coder_bpbf.c

用C++语言实现的基于小波分析的源代码,实现了小波分析的诸多算法

/*****

BP Binary Fast

*****/

#include <stdio.h>
#include <stdlib.h>
#include <crblib/inc.h>
#include <crblib/arithc.h>
#include "coder.h"

extern int tune_param;

#define	VAL_CONTEXTS		16
#define	VAL_CONTEXT_MAX		(VAL_CONTEXTS -1)
#define SHAPE_BASE			VAL_CONTEXTS
#define SHAPE(x)			(SHAPE_BASE<<(x))
#define NUM_SHAPES			2
#define NUM_CONTEXTS		(VAL_CONTEXTS<<NUM_SHAPES)

#define SIGN_CONTEXTS	9

#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 coderBPBF_encodeBandBP(coder *me,int *band,int w,int h,int fullw,int *parent,int);
void coderBPBF_decodeBandBP(coder *me,int *band,int w,int h,int fullw,int *parent,int);

typedef struct {
	int signs_p0[SIGN_CONTEXTS];
	int signs_pt[SIGN_CONTEXTS];
	int stats_p0[NUM_CONTEXTS];
	int stats_pt[NUM_CONTEXTS];
} myInfo;

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

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

	c->data = d;

	for(i=0;i<NUM_CONTEXTS;i++) {
		d->stats_p0[i] = P0_INIT+1; d->stats_pt[i] = 2+P0_INIT+P1_INIT;
	}

	for(i=0;i<SIGN_CONTEXTS;i++) {
		d->signs_p0[i] = 100;
		d->signs_pt[i] = 200;
	}

}

void coderBPBF_free(coder *c)
{
	if ( c->data ) {
		myInfo *d;
		d = c->data;
		free(d);
		c->data = NULL;
	}
}

coder coderBPBF = {
		"BP Bin Fast",
		coderBPBF_init,
		coderBPBF_free,
		NULL,NULL,
		coderBPBF_encodeBandBP,
		coderBPBF_decodeBandBP
	};

/**********

lazy way to pass the state from getStats to fixStats
	and also interacts with the codeBand()

these are re-initialized at each codeBand() call, so this is
	quite re-entrant as long as we aren't multi-threaded
	(that is, no more than one call to codeBand() at a time)

*********/

static int VD,donemask,nextmask,sign_context;

static int mcontext(int *dp,int pp,int x,int y,int fullw)
{
int P,N,W;
int context;

	/** <> all these absolute values are painfully slow ***/

	VD	= abs(*dp)&donemask;	// current val already done
	P	= abs(pp)&nextmask;

	sign_context = 0;

	if ( y == 0 ) {
		N = VD;
		if ( x == 0 ) W = VD; else W = abs(dp[-1]) & nextmask;
		if ( W ) {
			if ( isneg(dp[-1]) ) sign_context += 3;
			else sign_context += 6;
		}
	} else if ( x == 0 ) {
		W = VD;
		N  = abs(dp[-fullw])	& nextmask;
		if ( N ) {
			if ( isneg(dp[-fullw]) ) sign_context += 1;
			else sign_context += 2;
		}
	} else {
		N = abs(dp[-fullw])		& nextmask;
		W = abs(dp[-1])			& nextmask;
		if ( N ) {
			if ( isneg(dp[-fullw]) ) sign_context += 1;
			else sign_context += 2;
		}
		if ( W ) {
			if ( isneg(dp[-1]) ) sign_context += 3;
			else sign_context += 6;
		}
	}

	context = min(VAL_CONTEXT_MAX, ((VD + P + N + W)>>2));

	if ( N > VD ) context += VAL_CONTEXTS; 
	if ( W > VD ) context += VAL_CONTEXTS+VAL_CONTEXTS;

return context;
}

void coderBPBF_encodeBandBP(coder *me,int *band,int width,int height,int fullw,int *parent,int bitmask)
{
int x,y,bit,context;
int *dp,*pp;
arithInfo *ari = me->arith;
int *signs_p0,*signs_pt;
int *stats_p0,*stats_pt;

	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;

	for(x=bitmask,nextmask=0; x<(1<<29) ;x<<=1) nextmask += x;
	donemask = nextmask - bitmask;

	dp = band;	pp = parent;
	for(y=0;y<height;y++) {	
		if ( coder_timetostop(me) ) { coder_didstop(me,y); return; }
		for(x=0;x<width;x++) {

			context = mcontext(&dp[x],pp[x>>1],x,y,fullw);

			bit = (abs(dp[x])&bitmask)?1:0;
			bitEnc(bit,ari,stats_p0[context],stats_pt[context]);

			if ( bit && !VD ) {
				bitEnc( signbit(dp[x]) ,ari,signs_p0[sign_context],signs_pt[sign_context]);
			}
		}
		if ( y&1 ) pp += fullw;
		dp += fullw;
	}
}

void coderBPBF_decodeBandBP(coder *me,int *band,int width,int height,int fullw,int *parent,int bitmask)
{
int x,y,bit,context;
int *dp,*pp;
arithInfo *ari = me->arith;
int *signs_p0,*signs_pt;
int *stats_p0,*stats_pt;

	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;

	for(x=bitmask,nextmask=0; x<(1<<29) ;x<<=1) nextmask += x;
	donemask = nextmask - bitmask;

	dp = band;	pp = parent;
	for(y=0;y<height;y++) {
		if ( coder_timetostopd(me,y) )return;
		for(x=0;x<width;x++) {

			context = mcontext(&dp[x],pp[x>>1],x,y,fullw);

			bitDec(bit,ari,stats_p0[context],stats_pt[context]);

			if ( bit ) {
				if ( ! VD ) {
					bitDec(bit,ari,signs_p0[sign_context],signs_pt[sign_context]);
					if ( bit ) dp[x] = - bitmask;
					else dp[x] = bitmask;
				} else {
					if ( isneg(dp[x]) ) dp[x] -= bitmask;
					else dp[x] += bitmask; 
				}
			}
		}
		if ( y&1 ) pp += fullw;
		dp += fullw;
	}
}