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#import "XADBlockHandle.h"
@implementation XADBlockHandle
-(id)initWithHandle:(CSHandle *)handle blockSize:(int)size
{
if((self=[super initWithName:[handle name]]))
{
parent=[handle retain];
currpos=0;
length=CSHandleMaxLength;
numblocks=0;
blocksize=size;
blockoffsets=NULL;
}
return self;
}
-(id)initWithHandle:(CSHandle *)handle length:(off_t)maxlength blockSize:(int)size
{
if((self=[super initWithName:[handle name]]))
{
parent=[handle retain];
currpos=0;
length=maxlength;
numblocks=0;
blocksize=size;
blockoffsets=NULL;
}
return self;
}
-(void)dealloc
{
[parent release];
[super dealloc];
}
-(void)setBlockChain:(uint32_t *)blocktable numberOfBlocks:(int)totalblocks
firstBlock:(uint32_t)first headerSize:(off_t)headersize
{
numblocks=0;
uint32_t block=first;
while(block<totalblocks)
{
block=blocktable[block];
numblocks++;
}
free(blockoffsets);
blockoffsets=malloc(numblocks*sizeof(off_t));
block=first;
for(int i=0;i<numblocks;i++)
{
blockoffsets[i]=headersize+block*blocksize;
block=blocktable[block];
}
}
-(off_t)fileSize
{
if(length<numblocks*blocksize) return length;
return numblocks*blocksize;
}
-(off_t)offsetInFile
{
return currpos;
}
-(BOOL)atEndOfFile
{
if(currpos==numblocks*blocksize) return YES;
if(currpos==length) return YES;
return NO;
}
-(void)seekToFileOffset:(off_t)offs
{
if(offs<0) [self _raiseEOF];
if(offs>numblocks*blocksize) [self _raiseEOF];
if(offs>length) [self _raiseEOF];
int block=(offs-1)/blocksize;
[parent seekToFileOffset:blockoffsets[block]+offs-block*blocksize];
currpos=offs;
}
-(void)seekToEndOfFile
{
if(length!=CSHandleMaxLength) [self seekToFileOffset:length];
else [self seekToFileOffset:numblocks*blocksize];
}
-(int)readAtMost:(int)num toBuffer:(void *)buffer
{
uint8_t *bytebuffer=(uint8_t *)buffer;
int total=0;
if(currpos+num>length) num=length-currpos;
while(total<num)
{
int blockpos=currpos%blocksize;
if(blockpos==0)
{
int block=currpos/blocksize;
if(block==numblocks) return total;
[parent seekToFileOffset:blockoffsets[block]];
}
int numbytes=num-total;
if(numbytes>blocksize-blockpos) numbytes=blocksize-blockpos;
int actual=[parent readAtMost:numbytes toBuffer:&bytebuffer[total]];
if(actual==0) return total;
total+=actual;
currpos+=actual;
}
return total;
}
@end
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