Run at 60 Hz about deca HOT 1 OPEN

      let mut begin_cpu = time::PreciseTime::now();
      let mut begin_display = begin_cpu.clone();
      'running: loop {
            let now = time::PreciseTime::now();

            let delta_cpu = begin_cpu.to(now);
            if delta_cpu.num_milliseconds() >= (1000.0 / CPU_FREQUENCY).round() as i64 {
                  begin_cpu = now.clone();

                  if chip.running {
                        chip.cycle();
                  }
            }

            let delta_display = begin_display.to(now);
            if delta_display.num_milliseconds() >= (1000.0 / DRAW_FREQUENCY).round() as i64 {
                  begin_display = now.clone();

                  display.update(&mut chip);
                  if display.should_close() {
                        break 'running;
                  }
                  display.draw(&chip);
            }
      }




            // Delay & sound timers are decreased by 1 at a rate of 60Hz
            let now = time::precise_time_ns();
            if now - self.clock > 16666000 {
                  self.clock = now;
                  if self.delay_timer != 0 {
                        self.delay_timer -= 1;
                  }
                  if self.sound_timer != 0 {
                        self.sound_timer -= 1;
                  }
            }
extern crate time;

const BEEP_SAMPLE_RATE: u32 = 44100;
const BEEP_FREQUENCY: f32 = 1000.0;
fn generate_beep() -> Vec<i16> {
      const SAMPLES: usize = BEEP_SAMPLE_RATE as usize / 2;
      let mut data: Vec<i16> = Vec::new();
      data.resize(SAMPLES, 0);

      // generate half a second of a sine wave
      for i in 0..SAMPLES {
            let t = i as f32 / BEEP_SAMPLE_RATE as f32;
            data[i] = ((BEEP_FREQUENCY * t * 2.0 * 3.1415).sin() * 32767.0).round() as i16;
      }

      data
}