/*	histogram.c
**	this program ouputs the
**      histogram of an image.
*/

#include <stdio.h>
#include <stdlib.h>
#include <malloc.h>
#include <math.h>
#define pix_value_bound 255

main(int argc, char **argv)
{
  FILE 		*fin, *fout;
  unsigned long int img_length;
  unsigned long int img_width, max_num, step1,step2,buf;
  unsigned long int hist[pix_value_bound],count1, count2, pix_num;
  unsigned char *store, *sub_row_start;
  float step;

  if(argc == 5)
    {
      img_length = atoi(argv[3]);
      img_width = atoi(argv[4]);

      store = (unsigned char *)malloc(img_width);

      if((fin = fopen(argv[1],"rb")) == NULL)
	{
	  fprintf(stderr,"Failed to open %s\n",argv[1]);
	  exit(EXIT_FAILURE);
	}

      if((fout = fopen(argv[2],"w")) == NULL)
       {
         fprintf(stderr,"Failed to open %s\n",argv[2]);
         exit(EXIT_FAILURE);
       }

      for(count1 = 0; count1 <= pix_value_bound; count1++)
         hist[count1] = 0;

      for(count1 = 0; count1 < img_length; count1++)
	{
          fread(store,1,img_width,fin);
          for(count2 = 0; count2 < img_width; count2++)
	    {
             pix_num = store[count2];
             hist[pix_num]++;
	    }
	}

      max_num = 0;
      for(count1 = 0; count1 <= pix_value_bound; count1++)
         if(hist[count1] > max_num)
            max_num = hist[count1];


      step1 = max_num/100;
      if(step1 == 0)
         step1 = 1;

      for(count1 = 0; count1 < 50; count1++)
         fprintf(fout,"=");
      fprintf(fout,"==  HISTOGRAM  ==");
      for(count1 = 0; count1 < 50; count1++)
         fprintf(fout,"=");
      fprintf(fout,"\n");
      for(count1 = 0; count1 < 50; count1++)
         fprintf(fout,"*");
      fprintf(fout," by  Brandt Tso ");
      for(count1 = 0; count1 < 50; count1++)
         fprintf(fout,"*");
      fprintf(fout,"\n");
      fprintf(fout,"\n");
      for(count1 = 0; count1 <= pix_value_bound; count1++)
	{
            buf = hist[count1];
            step = buf/step1;
            step2= step;
            if(step2 > 130)
               step2 = 130;
            if(buf > 0)
	      {
               fprintf(fout,"%4d %8d ",count1, hist[count1]);
               printf("pix[%d] = %8d",count1,hist[count1]);
               for(count2 = 0;count2<step2;count2++)
	         {
                 printf("*");
                 fprintf(fout,"*");
	         }
               printf("\n");
               fprintf(fout,"\n");
	      }
	}


      fclose(fin);
      fclose(fout);
      free(store);
    }
  else
      printf("\nUsage:\n\thistogram   'input file'  'output file'  'rows in file' ' cols'  .\n\n");
}