mirror of
https://github.com/MacPaw/XADMaster.git
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108 lines
3.4 KiB
Objective-C
108 lines
3.4 KiB
Objective-C
/*
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* XADCRCSuffixHandle.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 "XADCRCSuffixHandle.h"
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@implementation XADCRCSuffixHandle
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+(XADCRCSuffixHandle *)IEEECRC32SuffixHandleWithHandle:(CSHandle *)handle CRCHandle:(CSHandle *)crchandle
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bigEndianCRC:(BOOL)bigendian conditioned:(BOOL)conditioned
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{
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if(conditioned) return [[[self alloc] initWithHandle:handle CRCHandle:crchandle initialCRC:0xffffffff
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CRCSize:4 bigEndianCRC:bigendian CRCTable:XADCRCTable_edb88320] autorelease];
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else return [[[self alloc] initWithHandle:handle CRCHandle:crchandle initialCRC:0
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CRCSize:4 bigEndianCRC:bigendian CRCTable:XADCRCTable_edb88320] autorelease];
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}
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+(XADCRCSuffixHandle *)CCITTCRC16SuffixHandleWithHandle:(CSHandle *)handle CRCHandle:(CSHandle *)crchandle
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bigEndianCRC:(BOOL)bigendian conditioned:(BOOL)conditioned
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{
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// Evil trick: negating the big endian flag does the same thing as XADUnReverseCRC16()
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if(conditioned) return [[[self alloc] initWithHandle:handle CRCHandle:crchandle initialCRC:0xffff
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CRCSize:2 bigEndianCRC:!bigendian CRCTable:XADCRCReverseTable_1021] autorelease];
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else return [[[self alloc] initWithHandle:handle CRCHandle:crchandle initialCRC:0
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CRCSize:2 bigEndianCRC:!bigendian CRCTable:XADCRCReverseTable_1021] autorelease];
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}
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-(id)initWithHandle:(CSHandle *)handle CRCHandle:(CSHandle *)crchandle initialCRC:(uint32_t)initialcrc
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CRCSize:(int)crcbytes bigEndianCRC:(BOOL)bigendian CRCTable:(const uint32_t *)crctable
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{
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if(self=[super initWithParentHandle:handle])
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{
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crcparent=[crchandle retain];
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crcsize=crcbytes;
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bigend=bigendian;
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crc=initcrc=initialcrc;
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table=crctable;
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didtest=wascorrect=NO;
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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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[crcparent release];
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[super dealloc];
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}
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-(void)resetStream
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{
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[parent seekToFileOffset:0];
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crc=initcrc;
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}
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-(int)streamAtMost:(int)num toBuffer:(void *)buffer
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{
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int actual=[parent readAtMost:num toBuffer:buffer];
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crc=XADCalculateCRC(crc,buffer,actual,table);
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return actual;
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}
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-(BOOL)hasChecksum { return YES; }
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-(BOOL)isChecksumCorrect
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{
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if(didtest) return wascorrect;
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if([parent hasChecksum]&&![parent isChecksumCorrect]) return NO;
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if(![parent atEndOfFile]) return NO;
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if(crcparent)
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{
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@try {
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if(bigend&&crcsize==2) compcrc=[crcparent readUInt16BE];
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else if(bigend&&crcsize==4) compcrc=[crcparent readUInt32BE];
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else if(!bigend&&crcsize==2) compcrc=[crcparent readUInt16LE];
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else if(!bigend&&crcsize==4) compcrc=[crcparent readUInt32LE];
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} @catch(id e) { compcrc=(crc+1)^initcrc; } // make sure check fails if reading failed
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[crcparent release];
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crcparent=nil;
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}
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didtest=YES;
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wascorrect=((crc^initcrc)==compcrc);
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return wascorrect;
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}
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-(double)estimatedProgress { return [parent estimatedProgress]; }
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@end
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