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#import "XADPowerPackerParser.h"
#import "CSMemoryHandle.h"
#import "XADException.h"
static NSData *PowerPackerUnpack(NSData *packeddata,int unpackedlength);
@implementation XADPowerPackerParser
+(int)requiredHeaderSize { return 4; }
+(BOOL)recognizeFileWithHandle:(CSHandle *)handle firstBytes:(NSData *)data name:(NSString *)name
{
int length=[data length];
const uint8_t *bytes=[data bytes];
return length>=8&&bytes[0]=='P'&&bytes[1]=='P'&&bytes[2]=='2'&&bytes[3]=='0';
}
-(void)parse
{
CSHandle *fh=[self handle];
[fh seekToEndOfFile];
off_t compsize=[fh offsetInFile]-4;
[fh skipBytes:-4];
int size=[fh readUInt8]<<16;
size|=[fh readUInt8]<<8;
size|=[fh readUInt8];
[self addEntryWithDictionary:[NSMutableDictionary dictionaryWithObjectsAndKeys:
[self XADPathWithUnseparatedString:[[self name] stringByDeletingPathExtension]],XADFileNameKey,
[NSNumber numberWithLongLong:size],XADFileSizeKey,
[NSNumber numberWithLongLong:compsize],XADCompressedSizeKey,
[self XADStringWithString:@"PowerPacker"],XADCompressionNameKey,
[NSNumber numberWithLongLong:4],XADDataOffsetKey,
[NSNumber numberWithLongLong:compsize],XADDataLengthKey,
nil]];
}
-(CSHandle *)handleForEntryWithDictionary:(NSDictionary *)dict wantChecksum:(BOOL)checksum
{
NSData *data=[dict objectForKey:@"PowerPackerFileContents"];
if(!data)
{
CSHandle *handle=[self handleAtDataOffsetForDictionary:dict];
data=PowerPackerUnpack([handle remainingFileContents],[[dict objectForKey:XADFileSizeKey] intValue]);
[(NSMutableDictionary *)dict setObject:data forKey:@"PowerPackerFileContents"];
}
return [CSMemoryHandle memoryHandleForReadingData:data];
}
-(NSString *)formatName { return @"PowerPacker"; }
@end
static uint32_t GetBits(int n,const uint8_t *buffer,int *bitpos)
{
uint32_t result=0;
for(int i=0;i<n;i++)
{
(*bitpos)--;
if(*bitpos<0) [XADException raiseDecrunchException];
int currbyte=*bitpos/8;
int currbit=7-(*bitpos&7);
result=(result<<1)|((buffer[currbyte]>>currbit)&1);
}
return result;
}
static NSData *PowerPackerUnpack(NSData *packeddata,int unpackedlength)
{
const uint8_t *packed=[packeddata bytes];
int packedlength=[packeddata length];
NSMutableData *unpackeddata=[NSMutableData dataWithLength:unpackedlength];
uint8_t *unpacked=[unpackeddata mutableBytes];
int bitpos=packedlength*8-32;
uint8_t *dest=unpacked+unpackedlength;
// Skip extra bits
GetBits(packed[packedlength-1],packed,&bitpos);
for(;;)
{
if(GetBits(1,packed,&bitpos)==0) // copy some bytes from the source
{
int add,numbytes=1;
do
{
add=GetBits(2,packed,&bitpos);
numbytes+=add;
} while(add==3);
for(int i=0;i<numbytes;i++)
{
if(dest<=unpacked) [XADException raiseDecrunchException];
*--dest=GetBits(8,packed,&bitpos);
}
if(dest==unpacked) return unpackeddata;
}
// decode what to copy from the destination file
int index=GetBits(2,packed,&bitpos);
int numbits=packed[index];
int numbytes=index+2;
int offset;
if(numbytes==5) // 5 means >=5
{
// and maybe a bigger offset
if(GetBits(1,packed,&bitpos)==0) offset=GetBits(7,packed,&bitpos);
else offset=GetBits(numbits,packed,&bitpos);
int add;
do {
add=GetBits(3,packed,&bitpos);
numbytes+=add;
} while(add==7);
}
else offset=GetBits(numbits,packed,&bitpos);
for(int i=0;i<numbytes;i++)
{
if(dest<=unpacked) [XADException raiseDecrunchException];
dest[-1]=dest[offset];
dest--;
}
if(dest==unpacked) return unpackeddata;
}
return nil; // can't happen
}
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