opcomplex/yang/2.c

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

const int h = 5, w = 5;
float kx[3] = {0.25f, 0.5f, 0.25f};
float ky[3] = {0.25f, 0.5f, 0.25f};

void separableGaussianBlur(float src[h][w], float dst[h][w], int h, int w, float kx[3], float ky[3]) {
    float buf[3][w];  
    int x, y;

    #define BUF_INDEX(i) ((i) % 3)

    for(y = 0; y < h; ++y){
        for(x = 0; x < w; ++x){
            buf[BUF_INDEX(y)][x] =
                src[y][x] * kx[1] +
                (x > 0 ? src[y][x - 1] * kx[0] : 0) +
                (x < w - 1 ? src[y][x + 1] * kx[2] : 0);
        }

        if(y >= 2){
            for(x = 1; x < w - 1; ++x){  
                dst[y - 1][x] =
                    buf[BUF_INDEX(y - 2)][x] * ky[0] +
                    buf[BUF_INDEX(y - 1)][x] * ky[1] +
                    buf[BUF_INDEX(y)][x] * ky[2];
            }
        }
    }
}

int main() {
    int i, j;
    float dst[h][w];
    for(i = 0; i < h; i++){
        for (j = 0; j < w; j++){
            dst[i][j] = 0.0;
        }
    }
    float src[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}
    };

    clock_t start, end;
    start = clock();
    separableGaussianBlur(src, dst, h, w, kx, ky);
    end = clock();

    printf("Blurred result:\n");
    for(i = 0; i < h; i++){
        for(j = 0; j < w; j++){
            printf("%.2f ", dst[i][j]);
        }
        printf("\n");
    }
    printf("Time: %f s\n", (float)(end - start) / CLOCKS_PER_SEC);
    return 0;
}