1 /* Bcj2.c -- Converter for x86 code (BCJ2)
2 2008-10-04 : Igor Pavlov : Public domain */
3
4 #include "Precomp.h"
5
6 #include "Bcj2.h"
7
8 #ifdef _LZMA_PROB32
9 #define CProb UInt32
10 #else
11 #define CProb UInt16
12 #endif
13
14 #define IsJcc(b0, b1) ((b0) == 0x0F && ((b1) & 0xF0) == 0x80)
15 #define IsJ(b0, b1) ((b1 & 0xFE) == 0xE8 || IsJcc(b0, b1))
16
17 #define kNumTopBits 24
18 #define kTopValue ((UInt32)1 << kNumTopBits)
19
20 #define kNumBitModelTotalBits 11
21 #define kBitModelTotal (1 << kNumBitModelTotalBits)
22 #define kNumMoveBits 5
23
24 #define RC_READ_BYTE (*buffer++)
25 #define RC_TEST { if (buffer == bufferLim) return SZ_ERROR_DATA; }
26 #define RC_INIT2 code = 0; range = 0xFFFFFFFF; \
27 { int i; for (i = 0; i < 5; i++) { RC_TEST; code = (code << 8) | RC_READ_BYTE; }}
28
29 #define NORMALIZE if (range < kTopValue) { RC_TEST; range <<= 8; code = (code << 8) | RC_READ_BYTE; }
30
31 #define IF_BIT_0(p) ttt = *(p); bound = (range >> kNumBitModelTotalBits) * ttt; if (code < bound)
32 #define UPDATE_0(p) range = bound; *(p) = (CProb)(ttt + ((kBitModelTotal - ttt) >> kNumMoveBits)); NORMALIZE;
33 #define UPDATE_1(p) range -= bound; code -= bound; *(p) = (CProb)(ttt - (ttt >> kNumMoveBits)); NORMALIZE;
34
Bcj2_Decode(const Byte * buf0,SizeT size0,const Byte * buf1,SizeT size1,const Byte * buf2,SizeT size2,const Byte * buf3,SizeT size3,Byte * outBuf,SizeT outSize)35 int Bcj2_Decode(
36 const Byte *buf0, SizeT size0,
37 const Byte *buf1, SizeT size1,
38 const Byte *buf2, SizeT size2,
39 const Byte *buf3, SizeT size3,
40 Byte *outBuf, SizeT outSize)
41 {
42 CProb p[256 + 2];
43 SizeT inPos = 0, outPos = 0;
44
45 const Byte *buffer, *bufferLim;
46 UInt32 range, code;
47 Byte prevByte = 0;
48
49 unsigned int i;
50 for (i = 0; i < sizeof(p) / sizeof(p[0]); i++)
51 p[i] = kBitModelTotal >> 1;
52
53 buffer = buf3;
54 bufferLim = buffer + size3;
55 RC_INIT2
56
57 if (outSize == 0)
58 return SZ_OK;
59
60 for (;;)
61 {
62 Byte b;
63 CProb *prob;
64 UInt32 bound;
65 UInt32 ttt;
66
67 SizeT limit = size0 - inPos;
68 if (outSize - outPos < limit)
69 limit = outSize - outPos;
70 while (limit != 0)
71 {
72 Byte b = buf0[inPos];
73 outBuf[outPos++] = b;
74 if (IsJ(prevByte, b))
75 break;
76 inPos++;
77 prevByte = b;
78 limit--;
79 }
80
81 if (limit == 0 || outPos == outSize)
82 break;
83
84 b = buf0[inPos++];
85
86 if (b == 0xE8)
87 prob = p + prevByte;
88 else if (b == 0xE9)
89 prob = p + 256;
90 else
91 prob = p + 257;
92
93 IF_BIT_0(prob)
94 {
95 UPDATE_0(prob)
96 prevByte = b;
97 }
98 else
99 {
100 UInt32 dest;
101 const Byte *v;
102 UPDATE_1(prob)
103 if (b == 0xE8)
104 {
105 v = buf1;
106 if (size1 < 4)
107 return SZ_ERROR_DATA;
108 buf1 += 4;
109 size1 -= 4;
110 }
111 else
112 {
113 v = buf2;
114 if (size2 < 4)
115 return SZ_ERROR_DATA;
116 buf2 += 4;
117 size2 -= 4;
118 }
119 dest = (((UInt32)v[0] << 24) | ((UInt32)v[1] << 16) |
120 ((UInt32)v[2] << 8) | ((UInt32)v[3])) - ((UInt32)outPos + 4);
121 outBuf[outPos++] = (Byte)dest;
122 if (outPos == outSize)
123 break;
124 outBuf[outPos++] = (Byte)(dest >> 8);
125 if (outPos == outSize)
126 break;
127 outBuf[outPos++] = (Byte)(dest >> 16);
128 if (outPos == outSize)
129 break;
130 outBuf[outPos++] = prevByte = (Byte)(dest >> 24);
131 }
132 }
133 return (outPos == outSize) ? SZ_OK : SZ_ERROR_DATA;
134 }
135