diff --git a/src/main.rs b/src/main.rs
index 91bc484..6ce0466 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -12,6 +12,11 @@ mod halfwidth;
 use core::fmt::Write;
 
 use gba::prelude::*;
+use voladdress::{Safe, VolAddress};
+
+#[macro_use]
+extern crate build_const;
+build_const!("lsdpack_bc");
 
 #[allow(unused_must_use)]
 #[panic_handler]
@@ -53,18 +58,379 @@ fn panic_handler(info: &core::panic::PanicInfo) -> ! {
 static FRAME_KEYS: GbaCell<KeyInput> = GbaCell::new(KeyInput::new());
 
 #[link_section = ".iwram"]
-extern "C" fn irq_handler(_: IrqBits) {
-    // We'll read the keys during vblank and store it for later.
-    FRAME_KEYS.write(KEYINPUT.read());
+static mut LSDJ_SONGS: Lsdpack = Lsdpack::new(&LSDPACK_DATA, &LSDPACK_SONG_POSITIONS);
+
+#[link_section = ".iwram"]
+extern "C" fn irq_handler(bits: IrqBits) {
+    if bits.vblank() {
+        // We'll read the keys during vblank and store it for later.
+        FRAME_KEYS.write(KEYINPUT.read());
+    }
+    if bits.timer0() {
+        unsafe {
+            LSDJ_SONGS.tick();
+        }
+    }
+}
+
+#[allow(dead_code)]
+#[repr(u8)]
+#[derive(Copy, Clone)]
+enum LsdpackCmd {
+    // special commands (not just plain register writes)
+    EndTick = 0,
+    SampleStart = 1,
+    SongStop = 2,
+    NextBank = 3,
+    AmpDecPu0 = 4,
+    AmpDecPu1 = 5,
+    AmpDecNoi = 6,
+    PitchPu0 = 7,
+    PitchPu1 = 8,
+    PitchWav = 9,
+    SampleNext = 10,
+
+    _Invalid0B = 0x0b,
+    _Invalid0C = 0x0c,
+    _Invalid0D = 0x0d,
+    _Invalid0E = 0x0e,
+    _Invalid0F = 0x0f,
+
+    // ch1 pulse
+    Pu0Sweep = 0x10,
+    Pu0LengthWave = 0x11,
+    Pu0Env = 0x12,
+    Pu0PitchLsb = 0x13,
+    Pu0PitchMsb = 0x14,
+
+    _Invalid15 = 0x15,
+
+    // ch2 pulse
+    Pu1LengthWave = 0x16,
+    Pu1Env = 0x17,
+    Pu1PitchLsb = 0x18,
+    Pu1PitchMsb = 0x19,
+
+    // ch3 wave
+    WavOnOff = 0x1a,
+    WavLength = 0x1b,
+    WavEnv = 0x1c,
+    WavPitchLsb = 0x1d,
+    WavPitchMsb = 0x1e,
+
+    _Invalid1F = 0x1f,
+
+    // ch4 noise
+    NoiLength = 0x20,
+    NoiEnv = 0x21,
+    NoiWave = 0x22,
+    NoiTrig = 0x23,
+
+    // general
+    ChannelVolume = 0x24,
+    Pan = 0x25,
+    SoundOffOn = 0x26,
+
+    _Invalid27 = 0x27,
+    _Invalid28 = 0x28,
+    _Invalid29 = 0x29,
+    _Invalid2A = 0x2a,
+    _Invalid2B = 0x2b,
+    _Invalid2C = 0x2c,
+    _Invalid2D = 0x2d,
+    _Invalid2E = 0x2e,
+    _Invalid2F = 0x2f,
+
+    // wave pattern
+    WavePattern0 = 0x30,
+    WavePattern1 = 0x31,
+    WavePattern2 = 0x32,
+    WavePattern3 = 0x33,
+    WavePattern4 = 0x34,
+    WavePattern5 = 0x35,
+    WavePattern6 = 0x36,
+    WavePattern7 = 0x37,
+    WavePattern8 = 0x38,
+    WavePattern9 = 0x39,
+    WavePatternA = 0x3a,
+    WavePatternB = 0x3b,
+    WavePatternC = 0x3c,
+    WavePatternD = 0x3d,
+    WavePatternE = 0x3e,
+    WavePatternF = 0x3f,
+}
+
+impl From<u8> for LsdpackCmd {
+    fn from(val: u8) -> Self {
+        assert!(val <= 0x3f);
+        unsafe { core::mem::transmute(val) }
+    }
+}
+
+struct Lsdpack {
+    data: &'static [u8],
+    setlist: &'static [usize],
+    current_ptr: usize,
+    sample_ptr: usize,
+    repeat_cmd: Option<LsdpackCmd>,
+    repeat_cmd_counter: usize,
+    sample_pitch: u16,
+    stopped: bool,
+}
+
+impl Lsdpack {
+    const fn new(data: &'static [u8], setlist: &'static [usize]) -> Self {
