1 /* Bra86.c -- Converter for x86 code (BCJ) 2 2008-10-04 : Igor Pavlov : Public domain */ 3 4 #include "Bra.h" 5 6 #define Test86MSByte(b) ((b) == 0 || (b) == 0xFF) 7 8 const Byte kMaskToAllowedStatus[8] = {1, 1, 1, 0, 1, 0, 0, 0}; 9 const Byte kMaskToBitNumber[8] = {0, 1, 2, 2, 3, 3, 3, 3}; 10 11 SizeT x86_Convert(Byte *data, SizeT size, UInt32 ip, UInt32 *state, int encoding) 12 { 13 SizeT bufferPos = 0, prevPosT; 14 UInt32 prevMask = *state & 0x7; 15 if (size < 5) 16 return 0; 17 ip += 5; 18 prevPosT = (SizeT)0 - 1; 19 20 for (;;) 21 { 22 Byte *p = data + bufferPos; 23 Byte *limit = data + size - 4; 24 for (; p < limit; p++) 25 if ((*p & 0xFE) == 0xE8) 26 break; 27 bufferPos = (SizeT)(p - data); 28 if (p >= limit) 29 break; 30 prevPosT = bufferPos - prevPosT; 31 if (prevPosT > 3) 32 prevMask = 0; 33 else 34 { 35 prevMask = (prevMask << ((int)prevPosT - 1)) & 0x7; 36 if (prevMask != 0) 37 { 38 Byte b = p[4 - kMaskToBitNumber[prevMask]]; 39 if (!kMaskToAllowedStatus[prevMask] || Test86MSByte(b)) 40 { 41 prevPosT = bufferPos; 42 prevMask = ((prevMask << 1) & 0x7) | 1; 43 bufferPos++; 44 continue; 45 } 46 } 47 } 48 prevPosT = bufferPos; 49 50 if (Test86MSByte(p[4])) 51 { 52 UInt32 src = ((UInt32)p[4] << 24) | ((UInt32)p[3] << 16) | ((UInt32)p[2] << 8) | ((UInt32)p[1]); 53 UInt32 dest; 54 for (;;) 55 { 56 Byte b; 57 int index; 58 if (encoding) 59 dest = (ip + (UInt32)bufferPos) + src; 60 else 61 dest = src - (ip + (UInt32)bufferPos); 62 if (prevMask == 0) 63 break; 64 index = kMaskToBitNumber[prevMask] * 8; 65 b = (Byte)(dest >> (24 - index)); 66 if (!Test86MSByte(b)) 67 break; 68 src = dest ^ ((1 << (32 - index)) - 1); 69 } 70 p[4] = (Byte)(~(((dest >> 24) & 1) - 1)); 71 p[3] = (Byte)(dest >> 16); 72 p[2] = (Byte)(dest >> 8); 73 p[1] = (Byte)dest; 74 bufferPos += 5; 75 } 76 else 77 { 78 prevMask = ((prevMask << 1) & 0x7) | 1; 79 bufferPos++; 80 } 81 } 82 prevPosT = bufferPos - prevPosT; 83 *state = ((prevPosT > 3) ? 0 : ((prevMask << ((int)prevPosT - 1)) & 0x7)); 84 return bufferPos; 85 } 86
