gb-emu/gb-vst/src/lib.rs

use async_ringbuf::AsyncHeapConsumer;
use futures::executor;
use gb_emu_lib::{
    connect::{AudioOutput, CpuSaveState, DownsampleType, EmulatorMessage, JoypadButtons, RomFile},
    EmulatorCore,
};
use nih_plug::prelude::*;
use nih_plug::{midi::MidiResult::Basic, params::persist::PersistentField};
use std::sync::{
    mpsc::{channel, Receiver, Sender},
    Arc, Mutex,
};
use ui::{Emulator, EmulatorRenderer};

mod ui;

#[derive(Default)]
struct SaveStateParam {
    state: Arc<Mutex<Option<CpuSaveState<[u8; 4]>>>>,
}

impl PersistentField<'_, Option<CpuSaveState<[u8; 4]>>> for SaveStateParam {
    fn set(&self, new_value: Option<CpuSaveState<[u8; 4]>>) {
        *self.state.lock().unwrap() = new_value;
    }

    fn map<F, R>(&self, f: F) -> R
    where
        F: Fn(&Option<CpuSaveState<[u8; 4]>>) -> R,
    {
        f(&self.state.lock().unwrap())
    }
}

#[derive(Params, Default)]
struct EmuParams {
    #[persist = "save_state"]
    last_save_state: SaveStateParam,
}

struct EmuVars {
    rx: AsyncHeapConsumer<[f32; 2]>,
    sender: Sender<EmulatorMessage>,
    emulator_core: EmulatorCore<[u8; 4]>,
}

#[derive(Default)]
pub struct GameboyEmu {
    vars: Option<EmuVars>,
    frame_receiver: Arc<FrameReceiver>,
    key_handler: Arc<JoypadSender>,
    params: Arc<EmuParams>,
}

type FrameReceiver = Mutex<Option<Receiver<Vec<[u8; 4]>>>>;
type JoypadSender = Mutex<Option<Sender<(JoypadButtons, bool)>>>;

const FRAMES_TO_BUFFER: usize = 1;
const INCLUDE_BOOTROM: bool = false;
const DOWNSAMPLE_TYPE: DownsampleType = DownsampleType::ZeroOrderHold;

const ROM: &[u8; 65536] = include_bytes!("../../test-roms/mGB1_3_0.gb");
const BOOTROM: &[u8; 256] = include_bytes!("../../bootrom/dmg_boot.bin");

impl Plugin for GameboyEmu {
    const NAME: &'static str = "Gameboy";

    const VENDOR: &'static str = "Alex Janka";

    const URL: &'static str = "alexjanka.com";

    const EMAIL: &'static str = "alex@alexjanka.com";

    const VERSION: &'static str = "0.1";

    const AUDIO_IO_LAYOUTS: &'static [AudioIOLayout] = &[AudioIOLayout {
        main_input_channels: None,
        main_output_channels: NonZeroU32::new(2),

        aux_input_ports: &[],
        aux_output_ports: &[],

        // Individual ports and the layout as a whole can be named here. By default these names
        // are generated as needed. This layout will be called 'Stereo', while the other one is
        // given the name 'Mono' based no the number of input and output channels.
        names: PortNames::const_default(),
    }];

    const MIDI_INPUT: MidiConfig = MidiConfig::MidiCCs;
    const SAMPLE_ACCURATE_AUTOMATION: bool = true;

    type SysExMessage = ();

    type BackgroundTask = ();

    fn params(&self) -> Arc<dyn Params> {
        self.params.clone()
    }

    fn process(
        &mut self,
        buffer: &mut Buffer,
        _: &mut AuxiliaryBuffers,
        _c: &mut impl ProcessContext<Self>,
    ) -> ProcessStatus {
        while let Some(event) = _c.next_event() {
            if let Some(Basic(_midi)) = event.as_midi() {}
        }
        if let Some(ref mut vars) = self.vars {
            if buffer.channels() != 2 {
                panic!()
            }
            for sample in buffer.iter_samples() {
                if vars.rx.is_empty() {
                    vars.emulator_core.run_until_buffer_full();
                }
                if let Some(a) = executor::block_on(vars.rx.pop()) {
                    for (source, dest) in a.iter().zip(sample) {
                        *dest = *source;
                    }
                }
            }
            vars.emulator_core.run_until_buffer_full();
        }
        self.update_save_state();
        ProcessStatus::KeepAlive
    }

    fn editor(&self, _: AsyncExecutor<Self>) -> Option<Box<dyn Editor>> {
        Some(Box::new(Emulator::new(
            self.frame_receiver.clone(),
            self.key_handler.clone(),
        )))
    }

    fn initialize(
        &mut self,
        _audio_io_layout: &AudioIOLayout,
        buffer_config: &BufferConfig,
        _context: &mut impl InitContext<Self>,
    ) -> bool {
        if let Some(ref mut vars) = self.vars {
            let (output, rx) = AudioOutput::new(
                buffer_config.sample_rate,
                false,
                FRAMES_TO_BUFFER,
                DOWNSAMPLE_TYPE,
            );

            vars.emulator_core.replace_output(output);
            vars.rx = rx;
        } else {
            let bootrom = if INCLUDE_BOOTROM {
                Some(RomFile::Raw(BOOTROM.to_vec()))
            } else {
                None
            };

            let rom = RomFile::Raw(ROM.to_vec());

            let (sender, receiver) = channel::<EmulatorMessage>();

            let (output, rx) = AudioOutput::new(
                buffer_config.sample_rate,
                false,
                FRAMES_TO_BUFFER,
                DOWNSAMPLE_TYPE,
            );

            let (renderer, frame_receiver, key_handler) = EmulatorRenderer::new();

            *self.frame_receiver.lock().unwrap() = Some(frame_receiver);
            *self.key_handler.lock().unwrap() = Some(key_handler);

            let window = Box::new(renderer);

            let mut emulator_core =
                if let Some(state) = self.params.last_save_state.state.lock().unwrap().take() {
                    EmulatorCore::from_save_state(state, rom, receiver, window, output)
                } else {
                    let options = gb_emu_lib::Options::new(rom)
                        .with_bootrom(bootrom)
                        .force_no_save();

                    EmulatorCore::init(receiver, options, window, output, None)
                };
            emulator_core.run_until_buffer_full();

            self.vars = Some(EmuVars {
                rx,
                sender,
                emulator_core,
            });
            self.update_save_state();
        }

        true
    }

    fn deactivate(&mut self) {
        nih_log!("deactivating");
        self.update_save_state();
        if let Some(ref mut vars) = self.vars {
            match vars.sender.send(EmulatorMessage::Stop) {
                Ok(_) => self.vars = None,
                Err(e) => nih_log!("error {e} sending message to emulator"),
            }
        }
    }
}

impl GameboyEmu {
    fn update_save_state(&mut self) {
        if let Some(ref mut vars) = self.vars {
            *self.params.last_save_state.state.lock().unwrap() =
                Some(vars.emulator_core.get_save_state());
        }
    }
}

impl Vst3Plugin for GameboyEmu {
    const VST3_CLASS_ID: [u8; 16] = *b"alexjankagbemula";

    const VST3_SUBCATEGORIES: &'static [Vst3SubCategory] =
        &[Vst3SubCategory::Instrument, Vst3SubCategory::Synth];
}

nih_export_vst3!(GameboyEmu);