mirror of
https://github.com/MacPaw/XADMaster.git
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81 lines
2.3 KiB
Objective-C
81 lines
2.3 KiB
Objective-C
/*
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* XADDeltaHandle.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 "XADDeltaHandle.h"
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@implementation XADDeltaHandle
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-(id)initWithHandle:(CSHandle *)handle
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{
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return [self initWithHandle:handle length:CSHandleMaxLength deltaDistance:1];
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}
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-(id)initWithHandle:(CSHandle *)handle length:(off_t)length
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{
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return [self initWithHandle:handle length:length deltaDistance:1];
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}
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-(id)initWithHandle:(CSHandle *)handle deltaDistance:(int)deltadistance
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{
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return [self initWithHandle:handle length:CSHandleMaxLength deltaDistance:deltadistance];
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}
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-(id)initWithHandle:(CSHandle *)handle length:(off_t)length deltaDistance:(int)deltadistance
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{
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if((self=[super initWithInputBufferForHandle:handle length:length]))
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{
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distance=deltadistance;
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}
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return self;
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}
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-(id)initWithHandle:(CSHandle *)handle propertyData:(NSData *)propertydata
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{
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return [self initWithHandle:handle length:CSHandleMaxLength propertyData:propertydata];
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}
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-(id)initWithHandle:(CSHandle *)handle length:(off_t)length propertyData:(NSData *)propertydata
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{
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int deltadistance=1;
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if(propertydata&&[propertydata length]>=1)
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deltadistance=((uint8_t *)[propertydata bytes])[0]+1;
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return [self initWithHandle:handle length:length deltaDistance:deltadistance];
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}
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-(void)resetByteStream
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{
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memset(deltabuffer,0,sizeof(deltabuffer));
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}
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-(uint8_t)produceByteAtOffset:(off_t)pos
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{
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if(CSInputAtEOF(input)) CSByteStreamEOF(self);
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uint8_t b=CSInputNextByte(input);
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uint8_t old=deltabuffer[(pos-distance+0x100)&0xff];
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uint8_t new=b+old;
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deltabuffer[pos&0xff]=new;
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return new;
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}
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@end
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