| 1 | /* Bra86.c -- Converter for x86 code (BCJ) |
| 2 | 2017-04-03 : Igor Pavlov : Public domain */ |
| 3 | |
| 4 | #include "Precomp.h" |
| 5 | |
| 6 | #include "Bra.h" |
| 7 | |
| 8 | #define Test86MSByte(b) ((((b) + 1) & 0xFE) == 0) |
| 9 | |
| 10 | SizeT x86_Convert(Byte *data, SizeT size, UInt32 ip, UInt32 *state, int encoding) |
| 11 | { |
| 12 | SizeT pos = 0; |
| 13 | UInt32 mask = *state & 7; |
| 14 | if (size < 5) |
| 15 | return 0; |
| 16 | size -= 4; |
| 17 | ip += 5; |
| 18 | |
| 19 | for (;;) |
| 20 | { |
| 21 | Byte *p = data + pos; |
| 22 | const Byte *limit = data + size; |
| 23 | for (; p < limit; p++) |
| 24 | if ((*p & 0xFE) == 0xE8) |
| 25 | break; |
| 26 | |
| 27 | { |
| 28 | SizeT d = (SizeT)(p - data - pos); |
| 29 | pos = (SizeT)(p - data); |
| 30 | if (p >= limit) |
| 31 | { |
| 32 | *state = (d > 2 ? 0 : mask >> (unsigned)d); |
| 33 | return pos; |
| 34 | } |
| 35 | if (d > 2) |
| 36 | mask = 0; |
| 37 | else |
| 38 | { |
| 39 | mask >>= (unsigned)d; |
| 40 | if (mask != 0 && (mask > 4 || mask == 3 || Test86MSByte(p[(size_t)(mask >> 1) + 1]))) |
| 41 | { |
| 42 | mask = (mask >> 1) | 4; |
| 43 | pos++; |
| 44 | continue; |
| 45 | } |
| 46 | } |
| 47 | } |
| 48 | |
| 49 | if (Test86MSByte(p[4])) |
| 50 | { |
| 51 | UInt32 v = ((UInt32)p[4] << 24) | ((UInt32)p[3] << 16) | ((UInt32)p[2] << 8) | ((UInt32)p[1]); |
| 52 | UInt32 cur = ip + (UInt32)pos; |
| 53 | pos += 5; |
| 54 | if (encoding) |
| 55 | v += cur; |
| 56 | else |
| 57 | v -= cur; |
| 58 | if (mask != 0) |
| 59 | { |
| 60 | unsigned sh = (mask & 6) << 2; |
| 61 | if (Test86MSByte((Byte)(v >> sh))) |
| 62 | { |
| 63 | v ^= (((UInt32)0x100 << sh) - 1); |
| 64 | if (encoding) |
| 65 | v += cur; |
| 66 | else |
| 67 | v -= cur; |
| 68 | } |
| 69 | mask = 0; |
| 70 | } |
| 71 | p[1] = (Byte)v; |
| 72 | p[2] = (Byte)(v >> 8); |
| 73 | p[3] = (Byte)(v >> 16); |
| 74 | p[4] = (Byte)(0 - ((v >> 24) & 1)); |
| 75 | } |
| 76 | else |
| 77 | { |
| 78 | mask = (mask >> 1) | 4; |
| 79 | pos++; |
| 80 | } |
| 81 | } |
| 82 | } |