int NextBitFromRangeCoder(CarrylessRangeCoder *self)
{
int bit=RangeCoderCurrentCount(self,2);
if(bit==0) RemoveRangeCoderSubRange(self,0,1);
else RemoveRangeCoderSubRange(self,1,2);
return bit;
}
int PPMdDecodeSymbol1(PPMdContext *self,PPMdCoreModel *model,BOOL greaterorequal)
{
model->scale=self->SummFreq;
PPMdState *states=PPMdContextStates(self,model);
int firstcount=states[0].Freq;
int count=RangeCoderCurrentCount(&model->coder,model->scale);
int adder=greaterorequal?1:0;
if(count<firstcount)
{
RemoveRangeCoderSubRange(&model->coder,0,firstcount);
if(2*firstcount+adder>model->scale)
{
model->PrevSuccess=1;
model->RunLength++;
}
else model->PrevSuccess=0;
model->FoundState=&states[0];
states[0].Freq=firstcount+4;
self->SummFreq+=4;
if(firstcount+4>MAX_FREQ) model->RescalePPMdContext(self,model);
return -1;
}
int highcount=firstcount;
model->PrevSuccess=0;
for(int i=1;i<=self->LastStateIndex;i++)
{
highcount+=states[i].Freq;
if(highcount>count)
{
RemoveRangeCoderSubRange(&model->coder,highcount-states[i].Freq,highcount);
UpdatePPMdContext1(self,model,&states[i]);
return -1;
}
}
int lastsym=model->FoundState->Symbol;
//if ( Suffix ) PrefetchData(Suffix);
RemoveRangeCoderSubRange(&model->coder,highcount,model->scale);
model->LastMaskIndex=self->LastStateIndex;
model->FoundState=NULL;
for(int i=0;i<=self->LastStateIndex;i++) model->CharMask[states[i].Symbol]=model->EscCount;
return lastsym;
}
int NextWeightedBitFromRangeCoder(CarrylessRangeCoder *self,int weight,int size)
{
int val=RangeCoderCurrentCount(self,size);
int bit;
if(val<weight) // <= ?
{
bit=0;
RemoveRangeCoderSubRange(self,0,weight);
}
else
{
bit=1;
RemoveRangeCoderSubRange(self,weight,size);
}
return bit;
}
void PPMdDecodeSymbol2(PPMdContext *self,PPMdCoreModel *model,SEE2Context *see)
{
int n=self->LastStateIndex-model->LastMaskIndex;
PPMdState *ps[256];
int total=0;
PPMdState *state=PPMdContextStates(self,model);
for(int i=0;i<n;i++)
{
while(model->CharMask[state->Symbol]==model->EscCount) state++;
total+=state->Freq;
ps[i]=state++;
}
model->scale+=total;
int count=RangeCoderCurrentCount(&model->coder,model->scale);
if(count<total)
{
int i=0,highcount=ps[0]->Freq;
while(highcount<=count) highcount+=ps[++i]->Freq;
RemoveRangeCoderSubRange(&model->coder,highcount-ps[i]->Freq,highcount);
UpdateSEE2(see);
UpdatePPMdContext2(self,model,ps[i]);
}
else
{
RemoveRangeCoderSubRange(&model->coder,total,model->scale);
model->LastMaskIndex=self->LastStateIndex;
see->Summ+=model->scale;
for(int i=0;i<n;i++) model->CharMask[ps[i]->Symbol]=model->EscCount;
}
}
int NextSymbolFromRangeCoder(CarrylessRangeCoder *self,uint32_t *freqtable,int numfreq)
{
uint32_t totalfreq=0;
uint32_t cumulativefreq=0;
int n=0;
uint32_t tmp;
int i;
for(i=0;i<numfreq;i++) totalfreq+=freqtable[i];
tmp=RangeCoderCurrentCount(self,totalfreq);
while(n<numfreq-1&&cumulativefreq+freqtable[n]<=tmp) cumulativefreq+=freqtable[n++];
RemoveRangeCoderSubRange(self,cumulativefreq,cumulativefreq+freqtable[n]);
return n;
}
