1/* Bcj2.c -- Converter for x86 code (BCJ2)
22008-10-04 : 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
33int 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 b2 = buf0[inPos];
71 outBuf[outPos++] = b2;
72 if (IsJ(prevByte, b2))
73 break;
74 inPos++;
75 prevByte = b2;
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}
133