apu.rs

        self.ch2_timer = ((2048 - self.ch2_wave_length) << 2) as i16;
        self.ch2_envelope_sequence = 0;
    }

    #[inline(always)]
    fn trigger_ch3(&mut self) {
        self.ch3_timer = 3;
        self.ch3_position = 0;
    }

    #[inline(always)]
    fn trigger_ch4(&mut self) {
        self.ch4_timer =
            ((CH4_DIVISORS[self.ch4_divisor as usize] as u16) << self.ch4_clock_shift) as i32;
        self.ch4_lfsr = 0x7ff1;
        self.ch4_envelope_sequence = 0;
    }
}

impl Default for Apu {
    fn default() -> Self {
        Self::new(44100, 1.0, GameBoy::CPU_FREQ)
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_trigger_ch1() {
        let mut apu = Apu {
            ch1_wave_length: 1024,
            ..Default::default()
        };
        apu.trigger_ch1();

        assert_eq!(apu.ch1_timer, 4096);
        assert_eq!(apu.ch1_envelope_sequence, 0);
        assert_eq!(apu.ch1_sweep_sequence, 0);
    }

    #[test]
    fn test_trigger_ch2() {
        let mut apu = Apu {
            ch2_wave_length: 1024,
            ..Default::default()
        };
        apu.trigger_ch2();

        assert_eq!(apu.ch2_timer, 4096);
        assert_eq!(apu.ch2_envelope_sequence, 0);
    }

    #[test]
    fn test_trigger_ch3() {
        let mut apu = Apu {
            ch3_wave_length: 1024,
            ..Default::default()
        };
        apu.trigger_ch3();

        assert_eq!(apu.ch3_timer, 3);
        assert_eq!(apu.ch3_position, 0);
    }

    #[test]
    fn test_trigger_ch4() {
        let mut apu = Apu {
            ch4_divisor: 3,
            ch4_clock_shift: 2,
            ..Default::default()
        };
        apu.trigger_ch4();

        assert_eq!(apu.ch4_timer, 192);
        assert_eq!(apu.ch4_lfsr, 0x7ff1);
        assert_eq!(apu.ch4_envelope_sequence, 0);
    }
}