third_party/lzma_sdk/Bcj2.c

   1 /* Bcj2.c -- Converter for x86 code (BCJ2)
   2 2008-10-04 : Igor Pavlov : Public domain */
   3
   4 #include "Bcj2.h"
   5
   6 #ifdef _LZMA_PROB32
   7 #define CProb UInt32
   8 #else
   9 #define CProb UInt16
  10 #endif
  11
  12 #define IsJcc(b0, b1) ((b0) == 0x0F && ((b1) & 0xF0) == 0x80)
  13 #define IsJ(b0, b1) ((b1 & 0xFE) == 0xE8 || IsJcc(b0, b1))
  14
  15 #define kNumTopBits 24
  16 #define kTopValue ((UInt32)1 << kNumTopBits)
  17
  18 #define kNumBitModelTotalBits 11
  19 #define kBitModelTotal (1 << kNumBitModelTotalBits)
  20 #define kNumMoveBits 5
  21
  22 #define RC_READ_BYTE (*buffer++)
  23 #define RC_TEST { if (buffer == bufferLim) return SZ_ERROR_DATA; }
  24 #define RC_INIT2 code = 0; range = 0xFFFFFFFF; \
  25   { int i; for (i = 0; i < 5; i++) { RC_TEST; code = (code << 8) | RC_READ_BYTE; }}
  26
  27 #define NORMALIZE if (range < kTopValue) { RC_TEST; range <<= 8; code = (code << 8) | RC_READ_BYTE; }
  28
  29 #define IF_BIT_0(p) ttt = *(p); bound = (range >> kNumBitModelTotalBits) * ttt; if (code < bound)
  30 #define UPDATE_0(p) range = bound; *(p) = (CProb)(ttt + ((kBitModelTotal - ttt) >> kNumMoveBits)); NORMALIZE;
  31 #define UPDATE_1(p) range -= bound; code -= bound; *(p) = (CProb)(ttt - (ttt >> kNumMoveBits)); NORMALIZE;
  32
  33 int Bcj2_Decode(
  34     const Byte *buf0, SizeT size0,
  35     const Byte *buf1, SizeT size1,
  36     const Byte *buf2, SizeT size2,
  37     const Byte *buf3, SizeT size3,
  38     Byte *outBuf, SizeT outSize)
  39 {
  40   CProb p[256 + 2];
  41   SizeT inPos = 0, outPos = 0;
  42
  43   const Byte *buffer, *bufferLim;
  44   UInt32 range, code;
  45   Byte prevByte = 0;
  46
  47   unsigned int i;
  48   for (i = 0; i < sizeof(p) / sizeof(p[0]); i++)
  49     p[i] = kBitModelTotal >> 1;
  50
  51   buffer = buf3;
  52   bufferLim = buffer + size3;
  53   RC_INIT2
  54
  55   if (outSize == 0)
  56     return SZ_OK;
  57
  58   for (;;)
  59   {
  60     Byte b;
  61     CProb *prob;
  62     UInt32 bound;
  63     UInt32 ttt;
  64
  65     SizeT limit = size0 - inPos;
  66     if (outSize - outPos < limit)
  67       limit = outSize - outPos;
  68     while (limit != 0)
  69     {
  70       Byte b = buf0[inPos];
  71       outBuf[outPos++] = b;
  72       if (IsJ(prevByte, b))
  73         break;
  74       inPos++;
  75       prevByte = b;
  76       limit--;
  77     }
  78
  79     if (limit == 0 || outPos == outSize)
  80       break;
  81
  82     b = buf0[inPos++];
  83
  84     if (b == 0xE8)
  85       prob = p + prevByte;
  86     else if (b == 0xE9)
  87       prob = p + 256;
  88     else
  89       prob = p + 257;
  90
  91     IF_BIT_0(prob)
  92     {
  93       UPDATE_0(prob)
  94       prevByte = b;
  95     }
  96     else
  97     {
  98       UInt32 dest;
  99       const Byte *v;
 100       UPDATE_1(prob)
 101       if (b == 0xE8)
 102       {
 103         v = buf1;
 104         if (size1 < 4)
 105           return SZ_ERROR_DATA;
 106         buf1 += 4;
 107         size1 -= 4;
 108       }
 109       else
 110       {
 111         v = buf2;
 112         if (size2 < 4)
 113           return SZ_ERROR_DATA;
 114         buf2 += 4;
 115         size2 -= 4;
 116       }
 117       dest = (((UInt32)v[0] << 24) | ((UInt32)v[1] << 16) |
 118           ((UInt32)v[2] << 8) | ((UInt32)v[3])) - ((UInt32)outPos + 4);
 119       outBuf[outPos++] = (Byte)dest;
 120       if (outPos == outSize)
 121         break;
 122       outBuf[outPos++] = (Byte)(dest >> 8);
 123       if (outPos == outSize)
 124         break;
 125       outBuf[outPos++] = (Byte)(dest >> 16);
 126       if (outPos == outSize)
 127         break;
 128       outBuf[outPos++] = prevByte = (Byte)(dest >> 24);
 129     }
 130   }
 131   return (outPos == outSize) ? SZ_OK : SZ_ERROR_DATA;
 132 }