paoda
/
gb
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

feat(snd): implement sweep behaviour

This commit is contained in:
Rekai Nyangadzayi Musuka 2021-06-23 23:51:30 -05:00
parent 29237f0a2c
commit d2e37da2b0
1 changed files with 148 additions and 77 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

225
src/sound.rs
View File

@ -33,73 +33,16 @@ impl Sound {
match self.frame_seq_state {
Step0Length => todo!(),
Step2LengthAndSweep => todo!(),
Step4Length => todo!(),
Step6LengthAndSweep => todo!(),
Step7VolumeEnvelope => {
use EnvelopeDirection::*;
// Channels 1, 2 and 4 have Volume Envelopes
if self.ch1.envelope.sweep_count() != 0 {
if self.ch1.period_timer > 0 {
self.ch1.period_timer -= 1;
}
if self.ch1.period_timer == 0 {
self.ch1.period_timer = self.ch1.envelope.sweep_count();
match self.ch1.envelope.direction() {
Decrease if self.ch1.current_volume > 0x00 => {
self.ch1.current_volume -= 1
}
Increase if self.ch1.current_volume < 0x0F => {
self.ch1.current_volume += 1
}
_ => {}
}
}
}
if self.ch2.envelope.sweep_count() != 0 {
if self.ch2.period_timer > 0 {
self.ch2.period_timer -= 1;
}
if self.ch2.period_timer == 0 {
self.ch2.period_timer = self.ch2.envelope.sweep_count();
match self.ch2.envelope.direction() {
Decrease if self.ch2.current_volume > 0x00 => {
self.ch2.current_volume -= 1
}
Increase if self.ch2.current_volume < 0x0F => {
self.ch2.current_volume += 1
}
_ => {}
}
}
}
if self.ch4.envelope.sweep_count() != 0 {
if self.ch4.period_timer > 0 {
self.ch4.period_timer -= 1;
}
if self.ch4.period_timer == 0 {
self.ch4.period_timer = self.ch4.envelope.sweep_count();
match self.ch4.envelope.direction() {
Decrease if self.ch4.current_volume > 0x00 => {
self.ch4.current_volume -= 1
}
Increase if self.ch4.current_volume < 0x0F => {
self.ch4.current_volume += 1
}
_ => {}
}
}
}
Step2LengthAndSweep => {
// Handle Length
self.handle_sweep();
}
Step4Length => todo!(),
Step6LengthAndSweep => {
// Handle Length
self.handle_sweep();
}
Step7VolumeEnvelope => self.handle_volume(),
Step1Nothing | Step3Nothing | Step5Nothing => {}
};
}
@ -107,6 +50,84 @@ impl Sound {
self.div_prev = Some(bit_5);
}
fn handle_sweep(&mut self) {
if self.ch1.sweep_timer > 0 {
self.ch1.sweep_timer -= 1;
}
if self.ch1.sweep_timer == 0 {
self.ch1.sweep_timer = if self.ch1.sweep.time() != 0 {
self.ch1.sweep.time()
} else {
8
};
if self.ch1.sweep_enabled && self.ch1.sweep.time() != 0 {
let new_freq = self.ch1.calc_sweep_freq();
if new_freq <= 2047 && self.ch1.sweep.shift_count() != 0 {
self.ch1.set_frequency(new_freq);
self.ch1.shadow_freq = new_freq & 0x07FF;
let _ = self.ch1.calc_sweep_freq();
}
}
}
}
fn handle_volume(&mut self) {
use EnvelopeDirection::*;
// Channels 1, 2 and 4 have Volume Envelopes
if self.ch1.envelope.sweep_count() != 0 {
if self.ch1.period_timer > 0 {
self.ch1.period_timer -= 1;
}
if self.ch1.period_timer == 0 {
self.ch1.period_timer = self.ch1.envelope.sweep_count();
match self.ch1.envelope.direction() {
Decrease if self.ch1.current_volume > 0x00 => self.ch1.current_volume -= 1,
Increase if self.ch1.current_volume < 0x0F => self.ch1.current_volume += 1,
_ => {}
}
}
}
if self.ch2.envelope.sweep_count() != 0 {
if self.ch2.period_timer > 0 {
self.ch2.period_timer -= 1;
}
if self.ch2.period_timer == 0 {
self.ch2.period_timer = self.ch2.envelope.sweep_count();
