mirror of https://github.com/jorio/Pomme.git
56 lines
1.4 KiB
C++
56 lines
1.4 KiB
C++
#include "PommeSound.h"
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#include <sstream>
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constexpr int kNumMidiNotes = 128;
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static double gMidiNoteFrequencies[kNumMidiNotes];
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void Pomme::Sound::InitMidiFrequencyTable()
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{
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// powers of twelfth root of two
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double gamme[12];
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gamme[0] = 1.0;
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for (int i = 1; i < 12; i++)
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{
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gamme[i] = gamme[i - 1] * 1.059630943592952646;
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}
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for (int i = 0; i < 128; i++)
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{
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int octave = 1 + (i + 3) / 12; // A440 and middle C are in octave 7
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int semitone = (i + 3) % 12; // halfsteps up from A in current octave
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float freq;
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if (octave < 7)
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freq = gamme[semitone] * 440.0 / (1 << (7 - octave)); // 440/(2**octaveDiff)
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else
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freq = gamme[semitone] * 440.0 * (1 << (octave - 7)); // 440*(2**octaveDiff)
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gMidiNoteFrequencies[i] = freq;
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}
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}
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double Pomme::Sound::GetMidiNoteFrequency(int note)
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{
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if (note < 0 || note >= kNumMidiNotes)
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return 440.0;
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else
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return gMidiNoteFrequencies[note];
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}
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// Note: these names are according to IM:S:2-43.
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// These names won't match real-world names.
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// E.g. for note 67 (A 440Hz), this will return "A6", whereas the real-world
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// convention for that note is "A4".
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std::string Pomme::Sound::GetMidiNoteName(int note)
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{
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static const char* gamme[12] = {"A", "A#", "B", "C", "C#", "D", "D#", "E", "F", "F#", "G", "G#"};
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int octave = 1 + (note + 3) / 12;
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int semitonesFromA = (note + 3) % 12;
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std::stringstream ss;
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ss << gamme[semitonesFromA] << octave;
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return ss.str();
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}
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