/*
  Dinky fixed point oscillators.
  https://git.poto.cafe/veclavtalica/stfu/src/branch/master/Source/oscillators.c
*/

#ifndef COM_SND_OSCS_H
#define COM_SND_OSCS_H

#include "../cfg.h"
#include "../fix.h"
#include "../std.h"
#include <stdint.h>

/* Intended to be executed offline with values then embedded in the binary. */
struct com_snd_swave {
  uint16_t f, s, c;
};

static struct com_snd_swave
com_snd_swave_init(com_fix_t frequency, uint16_t phase, uint16_t amplitude) {
  com_std_assert(frequency > 0);
  struct com_snd_swave r;
  r.f = 2.f * sinf((float)M_PI * frequency / STFU_AUDIO_FRAME_RATE);
  r.s = amplitude * sinf(phase);
  r.c = amplitude * cosf(phase);
  return r;
}

static inline int16_t com_snd_swave_pump(struct com_snd_swave *wave) {
  int16_t const f = com_fix_sin(com_fix_mul(
      wave->phase, com_fix_div(com_fix_mul(wave->frequency, COM_FIX_PI2),
                               COM_CFG_SNDFRMRATE)));
  wave->phase += 1;
  return f;
}

/* Implemented over sinewave */
// struct com_snd_oscs_sqrtwave {
//   struct com_snd_swave w;
//   union {
//     float f;
//     uint32_t u;
//   } v;
// } com_snd_oscs_init_sqrtwave(float frequency, float phase, float amplitude) {
//   struct com_snd_oscs_sqrtwave r;
//   union {
//     float f;
//     uint32_t u;
//   } v, a;
//   r.w = com_snd_oscs_init_sinewave(frequency, phase, 1.f);
//   v.f = r.w.s;
//   a.f = amplitude;
//   r.v.u = (a.u & 0x7fffffff) | (v.u & 0x80000000);
//   return r;
// }

// /* Use floating point bit representation to infer sign, all other bits are
// set
//  * to amplitude */
// struct com_snd_oscs_sqrtwave
// com_snd_oscs_pump_sqrtwave(struct com_snd_oscs_sqrtwave wave) {
//   union {
//     float f;
//     uint32_t u;
//   } v;
//   com_snd_oscs_pump_sinewave(wave.w);
//   v.f = wave.w.s;
//   wave.v.u = (wave.v.u & 0x7fffffff) | (v.u & 0x80000000);
//   return wave;
// }

// struct com_snd_oscs_sawtooth {
//   float v, a, i;
// } com_snd_oscs_init_sawtooth(float frequency, float phase, float amplitude) {
//   struct com_snd_oscs_sawtooth r;
//   r.v = sinf(phase) * amplitude;
//   r.a = amplitude;
//   r.i = 2.f * frequency / STFU_AUDIO_FRAME_RATE * amplitude;
//   return r;
// }

// /* Simple amplitude overflow check with truncation */
// struct com_snd_oscs_sawtooth
// com_snd_oscs_pump_sawtooth(struct com_snd_oscs_sawtooth wave) {
//   wave.v += wave.i;
//   if (wave.v > wave.a)
//     wave.v -= wave.a * 2.f;
//   return wave;
// }

#endif