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80a15039e0
...
2ef8fefbb7
240
src/apu.rs
240
src/apu.rs
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@ -7,7 +7,7 @@ use types::ch3::Volume as Ch3Volume;
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use types::ch4::{CounterWidth, Frequency as Ch4Frequency, PolynomialCounter};
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use types::common::{EnvelopeDirection, FrequencyHigh, SoundDuty, VolumeEnvelope};
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use types::fs::{FrameSequencer, State as FSState};
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use types::{ChannelControl, NRx4, SoundOutput};
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use types::{ChannelControl, SoundOutput};
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pub mod gen;
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mod types;
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@ -27,7 +27,7 @@ pub struct Apu {
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/// Noise
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ch4: Channel4,
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fs: FrameSequencer,
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sequencer: FrameSequencer,
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div_prev: Option<u16>,
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prod: Option<SampleProducer<f32>>,
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@ -69,20 +69,20 @@ impl BusIo for Apu {
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0x11 if self.ctrl.enabled => self.ch1.set_duty(byte),
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0x12 if self.ctrl.enabled => self.ch1.set_envelope(byte),
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0x13 if self.ctrl.enabled => self.ch1.set_freq_lo(byte),
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0x14 if self.ctrl.enabled => self.ch1.set_freq_hi(&self.fs, byte),
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0x14 if self.ctrl.enabled => self.ch1.set_freq_hi(&self.sequencer, byte),
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0x16 if self.ctrl.enabled => self.ch2.set_duty(byte),
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0x17 if self.ctrl.enabled => self.ch2.set_envelope(byte),
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0x18 if self.ctrl.enabled => self.ch2.set_freq_lo(byte),
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0x19 if self.ctrl.enabled => self.ch2.set_freq_hi(&self.fs, byte),
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0x19 if self.ctrl.enabled => self.ch2.set_freq_hi(byte),
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0x1A if self.ctrl.enabled => self.ch3.set_dac_enabled(byte),
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0x1B if self.ctrl.enabled => self.ch3.set_len(byte),
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0x1C if self.ctrl.enabled => self.ch3.set_volume(byte),
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0x1D if self.ctrl.enabled => self.ch3.set_freq_lo(byte),
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0x1E if self.ctrl.enabled => self.ch3.set_freq_hi(&self.fs, byte),
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0x1E if self.ctrl.enabled => self.ch3.set_freq_hi(byte),
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0x20 if self.ctrl.enabled => self.ch4.set_len(byte),
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0x21 if self.ctrl.enabled => self.ch4.set_envelope(byte),
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0x22 if self.ctrl.enabled => self.ch4.set_poly(byte),
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0x23 if self.ctrl.enabled => self.ch4.set_frequency(&self.fs, byte),
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0x23 if self.ctrl.enabled => self.ch4.set_frequency(byte),
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0x24 if self.ctrl.enabled => self.ctrl.set_channel(byte),
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0x25 if self.ctrl.enabled => self.ctrl.set_output(byte),
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0x26 => self.set_status(byte),
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@ -101,7 +101,7 @@ impl Apu {
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if self.is_falling_edge(12, div) {
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use FSState::*;
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match self.fs.state() {
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match self.sequencer.state() {
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Length => self.clock_length(),
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LengthAndSweep => {
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self.clock_length();
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@ -111,7 +111,7 @@ impl Apu {
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Nothing => {}
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}
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self.fs.next();
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self.sequencer.next();
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}
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self.div_prev = Some(div);
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@ -172,7 +172,7 @@ impl Apu {
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if self.ctrl.enabled {
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// Frame Sequencer reset to Step 0
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self.fs.reset();
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self.sequencer.reset();
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// Square Duty units are reset to first step
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self.ch1.duty_pos = 0;
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@ -225,8 +225,8 @@ impl Apu {
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self.ch4.enabled = Default::default();
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}
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fn process_length(freq: &impl NRx4, counter: &mut u16, enabled: &mut bool) {
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if freq.length_enable() && *counter > 0 {
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fn process_length(freq_hi: &FrequencyHigh, counter: &mut u16, enabled: &mut bool) {
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if freq_hi.length_enable() && *counter > 0 {
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*counter -= 1;
