euphony-units 0.1.1

Core types and traits for music composition
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153

use crate::pitch::{
    frequency::{BaseFrequency, Frequency, FrequencyRatio},
    interval::Interval,
};
use core::ops::Mul;
use euphony_macros::cents;

pub mod western {
    pub static ET12: super::Tuning = super::Tuning {
        base: super::BaseFrequency(440, 1),
        system: &super::ET12,
    };
}

#[derive(Clone, Copy)]
pub struct Tuning {
    pub base: BaseFrequency,
    pub system: &'static dyn System,
}

impl Mul<Tuning> for Interval {
    type Output = Frequency;

    fn mul(self, rhs: Tuning) -> Self::Output {
        rhs.system.to_frequency(rhs.base, self)
    }
}

impl Mul<Interval> for Tuning {
    type Output = Frequency;

    fn mul(self, rhs: Interval) -> Self::Output {
        self.system.to_frequency(self.base, rhs)
    }
}

pub trait System: 'static + Send + Sync {
    fn to_frequency(&self, base: BaseFrequency, interval: Interval) -> Frequency;
}

#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd)]
pub struct Octave<T>(&'static [T])
where
    T: 'static + Copy + core::ops::Mul<BaseFrequency, Output = Frequency>,
    &'static [T]: Send + Sync;

impl<T> System for Octave<T>
where
    T: 'static + Copy + core::ops::Mul<BaseFrequency, Output = Frequency>,
    &'static [T]: Send + Sync,
{
    fn to_frequency(&self, base: BaseFrequency, interval: Interval) -> Frequency {
        let mut octaves = interval.whole();
        let mut fraction = interval.fraction();

        if fraction.0 < 0 {
            fraction += Interval(1, 1);
            octaves -= 1;
        }

        let base = if octaves < 0 {
            base / 2u64.pow(octaves.unsigned_abs() as u32)
        } else {
            base * 2u64.pow(octaves as u32)
        };

        if fraction.0 == 0 {
            return base.into();
        }

        let index = (fraction * (self.0.len() + 1)).whole();
        assert!(
            (1..=self.0.len() as i64).contains(&index),
            "interval is out of range for scale: {:?}",
            interval,
        );
        let mul = self.0[index as usize - 1];
        mul * base
    }
}

macro_rules! et {
    ($($cent:literal),* $(,)?) => {
        Octave(&[$(cents!($cent)),*])
    };
}

pub static ET12: Octave<f64> = et!(100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100);

macro_rules! just {
    ($($n:literal / $d:literal),* $(,)?) => {
        Octave(&[$(FrequencyRatio($n, $d)),*])
    };
}

pub static JUST12: Octave<FrequencyRatio> = just!(
    16 / 15,
    9 / 8,
    6 / 5,
    5 / 4,
    4 / 3,
    64 / 45,
    3 / 2,
    8 / 5,
    5 / 3,
    16 / 9,
    15 / 8
);

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn et12_test() {
        let tuning = Tuning {
            base: 440.into(),
            system: &ET12,
        };

        let mut results = vec![];

        eprintln!("interval,frequency,idx");
        for octave in [-3, -2, -1, 0, 1, 2, 3] {
            for interval in 0..12 {
                let interval = Interval(interval, 12) + octave;
                let freq = tuning * interval;
                eprintln!("{:?},{},{}", interval, freq.0, results.len());
                results.push(freq);
            }
        }
    }

    #[test]
    fn just12_test() {
        let tuning = Tuning {
            base: 440.into(),
            system: &JUST12,
        };

        let mut results = vec![];

        eprintln!("interval,frequency,idx");
        for octave in [-3, -2, -1, 0, 1, 2, 3] {
            for interval in 0..12 {
                let interval = Interval(interval, 12) + octave;
                let freq = tuning * interval;
                eprintln!("{:?},{},{}", interval, freq.0, results.len());
                results.push(freq);
            }
        }
    }
}