coder_o1p1.c

好东西呢

//#define SIGN_JUST_XOR	/** much worse **/

/*********

a straightforward order1 coder : code pel conditioned on the 
	log2(parent)

"order1+1" also uses log2(neighbors) in the context

Order1 : S+P Lena lossless	:	4.250 bpp
Order1+1:					:	4.207 bpp

**********/

#include <stdio.h>
#include <stdlib.h>
#include <crblib/inc.h>
#include <crblib/arithc.h>
#include <crblib/o0coder.h>
#include <crblib/scontext.h>
#include <crblib/intmath.h>

extern int tune_param;

#define ORDER1_TOTMAX		10000
#define ORDER1_INC			15
#define ORDER1_ESCAPE		12
#define ORDER1_ALPHABET		(ORDER1_ESCAPE+1)

#define CN_MAX_PREV			4
#define CN_MAX_PARENT		4
#define CODE_CONTEXTS 		(1 + CN_MAX_PREV + (CN_MAX_PREV+1)*CN_MAX_PARENT)

#define ORDER0_TOTMAX		2000	/** totally irrelevant **/
#define ORDER0_ESCAPE		1		/** optimal at 1 !!! a unary code!!! **/
#define ORDER0_ALPHABET		(ORDER0_ESCAPE+1)

#include "coder.h"

void coderO1_1_encodeBand(coder *me,int *band,int w,int h,int fullw,int *parent);
void coderO1_1_decodeBand(coder *me,int *band,int w,int h,int fullw,int *parent);

typedef struct {
	ozero * o0;
	scontext * sign_sc[3];
	scontext ** o1;
} myInfo;

void coderO1_1_init(coder *c)
{
myInfo *d;
int i;

	if ( (d = new(myInfo)) == NULL )
		errexit("ozero init failed");

	c->data = d;

	if ( (d->o0 = ozeroCreateMax(c->arith,ORDER0_ALPHABET,ORDER0_TOTMAX)) == NULL )
		errexit("ozero init failed");

	for(i=0;i<3;i++) {
		if ( (d->sign_sc[i] = scontextCreate(c->arith,2,0,1000,10,true)) == NULL )
			errexit("sign ozero init failed");
	}

	if ( (d->o1 = newarray(void *,CODE_CONTEXTS)) == NULL )
		errexit("Order1_Init failed!");

	for(i=0;i<CODE_CONTEXTS;i++) {
		if ( (d->o1[i] = scontextCreate(c->arith,ORDER1_ALPHABET,0,
				ORDER1_TOTMAX,ORDER1_INC,true)) == NULL )
			errexit("context creation failed!");
	}
}

void coderO1_1_free(coder *c)
{
	if ( c->data ) {
		myInfo *d; int i;

		d = c->data;
		if ( d->o0 ) ozeroFree(d->o0);
		for(i=0;i<3;i++) {
			if ( d->sign_sc[i] ) scontextFree(d->sign_sc[i]);
		}
		if ( d->o1 ) {
			for(i=0;i<CODE_CONTEXTS;i++) {
				if ( d->o1[i] ) scontextFree(d->o1[i]);
			}
		}
		free(d);
		c->data = NULL;
	}
}

coder coderO1_1 = {
		"o1+1",
		coderO1_1_init,
		coderO1_1_free,
		coderO1_1_encodeBand,
		coderO1_1_decodeBand
	};

static void mcontext(int *cur_ptr,int parent,int x,int y,int width,int height,int fullw,
	int *cntx_ptr,int *sign_ptr)
{
int neighbors;

	/** cur_ptr[0] is about to be coded **/

	if ( x==0 ) {
		if ( y == 0 ) {
			neighbors = 0;
		} else {
			neighbors = (cur_ptr[-fullw] + cur_ptr[-fullw+1]) >> 1;
		}
	} else if ( y == 0 ) {
		neighbors = cur_ptr[-1];
	} else if ( x == (width-1) ) {
		neighbors = (cur_ptr[-1] + cur_ptr[-fullw] + cur_ptr[-fullw] + cur_ptr[-fullw-1]) >> 2;
	} else {
		neighbors = (cur_ptr[-1] + cur_ptr[-fullw] + cur_ptr[-fullw+1] + cur_ptr[-fullw-1]) >> 2;
	}

if ( neighbors == 0 ) *sign_ptr = 2;
else if ( isneg(neighbors) ) *sign_ptr = 1;
else *sign_ptr = 0;

parent = abs(parent);
neighbors = abs(neighbors);
parent = intlog2(parent+1);
neighbors = intlog2(neighbors);

