1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
|
#import "XADCompactProLZHHandle.h"
#import "XADException.h"
@implementation XADCompactProLZHHandle
-(id)initWithHandle:(CSHandle *)handle blockSize:(int)blocklen
{
if((self=[super initWithHandle:handle windowSize:8192]))
{
blocksize=blocklen;
literalcode=lengthcode=offsetcode=nil;
}
return self;
}
-(void)dealloc
{
[literalcode release];
[lengthcode release];
[offsetcode release];
[super dealloc];
}
-(void)resetLZSSHandle
{
blockcount=blocksize;
blockstart=0;
}
-(int)nextLiteralOrOffset:(int *)offset andLength:(int *)length atPosition:(off_t)pos
{
@try
{
if(blockcount>=blocksize)
{
if(blockstart)
{
// Don't let your bad implementations leak into your file formats, people!
CSInputSkipToByteBoundary(input);
if((CSInputBufferOffset(input)-blockstart)&1) CSInputSkipBytes(input,3);
else CSInputSkipBytes(input,2);
}
[literalcode release];
[lengthcode release];
[offsetcode release];
literalcode=lengthcode=offsetcode=nil;
literalcode=[self allocAndParseCodeOfSize:256];
lengthcode=[self allocAndParseCodeOfSize:64];
offsetcode=[self allocAndParseCodeOfSize:128];
blockcount=0;
blockstart=CSInputBufferOffset(input);
}
if(CSInputNextBit(input))
{
blockcount+=2;
return CSInputNextSymbolUsingCode(input,literalcode);
}
else
{
blockcount+=3;
*length=CSInputNextSymbolUsingCode(input,lengthcode);
*offset=CSInputNextSymbolUsingCode(input,offsetcode)<<6;
*offset|=CSInputNextBitString(input,6);
return XADLZSSMatch;
}
}
@catch(id e) { }
return XADLZSSEnd;
}
-(XADPrefixCode *)allocAndParseCodeOfSize:(int)size
{
int numbytes=CSInputNextByte(input);
if(numbytes*2>size) [XADException raiseIllegalDataException];
int codelengths[size];
for(int i=0;i<numbytes;i++)
{
int val=CSInputNextByte(input);
codelengths[2*i]=val>>4;
codelengths[2*i+1]=val&0x0f;
}
for(int i=numbytes*2;i<size;i++) codelengths[i]=0;
return [[XADPrefixCode alloc] initWithLengths:codelengths numberOfSymbols:size maximumLength:15 shortestCodeIsZeros:YES];
}
@end
|
