mirror of
https://github.com/MacPaw/XADMaster.git
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93 lines
2.2 KiB
Objective-C
93 lines
2.2 KiB
Objective-C
/*
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* XADSqueezeHandle.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 "XADSqueezeHandle.h"
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#import "XADException.h"
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@implementation XADSqueezeHandle
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-(id)initWithHandle:(CSHandle *)handle
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{
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return [self initWithHandle:handle length:CSHandleMaxLength];
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}
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-(id)initWithHandle:(CSHandle *)handle length:(off_t)length
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{
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if((self=[super initWithInputBufferForHandle:handle length:length]))
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{
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code=nil;
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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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[code release];
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[super dealloc];
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}
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static void BuildCodeFromTree(XADPrefixCode *code,int *tree,int node,int numnodes,int depth)
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{
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if(depth>64) [XADException raiseDecrunchException];
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if(node<0)
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{
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[code makeLeafWithValue:-(node+1)];
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}
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else if(2*node+1<numnodes)
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{
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[code startZeroBranch];
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BuildCodeFromTree(code,tree,tree[2*node],numnodes,depth+1);
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[code startOneBranch];
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BuildCodeFromTree(code,tree,tree[2*node+1],numnodes,depth+1);
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[code finishBranches];
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}
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else
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{
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[XADException raiseDecrunchException];
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}
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}
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-(void)resetByteStream
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{
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int numnodes=CSInputNextUInt16LE(input)*2;
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if(numnodes>=257*2) [XADException raiseDecrunchException];
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int nodes[numnodes];
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nodes[0]=nodes[1]=-(256+1);
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for(int i=0;i<numnodes;i++) nodes[i]=CSInputNextInt16LE(input);
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[code release];
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code=[XADPrefixCode new];
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[code startBuildingTree];
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BuildCodeFromTree(code,nodes,0,numnodes,0);
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}
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-(uint8_t)produceByteAtOffset:(off_t)pos
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{
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int symbol=CSInputNextSymbolUsingCodeLE(input,code);
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if(symbol==256) CSByteStreamEOF(self);
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return symbol;
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}
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@end
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