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// Check in this scope ensures (only) the above subtraction
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@ -237,6 +237,18 @@ impl Apu {
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}
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}
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fn ch4_process_length(freq: &Ch4Frequency, length_timer: &mut u16, enabled: &mut bool) {
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if freq.length_enable() && *length_timer > 0 {
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*length_timer -= 1;
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// Check in this scope ensures (only) the above subtraction
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// made length_timer 0
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if *length_timer == 0 {
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*enabled = false;
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}
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}
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}
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fn clock_length(&mut self) {
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Self::process_length(
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&self.ch1.freq_hi,
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@ -246,19 +258,19 @@ impl Apu {
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Self::process_length(
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&self.ch2.freq_hi,
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&mut self.ch2.length_counter,
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&mut self.ch2.length_timer,
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&mut self.ch2.enabled,
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);
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Self::process_length(
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&self.ch3.freq_hi,
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&mut self.ch3.length_counter,
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&mut self.ch3.length_timer,
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&mut self.ch3.enabled,
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);
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Self::process_length(
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Self::ch4_process_length(
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&self.ch4.freq,
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&mut self.ch4.length_counter,
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&mut self.ch4.length_timer,
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&mut self.ch4.enabled,
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);
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}
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@ -275,7 +287,7 @@ impl Apu {
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if self.ch1.sweep_enabled && period != 0 {
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let new_freq = self.ch1.calc_sweep_freq();
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if new_freq <= 0x7FF && self.ch1.sweep.shift_count() != 0 {
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if new_freq <= 2047 && self.ch1.sweep.shift_count() != 0 {
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self.ch1.set_frequency(new_freq);
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self.ch1.shadow_freq = new_freq;
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@ -473,29 +485,39 @@ impl Channel1 {
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/// 0xFF14 | NR14 - Channel 1 Frequency high
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pub(crate) fn set_freq_hi(&mut self, fs: &FrameSequencer, byte: u8) {
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let mut new_freq: FrequencyHigh = byte.into();
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let prev_le = self.freq_hi.length_enable();
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self.freq_hi = byte.into();
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if !fs.next_clocks_length() {
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if !prev_le && self.freq_hi.length_enable() && self.length_counter != 0 {
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self.length_counter -= 1;
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if self.length_counter == 0 && !self.freq_hi.initial() {
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self.enabled = false;
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}
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}
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}
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// If this bit is set, a trigger event occurs
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if new_freq.trigger() {
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if self.freq_hi.initial() {
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if self.is_dac_enabled() {
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self.enabled = true;
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}
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// Length behaviour during trigger event
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if self.length_counter == 0 {
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self.length_counter = 64;
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// length_counter was 0 so length evidently wasn't enabled
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self.freq_hi.set_length_enable(false);
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self.length_counter = if self.freq_hi.length_enable() && !fs.next_clocks_length() {
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63
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} else {
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64
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};
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};
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// reload freq_timer but last two bits are unmodified
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self.freq_timer = obscure::square::freq_timer_reload(self.freq_timer, self.frequency());
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// Volume Envelope loaded w/ period
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// Envelope Behaviour during trigger event
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self.period_timer = self.envelope.period();
