osc.h

#ifndef __AVR__
#define pgm_read_dword(x) (*(x))
#define pgm_read_byte(x) (*(x))
#endif

const uint32_t notes[] 
#ifdef __AVR__
PROGMEM
#endif
= { // Regenerate this, tuning will be a bit off until then.
  561833, 595241, 630636, 668136, 707865, 749957,
  794551, 841798, 891854, 944886, 1001072, 1060599,
  1123666, 1190482, 1261272, 1336271, 1415730, 1499913,
  1589103, 1683596, 1783708, 1889773, 2002144, 2121198,
  2247331, 2380964, 2522544, 2672542, 2831460, 2999827,
  3178206, 3367192, 3567416, 3779545, 4004289, 4242396,
  4494662, 4761929, 5045088, 5345084, 5662919, 5999654,
  6356412, 6734384, 7134831, 7559090, 8008577, 8484792,
  8989324, 9523857, 10090175, 10690168, 11325838, 11999307,
  12712823, 13468767, 14269662, 15118180, 16017154, 16969584,
  17978648, 19047714, 20180350, 21380336, 22651676, 23998614,
  25425646, 26937534, 28539324, 30236360, 32034308, 33939168,
  35957296, 38095428, 40360700, 42760672, 45303352, 47997228,
  50851292, 53875068, 57078648, 60472720, 64068616, 67878336,
  71914592, 76190856, 80721400, 85521344, 90606704, 95994456,
  101702584, 107750136, 114157296, 120945440, 128137232, 135756672,
  143829184, 152381712, 161442800, 171042688, 181213408, 191988912,
  203405168, 215500272, 228314592, 241890880, 256274464, 271513344,
  287658368, 304763424, 322885600, 342085376, 362426816, 383977824,
  406810336, 431000544, 456629184, 483781760, 512548928, 543026688,
  575316736, 609526848, 645771200, 684170752, 724853632, 767955648,
  813620672, 862001088, 1536518824,
};

template <uint32_t srate, typename sample_type>
class Oscillator : public SampleSource<sample_type> {
  public:
    static const uint32_t hz_phincr = UINT32_MAX / srate;

    enum waveform { wf_silence, wf_saw, wf_square, wf_sine };

    inline virtual ~Oscillator() {}

    int8_t octave;
    uint8_t amp;

  private:
    waveform wave;

  public:
    uint32_t phacc;
    uint32_t phincr;
    uint32_t detune_phincr;
    mutable uint8_t last_sine_msb;
    mutable sample_type last_sine_sample;

    inline Oscillator () :
      amp(255),
      wave(wf_saw),
      octave(0),
      phacc(0),
      phincr(0),
      detune_phincr(0),
      last_sine_msb(0),
      last_sine_sample(0)
    {
      set_wave(wave);
    }

    inline void set_hz(uint16_t hz_q16n0, uint8_t hz_q0n8 = 0) {
      phincr = (hz_phincr * hz_q16n0) + (hz_phincr * hz_q0n8 >> 8);
    }

    inline void set_note(uint8_t note) {
      phincr = (pgm_read_dword(notes + note) << octave) + detune_phincr;
    }

    inline void set_detune_hz(uint16_t hz_q4n4) {
      detune_phincr = hz_phincr * hz_q4n4 >> 4;
    }

    inline sample_type render_silence() const {
      return SampleSource<sample_type>::traits::silence;
    }

    inline sample_type render_saw() const {
      return (phacc >> 24) + SampleSource<sample_type>::traits::minimum;
    }

    inline sample_type render_square() const {
      return phacc & (1L << 31) ? SampleSource<sample_type>::traits::maximum : SampleSource<sample_type>::traits::minimum;
    }

    inline sample_type render_sine() const {
      uint8_t tmp = phacc >> 24;

      if (tmp != last_sine_msb) {
        last_sine_msb = tmp;
        last_sine_sample = pgm_read_byte(SampleSource<sample_type>::traits::sine_table + last_sine_msb);
      }

      return last_sine_sample;
    }

    inline void set_wave(waveform wf) {
      wave = wf;
    }

    virtual inline sample_type read() {
      phacc += phincr;

      switch (wave) {
        case 0:
          return render_silence();
        case 1:
          return render_saw();
        case 2:
          return render_square();
        case 3:
          return render_sine();
      }
    }
};