/* this code was written by 
   Donald Quon and Hai Pham for use in CISC 859
   These routines are for the 
   PGM,PBM (8 bit greyscale) images*/



#include <stdio.h>
#include <stdlib.h>
#include <malloc.h>

void readpbm(char *fname,long **image,int *dx,int *dy){
/* input:
   fname : name of input file
   output:
   **image: pointer to store image (memory will be allocated in this
           function;
   *dx,*dy; width and height of image*/ 
FILE *fptr;
int temp;
char buffer[100]; /*line shouldn't be over 70 characters*/
long w,h;
long count;
int numcolor;
	fptr=fopen(fname,"r");
	if (fptr==NULL){
		printf("error opening input file\n");
		exit(0);
	}
	/* filter out comment lines */
	buffer[0]='#';
	while (buffer[0]=='#')
	    fscanf(fptr,"%s",buffer);
	/*check MAGIC NUMBER "P5"*/
	if ((buffer[0]!='P')&&(buffer[1]!='5')){
		printf("not a 255 Greyscale PGM (PBM raw) file\n");
		fclose(fptr);
		exit (0);
	}
	/* filter out comment lines */
 	buffer[0]='#';  
	while (buffer[0]=='#'){
                fscanf(fptr,"%s",buffer);
		if (buffer[0]=='#') {
			fgets (&buffer[1],90,fptr);
		}
	}
	sscanf(buffer,"%ld",&w);
       
	buffer[0]='#';
	while (buffer[0]=='#'){
		fscanf(fptr,"%s",buffer);
		if (buffer[0]=='#'){
			fgets(&buffer[1],90,fptr);
		}
	}
	sscanf(buffer,"%ld",&h);
	buffer[0]='#';
	while (buffer[0]=='#'){
		fscanf(fptr,"%s",buffer);
		if (buffer[0]=='#'){
			fgets(&buffer[1],90,fptr);
		}
	}
	sscanf(buffer,"%d",&numcolor);
	if ((numcolor<0)||(numcolor>255)){
		printf("not a 255 Greyscale PGM (PBM raw) file\n");
		fclose(fptr);
		exit (0);
	}
	*image=(long *)malloc(w*h*sizeof(long));
	if (*image==NULL){
		printf("error allocating memory\n");
		fclose(fptr);
		exit(0);
	}
	for (count=0;count<w*h;count++){
	   	temp=fgetc(fptr);
		if (temp==EOF) break;
		(*image)[count]=(long) temp;
	}
	if (count < w*h){
		printf("error reading file\n");
		fclose(fptr);
		exit(0);
	}
	*dx=(int)w;
	*dy=(int)h;
	fclose(fptr);
}
void savepbm(char *fname,long *image,int dx,int dy){
/* input:
	fname : filename to store data
	image : image data
	dx,dy : width,height of image*/
FILE *fptr;
long count,h,w;
int temp;
        w=dx;
	h=dy;	    
	fptr=fopen(fname,"w");
	if (fptr==NULL){
		printf("error opening save file\n");
		exit(0);
	}
	fprintf(fptr,"P5\n");
	fprintf(fptr,"%d %d\n",dx,dy);
	fprintf(fptr,"255\n");
	for (count=0;count<w*h;count++){
		temp=fputc((char)image[count],fptr);
		if (temp==EOF) break;
	}
	if (count<dx*dy){
		printf("error saving file\n");
		fclose(fptr);
		exit(0);
	}
	fclose(fptr);
}