85 lines
2.5 KiB
Rust
85 lines
2.5 KiB
Rust
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mod noise;
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mod square;
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mod triangle;
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mod dmc;
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pub struct Apu {
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square1: Square,
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square2: Square,
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triangle: Triangle,
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noise: Noise,
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dmc: DMC,
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}
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struct Square {
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duty_cycle: usize,
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length_counter_halt: bool, // (this bit is also the envelope's loop flag)
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constant_volume_flag: bool, // (0: use volume from envelope; 1: use constant volume)
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timer: usize,
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length_counter: usize,
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envelope: usize,
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sweep: usize,
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}
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// $4008 Hlll.llll Triangle channel length counter halt and linear counter load (write)
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// bit 7 H--- ---- Halt length counter (this bit is also the linear counter's control flag)
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struct Triangle {
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timer: usize,
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length_counter: usize, // (this bit is also the linear counter's control flag)
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linear_counter: usize,
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}
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// $400E M---.PPPP Mode and period (write)
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// bit 7 M--- ---- Mode flag
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struct Noise {
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timer: usize,
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length_counter: usize,
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envelope: usize,
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linear_feedback_sr: u16,
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mode: bool, // also called loop noise, bit 7 of $400E
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}
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struct DMC {
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}
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impl Apu {
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fn new() -> Self {
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Apu {
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square1: Square::new(),
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square2: Square::new(),
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triangle: Triangle::new(),
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noise: Noise::new(),
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dmc: DMC::new(),
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}
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}
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fn write_reg(&mut self, address: usize, value: u8) {
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match address {
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0x4000 => self.square1.duty(value),
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0x4001 => self.square1.sweep(value),
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0x4002 => self.square1.timer_low(value),
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0x4003 => self.square1.timer_high(value),
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0x4004 => self.square2.duty(value),
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0x4005 => self.square2.sweep(value),
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0x4006 => self.square2.timer_low(value),
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0x4007 => self.square2.timer_high(value),
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0x4008 => self.triangle.counter(value),
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0x400A => self.triangle.timer_low(value),
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0x400B => self.triangle.timer_high(value),
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0x400C => self.noise.envelope(value),
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0x400D => (),
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0x400E => self.noise.loop_noise(value),
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0x400F => self.noise.load_length_counter(value),
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0x4010 => self.dmc.control(value),
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0x4011 => self.dmc.direct_load(value),
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0x4012 => self.dmc.sample_address(value),
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0x4013 => self.dmc.sample_length(value),
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0x4014 => (),
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0x4015 => self.control(value),
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0x4016 => (),
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0x4017 => self.frame_counter(value),
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}
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}
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}
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