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#import "XADCompressHandle.h"
#import "XADException.h"
@implementation XADCompressHandle
-(id)initWithHandle:(CSHandle *)handle flags:(int)compressflags
{
return [self initWithHandle:handle length:CSHandleMaxLength flags:compressflags];
}
-(id)initWithHandle:(CSHandle *)handle length:(off_t)length flags:(int)compressflags
{
if((self=[super initWithHandle:handle length:length]))
{
blockmode=(compressflags&0x80)!=0;
lzw=AllocLZW(1<<(compressflags&0x1f),blockmode?1:0);
}
return self;
}
-(void)dealloc
{
FreeLZW(lzw);
[super dealloc];
}
-(void)resetByteStream
{
ClearLZWTable(lzw);
symbolcounter=0;
buffer=bufferend=NULL;
}
-(uint8_t)produceByteAtOffset:(off_t)pos
{
if(buffer>=bufferend)
{
int symbol;
for(;;)
{
if(CSInputAtEOF(input)) CSByteStreamEOF(self);
symbol=CSInputNextBitStringLE(input,LZWSuggestedSymbolSize(lzw));
symbolcounter++;
if(symbol==256&&blockmode)
{
// Skip garbage data after a clear. God damn, this is dumb.
int symbolsize=LZWSuggestedSymbolSize(lzw);
if(symbolcounter%8) CSInputSkipBitsLE(input,symbolsize*(8-symbolcounter%8));
ClearLZWTable(lzw);
symbolcounter=0;
}
else break;
}
if(NextLZWSymbol(lzw,symbol)==LZWInvalidCodeError) [XADException raiseDecrunchException];
int n=LZWOutputToInternalBuffer(lzw);
buffer=LZWInternalBuffer(lzw);
bufferend=buffer+n;
}
return *buffer++;
}
@end
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