+        Self {
+            data,
+            setlist,
+            current_ptr: setlist[0],
+            sample_ptr: 0,
+            repeat_cmd: None,
+            repeat_cmd_counter: 0,
+            sample_pitch: 0,
+            stopped: false,
+        }
+    }
+}
+
+impl Lsdpack {
+    fn play_song(&mut self, song_id: usize) {
+        self.current_ptr = self.setlist[song_id];
+        self.sample_ptr = 0;
+        self.repeat_cmd = None;
+        self.repeat_cmd_counter = 0;
+        self.stopped = false;
+    }
+
+    #[link_section = ".iwram"]
+    fn next_byte(&mut self) -> u8 {
+        let val = self.data[self.current_ptr];
+        self.current_ptr += 1;
+        val
+    }
+
+    #[link_section = ".iwram"]
+    fn write_next_samples(&mut self) {
+        let ptr = self.sample_ptr;
+        self.sample_ptr += 16;
+        //let sound_enabled = SOUND_ENABLED.read();
+        //SOUND_ENABLED.write(sound_enabled.with_wave_playing(false));
+        let lrvol = LEFT_RIGHT_VOLUME.read();
+        LEFT_RIGHT_VOLUME.write(lrvol.with_wave_left(false).with_wave_right(false));
+        WAVE_BANK.write(WaveBank::new().with_enabled(false));
+        WAVE_RAM.index(0).write(u32::from_le_bytes(
+            TryFrom::try_from(&self.data[ptr..ptr + 4]).unwrap(),
+        ));
+        WAVE_RAM.index(1).write(u32::from_le_bytes(
+            TryFrom::try_from(&self.data[ptr + 4..ptr + 8]).unwrap(),
+        ));
+        WAVE_RAM.index(2).write(u32::from_le_bytes(
+            TryFrom::try_from(&self.data[ptr + 8..ptr + 12]).unwrap(),
+        ));
+        WAVE_RAM.index(3).write(u32::from_le_bytes(
+            TryFrom::try_from(&self.data[ptr + 12..ptr + 16]).unwrap(),
+        ));
+        WAVE_BANK.write(WaveBank::new().with_enabled(true));
+        //SOUND_ENABLED.write(sound_enabled);
+        LEFT_RIGHT_VOLUME.write(lrvol);
+        WAVE_FREQ.write(WaveFrequency::new().with_length(self.sample_pitch));
+    }
+
+    #[link_section = ".iwram"]
+    fn tick(&mut self) {
+        if self.stopped {
+            return;
+        }
+        let mut ongoing = true;
+        while ongoing {
+            if let Some(cmd) = self.repeat_cmd {
+                if self.repeat_cmd_counter > 0 {
+                    self.repeat_cmd_counter -= 1;
+                    ongoing = self.apply_cmd(cmd);
+                    continue;
+                } else {
+                    self.repeat_cmd = None;
+                }
+            }
+            let cmd = self.load_new_cmd_from_stream();
+            ongoing = self.apply_cmd(cmd);
+        }
+    }
+
+    #[link_section = ".iwram"]
+    fn load_new_cmd_from_stream(&mut self) -> LsdpackCmd {
+        let cmd = self.next_byte();
+        if cmd & 0x40 != 0 {
+            self.repeat_cmd = Some((cmd & 0x3f).into());
+            self.repeat_cmd_counter = self.next_byte() as usize;
+            self.repeat_cmd.unwrap()
+        } else {
+            cmd.into()
+        }
+    }
+
+    #[link_section = ".iwram"]
+    fn write_lsb<T>(&mut self, voladdr: VolAddress<T, Safe, Safe>) {
+        let voladdr = unsafe { voladdr.cast::<u16>() };
+        voladdr.write((voladdr.read() & 0xFF00) | (self.next_byte() as u16));
+    }
+
+    #[link_section = ".iwram"]
+    fn write_msb<T>(&mut self, voladdr: VolAddress<T, Safe, Safe>) {
