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
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
|
#import "CSBlockStreamHandle.h"
static inline int imin(int a,int b) { return a<b?a:b; }
@implementation CSBlockStreamHandle
-(id)initWithName:(NSString *)descname length:(off_t)length
{
if((self=[super initWithName:descname length:length]))
{
_currblock=NULL;
_blockstartpos=0;
_blocklength=0;
}
return self;
}
-(id)initWithHandle:(CSHandle *)handle length:(off_t)length bufferSize:(int)buffersize;
{
if((self=[super initWithHandle:handle length:length bufferSize:buffersize]))
{
_currblock=NULL;
_blockstartpos=0;
_blocklength=0;
}
return self;
}
-(id)initAsCopyOf:(CSBlockStreamHandle *)other
{
[self _raiseNotSupported:_cmd];
return nil;
}
-(void)seekToFileOffset:(off_t)offs
{
if(![self _prepareStreamSeekTo:offs]) return;
if(offs<_blockstartpos) [super seekToFileOffset:0];
while(_blockstartpos+_blocklength<offs)
{
[self _readNextBlock];
if(endofstream)
{
if(offs==_blockstartpos) break;
else [self _raiseEOF];
}
}
streampos=offs;
}
-(void)resetStream
{
_blockstartpos=0;
_blocklength=0;
_endofblocks=NO;
[self resetBlockStream];
}
-(int)streamAtMost:(int)num toBuffer:(void *)buffer
{
int n=0;
if(streampos>=_blockstartpos&&streampos<_blockstartpos+_blocklength)
{
if(!_currblock) return 0;
int offs=streampos-_blockstartpos;
int count=_blocklength-offs;
if(count>num) count=num;
memcpy(buffer,_currblock+offs,count);
n+=count;
}
while(n<num)
{
[self _readNextBlock];
if(endofstream) break;
int count=imin(_blocklength,num-n);
memcpy(buffer+n,_currblock,count);
n+=count;
}
return n;
}
-(void)_readNextBlock
{
_blockstartpos+=_blocklength;
if(_endofblocks) { [self endStream]; return; }
_blocklength=[self produceBlockAtOffset:_blockstartpos];
if(_blocklength<=0||!_currblock) [self endStream];
}
-(void)resetBlockStream { }
-(int)produceBlockAtOffset:(off_t)pos { return 0; }
-(void)setBlockPointer:(uint8_t *)blockpointer
{
_currblock=blockpointer;
}
-(void)endBlockStream
{
_endofblocks=YES;
}
@end
|
