1 files changed, 173 insertions, 0 deletions
diff --git a/graphics/src/audio/program.rs b/graphics/src/audio/program.rs
new file mode 100644
index 0000000..f31be06
--- /dev/null
+++ b/graphics/src/audio/program.rs
@@ -0,0 +1,173 @@
+use crate::audio::{
+	Channels,
+	channel::{Channel, DutyCycle},
+	parse,
+};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum ChanSpec {
+	PulseA,
+	PulseB,
+	Triangle,
+	Noise,
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum Instruction {
+	Pause,
+	Jump(usize),
+	SetVolume(ChanSpec, u8),
+	SetPitch(ChanSpec, u8),
+	SetPulseDutyA(DutyCycle),
+	SetPulseDutyB(DutyCycle),
+	SetNoiseMode(bool),
+}
+
+fn map_pitch(pitch: u8) -> f32 {
+	const HALF_STEP: f32 = 1.059_463_1;
+	HALF_STEP.powf(pitch as f32 - 128.0)
+}
+
+const fn map_volume(volume: u8) -> f32 {
+	if volume > 100 {
+		1.0
+	} else {
+		(volume as f32) / 100.0
+	}
+}
+
+#[derive(Debug, Clone)]
+pub struct Program {
+	ins: Vec<Instruction>,
+	pc: usize,
+	looping: bool,
+	tempo: u32,
+	pause: u32,
+}
+impl Program {
+	pub const fn new(ins: Vec<Instruction>, looping: bool) -> Self {
+		let pc = ins.len();
+		Self {
+			ins,
+			pc,
+			looping,
+			tempo: 120,
+			pause: 0,
+		}
+	}
+
+	pub fn parse(src: &str, looping: bool) -> parse::Result<Self> {
+		let ins = parse::parse(src)?;
+		Ok(Self::new(ins, looping))
+	}
+
+	pub fn merge(self, other: Self) -> Self {
+		let mut l_ins = self.ins;
+		let r_ins = other.ins;
+		let mut l = 0;
+		let mut r = 0;
+		loop {
+			if r >= r_ins.len() {
+				break;
+			}
+			let ins = r_ins[r];
+			if ins == Instruction::Pause {
+				// inc l until even
+				loop {
+					if l == l_ins.len() {
+						l_ins.push(Instruction::Pause);
+						break;
+					}
+					if l_ins[l] == Instruction::Pause {
+						l += 1;
+						break;
+					}
+					l += 1;
+				}
+			} else {
+				l_ins.insert(l, ins);
+			}
+			r += 1;
+		}
+
+		Self::new(l_ins, self.looping)
+	}
+
+	fn exec_ins(&mut self, channels: &mut Channels, ins: Instruction) {
+		use Instruction as I;
+		match ins {
+			I::Pause => {
+				// pause execution until next `exec` call
+				self.pause = self.tempo / 60;
+			}
+			I::Jump(pc) => {
+				self.pc = pc;
+			}
+			I::SetVolume(chan_spec, volume) => {
+				// set the volume (amplitude) on a given channel
+				use ChanSpec as C;
+				let v = map_volume(volume);
+				match chan_spec {
+					C::PulseA => channels.pulse_a.set_volume(v),
+					C::PulseB => channels.pulse_b.set_volume(v),
+					C::Triangle => channels.triangle.set_volume(v),
+					C::Noise => channels.noise.set_volume(v),
+				}
+			}
+			I::SetPitch(chan_spec, pitch) => {
+				// set the pitch (freq) on a given channel
+				use ChanSpec as C;
+				let p = map_pitch(pitch);
+				match chan_spec {
+					C::PulseA => channels.pulse_a.set_pitch(p),
+					C::PulseB => channels.pulse_b.set_pitch(p),
+					C::Triangle => channels.triangle.set_pitch(p),
+					C::Noise => channels.noise.set_pitch(p),
+				}
+			}
+			I::SetPulseDutyA(duty_cycle) => {
+				channels.pulse_a.set_duty(duty_cycle);
+			}
+			I::SetPulseDutyB(duty_cycle) => {
+				channels.pulse_b.set_duty(duty_cycle);
+			}
+			I::SetNoiseMode(mode) => {
+				channels.noise.set_mode(mode);
+			}
+		}
+	}
+
+	pub fn exec(&mut self, channels: &mut Channels) {
+		if self.pause > 0 {
+			self.pause -= 1;
+			return;
+		}
+		loop {
+			if self.pause > 0 {
+				break;
+			}
+			if self.finished() {
+				if self.looping {
+					self.pc = 0;
+				} else {
+					break;
+				}
+			}
+			let ins = self.ins[self.pc];
+			self.exec_ins(channels, ins);
+			self.pc += 1;
+		}
+	}
+
+	pub const fn finished(&self) -> bool {
+		self.pc >= self.ins.len()
+	}
+
+	pub const fn play(&mut self) {
+		self.pc = 0;
+	}
+
+	pub const fn set_looping(&mut self, looping: bool) {
+		self.looping = looping;
+	}
+}