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// Channel Volume reloaded
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self.current_volume = self.envelope.init_vol();
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// Channel 1 Sweep Behaviour
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// Sweep behaviour during trigger event
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let sweep_period = self.sweep.period();
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let sweep_shift = self.sweep.shift_count();
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@ -507,19 +529,7 @@ impl Channel1 {
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if sweep_shift != 0 {
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let _ = self.calc_sweep_freq();
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}
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self.enabled = self.is_dac_enabled();
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}
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obscure::nrx4::length_update(
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&mut new_freq,
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fs,
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&mut self.length_counter,
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&mut self.enabled,
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self.freq_hi.length_enable(),
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);
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self.freq_hi = new_freq;
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}
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fn tick(&mut self) {
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@ -593,7 +603,7 @@ pub(crate) struct Channel2 {
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current_volume: u8,
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// Length Functionality
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length_counter: u16,
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length_timer: u16,
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freq_timer: u16,
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duty_pos: u8,
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@ -610,7 +620,7 @@ impl Channel2 {
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/// 0xFF16 | NR21 - Channel 2 Sound length / Wave Pattern Duty
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pub(crate) fn set_duty(&mut self, byte: u8) {
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self.duty = byte.into();
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self.length_counter = 64 - self.duty.sound_length() as u16;
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self.length_timer = 64 - self.duty.sound_length() as u16;
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}
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/// 0xFF17 | NR22 - Channel 2 Volume ENvelope
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@ -638,36 +648,22 @@ impl Channel2 {
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}
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/// 0xFF19 | NR24 - Channel 2 Frequency high
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pub(crate) fn set_freq_hi(&mut self, fs: &FrameSequencer, byte: u8) {
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let prev_le = self.freq_hi.length_enable();
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pub(crate) fn set_freq_hi(&mut self, byte: u8) {
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self.freq_hi = byte.into();
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obscure::nrx4::length_update(
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&mut self.freq_hi,
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fs,
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&mut self.length_counter,
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&mut self.enabled,
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prev_le,
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);
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if self.freq_hi.trigger() {
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self.enabled = true;
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// Reload length counter if need be
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if self.length_counter == 0 {
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self.length_counter = 64;
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}
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// reload frequency timer
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self.freq_timer = obscure::square::freq_timer_reload(self.freq_timer, self.frequency());
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// reload envelope
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if self.freq_hi.initial() {
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// Envelope behaviour during trigger event
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self.period_timer = self.envelope.period();
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// reload volume
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self.current_volume = self.envelope.init_vol();
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self.enabled = self.is_dac_enabled();
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// Length behaviour during trigger event
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if self.length_timer == 0 {
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self.length_timer = 64;
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}
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if self.is_dac_enabled() {
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self.enabled = true;
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}
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}
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}
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@ -718,7 +714,7 @@ pub(crate) struct Channel3 {
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wave_ram: [u8; WAVE_PATTERN_RAM_LEN],
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// Length Functionality
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length_counter: u16,
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length_timer: u16,
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freq_timer: u16,
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offset: u8,
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@ -764,7 +760,7 @@ impl Channel3 {
