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use super::{Hz, Cents};
use std::iter::IntoIterator;
const A440: Hz = Hz(440.0);
pub trait Tuning {
fn reference_pitch(&self) -> Hz;
fn pitch(&self, step: i32) -> Option<Hz>;
fn interval(&self, from: i32, to: i32) -> Option<Cents> {
match (self.pitch(from), self.pitch(to)) {
(Some(to), Some(from)) => Some(to / from),
_ => None,
}
}
}
#[derive(Debug, Clone)]
pub struct Edo {
cardinality: u16,
reference: Hz,
}
impl Edo {
pub fn new(cardinality: u16, reference: Hz) -> Self {
Edo {
cardinality, reference
}
}
pub fn new_a440(cardinality: u16) -> Self {
Self::new(cardinality, A440)
}
}
impl Tuning for Edo {
fn reference_pitch(&self) -> Hz {
self.reference
}
fn pitch(&self, step: i32) -> Option<Hz> {
let int = Cents(1200.0 / self.cardinality as f32) * step as f32;
Some(self.reference + int)
}
fn interval(&self, from: i32, to: i32) -> Option<Cents> {
let delta = (to - from) as f32;
Some(Cents(1200.0 / self.cardinality as f32 * delta))
}
}
#[derive(Debug, Clone)]
pub struct EqualSteps {
step: Cents,
reference: Hz,
}
impl EqualSteps {
pub fn new(step: Cents, reference: Hz) -> Self {
EqualSteps {
step, reference
}
}
pub fn new_a440(step: Cents) -> Self {
Self::new(step, A440)
}
}
impl Tuning for EqualSteps {
fn reference_pitch(&self) -> Hz {
self.reference
}
fn pitch(&self, step: i32) -> Option<Hz> {
let int = self.step * step as f32;
Some(self.reference + int)
}
}
#[derive(Debug, Clone)]
pub struct CyclicTuning {
steps: Vec<Cents>,
reference: Hz,
}
impl CyclicTuning {
pub fn from_cents<'a, I: IntoIterator<Item=&'a Cents>>(steps: I, reference: Hz) -> Self {
let steps = steps.into_iter().cloned().collect();
CyclicTuning {
steps, reference
}
}
pub fn from_ratios<'a, I: IntoIterator<Item=&'a f32>>(steps: I, reference: Hz) -> Self {
let steps = steps.into_iter().map(|r| Cents::from_ratio(*r)).collect();
CyclicTuning {
steps, reference
}
}
}
impl Tuning for CyclicTuning {
fn reference_pitch(&self) -> Hz {
self.reference
}
fn pitch(&self, step: i32) -> Option<Hz> {
if self.steps.len() == 0 {
return Some(self.reference)
}
let len = self.steps.len() as i32;
let last = *self.steps.last().unwrap();
let (rem, div) = (step % len, step / len);
let hz = if rem == 0 {
self.reference + last * div as f32
} else {
let step =
if rem > 0 { self.steps[(rem - 1) as usize] }
else { self.steps[(len + rem - 1) as usize] - last };
self.reference + (last * div as f32 + step)
};
Some(hz)
}
}
#[derive(Debug, Clone)]
pub struct MidiTuning {
pitches: Vec<Hz>,
}
impl MidiTuning {
pub fn from_tuning<T: Tuning>(tuning: T, refkey: u8) -> Option<Self> {
assert!(refkey < 127);
let mut pitches = Vec::with_capacity(127);
for i in 0..127 {
if let Some(hz) = tuning.pitch(i - refkey as i32) {
pitches.push(hz)
}
else {
return None
}
}
Some(MidiTuning {
pitches
})
}
pub fn from_pitches(hzs: &[Hz]) -> Option<Self> {
if hzs.len() < 127 { return None }
let pitches = hzs[0..127].to_owned();
Some(MidiTuning {
pitches
})
}
}
impl ::std::default::Default for MidiTuning {
fn default() -> Self {
let mut pitches = Vec::with_capacity(127);
pitches.extend((0..127).map(|i| A440 + Cents((i - 69) as f32 * 100.0)));
MidiTuning {
pitches
}
}
}
impl Tuning for MidiTuning {
fn reference_pitch(&self) -> Hz {
self.pitches[0]
}
fn pitch(&self, step: i32) -> Option<Hz> {
if step < 0 { return None }
self.pitches.get(step as usize).cloned()
}
}
impl ::std::ops::Index<usize> for MidiTuning {
type Output = Hz;
fn index(&self, index: usize) -> &Hz {
&self.pitches[index]
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test] fn cyclic_tuning() {
let tuning = CyclicTuning::from_ratios(&[
3.0 / 2.0,
2.0_f32
], Hz(440.0));
assert_eq!(tuning.pitch(0).unwrap().0, 440.0);
assert_eq!(tuning.pitch(1).unwrap().0.round(), 660.0_f32);
assert_eq!(tuning.pitch(3).unwrap().0.round(), 1320.0_f32);
assert_eq!(tuning.pitch(-1).unwrap().0.round(), 330.0_f32);
assert_eq!(tuning.pitch(-3).unwrap().0.round(), 165.0_f32);
}
}