1/* Bcj2.c -- Converter for x86 code (BCJ2)
  22008-10-04 : Igor Pavlov : Public domain */
  3
  4#include "Precomp.h"
  5
  6#include "Bcj2.h"
  7
  8#ifdef _LZMA_PROB32
  9#define CProb UInt32
 10#else
 11#define CProb UInt16
 12#endif
 13
 14#define IsJcc(b0, b1) ((b0) == 0x0F && ((b1) & 0xF0) == 0x80)
 15#define IsJ(b0, b1) ((b1 & 0xFE) == 0xE8 || IsJcc(b0, b1))
 16
 17#define kNumTopBits 24
 18#define kTopValue ((UInt32)1 << kNumTopBits)
 19
 20#define kNumBitModelTotalBits 11
 21#define kBitModelTotal (1 << kNumBitModelTotalBits)
 22#define kNumMoveBits 5
 23
 24#define RC_READ_BYTE (*buffer++)
 25#define RC_TEST { if (buffer == bufferLim) return SZ_ERROR_DATA; }
 26#define RC_INIT2 code = 0; range = 0xFFFFFFFF; \
 27  { int i; for (i = 0; i < 5; i++) { RC_TEST; code = (code << 8) | RC_READ_BYTE; }}
 28
 29#define NORMALIZE if (range < kTopValue) { RC_TEST; range <<= 8; code = (code << 8) | RC_READ_BYTE; }
 30
 31#define IF_BIT_0(p) ttt = *(p); bound = (range >> kNumBitModelTotalBits) * ttt; if (code < bound)
 32#define UPDATE_0(p) range = bound; *(p) = (CProb)(ttt + ((kBitModelTotal - ttt) >> kNumMoveBits)); NORMALIZE;
 33#define UPDATE_1(p) range -= bound; code -= bound; *(p) = (CProb)(ttt - (ttt >> kNumMoveBits)); NORMALIZE;
 34
 35int Bcj2_Decode(
 36    const Byte *buf0, SizeT size0,
 37    const Byte *buf1, SizeT size1,
 38    const Byte *buf2, SizeT size2,
 39    const Byte *buf3, SizeT size3,
 40    Byte *outBuf, SizeT outSize)
 41{
 42  CProb p[256 + 2];
 43  SizeT inPos = 0, outPos = 0;
 44
 45  const Byte *buffer, *bufferLim;
 46  UInt32 range, code;
 47  Byte prevByte = 0;
 48
 49  unsigned int i;
 50  for (i = 0; i < sizeof(p) / sizeof(p[0]); i++)
 51    p[i] = kBitModelTotal >> 1;
 52
 53  buffer = buf3;
 54  bufferLim = buffer + size3;
 55  RC_INIT2
 56
 57  if (outSize == 0)
 58    return SZ_OK;
 59
 60  for (;;)
 61  {
 62    Byte b;
 63    CProb *prob;
 64    UInt32 bound;
 65    UInt32 ttt;
 66
 67    SizeT limit = size0 - inPos;
 68    if (outSize - outPos < limit)
 69      limit = outSize - outPos;
 70    while (limit != 0)
 71    {
 72      Byte b = buf0[inPos];
 73      outBuf[outPos++] = b;
 74      if (IsJ(prevByte, b))
 75        break;
 76      inPos++;
 77      prevByte = b;
 78      limit--;
 79    }
 80
 81    if (limit == 0 || outPos == outSize)
 82      break;
 83
 84    b = buf0[inPos++];
 85
 86    if (b == 0xE8)
 87      prob = p + prevByte;
 88    else if (b == 0xE9)
 89      prob = p + 256;
 90    else
 91      prob = p + 257;
 92
 93    IF_BIT_0(prob)
 94    {
 95      UPDATE_0(prob)
 96      prevByte = b;
 97    }
 98    else
 99    {
100      UInt32 dest;
101      const Byte *v;
102      UPDATE_1(prob)
103      if (b == 0xE8)
104      {
105        v = buf1;
106        if (size1 < 4)
107          return SZ_ERROR_DATA;
108        buf1 += 4;
109        size1 -= 4;
110      }
111      else
112      {
113        v = buf2;
114        if (size2 < 4)
115          return SZ_ERROR_DATA;
116        buf2 += 4;
117        size2 -= 4;
118      }
119      dest = (((UInt32)v[0] << 24) | ((UInt32)v[1] << 16) |
120          ((UInt32)v[2] << 8) | ((UInt32)v[3])) - ((UInt32)outPos + 4);
121      outBuf[outPos++] = (Byte)dest;
122      if (outPos == outSize)
123        break;
124      outBuf[outPos++] = (Byte)(dest >> 8);
125      if (outPos == outSize)
126        break;
127      outBuf[outPos++] = (Byte)(dest >> 16);
128      if (outPos == outSize)
129        break;
130      outBuf[outPos++] = prevByte = (Byte)(dest >> 24);
131    }
132  }
133  return (outPos == outSize) ? SZ_OK : SZ_ERROR_DATA;
134}