mirror of
https://github.com/MacPaw/XADMaster.git
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90 lines
2.3 KiB
Objective-C
90 lines
2.3 KiB
Objective-C
/*
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* XADCompressHandle.m
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*
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* Copyright (c) 2017-present, MacPaw Inc. All rights reserved.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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* MA 02110-1301 USA
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*/
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#import "XADCompressHandle.h"
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#import "XADException.h"
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@implementation XADCompressHandle
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-(id)initWithHandle:(CSHandle *)handle flags:(int)compressflags
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{
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return [self initWithHandle:handle length:CSHandleMaxLength flags:compressflags];
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}
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-(id)initWithHandle:(CSHandle *)handle length:(off_t)length flags:(int)compressflags
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{
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if((self=[super initWithInputBufferForHandle:handle length:length]))
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{
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blockmode=(compressflags&0x80)!=0;
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int maxsymbols=1<<(compressflags&0x1f);
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if(maxsymbols<=256) [XADException raiseDecrunchException];
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lzw=AllocLZW(maxsymbols,blockmode?1:0);
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}
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return self;
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}
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-(void)dealloc
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{
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FreeLZW(lzw);
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[super dealloc];
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}
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-(void)resetByteStream
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{
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ClearLZWTable(lzw);
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symbolcounter=0;
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buffer=bufferend=NULL;
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}
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-(uint8_t)produceByteAtOffset:(off_t)pos
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{
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if(buffer>=bufferend)
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{
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int symbol;
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for(;;)
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{
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if(CSInputAtEOF(input)) CSByteStreamEOF(self);
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symbol=CSInputNextBitStringLE(input,LZWSuggestedSymbolSize(lzw));
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symbolcounter++;
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if(symbol==256&&blockmode)
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{
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// Skip garbage data after a clear. God damn, this is dumb.
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int symbolsize=LZWSuggestedSymbolSize(lzw);
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if(symbolcounter%8) CSInputSkipBitsLE(input,symbolsize*(8-symbolcounter%8));
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ClearLZWTable(lzw);
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symbolcounter=0;
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}
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else break;
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}
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if(NextLZWSymbol(lzw,symbol)==LZWInvalidCodeError) [XADException raiseDecrunchException];
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int n=LZWOutputToInternalBuffer(lzw);
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buffer=LZWInternalBuffer(lzw);
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bufferend=buffer+n;
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}
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return *buffer++;
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}
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@end
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