pngpal.c

RMF-1.7.153.0-NODOLBY.tar.gz 神龙卡的驱动

/*
 * gif2png : Extract palette from a PNG file
 * Jasper DVD player utility
 * 
 * Fabrice Gautier, (c) 2002 Sigma Designs, Inc
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>

unsigned long swapl(unsigned long l)
{
	char *p;
	p=(char *)&l;
	return (p[0]<<24)+(p[1]<<16)+(p[2]<<8)+p[3];
}

void GetPLTE(int fd, int sz)
{
	int i;
	unsigned char *pal;

	if(sz%3){
		fprintf(stderr,"Error PLTE len = %d, not multiple of 3\n",sz);
		return;
	}

	pal=(char *)malloc(sz);
	i=read(fd, pal, sz);
	if(i!=sz) {
		fprintf(stderr,"Couldnt read palette read=%d\n",i);
		return;
	}

	printf("//PNG Palette, size= %d\n",sz);
	for(i=0;i<(sz/3); i++) {
		printf("RGBDEF( %3u, %3u, %3u ),\n",pal[3*i],pal[3*i+1],pal[3*i+2]);
	}
}

int main(int argc, char *argv[])
{
	char *buf;
	int fd,r,p;
	unsigned long cl;
	unsigned long ct;

	if(argc<2) {
		fprintf(stderr,"usage %s filename.gif\n",argv[0]);
		return 1;
	}

	fprintf(stderr,"%s %s\n",argv[0],argv[1]);

	buf=(char *)malloc(4*1024);

	if(buf==NULL)
		return 1;

	fd=open(argv[1], O_RDONLY);

	if(fd==-1){
		perror("Cannot open file");
		return 1;
	}

	lseek(fd, 8, SEEK_SET);  // skip PNG singature 
	do {
		// get chunk
		read(fd, &cl, 4);
		cl=swapl(cl);
		r=read(fd, &ct, 4);
		ct=swapl(ct);
		
		if(r==-1) {
			perror("Cannot read file");
			return -1;
		}
		if(r==0) {
			printf("End of file, PLTE not found\n");
			break;
		}
		if(ct==(('P'<<24) + ('L'<<16) + ('T'<<8) +'E')) {
			fprintf(stderr,"PLTE found\n");
			GetPLTE(fd,cl);
			break;
		}
		fprintf(stderr,"Chunk is %c%c%c%c len=%d\n",
		       ct>>24, ct>>16, ct>>8, ct, cl);
		lseek(fd, cl+4, SEEK_CUR);		
	} while(1);
	
	
	return 0;
}