/* ppm filter library              by kumagai masaaki*/
/* as example of xv algorithm extension              */

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

typedef unsigned char imgbyte;
int DEBUG=0;

void Exchange(int *a,int *b)
{ int t; t=*a; *a= *b; *b=t; } 

void RegulatePos(int w,int h,int *sx,int *sy,int *ex,int *ey)
{
    if(*sx<0) *sx=0;
    if(*sy<0) *sy=0;
    if(*ex<0) *ex=w-1;
    if(*ey<0) *ey=h-1;
    if(*ex>w-1) *ex=w-1;
    if(*ey>h-1) *ey=h-1;
    if(*sx>*ex) Exchange(sx,ex);
    if(*sy>*ey) Exchange(sy,ey);
}



/* PPM FILE load */
imgbyte* LoadPPM(FILE *fp,int *_w,int *_h,int *_max)
{
    char buff[1000];
    char magic[10];
    int w,h,max;
    imgbyte *data;
    int i,j;

    fgets(buff,1000,fp);
    if((buff[0]!='P')||((buff[1]!='3')&&(buff[1]!='6')))
      {
	  fprintf(stderr,"PPM format error \n");
	  return NULL;
      }
    while(sscanf(buff,"%s %d %d %d",magic,&w,&h,&max)!=4)
      {
	  fgets(buff+strlen(buff),990-strlen(buff),fp);
	  if(strlen(buff)>900)
	    {
		fprintf(stderr,"PPM format error\n");
		fclose(fp);
	    }
	  if(strchr(buff,'#'))
	    *(strchr(buff,'#'))='\0';
      }
    if(DEBUG)
      fprintf(stderr,"image size %dx%d\n",w,h);
    data=(imgbyte *)malloc(w*h*3);
    if(data==NULL)
      {
	  fprintf(stderr,"cannot alloc memory\n");
	  return NULL;
      }
    if(magic[1]=='6') /* RAW mode */
      {
	  if(fread(data,w*3,h,fp)!=h)
	    {
		fprintf(stderr,"PPM size error\n");
		free(data);
		return NULL;
	    }
	  *_w=w; *_h=h; *_max=max;
	  return data;
      }
    /* ASCII mode : does this work any time? */
    for(i=0;i<w*h*3;i++)
      {
	  if(fscanf(fp,"%d",&j)!=1)
	    {
		fprintf(stderr,"PPM size error\n");
		free(data);
		return NULL;
	    }
	  data[i]=j;
      }
    *_w=w; *_h=h; *_max=max;
    return data;
}

/* PGM FILE load */
imgbyte* LoadPGM(FILE *fp,int *_w,int *_h,int *_max)
{
    char buff[1000];
    char magic[10];
    int w,h,max;
    imgbyte *data;
    int i;

    fgets(buff,1000,fp);
    if((buff[0]!='P')||((buff[1]!='2')&&(buff[1]!='5')))
      {
	  fprintf(stderr,"PGM format error \n");
	  return NULL;
      }
    while(sscanf(buff,"%s %d %d %d",magic,&w,&h,&max)!=4)
      {
	  fgets(buff+strlen(buff),990-strlen(buff),fp);
	  if(strlen(buff)>900)
	    {
		fprintf(stderr,"PPM format error\n");
		fclose(fp);
	    }
	  if(strchr(buff,'#'))
	    *(strchr(buff,'#'))='\0';
      }
    if(DEBUG)
      fprintf(stderr,"image size %dx%d\n",w,h);
    data=(imgbyte *)malloc(w*h);
    if(data==NULL)
      {
	  fprintf(stderr,"cannot alloc memory\n");
	  return NULL;
      }
    if(magic[1]=='5') /* RAW mode */
      {
	  if(fread(data,w,h,fp)!=h)
	    {
		fprintf(stderr,"PPM size error\n");
		free(data);
		return NULL;
	    }
	  *_w=w; *_h=h; *_max=max;
	  return data;
      }
    /* ASCII mode : does this work any time? */
    for(i=0;i<w*h;i++)
      {
	  if(fscanf(fp,"%d",data[i])!=1)
	    {
		fprintf(stderr,"PPM size error\n");
		free(data);
		return NULL;
	    }
      }
    *_w=w; *_h=h; *_max=max;
    return 0;
}

/* PPM File save */
int SavePPM(FILE *fp, imgbyte *data,int max,
            int w,int h,int sx,int sy,int ex,int ey)
{
    int y;
    RegulatePos(w,h,&sx,&sy,&ex,&ey);
    if(max>255) max=255;
    if(max<0) max=0;

    fprintf(fp,"P6\n%d %d\n%d\n",ex-sx+1,ey-sy+1,max);
    for(y=sy;y<=ey;y++)
      fwrite(data+(y*w+sx)*3,3,ex-sx+1,fp);
    fclose(fp);
}

/* PGM File save */
int SavePGM(FILE *fp, imgbyte *data,int max,
            int w,int h,int sx,int sy,int ex,int ey)
{
    int y;
    RegulatePos(w,h,&sx,&sy,&ex,&ey);
    if(max>255) max=255;
    if(max<0) max=0;

    fprintf(fp,"P5\n%d %d\n%d\n",ex-sx+1,ey-sy+1,max);
    for(y=sy;y<=ey;y++)
      fwrite(data+(y*w+sx),1,ex-sx+1,fp);
    fclose(fp);
}