// Copyright 2007 Ian Elliot
//
// This file is part of Shoelacer.
//
// Shoelacer is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.
//
// Shoelacer is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Shoelacer.  If not, see <http://www.gnu.org/licenses/>.
//
// ALTHOUGH this specific file is licensed, the output of Shoelacer
// which may or may not include text very similar to this file is in
// no way restricted, guarenteed, or licensed.
//
// File begins after the first carrot: ^


static unsigned char lz[]={
//     0 1 2 3 4 5 6 7 8 9 A B C D E F
/*0*/  8,7,6,6,5,5,5,5,4,4,4,4,4,4,4,4,
/*1*/  3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
/*2*/  2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
/*3*/  2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
/*4*/  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
/*5*/  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
/*6*/  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
/*7*/  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
/*8*/  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
/*9*/  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
/*A*/  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
/*B*/  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
/*C*/  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
/*D*/  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
/*E*/  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
/*F*/  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
};

unsigned int shoelacer_encode(SHOELACER_MODEL* model,unsigned char* text,unsigned char* code,unsigned int textLen,unsigned int codeMax) {
	unsigned int reg=0;
	unsigned short int index;
	unsigned char sh=0;
	unsigned char c,rl,vl,v,t,a,s,i,u,ls,n=1,f;
	unsigned short int d;
	unsigned char* codeLim=code+codeMax;
	unsigned char* textLim=text+textLen;
	index=model->init_index;

encode_start:
	if (text==textLim) goto encode_textlim;
	c=*text++;
	s=c;
	i=0;
	vl=model->data[index];		// Rice coding
	u=model->data[index+2];
	do {
		if (s==model->data[index+3+i]) break;
		i++;
	} while (i<model->data[index+1]);
	if (i>=model->data[index+1] || i==u) {
		// Encode the symbol as an unaccounted value
		c=u;
		f=1;
	} else {
		c=i;
		f=0;
	}
	rl=c>>vl;
	v=c&((1<<vl)-1);
	while (rl>=8) {
		rl-=8;
		reg<<=8;
		if (code==codeLim) goto encode_end;
		*code++=reg>>sh;
	}
	t=rl+1;
	sh+=t;
	reg<<=t;
	reg|=1;
	if (sh>=8) {
		if (code==codeLim) goto encode_end;
		sh-=8;
		*code++=(unsigned char)(reg>>sh);
	}
	reg<<=vl;
	reg|=v;
	sh+=vl;
	if (sh>=8) {
		sh-=8;
		if (code==codeLim) goto encode_end;
		*code++=reg>>sh;
	}
	if (f) {
		reg<<=8;
		reg|=s;
		if (code==codeLim) goto encode_end;
		*code++=reg>>sh;
	}
	if (n) n=0; else {
		a=ls+s;
		d=ls^model->hash[a];
		ls=model->data[d];
		if ((a&((1<<(8-DIST_BITS))-1)) == (ls>>DIST_BITS)) index=model->index[ls&((1<<DIST_BITS)-1)];
		else index=model->init_index;
	}
	ls=s;
	goto encode_start;
encode_end:
	return codeMax;
encode_textlim:
	if (sh>8) {
		if (code==codeLim) goto encode_end;
		sh-=8;
		*code++=reg>>sh;
	}
	if (sh) {
		if (code==codeLim) goto encode_end;
		*code++=reg<<(8-sh);
	}
	return codeMax-(codeLim-code);
}

unsigned int shoelacer_decode(SHOELACER_MODEL* model,unsigned char* text,unsigned char* code,unsigned int textMax,unsigned int codeLen) {
	unsigned short int d,reg=0;
	unsigned char sh=0;
	unsigned char c,vl,v,l,rl,t,n=1,lv;
	unsigned char* tLim=text+textMax;
	unsigned char* cLim=code+codeLen;
	unsigned short int index=model->init_index;

decode_start:
	if (sh<8)
		if (code!=cLim) {
			sh+=8;
			reg<<=8; reg|=*code++;
			c=reg>>(sh-8);
		} else
			if (reg&((1<<sh)-1)) {
				c=reg<<=8-sh;
				sh=8;
			}
			else
				goto decode_end;
	else
		c=reg>>(sh-8);
	rl=0;
	while (!c)
		if (code!=cLim) {
			rl+=8;
			reg<<=8; reg|=*code++;
			c=reg>>(sh-8);
		} else if (reg&((1<<sh)-1)) {
			rl+=8;
			c=reg<<=16-sh;
			sh=8;
		} else
			goto decode_end;
	t=lz[c];
	rl+=t;
	sh-=t+1;
	vl=model->data[index];
	if (sh<8)
		if (code!=cLim) {
			sh+=8;
			reg<<=8; reg|=*code++;
			v=(reg>>(sh-8));
		} else {
			v=reg<<=8-sh;
			sh=8;
		}
	else
		v=(reg>>(sh-8));
	sh-=vl;
	v>>=8-vl;
	v|=rl<<vl;
	if (v==model->data[index+2]) {		// If it's an unaccounted value
		if (sh<8)
			if (code!=cLim) {
				sh+=8;
				reg<<=8; reg|=*code++;
				v=(reg>>(sh-8));
			} else {
				v=reg<<=(8-sh);
				sh=8;
			}
		else
			v=reg>>(sh-8);
		*text++=v;
		if (code!=cLim) {
			reg<<=8; reg|=*code++;
			c=reg>>(sh-8);
		} else if (reg&((1<<sh)-1)) {
			c=reg<<=16-sh;
			sh=8;
		} else
			goto decode_end;
	} else {
		v=model->data[index+3+v];
		*text++=v;
	}
	if (n) n=0; else {
		rl=lv+v;
		d=lv^model->hash[rl];
		vl=model->data[d];
		if ((rl&((1<<(8-DIST_BITS))-1)) == (vl>>DIST_BITS)) { index=model->index[vl&((1<<DIST_BITS)-1)];
		}
		else index=model->init_index;
	}
	lv=v;
	if (text==tLim) return textMax;
goto decode_start;
decode_end:
	return textMax-(tLim-text);
}