broken.c

BOOLEAN toggle = TRUE;
UWORD y = 0;
UWORD x = 0;
void loop()
{
    for (x = 0; x != WIDTH; x++)
    {
        for (y = 0; y != HEIGHT; y++)
        {
            UWORD index = x + y * WIDTH;
            background_map[index] = TRUE;
            show_board();
        }
    }
}

works1.c

BOOLEAN toggle = TRUE;
UWORD y = 0;
UWORD x = 0;
void loop()
{
    for (x = 0; x != WIDTH; x++)
    {
        UWORD index = x + y * WIDTH;
        background_map[index] = TRUE;
        show_board();
    }
    y++;
}

works2.c

BOOLEAN toggle = TRUE;
UWORD y = 0;
UWORD x = 0;
void loop()
{
    for (y = 0; y != HEIGHT; y++)
    {
        UWORD index = x + y * WIDTH;
        background_map[index] = TRUE;
        show_board();
    }
    // }
    x++;
}