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/// 0xFF1B | NR31 - Sound Length
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pub(crate) fn set_len(&mut self, byte: u8) {
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self.len = byte;
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self.length_counter = 256 - self.len as u16;
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self.length_timer = 256 - self.len as u16;
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}
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/// 0xFF1C | NR32 - Channel 3 Volume
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@ -796,32 +792,18 @@ impl Channel3 {
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}
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/// 0xFF1E | NR34 - Channel 3 Frequency high
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pub(crate) fn set_freq_hi(&mut self, fs: &FrameSequencer, byte: u8) {
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let prev_le = self.freq_hi.length_enable();
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pub(crate) fn set_freq_hi(&mut self, byte: u8) {
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self.freq_hi = byte.into();
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obscure::nrx4::length_update(
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&mut self.freq_hi,
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fs,
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&mut self.length_counter,
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&mut self.enabled,
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prev_le,
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);
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if self.freq_hi.trigger() {
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self.enabled = true;
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if self.freq_hi.initial() {
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// Length behaviour during trigger event
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if self.length_counter == 0 {
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self.length_counter = 256;
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if self.length_timer == 0 {
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self.length_timer = 256;
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}
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self.freq_timer = (2048 - self.frequency()) * 2;
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// reset wave channel's ptr into wave RAM
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self.offset = 0;
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self.enabled = self.dac_enabled;
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if self.dac_enabled {
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self.enabled = true;
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}
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}
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}
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@ -880,7 +862,7 @@ pub(crate) struct Channel4 {
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current_volume: u8,
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// Length Functionality
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length_counter: u16,
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length_timer: u16,
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/// Linear Feedback Shift Register (15-bit)
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lf_shift: u16,
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@ -894,7 +876,7 @@ impl Channel4 {
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/// 0xFF20 | NR41 - Channel 4 Sound Length
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pub(crate) fn set_len(&mut self, byte: u8) {
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self.len = byte & 0x3F;
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self.length_counter = 64 - self.len as u16;
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self.length_timer = 64 - self.len as u16;
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}
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/// 0xFF21 | NR42 - Channel 4 Volume Envelope
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@ -927,37 +909,25 @@ impl Channel4 {
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}
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/// 0xFF23 | NR44 - Channel 4 Counter / Consecutive Selector and Restart
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pub(crate) fn set_frequency(&mut self, fs: &FrameSequencer, byte: u8) {
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let prev_le = self.freq.length_enable();
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pub(crate) fn set_frequency(&mut self, byte: u8) {
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self.freq = byte.into();
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obscure::nrx4::length_update(
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&mut self.freq,
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fs,
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&mut self.length_counter,
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&mut self.enabled,
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prev_le,
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);
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if self.freq.trigger() {
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self.enabled = true;
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if self.length_counter == 0 {
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self.length_counter = 64;
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}
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// FIXME: Frequency Timer reloaded?
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// reload envelope
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if self.freq.initial() {
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// Envelope behaviour during trigger event
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self.period_timer = self.envelope.period();
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//reload volume
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self.current_volume = self.envelope.init_vol();
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// LFSR reset
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// Length behaviour during trigger event