*cntx_ptr = min(CN_MAX_PREV,neighbors) + (CN_MAX_PREV+1)*(min(CN_MAX_PARENT,parent));
}

void coderO1_1_encodeBand(coder *me,int *band,int width,int height,int fullw,int *parent)
{
int x,y,val,cntx,sign,sign_cntx;
int *dp,*pp,*dpp,*ppp;
ozero *o0 = ((myInfo *)me->data)->o0;
scontext **sign_sc = ((myInfo *)me->data)->sign_sc;
scontext **o1 = ((myInfo *)me->data)->o1;
arithInfo *ari = me->arith;

	dp = band;
	pp = parent;
	for(y=0;y<height;y++) {
		dpp = dp; ppp = pp;
		if ( coder_timetostop(me) ) { coder_didstop(me,y); return; }
		for(x=0;x<width;x++) {
			mcontext(dpp,*ppp,x,y,width,height,fullw,&cntx,&sign_cntx);

			val = *dpp++;	if ( x&1 ) ppp++;

			if ( val == 0 ) {
				scontextEncode(o1[cntx],0);
				continue;
			} else if ( val < 0 ) { sign = 1; val = -val;
			} else sign = 0;

			if ( val < ORDER1_ESCAPE ) {
				scontextEncode(o1[cntx],val);
			} else {
				scontextEncode(o1[cntx],ORDER1_ESCAPE);
				val -= ORDER1_ESCAPE;

				while( val >= ORDER0_ESCAPE ) {
					ozeroEncode(o0,ORDER0_ESCAPE);
					val -= ORDER0_ESCAPE;
				}
				ozeroEncode(o0,val);
			}

#ifdef SIGN_JUST_XOR
			if ( sign_cntx != 2 ) sign ^= sign_cntx;
			scontextEncode(sign_sc[0],sign);
#else
			scontextEncode(sign_sc[sign_cntx],sign);
#endif // SIGN_JUST_XOR
		}
		if ( y & 1 ) pp += fullw;
		dp += fullw;
	}
}

void coderO1_1_decodeBand(coder *me,int *band,int width,int height,int fullw,int *parent)
{
int x,y,val,cntx,got,sign_cntx;
int *dp,*pp,*dpp,*ppp;
ozero *o0 = ((myInfo *)me->data)->o0;
scontext **sign_sc = ((myInfo *)me->data)->sign_sc;
scontext **o1 = ((myInfo *)me->data)->o1;
arithInfo *ari = me->arith;

	dp = band;
	pp = parent;
	for(y=0;y<height;y++) {
		dpp = dp; ppp = pp;
		if ( coder_timetostopd(me,y) ) return;
		for(x=0;x<width;x++) {
			mcontext(dpp,*ppp,x,y,width,height,fullw,&cntx,&sign_cntx);

			if ( x&1 ) ppp++;

			got = scontextDecode(o1[cntx]);
			if ( got == 0 ) {
				*dpp++ = 0;
				continue;
			} else if ( got < ORDER1_ESCAPE ) {
				val = got;
			} else {
				val = ORDER1_ESCAPE;
				got = ozeroDecode(o0);
				while ( got == ORDER0_ESCAPE ) {
					val += ORDER0_ESCAPE;
					got = ozeroDecode(o0);
				}
				val += got;
			}

#ifdef SIGN_JUST_XOR
			if ( scontextDecode(sign_sc[0]) ) {
				if ( sign_cntx == 2 || sign_cntx == 0 ) val = -val;
			} else {
				if ( sign_cntx == 1 ) val = -val;
			}
#else
			if ( scontextDecode(sign_sc[sign_cntx]) ) val = -val;
#endif // SIGN_JUST_XOR

			*dpp++ = val;
		}
		if ( y & 1 ) pp += fullw;
		dp += fullw;
	}
}