/*
 *	fsk4.c
 *	By SQ2DK
 */

#include "fsk4.h"
#include "adf.h"
#include "config.h"
#include "main.h"

/*
 * In this file i will try to prepare procedure for transmitting earlier
 * prepared message using 4fsk We will be using adf.c - library for handling
 * ADF7012 chip. Frequency setting and initialization of chip will be done
 * outside of this library idea is to use frequency correction register for
 * shifting base frequency, which should produce 244Hz steps in frequency. This
 * will limit minimum baud rate to 100bd and its multipliers. As experience
 * showed, 244Hz tone-spacing is not sufficient for efficient decoding of
 * packets using standard 270Hz shift Thus generation of 9MHz signal for radio
 * chip was required via STM32 PLL to achieve spacing close to 270Hz. Baud rate
 * will be generated by microcontroler's timer. we will use timer2 for this,
 * setting prescaler to (cpu_freuency/100000)-1, so, for 100bd single pulse we
 * should set counter to 1000-1
 */

static uint16_t current_2_bit = 0;
static bool FSK_Active = false;
static char *buffer;
static uint8_t buffer_len;
static uint8_t QRGCounter = 0;

void FSK4_stop_TX() {
  TIM2->DIER &= ~(TIM_DIER_UIE); // Disable the interrupt
  adf_RF_off();                  // turn TX off
  FSK_Active = false;
}

static void FSK4_send_2bit(uint8_t bits_to_send) { // sends 2 bit value
  bits_to_send =
      (bits_to_send & 3); // make sure to take only 2 last bites of value - we
                          // cannot send more than 2 bits at the same time
  adf_4fsk_fone(bits_to_send * FSK4_SPACE_MULTIPLIER);
}

bool FSK4_is_active() { // returns 1 if transmitter is active for 4FSK
  return FSK_Active;
}

static void FSK4_write(char *buff, uint16_t address_2bit) {
  int full_bytes = address_2bit / 4; // number of full bytes of address
  int fraction_part =
      address_2bit -
      (full_bytes * 4); // fraction part of address (number of 2bytes offset)
  uint8_t byte_to_send = (buff[full_bytes] >> (6 - (fraction_part * 2)) &
                          3);   // returns 2 bytes of buffer at address
  FSK4_send_2bit(byte_to_send); // sends those 2 bytes
}

void FSK4_timer_handler() { // called out by interrupt handling procedure in
                            // main

  TIM2->CNT = 0; // reset timer  - make sure to have it at the beginning of
                 // procedure, otherwise there will be some delays.
  if (current_2_bit < (FSK4_HEADER_LENGTH * 4)) { // we are still in header
    uint8_t tmp_offset = ((0xD8 >> current_2_bit % 4) & 3);

    FSK4_send_2bit(tmp_offset);
  } else {
    FSK4_write(buffer,
               (current_2_bit -
                (FSK4_HEADER_LENGTH *
                 4))); // send 2 bits of data from address of current_2_bit * 2
  }
  current_2_bit++;

  if (current_2_bit > ((buffer_len + FSK4_HEADER_LENGTH) * 4)) {
    FSK4_stop_TX();
  } // if we got to the end of data - finish transmitting
}

void FSK4_start_TX(char *buff, uint8_t len) {
  buffer = buff;
  buffer_len = len;
  // adf_setup();
  current_2_bit = 0; // reset counter of current position of bit address
  adf_RF_on(QRG_FSK4[QRGCounter++], PA_FSK4); // turn on radio TX
  if (QRGCounter >= sizeof(QRG_FSK4) / sizeof(QRG_FSK4[0]))
    QRGCounter = 0;
  FSK_Active = true;                                 // change status
  TIM2->CR1 &= (uint16_t)(~((uint16_t)TIM_CR1_CEN)); // Disable the TIM Counter
  uint16_t timer2StartValue =
      (100000 / FSK4_BAUD) -
      1; // timer value calculated according to baud rate 999 for 100bd
  TIM2->ARR = timer2StartValue; // set timer counter max value to pre-set value
                                // for baudrate (auto-reload register)
  TIM2->CR1 |= TIM_CR1_CEN;     // enable timer again
  TIM2->DIER |= TIM_DIER_UIE;   // Enable the interrupt
  FSK4_timer_handler();         // force execution of procedure responsible for
                                // interrupt handling
}