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#import "XADPaddedBlockHandle.h"
@implementation XADPaddedBlockHandle
-(id)initWithHandle:(CSHandle *)handle startOffset:(off_t)start
logicalBlockSize:(int)logical physicalBlockSize:(int)physical;
{
if((self=[super initWithName:[handle name]]))
{
parent=[handle retain];
startoffset=start;
logicalsize=logical;
physicalsize=physical;
}
return self;
}
-(void)dealloc
{
[parent release];
[super dealloc];
}
static inline off_t PhysicalToLogical(XADPaddedBlockHandle *self,off_t physical)
{
off_t block=(physical-self->startoffset)/self->physicalsize;
int offset=(physical-self->startoffset)%self->physicalsize;
if(offset>self->logicalsize) physical-=offset-self->logicalsize;
return physical-self->startoffset-block*(self->physicalsize-self->logicalsize);
}
static inline off_t LogicalToPhysical(XADPaddedBlockHandle *self,off_t logical)
{
off_t block=logical/self->logicalsize;
return logical+self->startoffset+block*(self->physicalsize-self->logicalsize);
}
-(off_t)fileSize
{
off_t size=[parent fileSize];
if(size==CSHandleMaxLength) return CSHandleMaxLength;
return PhysicalToLogical(self,size);
}
-(off_t)offsetInFile
{
return PhysicalToLogical(self,[parent offsetInFile]);
}
-(BOOL)atEndOfFile
{
return [parent atEndOfFile];
}
-(void)seekToFileOffset:(off_t)offs
{
if(offs<0) [self _raiseEOF];
[parent seekToFileOffset:LogicalToPhysical(self,offs)];
}
-(void)seekToEndOfFile
{
[parent seekToEndOfFile];
}
-(int)readAtMost:(int)num toBuffer:(void *)buffer
{
if(!num) return 0;
uint8_t *bytebuffer=(uint8_t *)buffer;
off_t pos=[parent offsetInFile];
int total=0;
while(total<num)
{
int offset=(pos-startoffset)%physicalsize;
if(offset>=logicalsize)
{
pos+=physicalsize-offset;
offset=0;
[parent seekToFileOffset:pos];
}
int numbytes=logicalsize-offset;
if(numbytes>num-total) numbytes=num-total;
int actual=[parent readAtMost:numbytes toBuffer:&bytebuffer[total]];
if(actual==0) return total;
total+=actual;
pos+=actual;
}
return total;
}
@end
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