match self.ch2.envelope.direction() {
Decrease if self.ch2.current_volume > 0x00 => self.ch2.current_volume -= 1,
Increase if self.ch2.current_volume < 0x0F => self.ch2.current_volume += 1,
_ => {}
}
}
}
if self.ch4.envelope.sweep_count() != 0 {
if self.ch4.period_timer > 0 {
self.ch4.period_timer -= 1;
}
if self.ch4.period_timer == 0 {
self.ch4.period_timer = self.ch4.envelope.sweep_count();
match self.ch4.envelope.direction() {
Decrease if self.ch4.current_volume > 0x00 => self.ch4.current_volume -= 1,
Increase if self.ch4.current_volume < 0x0F => self.ch4.current_volume += 1,
_ => {}
}
}
}
}
}
#[derive(Debug, Clone, Copy)]
@ -160,8 +181,8 @@ bitfield! {
pub struct FrequencyHigh(u8);
impl Debug;
initial, _set_initial: 7;
pub from into FrequencyType, get_freq_type, set_freq_type: 6;
pub _, set_freq_bits: 2, 0;
from into FrequencyType, freq_type, set_freq_type: 6, 6;
freq_bits, set_freq_bits: 2, 0;
}
impl FrequencyHigh {
@ -274,6 +295,11 @@ pub(crate) struct Channel1 {
// Envelope Functionality
period_timer: u8,
current_volume: u8,
// Sweep Functionality
sweep_timer: u8,
shadow_freq: u16,
sweep_enabled: bool,
}
impl Channel1 {
@ -286,10 +312,55 @@ impl Channel1 {
pub(crate) fn set_freq_hi(&mut self, byte: u8) {
self.freq_hi = byte.into();
// Envelope Behaviour during trigger event
if self.freq_hi.initial() {
self.period_timer = self.envelope.sweep_count();
self.current_volume = self.envelope.init_vol();
}
// Sweep behaviour during trigger event
self.shadow_freq = self.frequency();
self.sweep_timer = if self.sweep.time() != 0 {
self.sweep.time()
} else {
8
};
if self.sweep.time() != 0 || self.sweep.shift_count() != 0 {
self.sweep_enabled = true;
}
if self.sweep.shift_count() != 0 {
let _ = self.calc_sweep_freq();
}
}
fn calc_sweep_freq(&mut self) -> u16 {
use SweepDirection::*;
let shifted_shadow_freq = self.shadow_freq >> self.sweep.shift_count();
let new_freq = match self.sweep.direction() {
Increase => self.shadow_freq + shifted_shadow_freq,
Decrease => self.shadow_freq - shifted_shadow_freq,
};
// Overflow check
if new_freq > 2047 {
todo!("Frequency failed the overflow check. Disable the channel");
}
new_freq
}
fn set_frequency(&mut self, word: u16) {
let freq_bits = word & 0x07FF;
self.freq_lo = (freq_bits & 0x00FF) as u8;
self.freq_hi
.set_freq_bits(((freq_bits & 0x0700) >> 8) as u8);
}
fn frequency(&self) -> u16 {
(self.freq_hi.freq_bits() as u16) << 8 | self.freq_lo as u16
}
}
@ -297,7 +368,7 @@ bitfield! {
pub struct Sweep(u8);
impl Debug;
time, set_time: 6, 4;
from into SweepChange, change, set_change: 3, 3;
from into SweepDirection, direction, set_direction: 3, 3;
shift_count, set_shift_count: 2, 0;
}
@ -327,23 +398,23 @@ impl From<Sweep> for u8 {
}
#[derive(Debug, Clone, Copy)]
pub(crate) enum SweepChange {
Additive = 0,
Subtractive = 1,
pub(crate) enum SweepDirection {
Increase = 0,
Decrease = 1,
}
impl From<u8> for SweepChange {
impl From<u8> for SweepDirection {
fn from(byte: u8) -> Self {
match byte & 0x01 {
0b00 => Self::Additive,
0b01 => Self::Subtractive,
0b00 => Self::Increase,
0b01 => Self::Decrease,
_ => unreachable!("{:04X} is not a valid value for SweepChange", byte),
}
}
}
impl From<SweepChange> for u8 {
fn from(change: SweepChange) -> Self {
impl From<SweepDirection> for u8 {
fn from(change: SweepDirection) -> Self {
change as u8
}
}