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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 99 | pmbaty | 1 | /* Bra86.c -- Converter for x86 code (BCJ) |
| 2 | 2008-10-04 : Igor Pavlov : Public domain */ |
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| 3 | |||
| 4 | #include "Bra.h" |
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| 5 | |||
| 6 | #define Test86MSByte(b) ((b) == 0 || (b) == 0xFF) |
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| 7 | |||
| 8 | const Byte kMaskToAllowedStatus[8] = {1, 1, 1, 0, 1, 0, 0, 0}; |
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| 9 | const Byte kMaskToBitNumber[8] = {0, 1, 2, 2, 3, 3, 3, 3}; |
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| 10 | |||
| 11 | SizeT x86_Convert(Byte *data, SizeT size, UInt32 ip, UInt32 *state, int encoding) |
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| 12 | { |
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| 13 | SizeT bufferPos = 0, prevPosT; |
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| 14 | UInt32 prevMask = *state & 0x7; |
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| 15 | if (size < 5) |
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| 16 | return 0; |
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| 17 | ip += 5; |
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| 18 | prevPosT = (SizeT)0 - 1; |
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| 19 | |||
| 20 | for (;;) |
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| 21 | { |
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| 22 | Byte *p = data + bufferPos; |
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| 23 | Byte *limit = data + size - 4; |
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| 24 | for (; p < limit; p++) |
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| 25 | if ((*p & 0xFE) == 0xE8) |
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| 26 | break; |
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| 27 | bufferPos = (SizeT)(p - data); |
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| 28 | if (p >= limit) |
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| 29 | break; |
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| 30 | prevPosT = bufferPos - prevPosT; |
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| 31 | if (prevPosT > 3) |
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| 32 | prevMask = 0; |
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| 33 | else |
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| 34 | { |
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| 35 | prevMask = (prevMask << ((int)prevPosT - 1)) & 0x7; |
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| 36 | if (prevMask != 0) |
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| 37 | { |
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| 38 | Byte b = p[4 - kMaskToBitNumber[prevMask]]; |
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| 39 | if (!kMaskToAllowedStatus[prevMask] || Test86MSByte(b)) |
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| 40 | { |
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| 41 | prevPosT = bufferPos; |
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| 42 | prevMask = ((prevMask << 1) & 0x7) | 1; |
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| 43 | bufferPos++; |
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| 44 | continue; |
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| 45 | } |
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| 46 | } |
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| 47 | } |
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| 48 | prevPosT = bufferPos; |
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| 49 | |||
| 50 | if (Test86MSByte(p[4])) |
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| 51 | { |
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| 52 | UInt32 src = ((UInt32)p[4] << 24) | ((UInt32)p[3] << 16) | ((UInt32)p[2] << 8) | ((UInt32)p[1]); |
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| 53 | UInt32 dest; |
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| 54 | for (;;) |
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| 55 | { |
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| 56 | Byte b; |
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| 57 | int index; |
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| 58 | if (encoding) |
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| 59 | dest = (ip + (UInt32)bufferPos) + src; |
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| 60 | else |
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| 61 | dest = src - (ip + (UInt32)bufferPos); |
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| 62 | if (prevMask == 0) |
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| 63 | break; |
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| 64 | index = kMaskToBitNumber[prevMask] * 8; |
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| 65 | b = (Byte)(dest >> (24 - index)); |
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| 66 | if (!Test86MSByte(b)) |
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| 67 | break; |
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| 68 | src = dest ^ (((UInt32)1 << (32 - index)) - (UInt32)1); |
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| 69 | } |
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| 70 | p[4] = (Byte)(~(((dest >> 24) & 1) - 1)); |
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| 71 | p[3] = (Byte)(dest >> 16); |
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| 72 | p[2] = (Byte)(dest >> 8); |
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| 73 | p[1] = (Byte)dest; |
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| 74 | bufferPos += 5; |
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| 75 | } |
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| 76 | else |
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| 77 | { |
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| 78 | prevMask = ((prevMask << 1) & 0x7) | 1; |
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| 79 | bufferPos++; |
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| 80 | } |
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| 81 | } |
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| 82 | prevPosT = bufferPos - prevPosT; |
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| 83 | *state = ((prevPosT > 3) ? 0 : ((prevMask << ((int)prevPosT - 1)) & 0x7)); |
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| 84 | return bufferPos; |
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| 85 | } |