text: /*
   * Copyright (c) 2009, Swedish Institute of Computer Science
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the name of the Institute nor the names of its contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   *
   */
  
  #include "contiki.h"
  #include "dev/spi-legacy.h"
  #include "cc2420.h"
  #include "isr_compat.h"
  
  extern volatile uint8_t cc2420_sfd_counter;
  extern volatile uint16_t cc2420_sfd_start_time;
  extern volatile uint16_t cc2420_sfd_end_time;
  
  /*---------------------------------------------------------------------------*/
  /* SFD interrupt for timestamping radio packets */
  ISR(TIMERB1, cc2420_timerb1_interrupt)
  {
    int tbiv;
  
    /* always read TBIV to clear IFG */
    tbiv = TBIV;
    /* read and discard tbiv to avoid "variable set but not used" warning */
    (void)tbiv;
    if(CC2420_SFD_IS_1) {
      cc2420_sfd_counter++;
      cc2420_sfd_start_time = TBCCR1;
    } else {
      cc2420_sfd_counter = 0;
      cc2420_sfd_end_time = TBCCR1;
    }
  }
  /*---------------------------------------------------------------------------*/
  void
  cc2420_arch_sfd_init(void)
  {
    /* Need to select the special function! */
    CC2420_SFD_PORT(SEL) = BV(CC2420_SFD_PIN);
    
    /* start timer B - 32768 ticks per second */
    TBCTL = TBSSEL_1 | TBCLR;
    
    /* CM_3 = capture mode - capture on both edges */
    TBCCTL1 = CM_3 | CAP | SCS;
    TBCCTL1 |= CCIE;
    
    /* Start Timer_B in continuous mode. */
    TBCTL |= MC1;
  
    TBR = RTIMER_NOW();
  }
  /*---------------------------------------------------------------------------*/
  