nes-emu/src/apu.rs

use tracing::debug;

bitfield::bitfield! {
    pub struct DutyVol(u8);
    impl Debug;
    duty, set_duty: 7, 6;
    r#loop, set_loop: 5;
    const_vol, set_const_vol: 4;
    volume, set_volume: 3, 0;
}

bitfield::bitfield! {
    pub struct Sweep(u8);
    impl Debug;
    enable, set_enable: 7;
    period, set_period: 6, 4;
    negate, set_negate: 3;
    shift, set_shift: 2, 0;
}

bitfield::bitfield! {
    pub struct LengthTimerHigh(u8);
    impl Debug;
    length, set_length: 7, 3;
    timer_high, set_timer_high: 2, 0;
}

struct PulseChannel {
    enabled: bool,
}

bitfield::bitfield! {
    pub struct CounterLoad(u8);
    impl Debug;
    halt, set_halt: 7;
    value, set_value: 6, 0;
}

struct TriangleChannel {
    enabled: bool,
}
struct NoiseChannel {
    enabled: bool,
}
struct DeltaChannel {
    enabled: bool,
}

pub struct APU {
    pulse_1: PulseChannel,
    pulse_2: PulseChannel,
    triangle: TriangleChannel,
    noise: NoiseChannel,
    dmc: DeltaChannel,
    frame_counter: u8,
}

impl std::fmt::Debug for APU {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        // write!(
        //     f,
        //     "PPU: f {}, s {}, p {}",
        //     self.frame_count, self.scanline, self.pixel
        // )
        Ok(())
    }
}

impl APU {
    pub fn init() -> Self {
        Self {
            pulse_1: PulseChannel { enabled: false },
            pulse_2: PulseChannel { enabled: false },
            triangle: TriangleChannel { enabled: false },
            noise: NoiseChannel { enabled: false },
            dmc: DeltaChannel { enabled: false },
            frame_counter: 0,
        }
    }
    pub fn read_reg(&mut self, offset: u16) -> u8 {
        match offset {
            _ => panic!("No register at {:X}", offset),
        }
    }
    pub fn write_reg(&mut self, offset: u16, val: u8) {
        match offset {
            0x15 => {
                self.dmc.enabled = val & 0b0001_0000 != 0;
                self.noise.enabled = val & 0b0000_1000 != 0;
                self.triangle.enabled = val & 0b0000_0100 != 0;
                self.pulse_2.enabled = val & 0b0000_0010 != 0;
                self.pulse_1.enabled = val & 0b0000_0001 != 0;
            }
            0x10 => {
                assert_eq!(val, 0x00);
                // TODO: implement this value
            }
            0x11 => {
                // TODO: load dmc counter with (val & 7F)
            }
            _ => panic!("No register at {:X}", offset),
        }
    }

    pub fn run_one_clock_cycle(&mut self) -> bool {
        false
    }
    pub fn peek_nmi(&self) -> bool {
        false
    }
    pub fn nmi_waiting(&mut self) -> bool {
        false
    }
    pub fn peek_irq(&self) -> bool {
        false
    }
    pub fn irq_waiting(&mut self) -> bool {
        // TODO: implement logic
        false
    }
}