
    if (!BIT_endOfDStream(&bitD)) return ERROR(corruption_detected);

    /* decoded size */
    return dstSize;
}

static TARGET size_t FUNCTION(HUF_decompress4X4_usingDTable_internal)(
          void* dst,  size_t dstSize,
    const void* cSrc, size_t cSrcSize,
    const HUF_DTable* DTable)
{
    if (cSrcSize < 10) return ERROR(corruption_detected);   /* strict minimum : jump table + 1 byte per stream */

    {   const BYTE* const istart = (const BYTE*) cSrc;
        BYTE* const ostart = (BYTE*) dst;
        BYTE* const oend = ostart + dstSize;
        const void* const dtPtr = DTable+1;
        const HUF_DEltX4* const dt = (const HUF_DEltX4*)dtPtr;

        /* Init */
        BIT_DStream_t bitD1;
        BIT_DStream_t bitD2;
        BIT_DStream_t bitD3;
        BIT_DStream_t bitD4;
        size_t const length1 = MEM_readLE16(istart);
        size_t const length2 = MEM_readLE16(istart+2);
        size_t const length3 = MEM_readLE16(istart+4);
        size_t const length4 = cSrcSize - (length1 + length2 + length3 + 6);
        const BYTE* const istart1 = istart + 6;  /* jumpTable */
        const BYTE* const istart2 = istart1 + length1;
        const BYTE* const istart3 = istart2 + length2;
        const BYTE* const istart4 = istart3 + length3;
        size_t const segmentSize = (dstSize+3) / 4;
        BYTE* const opStart2 = ostart + segmentSize;
        BYTE* const opStart3 = opStart2 + segmentSize;
        BYTE* const opStart4 = opStart3 + segmentSize;
        BYTE* op1 = ostart;
        BYTE* op2 = opStart2;
        BYTE* op3 = opStart3;
        BYTE* op4 = opStart4;
        U32 endSignal;
        DTableDesc const dtd = HUF_getDTableDesc(DTable);
        U32 const dtLog = dtd.tableLog;

        if (length4 > cSrcSize) return ERROR(corruption_detected);   /* overflow */
        { size_t const errorCode = BIT_initDStream(&bitD1, istart1, length1);
          if (HUF_isError(errorCode)) return errorCode; }
        { size_t const errorCode = BIT_initDStream(&bitD2, istart2, length2);
          if (HUF_isError(errorCode)) return errorCode; }
        { size_t const errorCode = BIT_initDStream(&bitD3, istart3, length3);
          if (HUF_isError(errorCode)) return errorCode; }
        { size_t const errorCode = BIT_initDStream(&bitD4, istart4, length4);
          if (HUF_isError(errorCode)) return errorCode; }

        /* 16-32 symbols per loop (4-8 symbols per stream) */
        endSignal = BIT_reloadDStream(&bitD1) | BIT_reloadDStream(&bitD2) | BIT_reloadDStream(&bitD3) | BIT_reloadDStream(&bitD4);
        for ( ; (endSignal==BIT_DStream_unfinished) & (op4<(oend-(sizeof(bitD4.bitContainer)-1))) ; ) {
            HUF_DECODE_SYMBOLX4_2(op1, &bitD1);
            HUF_DECODE_SYMBOLX4_2(op2, &bitD2);
            HUF_DECODE_SYMBOLX4_2(op3, &bitD3);
            HUF_DECODE_SYMBOLX4_2(op4, &bitD4);
            HUF_DECODE_SYMBOLX4_1(op1, &bitD1);
            HUF_DECODE_SYMBOLX4_1(op2, &bitD2);
            HUF_DECODE_SYMBOLX4_1(op3, &bitD3);
            HUF_DECODE_SYMBOLX4_1(op4, &bitD4);
            HUF_DECODE_SYMBOLX4_2(op1, &bitD1);
            HUF_DECODE_SYMBOLX4_2(op2, &bitD2);
            HUF_DECODE_SYMBOLX4_2(op3, &bitD3);
            HUF_DECODE_SYMBOLX4_2(op4, &bitD4);
            HUF_DECODE_SYMBOLX4_0(op1, &bitD1);
            HUF_DECODE_SYMBOLX4_0(op2, &bitD2);
            HUF_DECODE_SYMBOLX4_0(op3, &bitD3);
            HUF_DECODE_SYMBOLX4_0(op4, &bitD4);

            endSignal = BIT_reloadDStream(&bitD1) | BIT_reloadDStream(&bitD2) | BIT_reloadDStream(&bitD3) | BIT_reloadDStream(&bitD4);
        }

        /* check corruption */
        if (op1 > opStart2) return ERROR(corruption_detected);
        if (op2 > opStart3) return ERROR(corruption_detected);
        if (op3 > opStart4) return ERROR(corruption_detected);
        /* note : op4 already verified within main loop */

        /* finish bitStreams one by one */
        FUNCTION(HUF_decodeStreamX4)(op1, &bitD1, opStart2, dt, dtLog);
        FUNCTION(HUF_decodeStreamX4)(op2, &bitD2, opStart3, dt, dtLog);
        FUNCTION(HUF_decodeStreamX4)(op3, &bitD3, opStart4, dt, dtLog);
        FUNCTION(HUF_decodeStreamX4)(op4, &bitD4, oend,     dt, dtLog);

        /* check */
        { U32 const endCheck = BIT_endOfDStream(&bitD1) & BIT_endOfDStream(&bitD2) & BIT_endOfDStream(&bitD3) & BIT_endOfDStream(&bitD4);
          if (!endCheck) return ERROR(corruption_detected); }

        /* decoded size */
        return dstSize;
    }
}

#undef HUF_DECODE_SYMBOLX4_0
#undef HUF_DECODE_SYMBOLX4_1
#undef HUF_DECODE_SYMBOLX4_2