112 lines
3.2 KiB
C++
112 lines
3.2 KiB
C++
#include "tuning.h"
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#include <math.h>
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// 12th root of 2, used for Twelvetone Equal Temperament
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#define TET_CONST 1.059463
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Tuning::Tuning(Note base, float pitch, TuningSystem system) {
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Setup(base, pitch, system);
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}
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Tuning::Tuning(Note base, float pitch) {
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Tuning(base, pitch, TUNINGSYSTEM_JUST);
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}
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// I like just Intonation.
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Tuning::Tuning() {
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#if 0
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Tuning(NOTE_D4, PITCH_CONCERT_D4, TUNINGSYSTEM_JUST);
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#endif
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}
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Note Tuning::GetBaseNote() { return baseNote; }
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void Tuning::SetTuningSystem(TuningSystem system) {
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Setup(baseNote, GetPitch(baseNote), system);
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}
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TuningSystem Tuning::GetSystem() { return system; }
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// setupOctaves computes the entire tuning frequency chart.
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//
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// You must call this after setting a full octave chromatic scale, rooted at
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// base.
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void Tuning::setupOctaves(Note base) {
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int multiplier = 1;
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for (Note octave = NOTE_ZERO; octave < NOTE_MAX; octave += NOTE_OCTAVE) {
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for (Note note = base; note < base + NOTE_OCTAVE; note += NOTE_SEMITONE) {
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Note upNote = note + octave;
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Note dnNote = note - octave;
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if (upNote < NOTE_MAX) {
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pitches[upNote] = pitches[note] * multiplier;
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}
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if (dnNote >= NOTE_ZERO) {
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pitches[dnNote] = pitches[note] / multiplier;
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}
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}
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multiplier <<= 1;
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}
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}
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// setupEqual sets an even-temperament chromatic scale rooted at base
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void Tuning::setupEqual(Note base, float pitch) {
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pitches[base] = pitch;
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for (int i = 1; i < 12; i++) {
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pitches[base + i] = pitches[base + i - 1] * TET_CONST;
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}
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}
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// setupJust sets a just-temperament chromatic scale rooted at base
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void Tuning::setupJust(Note base, float pitch) {
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// Diatonic scale
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pitches[base + 0] = pitch * 1 / 1; // Unison
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pitches[base + 2] = pitch * 9 / 8; // Second
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pitches[base + 4] = pitch * 5 / 4; // Third
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pitches[base + 5] = pitch * 4 / 3; // Fourth
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pitches[base + 7] = pitch * 3 / 2; // Fifth
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pitches[base + 9] = pitch * 5 / 3; // Sixth
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pitches[base + 11] = pitch * 15 / 8; // Seventh
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// I got this off various Wikipedia pages.
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// The main thing here is that the minor seventh works out to be a diatonic
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// fourth up from the fourth computed above, since the music I want to play
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// frequently wants to play G major on a D major instrument
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pitches[base + 1] = pitch * 16 / 15; // min2
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pitches[base + 3] = pitch * 6 / 5; // min3
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pitches[base + 6] = pitch * 10 / 7; // dim5
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pitches[base + 8] = pitch * 8 / 5; // min6
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pitches[base + 10] = pitch * 16 / 9; // min7 = fourth + fourth
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}
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void Tuning::Setup(Note base, float pitch, TuningSystem system) {
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this->baseNote = base;
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this->system = system;
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switch (system) {
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case TUNINGSYSTEM_EQUAL:
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setupEqual(base, pitch);
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break;
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case TUNINGSYSTEM_JUST:
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default:
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setupJust(base, pitch);
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break;
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}
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setupOctaves(base);
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}
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void Tuning::Setup(Note base, float pitch) { Setup(base, pitch, system); }
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float Tuning::GetPitch(Note note) { return pitches[note]; }
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Note NearestNote(float pitch) {
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return Note(round(log2(pitch / PITCH_CONCERT_C0)));
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}
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const char *noteNames[]{
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"C ", "C#", "D ", "Eb", "E ", "F ", "F#", "G ", "Ab", "A ", "Bb", "B ",
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};
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const char *NoteName(Note note) { return noteNames[note % 12]; }
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