This repository has been archived on 2023-08-08. You can view files and clone it, but cannot push or open issues or pull requests.
tomo-old/elements/fun/music/music.go

71 lines
1.4 KiB
Go
Raw Normal View History

2023-02-08 21:41:31 -07:00
package music
import "math"
var semitone = math.Pow(2, 1.0 / 12.0)
// Tuning is an interface representing a tuning.
type Tuning interface {
// Tune returns the frequency of a given note in Hz.
Tune (Note) float64
}
// EqualTemparment implements twelve-tone equal temparment.
type EqualTemparment struct { A4 float64 }
// Tune returns the EqualTemparment frequency of a given note in Hz.
func (tuning EqualTemparment) Tune (note Note) float64 {
return tuning.A4 * math.Pow(semitone, float64(note - NoteA4))
}
// Octave represents a MIDI octave.
type Octave int
// Note returns the note at the specified scale degree in the chromatic scale.
func (octave Octave) Note (degree int) Note {
return Note(int(octave + 1) * 12 + degree)
}
// Note represents a MIDI note.
type Note int
const (
NoteC0 Note = iota
NoteDb0
NoteD0
NoteEb0
NoteE0
NoteF0
NoteGb0
NoteG0
NoteAb0
NoteA0
NoteBb0
NoteB0
2023-02-09 13:05:13 -07:00
// nice
2023-02-08 21:41:31 -07:00
NoteA4 Note = 69
)
// Octave returns the octave of the note
2023-02-09 13:06:41 -07:00
func (note Note) Octave () Octave {
return Octave(note / 12 - 1)
2023-02-08 21:41:31 -07:00
}
// Degree returns the scale degree of the note in the chromatic scale.
func (note Note) Degree () int {
mod := note % 12
if mod < 0 { mod += 12 }
return int(mod)
}
// IsSharp returns whether or not the note is a sharp.
func (note Note) IsSharp () bool {
degree := note.Degree()
return degree == 1 ||
degree == 3 ||
degree == 6 ||
degree == 8 ||
degree == 10
}