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if self.length_timer == 0 {
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self.length_timer = 64;
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}
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// LFSR behaviour during trigger event
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self.lf_shift = 0x7FFF;
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self.enabled = self.is_dac_enabled();
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if self.is_dac_enabled() {
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self.enabled = true;
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}
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}
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}
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@ -1002,39 +972,3 @@ impl Channel4 {
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code << 4
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}
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}
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mod obscure {
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pub(super) mod square {
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pub(crate) fn freq_timer_reload(freq_timer: u16, frequency: u16) -> u16 {
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(freq_timer & 0x0003) | (((2048 - frequency) * 4) & 0xFFFC)
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}
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}
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pub(super) mod nrx4 {
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use super::super::{FrameSequencer, NRx4};
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|
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/// Implements the obscure behaviour when writing to NRX4 under certain
|
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/// conditions
|
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///
|
||||
/// # Arguments
|
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/// * `freq_hi` - mutable reference to a channel's frequency high register
|
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/// * `fs` - reference to the APU's frame sequencer
|
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/// * `counter` - mutable reference to a channel's internal enabled flag
|
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/// * `prev_le` - what length_enable was before NRx4 was written with a new value
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pub(crate) fn length_update(
|
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freq: &mut impl NRx4,
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fs: &FrameSequencer,
|
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counter: &mut u16,
|
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enabled: &mut bool,
|
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prev_le: bool,
|
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) {
|
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if !fs.next_clocks_length() && !prev_le && freq.length_enable() && *counter != 0 {
|
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*counter -= 1;
|
||||
|
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if *counter == 0 && !freq.trigger() {
|
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*enabled = false;
|
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}
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
|
|
|||
|
|
@ -1,11 +1,5 @@
|
|||
use bitfield::bitfield;
|
||||
|
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pub(crate) trait NRx4 {
|
||||
fn trigger(&self) -> bool;
|
||||
fn length_enable(&self) -> bool;
|
||||
fn set_length_enable(&mut self, value: bool);
|
||||
}
|
||||
|
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pub(crate) mod ch1 {
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use super::bitfield;
|
||||
|
||||
|
|
@ -109,7 +103,7 @@ pub(super) mod ch3 {
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|||
}
|
||||
|
||||
pub(super) mod ch4 {
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use super::{bitfield, NRx4};
|
||||
use super::bitfield;
|
||||
|
||||
bitfield! {
|
||||
pub struct PolynomialCounter(u8);
|
||||
|
|
@ -183,21 +177,17 @@ pub(super) mod ch4 {
|
|||
bitfield! {
|
||||
pub struct Frequency(u8);
|
||||
impl Debug;
|
||||
_trigger, _: 7;
|
||||
_length_enable, _set_length_enable: 6;
|
||||
_initial, _: 7;
|
||||
_length_enable, _: 6;
|
||||
}
|
||||
|
||||
impl NRx4 for Frequency {
|
||||
fn trigger(&self) -> bool {
|
||||
self._trigger()
|
||||
}
|
||||
|
||||
fn length_enable(&self) -> bool {
|
||||
impl Frequency {
|
||||
pub(crate) fn length_enable(&self) -> bool {
|
||||
self._length_enable()
|
||||
}
|
||||
|
||||
fn set_length_enable(&mut self, value: bool) {
|
||||
self._set_length_enable(value);
|
||||
pub(crate) fn initial(&self) -> bool {
|
||||
self._initial()
|
||||
}
|
||||
}
|
||||
|
||||
|
|
@ -228,28 +218,24 @@ pub(super) mod ch4 {
|
|||
}
|
||||
|
||||
pub(super) mod common {
|
||||
use super::{bitfield, NRx4};
|
||||
use super::bitfield;
|
||||
|
||||
bitfield! {
|
||||
pub struct FrequencyHigh(u8);
|
||||
impl Debug;
|
||||
_trigger, _: 7;
|
||||
_length_enable, _set_length_enable: 6;
|
||||
_initial, _: 7;
|
||||
_length_enable, _: 6;
|
||||
pub freq_bits, set_freq_bits: 2, 0;
|
||||
}
|
||||
|
||||
impl NRx4 for FrequencyHigh {
|
||||
fn trigger(&self) -> bool {
|
||||
self._trigger()
|
||||
impl FrequencyHigh {
|
||||
pub(crate) fn initial(&self) -> bool {
|
||||
self._initial()
|
||||
}
|
||||
|
||||
fn length_enable(&self) -> bool {
|
||||
pub(crate) fn length_enable(&self) -> bool {
|
||||
self._length_enable()
|
||||
}
|
||||
|
||||
fn set_length_enable(&mut self, value: bool) {
|
||||
self._set_length_enable(value);
|
||||
}
|
||||
}
|
||||
|
||||
impl Copy for FrequencyHigh {}
|
||||
|
|
@ -571,10 +557,22 @@ pub(super) mod fs {
|
|||
};
|
||||
}
|
||||
|
||||
fn peek(&self) -> State {
|
||||
use State::*;
|
||||
|
||||
match (self.step + 1) % 8 {
|
||||
1 | 3 | 5 => Nothing,
|
||||
0 | 4 => Length,
|
||||
2 | 6 => LengthAndSweep,
|
||||
7 => Envelope,
|
||||
num => unreachable!("Step {} is invalid for the Frame Sequencer", num),
|
||||
}
|
||||
}
|
||||
|
||||
pub(crate) fn next_clocks_length(&self) -> bool {
|
||||
use State::*;
|
||||
|
||||
match self.state {
|
||||
match self.peek() {
|
||||
Length | LengthAndSweep => true,
|
||||
Nothing | Envelope => false,
|
||||
}
|
||||
|
|
|
|||
Loading…
Reference in New Issue