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

void applyGaussianBlur(void*, void*, int, int, float[3][3]);
void print(void* _a, int h, int w);
int main() {
	float inputImage[5][5] = {
		{1,2,3,4,5},
		{6,7,8,9,10},
		{11,12,13,14,15},
		{16,17,18,19,20},
		{21,22,23,24,25}
	};
	float kernel[3][3] = {
		{1.0f/16, 2.0f/16, 1.0f/16},
		{2.0f/16, 4.0f/16, 2.0f/16},
		{1.0f/16, 2.0f/16, 1.0f/16}
	};
	float outputImage[5][5] = {0};
	clock_t start = clock();
	applyGaussianBlur(inputImage, outputImage, 5, 5, kernel);
	clock_t end   = clock();
	printf("Time: %lf s\n", (double)(end-start) / CLOCKS_PER_SEC);
	print(outputImage, 5, 5);
}

void applyGaussianBlur(void* _src, void* _dst, 
	int h, int w, float kernel[3][3]) {
	int i, j;
	float (*src)[w] = (float(*)[w])_src;
	float (*dst)[w] = (float(*)[w])_dst;
	for(i=1; i<h-1; i++)
	for(j=1; j<w-1; j++) {
		dst[i][j] = 
		src[i-1][j-1]*kernel[0][0]+src[i-1][j  ]*kernel[0][1]+src[i-1][j+1]*kernel[0][2]+
		src[i  ][j-1]*kernel[1][0]+src[i  ][j  ]*kernel[1][1]+src[i  ][j+1]*kernel[1][2]+
		src[i+1][j-1]*kernel[2][0]+src[i+1][j  ]*kernel[2][1]+src[i+1][j+1]*kernel[2][2];
	}
}

void print(void* _a, int h, int w) {
	float (*a)[w] = (float(*)[w])_a;
	int i, j;
	for(i=0; i<h; i++) {
		for(j=0; j<w; j++) {
			printf("%5.1f ", a[i][j]);
		}
		printf("\n");
	}
}