+        let voladdr = unsafe { voladdr.cast::<u16>() };
+        voladdr.write((voladdr.read() & 0xFF) | ((self.next_byte() as u16) << 8));
+    }
+
+    #[link_section = ".iwram"]
+    fn write_u16le<T>(&mut self, voladdr: VolAddress<T, Safe, Safe>) {
+        let voladdr = unsafe { voladdr.cast::<u16>() };
+        let halfword = u16::from_le_bytes([self.next_byte(), self.next_byte()]);
+        voladdr.write(halfword);
+    }
+
+    #[link_section = ".iwram"]
+    fn apply_cmd(&mut self, cmd: LsdpackCmd) -> bool {
+        use LsdpackCmd::*;
+        match cmd {
+            // special commands:
+            EndTick => return false,
+            SampleStart => {
+                let _sample_bank = self.next_byte(); // TODO?
+                self.sample_ptr = u16::from_le_bytes([self.next_byte(), self.next_byte()]) as usize;
+                // big endian order for the pitch here? don't know why
+                self.sample_pitch = u16::from_be_bytes([self.next_byte(), self.next_byte()]);
+                self.write_next_samples(); // also writes pitch
+            }
+            SongStop => {
+                self.stopped = true;
+                return false;
+            }
+            NextBank => { /* lol */ }
+            AmpDecPu0 => {
+                let base = TONE1_PATTERN.read();
+                TONE1_PATTERN.write(
+                    base.with_volume(0)
+                        .with_step_increasing(true)
+                        .with_step_time(1),
+                ); // $FF12 <- $9
+                TONE1_PATTERN.write(
+                    base.with_volume(1)
+                        .with_step_increasing(false)
+                        .with_step_time(1),
+                ); // $FF12 <- $11
+                TONE1_PATTERN.write(
+                    base.with_volume(1)
+                        .with_step_increasing(true)
+                        .with_step_time(0),
+                ); // $FF12 <- $18
+            }
+            AmpDecPu1 => {
+                let base = TONE2_PATTERN.read();
+                TONE2_PATTERN.write(
+                    base.with_volume(0)
+                        .with_step_increasing(true)
+                        .with_step_time(1),
+                ); // $FF17 <- $9
+                TONE2_PATTERN.write(
+                    base.with_volume(1)
+                        .with_step_increasing(false)
+                        .with_step_time(1),
+                ); // $FF17 <- $11
+                TONE2_PATTERN.write(
+                    base.with_volume(1)
+                        .with_step_increasing(true)
+                        .with_step_time(0),
+                ); // $FF17 <- $18
+            }
+            AmpDecNoi => {
+                let base = NOISE_LEN_ENV.read();
+                NOISE_LEN_ENV.write(
+                    base.with_volume(0)
+                        .with_step_increasing(true)
+                        .with_step_time(1),
+                ); // $FF21 <- $9
+                NOISE_LEN_ENV.write(
+                    base.with_volume(1)
+                        .with_step_increasing(false)
+                        .with_step_time(1),
+                ); // $FF21 <- $11
+                NOISE_LEN_ENV.write(
+                    base.with_volume(1)
+                        .with_step_increasing(true)
