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1 /* BranchX86.c */ | |
2 | |
3 #include "BranchX86.h" | |
4 | |
5 #define Test86MSByte(b) ((b) == 0 || (b) == 0xFF) | |
6 | |
7 const Byte kMaskToAllowedStatus[8] = {1, 1, 1, 0, 1, 0, 0, 0}; | |
8 const Byte kMaskToBitNumber[8] = {0, 1, 2, 2, 3, 3, 3, 3}; | |
9 | |
10 SizeT x86_Convert(Byte *buffer, SizeT endPos, UInt32 nowPos, UInt32 *prevMaskMix
, int encoding) | |
11 { | |
12 SizeT bufferPos = 0, prevPosT; | |
13 UInt32 prevMask = *prevMaskMix & 0x7; | |
14 if (endPos < 5) | |
15 return 0; | |
16 nowPos += 5; | |
17 prevPosT = (SizeT)0 - 1; | |
18 | |
19 for(;;) | |
20 { | |
21 Byte *p = buffer + bufferPos; | |
22 Byte *limit = buffer + endPos - 4; | |
23 for (; p < limit; p++) | |
24 if ((*p & 0xFE) == 0xE8) | |
25 break; | |
26 bufferPos = (SizeT)(p - buffer); | |
27 if (p >= limit) | |
28 break; | |
29 prevPosT = bufferPos - prevPosT; | |
30 if (prevPosT > 3) | |
31 prevMask = 0; | |
32 else | |
33 { | |
34 prevMask = (prevMask << ((int)prevPosT - 1)) & 0x7; | |
35 if (prevMask != 0) | |
36 { | |
37 Byte b = p[4 - kMaskToBitNumber[prevMask]]; | |
38 if (!kMaskToAllowedStatus[prevMask] || Test86MSByte(b)) | |
39 { | |
40 prevPosT = bufferPos; | |
41 prevMask = ((prevMask << 1) & 0x7) | 1; | |
42 bufferPos++; | |
43 continue; | |
44 } | |
45 } | |
46 } | |
47 prevPosT = bufferPos; | |
48 | |
49 if (Test86MSByte(p[4])) | |
50 { | |
51 UInt32 src = ((UInt32)p[4] << 24) | ((UInt32)p[3] << 16) | ((UInt32)p[2] <
< 8) | ((UInt32)p[1]); | |
52 UInt32 dest; | |
53 for (;;) | |
54 { | |
55 Byte b; | |
56 int index; | |
57 if (encoding) | |
58 dest = (nowPos + (UInt32)bufferPos) + src; | |
59 else | |
60 dest = src - (nowPos + (UInt32)bufferPos); | |
61 if (prevMask == 0) | |
62 break; | |
63 index = kMaskToBitNumber[prevMask] * 8; | |
64 b = (Byte)(dest >> (24 - index)); | |
65 if (!Test86MSByte(b)) | |
66 break; | |
67 src = dest ^ ((1 << (32 - index)) - 1); | |
68 } | |
69 p[4] = (Byte)(~(((dest >> 24) & 1) - 1)); | |
70 p[3] = (Byte)(dest >> 16); | |
71 p[2] = (Byte)(dest >> 8); | |
72 p[1] = (Byte)dest; | |
73 bufferPos += 5; | |
74 } | |
75 else | |
76 { | |
77 prevMask = ((prevMask << 1) & 0x7) | 1; | |
78 bufferPos++; | |
79 } | |
80 } | |
81 prevPosT = bufferPos - prevPosT; | |
82 *prevMaskMix = ((prevPosT > 3) ? 0 : ((prevMask << ((int)prevPosT - 1)) & 0x7)
); | |
83 return bufferPos; | |
84 } | |
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