+struct ao_task ball_task;
+
+#define BALL_WIDTH 5
+#define BALL_HEIGHT 5
+
+static int ball_x;
+static int ball_y;
+static int ball_dx, ball_dy;
+
+uint8_t ball_enable;
+
+void
+ao_ball(void)
+{
+ ball_dx = 1;
+ ball_dy = 1;
+ ball_x = 0;
+ ball_y = 0;
+ for (;;) {
+ while (!ball_enable)
+ ao_sleep(&ball_enable);
+ for (;;) {
+ ao_solid(AO_ALLONES,
+ AO_ALLONES,
+ ao_vga_fb + ball_y * AO_VGA_STRIDE,
+ AO_VGA_STRIDE,
+ ball_x,
+ BALL_WIDTH,
+ BALL_HEIGHT);
+ ao_delay(AO_MS_TO_TICKS(10));
+ ao_solid(AO_ALLONES,
+ AO_ALLONES,
+ ao_vga_fb + ball_y * AO_VGA_STRIDE,
+ AO_VGA_STRIDE,
+ ball_x,
+ BALL_WIDTH,
+ BALL_HEIGHT);
+ if (!ball_enable)
+ break;
+ ball_x += ball_dx;
+ ball_y += ball_dy;
+ if (ball_x + BALL_WIDTH > AO_VGA_WIDTH) {
+ ball_x = AO_VGA_WIDTH - BALL_WIDTH;
+ ball_dx = -ball_dx;
+ }
+ if (ball_x < 0) {
+ ball_x = -ball_x;
+ ball_dx = -ball_dx;
+ }
+ if (ball_y + BALL_HEIGHT > AO_VGA_HEIGHT) {
+ ball_y = AO_VGA_HEIGHT - BALL_HEIGHT;
+ ball_dy = -ball_dy;
+ }
+ if (ball_y < 0) {
+ ball_y = -ball_y;
+ ball_dy = -ball_dy;
+ }
+ }
+ }
+}
+