+                        .with_step_time(0),
+                ); // $FF21 <- $18
+            }
+            PitchPu0 => self.write_u16le(TONE1_FREQUENCY),
+            PitchPu1 => self.write_u16le(TONE2_FREQUENCY),
+            PitchWav => self.write_u16le(WAVE_FREQ),
+            SampleNext => self.write_next_samples(),
+
+            // general register writes:
+            Pu0Sweep => unsafe { TONE1_SWEEP.cast() }.write(self.next_byte()),
+            Pu0LengthWave => self.write_lsb(TONE1_PATTERN),
+            Pu0Env => self.write_msb(TONE1_PATTERN),
+            Pu0PitchLsb => self.write_lsb(TONE1_FREQUENCY),
+            Pu0PitchMsb => self.write_msb(TONE1_FREQUENCY),
+            Pu1LengthWave => self.write_lsb(TONE2_PATTERN),
+            Pu1Env => self.write_msb(TONE2_PATTERN),
+            Pu1PitchLsb => self.write_lsb(TONE2_FREQUENCY),
+            Pu1PitchMsb => self.write_msb(TONE2_FREQUENCY),
+            WavOnOff => WAVE_BANK.write(WaveBank::new().with_enabled(self.next_byte() != 0)),
+            WavLength => self.write_lsb(WAVE_LEN_VOLUME),
+            WavEnv => self.write_msb(WAVE_LEN_VOLUME),
+            WavPitchLsb => self.write_lsb(WAVE_FREQ),
+            WavPitchMsb => self.write_msb(WAVE_FREQ),
+            NoiLength => self.write_lsb(NOISE_LEN_ENV),
+            NoiEnv => self.write_msb(NOISE_LEN_ENV),
+            NoiWave => self.write_lsb(NOISE_FREQ),
+            NoiTrig => self.write_msb(NOISE_FREQ),
+            ChannelVolume => self.write_lsb(LEFT_RIGHT_VOLUME),
+            Pan => self.write_msb(LEFT_RIGHT_VOLUME),
+            SoundOffOn => unsafe { SOUND_ENABLED.cast() }.write(self.next_byte()),
+            WavePattern0 => todo!(),
+            WavePattern1 => todo!(),
+            WavePattern2 => todo!(),
+            WavePattern3 => todo!(),
+            WavePattern4 => todo!(),
+            WavePattern5 => todo!(),
+            WavePattern6 => todo!(),
+            WavePattern7 => todo!(),
+            WavePattern8 => todo!(),
+            WavePattern9 => todo!(),
+            WavePatternA => todo!(),
+            WavePatternB => todo!(),
+            WavePatternC => todo!(),
+            WavePatternD => todo!(),
+            WavePatternE => todo!(),
+            WavePatternF => todo!(),
+            _Invalid0B | _Invalid0C | _Invalid0D | _Invalid0E | _Invalid0F | _Invalid15
+            | _Invalid1F | _Invalid27 | _Invalid28 | _Invalid29 | _Invalid2A | _Invalid2B
+            | _Invalid2C | _Invalid2D | _Invalid2E | _Invalid2F => unimplemented!(),
+        }
+        true
+    }
 }
 
 #[no_mangle]
 extern "C" fn main() -> ! {
     RUST_IRQ_HANDLER.write(Some(irq_handler));
     DISPSTAT.write(DisplayStatus::new().with_irq_vblank(true));
-    IE.write(IrqBits::VBLANK);
+    IE.write(IrqBits::VBLANK.with_timer0(true));
     IME.write(true);
 
+    TIMER0_RELOAD.write((((16777216 / 256) / 6) as u16).wrapping_neg());
+    TIMER0_CONTROL.write(
+        TimerControl::new()
+            .with_overflow_irq(true)
+            .with_cascade(false)
+            .with_scale(TimerScale::_256)
+            .with_enabled(true),
+    );
+
+    unsafe {
+        LSDJ_SONGS.play_song(0);
+    }
+
     if let Ok(mut logger) = MgbaBufferedLogger::try_new(MgbaMessageLevel::Debug) {
         writeln!(logger, "hello!").ok();