/* listing 1: Un-optimized code to perform general image filtering

Blurs a monochrome 8 bit image in "src" of dimensions src_w x src_h,
outputs to dst using a filter kernel in ker which must be a 2D float
array of size [2*k+1][2*k+1] */

void DoBlur(UBYTE *src, int src_w, int src_h, UBYTE *dst, float *ker, int k)
{	
	if (k<0)
	{
		memcpy(dst,src,src_w*src_h); // deal with degenerate kernel sizes
		return;
	}
	for (int y=0;y<src_h;y++)
	{
		for (int x=0;x<src_w;x++)
		{
			float total=0;
			float *kp=ker;
			for (int j=-k;j<=k;j++)
			for (int i=-k;i<=k;i++)
			{
				int x2=x+i;
				int y2=y+j;
				if (x2>=0 && x2<src_w && y2>=0 && y2<src_h) 
					total+=kp[0]*src[y2*src_w+x];
				kp++;
			}
			if (total<0) total=0; else if (total>255) total=255;
			*dst++=UBYTE(total);
		}
	}
}