tek/src/device/sequencer/process.rs

use crate::prelude::*;
use super::*;

pub fn process (state: &mut Sequencer, _: &Client, scope: &ProcessScope) -> Control {

    // Get currently playing sequence
    let sequence = state.sequences.get_mut(state.sequence);
    if sequence.is_none() {
        return Control::Continue
    }
    let sequence = sequence.unwrap();

    // Prepare output buffer and transport
    let frames = scope.n_frames() as usize;
    let mut output: Vec<Option<Vec<Vec<u8>>>> = vec![None;frames];
    let transport = state.transport.query().unwrap();

    // If starting or stopping, send "all notes off":
    if transport.state != state.playing {
        all_notes_off(&mut output);
    }

    // Update time
    state.playing = transport.state;
    let frame = transport.pos.frame() as usize;
    let usecs = state.timebase.frame_to_usec(frame);
    let steps = usecs / state.timebase.usec_per_step(state.resolution as usize);
    let step  = steps % state.steps;
    let tick  = step * state.timebase.ppq() / state.resolution;

    // Play from sequence into output buffer
    if state.playing == TransportState::Rolling {
        play_from_sequence(
            &mut output,
            &sequence.notes,
            &state.timebase,
            state.steps,
            state.resolution,
            frame,
            frames,
        );
    }

    // Play from input to monitor, and record into sequence.
    monitor_and_record(
        &scope,
        &mut output,
        &mut sequence.notes,
        &state.midi_in,
        &mut state.notes_on,
        state.playing,
        state.monitoring,
        state.recording,
        tick as u32
    );

    // Write to port from output buffer
    // (containing notes from sequence and/or monitor)
    let mut writer = state.midi_out.writer(scope);
    for time in 0..scope.n_frames() {
        if let Some(Some(frame)) = output.get_mut(time as usize) {
            for event in frame.iter() {
                writer.write(&::jack::RawMidi { time, bytes: &event })
                    .expect(&format!("{event:?}"));
            }
        }
    }

    Control::Continue
}

type MIDIChunk = [Option<Vec<Vec<u8>>>];

/// Add "all notes off" to the start of a buffer.
fn all_notes_off (output: &mut MIDIChunk) {
    output[0] = Some(vec![]);
    if let Some(Some(frame)) = output.get_mut(0) {
        let mut buf = vec![];
        let msg = MidiMessage::Controller { controller: 123.into(), value: 0.into() };
        let evt = LiveEvent::Midi { channel: 0.into(), message: msg };
        evt.write(&mut buf).unwrap();
        frame.push(buf);
    }
}

fn play_from_sequence (
    output:     &mut MIDIChunk,
    sequence:   &PhraseData,
    timebase:   &Arc<Timebase>,
    steps:      usize,
    resolution: usize,
    frame:      usize,
    frames:     usize,
) {
    let quant = timebase.frames_per_beat() as usize * steps / resolution;
    let ticks = timebase.frames_to_ticks(frame, frame + frames, quant);
    for (time, tick) in ticks.iter() {
        if let Some(events) = sequence.get(&(*tick as u32)) {
            for message in events.iter() {
                let mut buf = vec![];
                let channel = 0.into();
                let message = *message;
                LiveEvent::Midi { channel, message }.write(&mut buf).unwrap();
                let t = *time as usize;
                if output[t].is_none() {
                    output[t] = Some(vec![]);
                }
                if let Some(Some(frame)) = output.get_mut(t) {
                    frame.push(buf);
                }
            }
        }
    }
}

fn monitor_and_record (
    scope:      &ProcessScope,
    output:     &mut MIDIChunk,
    sequence:   &mut PhraseData,
    midi_in:    &Port<MidiIn>,
    notes_on:   &mut Vec<bool>,
    playing:    TransportState,
    monitoring: bool,
    recording:  bool,
    tick:       u32,
) {
    for event in midi_in.iter(scope) {
        let msg  = midly::live::LiveEvent::parse(event.bytes).unwrap();
        match msg {
            midly::live::LiveEvent::Midi { channel: _, message } => match message {
                midly::MidiMessage::NoteOn { key, vel: _ } => {
                    notes_on[key.as_int() as usize] = true;
                    if monitoring {
                        let t = event.time as usize;
                        if output[t].is_none() {
                            output[t] = Some(vec![]);
                        }
                        if let Some(Some(frame)) = output.get_mut(t) {
                            frame.push(event.bytes.into())
                        }
                    }
                    if recording && playing == TransportState::Rolling {
                        let contains = sequence.contains_key(&tick);
                        if contains {
                            sequence.get_mut(&tick).unwrap().push(message.clone());
                        } else {
                            sequence.insert(tick, vec![message.clone()]);
                        }
                    }
                },
                midly::MidiMessage::NoteOff { key, vel: _ } => {
                    notes_on[key.as_int() as usize] = false;
                    if monitoring {
                        let t = event.time as usize;
                        if output[t].is_none() {
                            output[t] = Some(vec![]);
                        }
                        if let Some(Some(frame)) = output.get_mut(t) {
                            frame.push(event.bytes.into())
                        }
                    }
                    if recording && playing == TransportState::Rolling {
                        let contains = sequence.contains_key(&tick);
                        if contains {
                            sequence.get_mut(&tick).unwrap().push(message.clone());
                        } else {
                            sequence.insert(tick, vec![message.clone()]);
                        }
                    }
                },
                _ => {}
            },
            _ => {}
        }
    }
}