text: /*
   * Copyright (c) 2007, Vanderbilt University
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * - Redistributions of source code must retain the above copyright
   *   notice, this list of conditions and the following disclaimer.
   * - 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.
   * - Neither the name of the copyright holder 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 COPYRIGHT HOLDERS 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 COPYRIGHT HOLDER 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.
   *
   * Author: Miklos Maroti
   * Author: Andreas Weigel (modifications for CometOS)
   */
  
  #include "CcaLayer.h"
  #include "cometos.h"
  #include "tosUtil.h"
  #include "RFA1DriverLayer.h"
  
  //tasklet_norace
  static message_t *txMsg;
  
  //tasklet_norace
  static uint8_t ccaState;
  enum
  {
      STATE_READY = 0,
      STATE_CCA_WAIT = 1,
      STATE_SEND = 2,
  };
  
  //tasklet_async event
  void radioSend_ready()
  {
      if( ccaState == STATE_READY )
          ccaSend_ready();
  }
  
  //tasklet_async command
  mac_result_t ccaSend_send(message_t* msg)
  {
      mac_result_t error;
  
      if( ccaState == STATE_READY )
      {
          if( tosUtil_requiresCca(msg) )
          {
              txMsg = msg;
              if( (error = radioCCA_request()) == MAC_SUCCESS )
                  ccaState = STATE_CCA_WAIT;
          }
          else if( (error = radioSend_send(msg)) == MAC_SUCCESS ){
              ccaState = STATE_SEND;
          }
      }
      else
          error = MAC_ERROR_BUSY;
  
      return error;
  }
  
  //tasklet_async event
  void radioCCA_done(mac_result_t error)
  {
      ASSERT( ccaState == STATE_CCA_WAIT );
  
      if( error == MAC_SUCCESS && (error = radioSend_send(txMsg)) == MAC_SUCCESS ) {
          ccaState = STATE_SEND;
      } else {
          ccaState = STATE_READY;
          ccaSend_sendDone(txMsg, MAC_ERROR_BUSY);
      }
  }
  
  //tasklet_async event
  void radioSend_sendDone(message_t* msg, mac_result_t error)
  {
      ASSERT( ccaState == STATE_SEND );
  
      ccaState = STATE_READY;
      ccaSend_sendDone(msg, error);
  }
  