Sample source for Halide - http://halide-lang.org

halide_sample.cpp

// Halide
#include "Halide.h"

// Include some support code for loading pngs.
#include "halide_image_io.h"

// for performance test
#include <sys/time.h>
double currentTime() {
    timeval t;
    gettimeofday(&t, NULL);
    return t.tv_sec * 1000.0 + t.tv_usec / 1000.0f;
}

int main(int argc, char **argv) {
    int count = 100;
    Halide::Image<uint8_t> input = Halide::Tools::load_image("rgb.png");
    Halide::Func blur, clamped, blur_x;
    Halide::Var x, y, c;

    // clampled image because output image is smaller than input image.
    clamped(x,y,c) = input(clamp(x,1,input.width()-2),clamp(y,1,input.height()-2),c);

    // Filtering
    blur_x(x,y,c) = 0.2f * clamped(x-2, y, c) +  0.2f * clamped(x-1, y, c) + 0.2f * clamped(x, y, c) + 0.2f * clamped(x+1, y, c) + 0.2f * clamped(x+2, y, c);
    Halide::Expr value = 0.2f * blur_x(x, y-2, c) + 0.2f * blur_x(x, y-1, c) + 0.2f * blur_x(x, y, c) + 0.2f * blur_x(x, y+1, c) + 0.2f * blur_x(x, y+2, c);

    // Cast it back to an 8-bit unsigned integer.
    value = Halide::cast<uint8_t>(value);

    // Define the function.
    blur(x, y, c) = value;

    // do it
    Halide::Image<uint8_t> output = blur.realize(input.width(), input.height(), input.channels());

    // save image
    Halide::Tools::save_image(output, "blured.png");

    // performance test
    {
        Halide::Func temp = blur;
        double t = currentTime();
        for (int i = 0; i < count; i++) {
            Halide::Image<uint8_t> output = blur.realize(input.width(), input.height(), input.channels());
        }
        printf("%f[msec] = Normal\n", (currentTime()- t)/count);
    }

    {
        Halide::Var yi;
        Halide::Func temp = blur;
        temp.split(y, y, yi, 8).parallel(y).vectorize(x, 4);
        double t = currentTime();
        for (int i = 0; i < count; i++) {
            Halide::Image<uint8_t> output = temp.realize(input.width(), input.height(), input.channels());
        }
        printf("%f[msec] = Compute oncurrently. \n", (currentTime()- t)/count);
    }
    return 0;
}