Exemplo n.º 1
0
void PPMdDecodeBinSymbol(PPMdContext *self,PPMdCoreModel *model,uint16_t *bs,int freqlimit,BOOL altnextbit)
{
	PPMdState *rs=PPMdContextOneState(self);

	int bit;
	if(altnextbit) bit=NextWeightedBitFromRangeCoder2(&model->coder,*bs,TOT_BITS);
	else bit=NextWeightedBitFromRangeCoder(&model->coder,*bs,1<<TOT_BITS);

	if(bit==0)
	{
		model->PrevSuccess=1;
		model->RunLength++;
		model->FoundState=rs;

		if(rs->Freq<freqlimit) rs->Freq++;
		*bs+=INTERVAL-GET_MEAN(*bs,PERIOD_BITS,2);
	}
	else
	{
		model->PrevSuccess=0;
		model->FoundState=NULL;
		model->LastMaskIndex=0;
		model->CharMask[rs->Symbol]=model->EscCount;

		*bs-=GET_MEAN(*bs,PERIOD_BITS,2);
		model->InitEsc=ExpEscape[*bs>>10];
	}
}
Exemplo n.º 2
0
void RescalePPMdContext(PPMdContext *self,PPMdCoreModel *model)
{
	PPMdState *states=PPMdContextStates(self,model);
	int n=self->LastStateIndex+1;

	// Bump frequency of found state
	model->FoundState->Freq+=4;

	// Divide all frequencies and sort list
	int escfreq=self->SummFreq+4;
	int adder=(model->OrderFall==0?0:1);
	self->SummFreq=0;

	for(int i=0;i<n;i++)
	{
		escfreq-=states[i].Freq;
		states[i].Freq=(states[i].Freq+adder)>>1;
		self->SummFreq+=states[i].Freq;

		// Keep states sorted by decreasing frequency
		if(i>0&&states[i].Freq>states[i-1].Freq)
		{
			// If not sorted, move current state upwards until list is sorted
			PPMdState tmp=states[i];

			int j=i-1;
			while(j>0&&tmp.Freq>states[j-1].Freq) j--;

			memmove(&states[j+1],&states[j],sizeof(PPMdState)*(i-j));
			states[j]=tmp;
		}
	}

	// TODO: add better sorting stage here.

	// Drop states whose frequency has fallen to 0
	if(states[n-1].Freq==0)
	{
		int numzeros=1;
		while(numzeros<n&&states[n-1-numzeros].Freq==0) numzeros++;

		escfreq+=numzeros;

		self->LastStateIndex-=numzeros;
		if(self->LastStateIndex==0)
		{
			PPMdState tmp=states[0];
			do
			{
				tmp.Freq=(tmp.Freq+1)>>1;
				escfreq>>=1;
			}
			while(escfreq>1);

			FreeUnits(model->alloc,self->States,(n+1)>>1);
			model->FoundState=PPMdContextOneState(self);
			*model->FoundState=tmp;

			return;
		}
Exemplo n.º 3
0
PPMdContext *NewPPMdContextAsChildOf(PPMdCoreModel *model,PPMdContext *suffixcontext,PPMdState *suffixstate,PPMdState *firststate)
{
	PPMdContext *context=OffsetToPointer(model->alloc,AllocContext(model->alloc));
	if(context)
	{
		context->LastStateIndex=0;
		context->Flags=0;
		SetPPMdContextSuffixPointer(context,suffixcontext,model);
		SetPPMdStateSuccessorPointer(suffixstate,context,model);
		if(firststate) *(PPMdContextOneState(context))=*firststate;
	}
	return context;
}
Exemplo n.º 4
0
static void UpdateModel(PPMdModelVariantI *self,PPMdContext *mincontext)
{
	PPMdState fs=*self->core.FoundState;
	PPMdState *state=NULL;
	PPMdContext *currcontext=self->MaxContext;

	if(fs.Freq<MAX_FREQ/4&&mincontext->Suffix)
	{
		PPMdContext *context=PPMdContextSuffix(mincontext,&self->core);
		if(context->LastStateIndex!=0)
		{
			state=PPMdContextStates(context,&self->core);

			if(state->Symbol!=fs.Symbol)
			{
				do state++;
				while(state->Symbol!=fs.Symbol);

				if(state[0].Freq>=state[-1].Freq)
				{
					SWAP(state[0],state[-1]);
					state--;
				}
			}

			if(state->Freq<MAX_FREQ-9)
			{
				state->Freq+=2;
				context->SummFreq+=2;
			}
		}
		else
		{
			state=PPMdContextOneState(context);
			if(state->Freq<32) state->Freq++;
		}
	}

	if(self->core.OrderFall==0&&fs.Successor)
	{
		PPMdContext *newsuccessor=CreateSuccessors(self,true,state,mincontext);
		SetPPMdStateSuccessorPointer(self->core.FoundState,newsuccessor,&self->core);
		if(!newsuccessor) goto RESTART_MODEL;
		self->MaxContext=newsuccessor;
		return;
	}

	*self->alloc->pText++=fs.Symbol;
	PPMdContext *Successor=(PPMdContext *)self->alloc->pText;

	if(self->alloc->pText>=self->alloc->UnitsStart) goto RESTART_MODEL;

	if(fs.Successor)
	{
		if((uint8_t *)PPMdStateSuccessor(&fs,&self->core)<self->alloc->UnitsStart)
		{
			SetPPMdStateSuccessorPointer(&fs,CreateSuccessors(self,false,state,mincontext),&self->core);
		}
	}
	else
	{
		SetPPMdStateSuccessorPointer(&fs,ReduceOrder(self,state,mincontext),&self->core);
	}

	if(!fs.Successor) goto RESTART_MODEL;

	if(--self->core.OrderFall==0)
	{
		Successor=PPMdStateSuccessor(&fs,&self->core);
		if(self->MaxContext!=mincontext) self->alloc->pText--;
	}
	else if(self->MRMethod>MRM_FREEZE)
	{
		Successor=PPMdStateSuccessor(&fs,&self->core);
		self->alloc->pText=self->alloc->HeapStart;
		self->core.OrderFall=0;
	}

	int minnum=mincontext->LastStateIndex+1;
	int s0=mincontext->SummFreq-minnum-(fs.Freq-1);
	uint8_t flag=fs.Symbol>=0x40?8:0;

	for(;currcontext!=mincontext;currcontext=PPMdContextSuffix(currcontext,&self->core))
	{
		int currnum=currcontext->LastStateIndex+1;
		if(currnum!=1)
		{
			if((currnum&1)==0)
			{
				uint32_t states=ExpandUnits(self->core.alloc,currcontext->States,currnum>>1);
				if(!states) goto RESTART_MODEL;
				currcontext->States=states;
			}
			if(3*currnum-1<minnum) currcontext->SummFreq++;
		}
		else
		{