Struct Synth 

pub struct Synth { /* private fields */ }

The synthesizer: voices, sequencer and a copy of the cart’s audio data.

Implementations

impl Synth

pub fn new(sample_rate: f32) -> Self

pub fn load(&mut self, sfx: Vec<Sfx>, music: Vec<MusicPattern>)

Replace the audio data (called when a cart starts or assets change).

pub fn stop_all(&mut self)

Stop all voices and the sequencer.

pub fn play_sfx(&mut self, n: i32, channel: i32)

Play SFX n. channel < 0 picks a free channel (preferring ones not used by music); n < 0 with a valid channel stops that channel.

pub fn play_music( &mut self, n: i32, fade_duration: i32, channel_mask: i32, token: i32, ) -> i32

Start music at pattern n (mints and returns a nonzero play-token) or, when n < 0, stop. A start is refused — returns 0 — while a song is already playing and not fading out. A stop acts only when token <= 0 (unconditional) or token equals the current song’s play-token. channel_mask bits 0-3 mark which channels are reserved for music; auto-routed sfx will skip those channels while music is playing.

pub fn stop_music(&mut self)

pub fn playing_pattern(&self) -> Option<usize>

Index of the playing music pattern, if any.

pub fn next_sample(&mut self) -> f32

Render one mono sample at the device rate.

The synth core runs at INTERNAL_RATE; this resamples up to the device rate with linear interpolation, then applies a two-pole reconstruction low-pass to suppress interpolation imaging and match PICO-8’s clean top end. Calling it N times advances device time by N / sample_rate seconds.

pub fn channel_sfx(&self) -> [Option<usize>; 4]

Which SFX index is playing on each channel (for editor UI).

pub fn channel_step(&self) -> [Option<usize>; 4]

Which step each channel’s voice is currently sounding (for editor playheads); None when the channel is idle.