/* Bcj2.c -- Converter for x86 code (BCJ2)
2008-10-04 : Igor Pavlov : Public domain */

#include "Bcj2.h"

#ifdef _LZMA_PROB32
#define CProb UInt32
#else
#define CProb UInt16
#endif

#define IsJcc(b0, b1) ((b0) == 0x0F && ((b1)&0xF0) == 0x80)
#define IsJ(b0, b1) ((b1 & 0xFE) == 0xE8 || IsJcc(b0, b1))

#define kNumTopBits 24
#define kTopValue ((UInt32)1 << kNumTopBits)

#define kNumBitModelTotalBits 11
#define kBitModelTotal (1 << kNumBitModelTotalBits)
#define kNumMoveBits 5

#define RC_READ_BYTE (*buffer++)
#define RC_TEST                   \
    {                             \
        if (buffer == bufferLim)  \
            return SZ_ERROR_DATA; \
    }
#define RC_INIT2                               \
    code = 0;                                  \
    range = 0xFFFFFFFF;                        \
    {                                          \
        int i;                                 \
        for (i = 0; i < 5; i++) {              \
            RC_TEST;                           \
            code = (code << 8) | RC_READ_BYTE; \
        }                                      \
    }

#define NORMALIZE                          \
    if (range < kTopValue) {               \
        RC_TEST;                           \
        range <<= 8;                       \
        code = (code << 8) | RC_READ_BYTE; \
    }

#define IF_BIT_0(p)                                 \
    ttt = *(p);                                     \
    bound = (range >> kNumBitModelTotalBits) * ttt; \
    if (code < bound)
#define UPDATE_0(p)                                                 \
    range = bound;                                                  \
    *(p) = (CProb)(ttt + ((kBitModelTotal - ttt) >> kNumMoveBits)); \
    NORMALIZE;
#define UPDATE_1(p)                              \
    range -= bound;                              \
    code -= bound;                               \
    *(p) = (CProb)(ttt - (ttt >> kNumMoveBits)); \
    NORMALIZE;

int Bcj2_Decode(
    const Byte* buf0, SizeT size0,
    const Byte* buf1, SizeT size1,
    const Byte* buf2, SizeT size2,
    const Byte* buf3, SizeT size3,
    Byte* outBuf, SizeT outSize)
{
    CProb p[256 + 2];
    SizeT inPos = 0, outPos = 0;

    const Byte *buffer, *bufferLim;
    UInt32 range, code;
    Byte prevByte = 0;

    unsigned int i;
    for (i = 0; i < sizeof(p) / sizeof(p[0]); i++)
        p[i] = kBitModelTotal >> 1;

    buffer = buf3;
    bufferLim = buffer + size3;
    RC_INIT2

    if (outSize == 0)
        return SZ_OK;

    for (;;) {
        Byte b;
        CProb* prob;
        UInt32 bound;
        UInt32 ttt;

        SizeT limit = size0 - inPos;
        if (outSize - outPos < limit)
            limit = outSize - outPos;
        while (limit != 0) {
            Byte b = buf0[inPos];
            outBuf[outPos++] = b;
            if (IsJ(prevByte, b))
                break;
            inPos++;
            prevByte = b;
            limit--;
        }

        if (limit == 0 || outPos == outSize)
            break;

        b = buf0[inPos++];

        if (b == 0xE8)
            prob = p + prevByte;
        else if (b == 0xE9)
            prob = p + 256;
        else
            prob = p + 257;

        IF_BIT_0(prob)
        {
            UPDATE_0(prob)
            prevByte = b;
        }
        else
        {
            UInt32 dest;
            const Byte* v;
            UPDATE_1(prob)
            if (b == 0xE8) {
                v = buf1;
                if (size1 < 4)
                    return SZ_ERROR_DATA;
                buf1 += 4;
                size1 -= 4;
            } else {
                v = buf2;
                if (size2 < 4)
                    return SZ_ERROR_DATA;
                buf2 += 4;
                size2 -= 4;
            }
            dest = (((UInt32)v[0] << 24) | ((UInt32)v[1] << 16) | ((UInt32)v[2] << 8) | ((UInt32)v[3])) - ((UInt32)outPos + 4);
            outBuf[outPos++] = (Byte)dest;
            if (outPos == outSize)
                break;
            outBuf[outPos++] = (Byte)(dest >> 8);
            if (outPos == outSize)
                break;
            outBuf[outPos++] = (Byte)(dest >> 16);
            if (outPos == outSize)
                break;
            outBuf[outPos++] = prevByte = (Byte)(dest >> 24);
        }
    }
    return (outPos == outSize) ? SZ_OK : SZ_ERROR_DATA;
}
