/*
 * Authors (alphabetical order)
 * - Andre Bernet <bernet.andre@gmail.com>
 * - Andreas Weitl
 * - Bertrand Songis <bsongis@gmail.com>
 * - Bryan J. Rentoul (Gruvin) <gruvin@gmail.com>
 * - Cameron Weeks <th9xer@gmail.com>
 * - Erez Raviv
 * - Gabriel Birkus
 * - Jean-Pierre Parisy
 * - Karl Szmutny
 * - Michael Blandford
 * - Michal Hlavinka
 * - Pat Mackenzie
 * - Philip Moss
 * - Rob Thomson
 * - Romolo Manfredini <romolo.manfredini@gmail.com>
 * - Thomas Husterer
 *
 * opentx is based on code named
 * gruvin9x by Bryan J. Rentoul: http://code.google.com/p/gruvin9x/,
 * er9x by Erez Raviv: http://code.google.com/p/er9x/,
 * and the original (and ongoing) project by
 * Thomas Husterer, th9x: http://code.google.com/p/th9x/
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */

#include "../../opentx.h"

#if defined(FRSKY)

void telemetryEnableTx(void)
{
  UCSR0B |= (1 << TXEN0); // enable TX
}

void telemetryEnableRx(void)
{
  UCSR0B |= (1 << RXEN0);  // enable RX
  UCSR0B |= (1 << RXCIE0); // enable Interrupt
}

void processSerialData(uint8_t data);
extern uint8_t frskyRxBufferCount; // TODO not driver, change name

ISR(USART0_RX_vect)
{
  uint8_t stat;
  uint8_t data;

  UCSR0B &= ~(1 << RXCIE0); // disable Interrupt
  sei();

  stat = UCSR0A; // USART control and Status Register 0 A

  /*
              bit      7      6      5      4      3      2      1      0
                      RxC0  TxC0  UDRE0    FE0   DOR0   UPE0   U2X0  MPCM0

              RxC0:   Receive complete
              TXC0:   Transmit Complete
              UDRE0:  USART Data Register Empty
              FE0:    Frame Error
              DOR0:   Data OverRun
              UPE0:   USART Parity Error
              U2X0:   Double Tx Speed
              PCM0:   MultiProcessor Comms Mode
   */
  // rh = UCSR0B; //USART control and Status Register 0 B

    /*
              bit      7      6      5      4      3      2      1      0
                   RXCIE0 TxCIE0 UDRIE0  RXEN0  TXEN0 UCSZ02  RXB80  TXB80

              RxCIE0:   Receive Complete int enable
              TXCIE0:   Transmit Complete int enable
              UDRIE0:   USART Data Register Empty int enable
              RXEN0:    Rx Enable
              TXEN0:    Tx Enable
              UCSZ02:   Character Size bit 2
              RXB80:    Rx data bit 8
              TXB80:    Tx data bit 8
    */

  data = UDR0; // USART data register 0

  if (stat & ((1 << FE0) | (1 << DOR0) | (1 << UPE0))) {
    // discard buffer and start fresh on any comms error
    frskyRxBufferCount = 0;
  }
  else {
    processSerialData(data);
  }

  cli() ;
  UCSR0B |= (1 << RXCIE0); // enable Interrupt
}

void telemetryPortInit()
{
#if !defined(SIMU)
  DDRE &= ~(1 << DDE0);    // set RXD0 pin as input
  PORTE &= ~(1 << PORTE0); // disable pullup on RXD0 pin

  #undef BAUD
  #define BAUD 9600
  #include <util/setbaud.h>

  UBRR0H = UBRRH_VALUE;
  UBRR0L = UBRRL_VALUE;
  UCSR0A &= ~(1 << U2X0); // disable double speed operation.

  // set 8N1
  UCSR0B = 0 | (0 << RXCIE0) | (0 << TXCIE0) | (0 << UDRIE0) | (0 << RXEN0) | (0 << TXEN0) | (0 << UCSZ02);
  UCSR0C = 0 | (1 << UCSZ01) | (1 << UCSZ00);


  while (UCSR0A & (1 << RXC0)) UDR0; // flush receive buffer

  // These should be running right from power up on a FrSky enabled '9X.
  telemetryEnableTx(); // enable FrSky-Telemetry emission
  frskyTxBufferCount = 0; // TODO not driver code

  telemetryEnableRx(); // enable FrSky-Telemetry reception
#endif
}

void telemetryTransmitBuffer()
{
  UCSR0B |= (1 << UDRIE0); // enable  UDRE0 interrupt
}

#endif