www.pudn.com > wavecode.rar > coder_zf.c

 
/***** 
 
ZeroFlag coder: 
 
codes bytewise but only using binary arithcoders. 
 
	sends "is byte == 0"	(conditioned on activity of N and W) 
	then sign				(conditioned on signs of N and W) 
	then (abs(byte)-1)	using a unary adaptive binary code 
 
fast AND excellent compression 
 
*****/ 
 
#include  
#include  
#include  
#include  
#include  
#include "coder.h" 
 
extern int tune_param; 
 
#define	VAL_CONTEXTS		16 
#define	VAL_CONTEXT_MAX		(VAL_CONTEXTS -1) 
#define NUM_CONTEXTS		VAL_CONTEXTS 
#define TAIL_CONTEXTS		VAL_CONTEXTS 
 
#define SIGN_CONTEXTS		4 
 
#define TOTMAX			4000 
#define INC				30 
 
#define P0_INIT			8 
#define P1_INIT			0 
 
#define bitModel(bit,P0,PT)		do { PT += INC; if (!(bit)) P0 += INC;  if ( PT > TOTMAX ) { PT >>= 1; P0 >>= 1; P0++; PT += 2; } } while(0) 
#define bitEnc(bit,ari,P0,PT)	do { arithEncBit(ari,P0,PT,bit);	bitModel(bit,P0,PT); } while(0) 
#define bitDec(bit,ari,P0,PT)	do { bit = arithDecBit(ari,P0,PT);	bitModel(bit,P0,PT); } while(0) 
 
void coderZF_encodeBand(coder *me,int *band,int w,int h,int fullw,int *parent); 
void coderZF_decodeBand(coder *me,int *band,int w,int h,int fullw,int *parent); 
 
typedef struct { 
	int signs_p0[SIGN_CONTEXTS]; 
	int signs_pt[SIGN_CONTEXTS]; 
	int stats_p0[NUM_CONTEXTS]; 
	int stats_pt[NUM_CONTEXTS]; 
	int tails_p0[TAIL_CONTEXTS]; 
	int tails_pt[TAIL_CONTEXTS]; 
} myInfo; 
 
void coderZF_init(coder *c) 
{ 
myInfo *d; 
int i; 
 
	if ( (d = new(myInfo)) == NULL ) 
		errexit("ozero init failed"); 
 
	c->data = d; 
 
	for(i=0;istats_p0[i] = P0_INIT+1; d->stats_pt[i] = 2+P0_INIT+P1_INIT; 
	} 
 
	for(i=0;isigns_p0[i] = 100; 
		d->signs_pt[i] = 200; 
	} 
 
	for(i=0;itails_p0[i] = 100; 
		d->tails_pt[i] = 2000; 
	} 
 
} 
 
void coderZF_free(coder *c) 
{ 
	if ( c->data ) { 
		myInfo *d; 
		d = c->data; 
		free(d); 
		c->data = NULL; 
	} 
} 
 
coder coderZF = { 
		"ZeroFlag", 
		coderZF_init, 
		coderZF_free, 
		coderZF_encodeBand, 
		coderZF_decodeBand 
	}; 
 
static int sign_context;	/** cheesy way to return two values **/ 
 
static int mcontext(int *dp,int x,int y,int fullw) 
{ 
	if ( y == 0 ) { 
		if ( x > 0 ) { 
			int W; 
 
			W = dp[-1]; 
 
			if ( isneg(W) ) { sign_context = 2; W = - W; } 
			else sign_context =0; 
 
			return min(VAL_CONTEXT_MAX, (W>>1)); 
		} else { 
			 sign_context = 0 ; 
			return 0; 
		} 
	} else if ( x == 0 ) { 
		int N; 
 
		N = dp[-fullw]; 
 
		if ( isneg(N) ) { sign_context = 1; N = - N; } 
		else sign_context = 0; 
 
		return min(VAL_CONTEXT_MAX, (N>>1)); 
	} else { 
		int N,W; 
 
		N = dp[-fullw]; 
		W = dp[-1]; 
 
		if ( isneg(N) ) { sign_context = 1; N = - N; } 
		else sign_context = 0; 
		if ( isneg(W) ) { sign_context += 2; W = - W; } 
 
		return min(VAL_CONTEXT_MAX, ((N + W)>>2)); 
	} 
} 
 
void coderZF_encodeBand(coder *me,int *band,int width,int height,int fullw,int *parent) 
{ 
int x,y,context,V; 
int *dp; 
arithInfo *ari; 
int *signs_p0,*signs_pt; 
int *tails_p0,*tails_pt; 
int *stats_p0,*stats_pt; 
 
	ari = me->arith; 
	stats_p0 = ((myInfo *)me->data)->stats_p0; 
	stats_pt = ((myInfo *)me->data)->stats_pt; 
	signs_p0 = ((myInfo *)me->data)->signs_p0; 
	signs_pt = ((myInfo *)me->data)->signs_pt; 
	tails_p0 = ((myInfo *)me->data)->tails_p0; 
	tails_pt = ((myInfo *)me->data)->tails_pt; 
 
	dp = band; 
	for(y=0;y 0 ) { 
							bitEnc(0,ari,signs_p0[sign_context],signs_pt[sign_context]); 
							V--; 
						} else { 
							bitEnc(1,ari,signs_p0[sign_context],signs_pt[sign_context]); 
							V = - V -1; 
						} 
 
						/* send remainder */ 
						while(V--) bitEnc(1,ari,tails_p0[context],tails_pt[context]); 
						bitEnc(0,ari,tails_p0[context],tails_pt[context]); 
 
						break; 
				} 
 
			} 
		} 
		dp += fullw; 
	} 
} 
 
void coderZF_decodeBand(coder *me,int *band,int width,int height,int fullw,int *parent) 
{ 
int x,y,bit,sign,context,V; 
int *dp; 
arithInfo *ari; 
int *signs_p0,*signs_pt; 
int *stats_p0,*stats_pt; 
int *tails_p0,*tails_pt; 
 
	ari = me->arith; 
	stats_p0 = ((myInfo *)me->data)->stats_p0; 
	stats_pt = ((myInfo *)me->data)->stats_pt; 
	signs_p0 = ((myInfo *)me->data)->signs_p0; 
	signs_pt = ((myInfo *)me->data)->signs_pt; 
	tails_p0 = ((myInfo *)me->data)->tails_p0; 
	tails_pt = ((myInfo *)me->data)->tails_pt; 
 
	dp = band; 
	for(y=0;y