euphony_core/time/
tempo.rs

1use crate::time::{beat::Beat, duration::Duration, unquantized_beat::UnquantizedBeat};
2use core::ops::{Div, Mul};
3
4new_ratio!(Tempo, u64);
5
6const MINUTE: Duration = Duration::from_secs(60);
7
8impl Tempo {
9    pub fn as_beat_duration(self) -> Duration {
10        MINUTE / self.as_ratio()
11    }
12
13    pub fn from_beat_duration(duration: Duration) -> Self {
14        Tempo(MINUTE.as_nanos() as u64, duration.as_nanos() as u64)
15            .reduce()
16            .simplify(64)
17    }
18}
19
20impl Mul<Beat> for Tempo {
21    type Output = Duration;
22
23    fn mul(self, beat: Beat) -> Self::Output {
24        self.as_beat_duration() * beat.as_ratio()
25    }
26}
27
28impl Div<Tempo> for Duration {
29    type Output = UnquantizedBeat;
30
31    fn div(self, tempo: Tempo) -> Self::Output {
32        let a = self.as_nanos();
33        let b = tempo.as_beat_duration().as_nanos();
34
35        let whole = (a / b) as u64;
36        let fract = (a % b) as u64;
37
38        UnquantizedBeat(whole, Beat(fract, b as u64).reduce())
39    }
40}
41
42#[test]
43fn beat_round_trip_test() {
44    let tempos = 60..320;
45    let beats = [
46        Beat(1, 64),
47        Beat(1, 48),
48        Beat(1, 32),
49        Beat(1, 24),
50        Beat(1, 16),
51        Beat(1, 12),
52        Beat(1, 8),
53        Beat(1, 6),
54        Beat(1, 4),
55        Beat(1, 3),
56        Beat(1, 2),
57        Beat(1, 1),
58    ];
59    let counts = [
60        1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 100, 1000, 10_000, 100_000, 1_000_000,
61    ];
62    for tempo in tempos {
63        let tempo = Tempo(tempo, 1);
64        assert_eq!(tempo, Tempo::from_beat_duration(tempo.as_beat_duration()));
65
66        for count in counts.iter() {
67            for beat in beats.iter() {
68                let expected = *beat * *count;
69                let actual: UnquantizedBeat = (tempo * expected) / tempo;
70                assert_eq!(
71                    actual.quantize(Beat(1, 192)),
72                    expected,
73                    "{:?} {:?}",
74                    tempo,
75                    beat
76                );
77            }
78        }
79    }
80}
euphony_core/time/tempo.rs

euphony_core/time/
tempo.rs
