#include <SDL2/SDL.h>
#include <stdio.h>
#include <stdlib.h>

Uint16 CreateHiColorPixel(SDL_PixelFormat * fmt, Uint8 red,
Uint8 green, Uint8 blue)
{
    Uint16 value;

    value = ((red >> fmt->Rloss)<< fmt->Rshift) +
    ((green >> fmt->Gloss) << fmt->Gshift) +
    ((blue >> fmt->Bloss) << fmt->Bshift );

    return value;
}

int main()
{
    SDL_Surface *screen;
    Uint16 *raw_pixels;
    int x,y;

    if (SDL_Init(SDL_INIT_VIDEO) != 0) {
        printf("Unable to initialize SDL: %s\n", SDL_GetError());
        return -1;
    }

    atexit(SDL_Quit);

    screen = SDL_SetVideoMode(256, 256, 16, 0);
    if (screen == NULL) {
        printf("Unable to set video mode: %s\n", SDL_GetError());
        return -1;
    }

    SDL_LockSurface(screen);

    raw_pixels = (Uint16 *) screen->pixels;

    for (x=0; x < 256; x++)
        for (y=0; y < 256; y++) {
            Uint16 pixel_color;
            int offset;
            pixel_color = CreateHicolorPixel(screen->format, x, 0, y);
            offset = (screen->pitch / 2 * y + x);
            raw_pixels[offset] = pixel_color;
    }



SDL_UnlockSurface(screen);

SDL_UpdateRect(screen, 0, 0, 0, 0);

SDL_Delay(3000);

return 0;

}