#include<stdio.h>
#include<math.h>
#include<stdlib.h>
#define N 512

void convolve(float *source, int cols, int rows, int kwidth, int kheight,
 float *kernel, int bias, char *filename);
void main(void)
{
 int i, j;
 float in_data[N][N];
 FILE *in;
 float coef[3][3] = { 1., 2., 1.,
  2., 4., 2.,
  1., 2., 1. };
 for (i = 0; i<512; i++)
 {
  for (j = 0; j<512; j++)
  {
   in_data[i][j] = 0;
  
  }
 }
 in = fopen_s("&in","123.bmp", "rb");
 for (i = 0; i<512; i++)
 {
  for (j = 0; j<512; j++)
  {
   in_data[512 - i - 1][j] = fgetc_s(in);
  }
 }
 convolve(in_data, 512, 512, 3, 3, coef, 0, "after.raw");
}
void convolve(float *source, int cols, int rows, int kwidth, int kheight,
 float *kernel, int bias, char *filename)
{
 int x, y, i;
 int kernx = 0, kerny = 0;
 int index = 0;
 int xextra, yextra;
 int conv_line;
 float sum;
 unsigned long destadd;
 unsigned long sourceadd;
 unsigned long sourcebase;
 unsigned char *dest;
 FILE *fp;
 unsigned char left[25];
 unsigned char right[25];
 int xpad, ypad;
 int last_line;

 yextra = (kheight / 2) * 2;
 ypad = yextra / 2;
 xextra = (kwidth / 2) * 2;
 xpad = xextra / 2;
 conv_line = cols - xextra;
 last_line = rows - yextra;
 dest = malloc(cols);

 if ((fp = fopen_s("&fp",filename, "wb")) == NULL)
 {
  printf("Unable to open &s for output\n", filename);
  exit(1);
 }
 for (y = 0; y < last_line; y++)
 {
  sourcebase = (unsigned long)cols *y;
  destadd = 0;
  for (x = xextra / 2; x < (cols - xpad); x++)
  {
   for (kernx = 0; kernx < kwidth; kernx++)
   {
    sourceadd = sourcebase + kernx + kerny*cols;
    sum += (source[sourceadd]*kernel[index++]);
   }
   sum += bias;
   //CLIP(sum, 0.0, 255, 0);

   dest[destadd++] = (unsigned char)sum;
   sourcebase++;

  }
  
 }
 for (i = 0; i < xpad; i++)
  left[i] = dest[0];
 for (i = 0; i < xpad; i++)
  right[i] = dest[conv_line - 1];
 if (y = 0)
 {
  for (i = 0; i < xpad; i++)
  {
   fwrite(left, 1, xpad, fp);
   fwrite(dest, 1, conv_line, fp);
   fwrite(right, 1, xpad, fp);
  }
 }
 fwrite(left, 1, xpad, fp);
}