#include "project.h"

#define OT_THM_IN       GPIO6
#define OT_THM_IN_PORT    GPIOB

#define OT_BLR_IN       GPIO7
#define OT_BLR_IN_PORT    GPIOB


#define OT_RX_IRQ     NVIC_EXTI9_5_IRQ


typedef struct rx_phy  {
  uint32_t last_cycle;
  int last_v;
  unsigned half_bits;
  unsigned data_bits;
  int frame_error;
  uint8_t data[10];
  int parity;
} RX_Phy;


static RX_Phy p_thm, p_blr;


static uint32_t
cycle_diff (uint32_t a, uint32_t b)
{
  return b - a;
}




static void ot_phy_rx_bit (RX_Phy *p)
{


  if (p->half_bits & 1)
    p->frame_error = 1;

  if (!p->half_bits) {
    if (!p->last_v)
      p->frame_error = 1;

    return;
  }

  if (p->data_bits < 32) {
    if (p->last_v) p->data[p->data_bits >> 3] |= 0x80 >> (p->data_bits & 7);

    p->parity ^= p->last_v;
  } else if (p->data_bits == 32) {
    if ((!p->last_v) || (p->parity))
      p->frame_error = 1;

    led_blink();

    if (p == &p_thm)
      ot_rx_thm (p->data, p->frame_error);
    else
      ot_rx_blr (p->data, p->frame_error);
  }


  p->data_bits++;

}


static void ot_phy_rx_worker (RX_Phy *p, int v)
{
  uint32_t now, diff;

  if (v == p->last_v) return;


  now = dwt_read_cycle_counter();
  diff = cycle_diff (p->last_cycle, now);


  if (diff < 10000) return;

  if (diff < 50000) {
    if (! (p->half_bits & 1)) ot_phy_rx_bit (p);

    p->half_bits++;
  } else if (diff < 85000) {
    p->half_bits++;
    ot_phy_rx_bit (p);
    p->half_bits++;
  } else {
    p->parity = 0;
    p->half_bits = 0;
    p->frame_error = 0;
    p->data_bits = 0;
    memset (p->data, 0, sizeof (p->data));
  }

  p->last_cycle = now;
  p->last_v = v;
}



void
exti9_5_isr (void)
{
  int v;

  if (EXTI_PR & OT_THM_IN) {
    EXTI_PR = OT_THM_IN;
    v = !GET (OT_THM_IN);

#if 0

    if (v)
      CLEAR (OT_BLR_OUT);
    else
      SET (OT_BLR_OUT);

#endif

    ot_phy_rx_worker (&p_thm, v);


  }

  if (EXTI_PR & OT_BLR_IN) {
    EXTI_PR = OT_BLR_IN;
    v = !GET (OT_BLR_IN);

#if 0

    if (v)
      CLEAR (OT_THM_OUT);
    else
      SET (OT_THM_OUT);

#endif

    ot_phy_rx_worker (&p_blr, v);
  }

  return;
}


void ot_phy_rx_tick (void)
{
}



void ot_phy_rx_init (void)
{
  MAP_INPUT_PU (OT_THM_IN);
  MAP_INPUT_PU (OT_BLR_IN);


  exti_select_source (OT_THM_IN, OT_THM_IN_PORT);
  exti_set_trigger (OT_THM_IN, EXTI_TRIGGER_BOTH);
  exti_enable_request (OT_THM_IN);
  exti_reset_request (OT_THM_IN);

  exti_select_source (OT_BLR_IN, OT_BLR_IN_PORT);
  exti_set_trigger (OT_BLR_IN, EXTI_TRIGGER_BOTH);
  exti_enable_request (OT_BLR_IN);
  exti_reset_request (OT_BLR_IN);

  nvic_enable_irq (OT_RX_IRQ);

}