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feat(apu): add timer/sequencer/LFSR fields for channel output tracking

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This commit is contained in:
Sergey Cherkasov
2026-03-13 16:06:37 +03:00
parent 6f81eb4b08
commit cd0a99a813
4 changed files with 66 additions and 1 deletions
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19
src/native_core/apu/api.rs
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@@ -34,6 +34,12 @@ impl Apu {
frame_reset_delay: 0,
pending_frame_mode_5step: false,
pending_frame_irq_inhibit: false,
pulse_timer_counter: [0; 2],
pulse_duty_step: [0; 2],
triangle_timer_counter: 0,
triangle_step: 0,
noise_timer_counter: 0,
noise_lfsr: 1, // LFSR initialized to 1 per NES hardware
}
}
@@ -227,6 +233,13 @@ impl Apu {
out.push(self.frame_reset_delay);
out.push(u8::from(self.pending_frame_mode_5step));
out.push(u8::from(self.pending_frame_irq_inhibit));
out.extend_from_slice(&self.pulse_timer_counter[0].to_le_bytes());
out.extend_from_slice(&self.pulse_timer_counter[1].to_le_bytes());
out.extend_from_slice(&self.pulse_duty_step);
out.extend_from_slice(&self.triangle_timer_counter.to_le_bytes());
out.push(self.triangle_step);
out.extend_from_slice(&self.noise_timer_counter.to_le_bytes());
out.extend_from_slice(&self.noise_lfsr.to_le_bytes());
}
pub fn load_state_tail(&mut self, state: ApuStateTail) {
@@ -260,5 +273,11 @@ impl Apu {
self.frame_reset_delay = state.frame_reset_delay;
self.pending_frame_mode_5step = state.pending_frame_mode_5step;
self.pending_frame_irq_inhibit = state.pending_frame_irq_inhibit;
self.pulse_timer_counter = state.pulse_timer_counter;
self.pulse_duty_step = [state.pulse_duty_step[0] & 0x07, state.pulse_duty_step[1] & 0x07];
self.triangle_timer_counter = state.triangle_timer_counter;
self.triangle_step = state.triangle_step & 0x1F;
self.noise_timer_counter = state.noise_timer_counter;
self.noise_lfsr = if state.noise_lfsr == 0 { 1 } else { state.noise_lfsr };
}
}

15
src/native_core/apu/types.rs
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@@ -48,6 +48,15 @@ pub struct Apu {
pub(crate) frame_reset_delay: u8,
pub(crate) pending_frame_mode_5step: bool,
pub(crate) pending_frame_irq_inhibit: bool,
// Pulse channel timers & duty sequencers
pub(crate) pulse_timer_counter: [u16; 2],
pub(crate) pulse_duty_step: [u8; 2],
// Triangle channel timer & sequencer
pub(crate) triangle_timer_counter: u16,
pub(crate) triangle_step: u8,
// Noise channel timer & LFSR
pub(crate) noise_timer_counter: u16,
pub(crate) noise_lfsr: u16,
}
pub struct ApuStateTail {
@@ -81,6 +90,12 @@ pub struct ApuStateTail {
pub frame_reset_delay: u8,
pub pending_frame_mode_5step: bool,
pub pending_frame_irq_inhibit: bool,
pub pulse_timer_counter: [u16; 2],
pub pulse_duty_step: [u8; 2],
pub triangle_timer_counter: u16,
pub triangle_step: u8,
pub noise_timer_counter: u16,
pub noise_lfsr: u16,
}
impl Default for Apu {

31
src/native_core/bus/state.rs
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@@ -112,6 +112,31 @@ impl NativeBus {
let frame_reset_delay = sio::take_u8(data, &mut cursor, BUS_STATE_CTX)?;
let pending_frame_mode_5step = sio::take_u8(data, &mut cursor, BUS_STATE_CTX)? != 0;
let pending_frame_irq_inhibit = sio::take_u8(data, &mut cursor, BUS_STATE_CTX)? != 0;
let pulse_timer_counter = [
u16::from_le_bytes([
sio::take_u8(data, &mut cursor, BUS_STATE_CTX)?,
sio::take_u8(data, &mut cursor, BUS_STATE_CTX)?,
]),
u16::from_le_bytes([
sio::take_u8(data, &mut cursor, BUS_STATE_CTX)?,
sio::take_u8(data, &mut cursor, BUS_STATE_CTX)?,
]),
];
let mut pulse_duty_step = [0u8; 2];
pulse_duty_step.copy_from_slice(sio::take_exact(data, &mut cursor, 2, BUS_STATE_CTX)?);
let triangle_timer_counter = u16::from_le_bytes([
sio::take_u8(data, &mut cursor, BUS_STATE_CTX)?,
sio::take_u8(data, &mut cursor, BUS_STATE_CTX)?,
]);
let triangle_step = sio::take_u8(data, &mut cursor, BUS_STATE_CTX)?;
let noise_timer_counter = u16::from_le_bytes([
sio::take_u8(data, &mut cursor, BUS_STATE_CTX)?,
sio::take_u8(data, &mut cursor, BUS_STATE_CTX)?,
]);
let noise_lfsr = u16::from_le_bytes([
sio::take_u8(data, &mut cursor, BUS_STATE_CTX)?,
sio::take_u8(data, &mut cursor, BUS_STATE_CTX)?,
]);
self.apu.load_state_tail(ApuStateTail {
frame_cycle,
frame_mode_5step,
@@ -143,6 +168,12 @@ impl NativeBus {
frame_reset_delay,
pending_frame_mode_5step,
pending_frame_irq_inhibit,
pulse_timer_counter,
pulse_duty_step,
triangle_timer_counter,
triangle_step,
noise_timer_counter,
noise_lfsr,
});
let mapper_len = sio::take_u32(data, &mut cursor, BUS_STATE_CTX)? as usize;
let mapper_state = sio::take_exact(data, &mut cursor, mapper_len, BUS_STATE_CTX)?;

2
src/runtime/constants.rs
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@@ -1,6 +1,6 @@
pub const FRAME_WIDTH: usize = 256;
pub const FRAME_HEIGHT: usize = 240;
pub const FRAME_RGBA_BYTES: usize = FRAME_WIDTH * FRAME_HEIGHT * 4;
pub const SAVE_STATE_VERSION: u32 = 1;
pub const SAVE_STATE_VERSION: u32 = 2;
pub(crate) const SAVE_STATE_MAGIC: &[u8; 8] = b"NESRT001";