#include "opnatimer.h"
#include "opna.h"

enum {
  TIMERB_SHIFT = 4,
  TIMERB_BITS = 8 + TIMERB_SHIFT,
};

void opna_timer_reset(struct opna_timer *timer, struct opna *opna) {
  timer->opna = opna;
  timer->status = 0;
  timer->interrupt_cb = 0;
  timer->interrupt_userptr = 0;
  timer->mix_cb = 0;
  timer->mix_userptr = 0;
  timer->timerb = 0;
  timer->timerb_load = false;
  timer->timerb_enable = false;
  timer->timerb_cnt = 0;
}

uint8_t opna_timer_status(const struct opna_timer *timer) {
  return timer->status;
}

void opna_timer_set_int_callback(struct opna_timer *timer, opna_timer_int_cb_t func, void *userptr) {
  timer->interrupt_cb = func;
  timer->interrupt_userptr = userptr;
}

void opna_timer_set_mix_callback(struct opna_timer *timer, opna_timer_mix_cb_t func, void *userptr) {
  timer->mix_cb = func;
  timer->mix_userptr = userptr;
}

void opna_timer_writereg(struct opna_timer *timer, unsigned reg, unsigned val) {
  val &= 0xff;
  opna_writereg(timer->opna, reg, val);
  switch (reg) {
  case 0x26:
    timer->timerb = val;
    timer->timerb_cnt = timer->timerb << TIMERB_SHIFT;
    break;
  case 0x27:
    timer->timerb_load = val & (1<<1);
    timer->timerb_enable = val & (1<<3);
    if (val & (1<<5)) {
      //timer->timerb_cnt = timer->timerb << TIMERB_SHIFT;
      timer->status &= ~(1<<1);
    }
  }
}

void opna_timer_mix(struct opna_timer *timer, int16_t *buf, unsigned samples) {
  do {
    unsigned generate_samples = samples;
    if (timer->timerb_enable) {
      unsigned timerb_samples = (1<<TIMERB_BITS) - timer->timerb_cnt;
      if (timerb_samples < generate_samples) {
        generate_samples = timerb_samples;
      }
    }
    opna_mix(timer->opna, buf, generate_samples);
    if (timer->mix_cb) {
      timer->mix_cb(timer->mix_userptr, buf, generate_samples);
    }
    buf += generate_samples*2;
    samples -= generate_samples;
    if (timer->timerb_load) {
      timer->timerb_cnt = (timer->timerb_cnt + generate_samples) & ((1<<TIMERB_BITS)-1);
      if (!timer->timerb_cnt && timer->timerb_enable) {
        if (!(timer->status & (1<<1))) {
          timer->status |= (1<<1);
          timer->interrupt_cb(timer->interrupt_userptr);
        }
      }
    }
  } while (samples);
}