/*

Copyright (c) 2013 Chris Chunick, email@chrischunick.com

All rights reserved.



Redistribution and use in source and binary forms are permitted

provided that the above copyright notice and this paragraph are

duplicated in all such forms and that any documentation,

advertising materials, and other materials related to such

distribution and use acknowledge that the software was developed

by Chris Chunick  The name of Chris Chunick may not be used to 

endorse or promote products derived from this software without 

specific prior written permission.



THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR

IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED

WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

*/



class bitcoder

{



private:

	FILE *fin;

	FILE *fout;	

	unsigned int top,bot,range;

	unsigned int code;

	unsigned int m[32];



	void init()

	{

		passed=0;

		bot=0, top=-1;

		range=top-bot;

		code=0;

		for(unsigned int i=0;i<32;i++)m[i]=(0x7FFFFFFF>>(31-i));

	}



public:

	unsigned int passed;

	unsigned int fsize;



	void initcoder(FILE* fin, FILE* fout)

	{

		init();

		this->fin=fin;

		this->fout=fout;

	}



	void startdecoder()

	{

		for(unsigned int i=0;i<4;i++)fsize=(fsize<<8)|getc(fin);

		for(unsigned int i=0;i<4;i++)code=(code<<8)|getc(fin);

	}



	void startencoder()

	{

		fseek(fin,0,SEEK_END),fsize=ftell(fin),fseek(fin,0,SEEK_SET);

		putc((fsize>>24),fout),putc((fsize>>16),fout),putc((fsize>>8),fout),putc(fsize,fout);

		passed+=4;

	}



	void flushencoder()

	{

		putc(bot>>24,fout);putc(bot>>16,fout);putc(bot>>8,fout);putc(bot,fout);

		passed+=4;

	}



	void fencode(const unsigned int bit, const unsigned int c0, const unsigned int c1)

	{

		unsigned int lbit=(c0>c1),w=31,lo=c0,tc=c0+c1,tr=top-bot;



		if(lbit)lo=c1;





		while(((tc)>=(tr>>w))&&w!=-1)w--;

	

		if(w<-1)

		{

			if (lbit^bit)bot=(((bot>>w)+(lo)+1)<<w)|(bot&m[w]);

			else top=(((bot>>w)+(lo))<<w)|(top&m[w]);

		}

		else 

		{

			top=bot=bot+bit;

		}



		while((top^bot)<=0xFFFFFF || top<bot)

		{

			putc(bot>>24,fout);

			bot<<=8,top=(top<<=8)|0xFF;

			passed++;

		}

	}



	unsigned int fdecode(const unsigned int c0, const unsigned int c1)

	{

		unsigned int lbit=(c0>c1),w=31,lo=c0,bit,tc=c0+c1,tr=top-bot;



		if(lbit)lo=c1;

		while(((tc)>=(tr>>w))&&w!=-1)w--;

			

		if(w<-1)

		{

			bit=lbit^((code>>w)>((bot>>w)+lo));

			if (lbit^bit)bot=(((bot>>w)+(lo)+1)<<w)|(bot&m[w]);

			else top=(((bot>>w)+(lo))<<w)|(top&m[w]);

		}

		else top=bot=bot+(bit=code!=bot);

			

		while((top^bot)<=0xFFFFFF || top<bot)

		{

			code=(code<<8)|fgetc(fin);					

			bot<<=8,top=(top<<=8)|0xFF;

		}

		

		return bit;

	}





};