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#import "XADDiskDoublerMethod2Handle.h"
#import "XADException.h"
@implementation XADDiskDoublerMethod2Handle
-(id)initWithHandle:(CSHandle *)handle length:(off_t)length numberOfTrees:(int)num
{
if((self=[super initWithHandle:handle length:length]))
{
numtrees=num;
}
return self;
}
-(void)resetByteStream
{
for(int i=0;i<numtrees;i++)
{
for(int j=0;j<256;j++)
{
trees[i].parents[2*j]=j;
trees[i].parents[2*j+1]=j;
trees[i].leftchildren[j]=j*2;
trees[i].rightchildren[j]=j*2+1;
}
}
currtree=0;
}
-(uint8_t)produceByteAtOffset:(off_t)pos
{
int node=1;
for(;;)
{
int bit=CSInputNextBit(input);
if(bit==1) node=trees[currtree].rightchildren[node];
else node=trees[currtree].leftchildren[node];
if(node>=0x100)
{
int byte=node-0x100;
[self updateStateForByte:byte];
return byte;
}
}
}
-(void)updateStateForByte:(int)byte
{
uint8_t *parents=trees[currtree].parents;
uint16_t *leftchildren=trees[currtree].leftchildren;
uint16_t *rightchildren=trees[currtree].rightchildren;
int node=byte+0x100;
for(;;)
{
int parent=parents[node];
if(parent==1) break;
int grandparent=parents[parent];
int uncle=leftchildren[grandparent];
if(uncle==parent)
{
uncle=rightchildren[grandparent];
rightchildren[grandparent]=node;
}
else
{
leftchildren[grandparent]=node;
}
if(leftchildren[parent]!=node) rightchildren[parent]=uncle;
else leftchildren[parent]=uncle;
parents[node]=grandparent;
parents[uncle]=parent;
node=grandparent;
if(node==1) break;
}
currtree=byte%numtrees;
}
@end
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