#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <time.h>
#include <string.h>
struct stats {int mem;int xdim;int ydim;};
struct pixel {unsigned char b;unsigned char g;unsigned char r;};
long t;
struct stats filestats(unsigned char *filename);
int readbmpintoarray(unsigned char *filename,unsigned char *bmparray);
int writearrayintobmp(unsigned char *filename,unsigned char *bmparray);
int pixloc(int x,int y,int xdim);
int totsize(int xdim, int ydim);
int xdrf(int xdim);
float disfctr(int x,int y);
/****************************************************************************/
int main(int argc, char *argv[])
{
  struct stats stat;
  FILE *fp[9];
  float dis;
  int loc,cnt,mem,x=0,y=0,no_of_files,fnum,size;
  struct pixel colors;
  unsigned char file[9][64],*bmparray[9];
  srand((unsigned)time(&t));
  if (argc<2)
  {
    fprintf(stderr,"Usage: %s filename(s)\n",argv[0]);
    exit(2);
  }   
  for (cnt=1;cnt<argc;cnt++)
  {
    strcpy(file[cnt],argv[cnt]);
    stat=filestats(file[cnt]);
    printf("File %s: %10d bytes, %4d by %4d\n",file[cnt],stat.mem,stat.xdim,stat.ydim);
    bmparray[cnt]=malloc(totsize(stat.xdim,stat.ydim));
    size=readbmpintoarray(file[cnt],bmparray[cnt]);
    printf("*** Size of array created: %10d\n\n",size);
  }
  for (cnt=55;cnt<size;cnt++)
  {
    bmparray[1][cnt]+=rand()%64;
  }  
  writearrayintobmp(file[1],bmparray[1]);
  for (cnt=1;cnt<argc;cnt++) free(bmparray[cnt]);
  return 0;
}
/****************************************************************************/
struct stats filestats(unsigned char *filename)
// PARAMETER LIST
// *filename - Character array storing name of file
// RETURN VALUE
// stat - structure of file statistics
// stat.xdim - X-dimensions (width) of file
// stat.ydim - Y-dimensions (height) of file
// stat.mem - total size (memory) of file
{
  int mem,xdim,ydim;
  struct stats stat;
  FILE *fp;
  if ((fp=fopen(filename,"r+b"))==NULL)
  {
    fprintf(stderr,"Error opening %s\n",filename);
    stat.mem=0;
    stat.xdim=0;
    stat.ydim=0;
    return stat;
  }    
  fseek(fp,2,SEEK_SET);
  fread(&mem,4,1,fp);
  fseek(fp,18,SEEK_SET);
  fread(&xdim,4,1,fp);
  fseek(fp,22,SEEK_SET);
  fread(&ydim,4,1,fp);
  fclose(fp);
  stat.mem=mem;
  stat.xdim=xdim;
  stat.ydim=ydim;
  return stat;
}
/***************************************************************************/
int readbmpintoarray(unsigned char *filename,unsigned char *bmparray)
// PARAMETER LIST
// *filename - character array storing name of file
// *bmparray - array of bytes in which to read file values
// RETURN VALUE
// size - total size (memory) of array created by function
{
  FILE *fp;
  int cnt,xdim,ydim,size;
  unsigned char byte;
  if ((fp=fopen(filename,"r+b"))==NULL)
  {
    fprintf(stderr,"File \"%s\" could not be opened\n");
    exit(1);
  }
  fseek(fp,18L,SEEK_SET);
  fread(&xdim,4,1,fp);
  fseek(fp,22L,SEEK_SET);
  fread(&ydim,4,1,fp);
  size=totsize(xdim,ydim);
  fseek(fp,0L,SEEK_SET);
  fread(bmparray,1,size,fp);
  fclose(fp);  
  return size;
}
/****************************************************************************/
int writearrayintobmp(unsigned char *filename,unsigned char *bmparray)
{
  FILE *fp;
  int cnt,xdim,ydim,size;
  unsigned char byte;
  size=bmparray[2];
  size+=bmparray[3]*256;
  size+=bmparray[4]*256*256;
  size+=bmparray[5]*256*256*256;
  if ((fp=fopen(filename,"r+b"))==NULL)
  {
    fprintf(stderr,"File \"%s\" could not be opened\n");
    exit(1);
  }
  fseek(fp,0L,SEEK_SET);
  fwrite(bmparray,1,size,fp);
  fclose(fp);  
  return size;
}
/*****************************************************************************/
int totsize(int xdim,int ydim)
// PARAMETER LIST
// xdim, ydim - dimensions of bitmap image
// RETURN VALUE
// Total size (memory) of file or array with dimensions of parameters
{
  int xdrf=(4-(xdim*3)%4)%4;
  return 54+(ydim)*(xdim*3+xdrf);
}
/****************************************************************************/
int pixloc(int x,int y,int xdim)
// PARAMETER LIST
// x,y - coordinates of pixel
// RETURN VALUE
// Linear (one-dimensional) location of blue color value in  file or array
{
  int xdrf=(4-(xdim*3)%4)%4;
  return 54+(y*xdim*3+xdrf)+(x*3);
}  
/****************************************************************************/