CC5.8.java

    public static void drawHorizontalLine(byte[] screen, int width, int x1, int x2, int y) {
        int height = screen.length / width;
        if (y < 0 || y >= height || x1 < 0 || x1 >= screen.length * 8 || x2 < 0 || x2 >= screen.length * 8)
            return;
        int base = y * width / 8;
        int start = base + x1 / 8;
        int end = base + x2 / 8;
        
        byte mask1;
        if (x1 % 8 == 0)
            mask1 = (byte) ~0;
        else
            mask1 = (byte) ((byte) (1 << (8 - x1 % 8)) - 1);
        byte mask2 = (byte) (~0 << (8 - x2 % 8 - 1));
        if (start == end)
            screen[start] |= mask1 & mask2;
        else {
            screen[start] |= mask1;
            screen[end] |= mask2;
        }
        for (int i = start + 1; i < end; i++)
            screen[i] |= (byte) ~0;
    }