text: /*-
   * Copyright (c) 2010-2011 Monthadar Al Jaberi, TerraNet AB
   * 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,
   *    without modification.
   * 2. Redistributions in binary form must reproduce at minimum a disclaimer
   *    similar to the "NO WARRANTY" disclaimer below ("Disclaimer") and any
   *    redistribution must be conditioned upon including a substantially
   *    similar Disclaimer requirement for further binary redistribution.
   *
   * NO WARRANTY
   * 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 NONINFRINGEMENT, MERCHANTIBILITY
   * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
   * THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR 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 DAMAGES.
   *
   * $FreeBSD: soc2013/dpl/head/sys/dev/wtap/if_medium.c 230252 2012-01-11 17:41:14Z adrian $
   */
  #include "if_wtapvar.h"
  #include "if_medium.h"
  
  void
  init_medium(struct wtap_medium *md)
  {
  
  	DWTAP_PRINTF("%s\n", __func__);
  	STAILQ_INIT(&md->md_pktbuf);
  	mtx_init(&md->md_mtx, "wtap_medium mtx", NULL, MTX_DEF | MTX_RECURSE);
  
  	/* Event handler for sending packets between wtaps */
  	struct eventhandler *eh = (struct eventhandler *)
  	    malloc(sizeof(struct eventhandler), M_WTAP, M_NOWAIT | M_ZERO);
  	eh->tq = taskqueue_create("wtap_tx_taskq",  M_NOWAIT | M_ZERO,
  	    taskqueue_thread_enqueue, &eh->tq);
  	taskqueue_start_threads(&eh->tq, 1, PI_NET, "%s taskq", "wtap_medium");
  	md->tx_handler = eh;
  	/* Mark medium closed by default */
  	md->open = 0;
  }
  
  void
  deinit_medium(struct wtap_medium *md)
  {
  
  	DWTAP_PRINTF("%s\n", __func__);
  	taskqueue_free(md->tx_handler->tq);
  	free(md->tx_handler, M_WTAP);
  }
  
  int
  medium_transmit(struct wtap_medium *md, int id, struct mbuf*m)
  {
  
  	mtx_lock(&md->md_mtx);
  	if (md->open == 0){
  		DWTAP_PRINTF("[%d] dropping m=%p\n", id, m);
  		m_free(m);
  		mtx_unlock(&md->md_mtx);
  		return 0;
  	}
  
  	DWTAP_PRINTF("[%d] transmiting m=%p\n", id, m);
  	struct packet *p = (struct packet *)malloc(sizeof(struct packet),
  	    M_WTAP_PACKET, M_ZERO | M_NOWAIT);
  	p->id = id;
  	p->m = m;
  
  	STAILQ_INSERT_TAIL(&md->md_pktbuf, p, pf_list);
  	taskqueue_enqueue(md->tx_handler->tq, &md->tx_handler->proc);
  	mtx_unlock(&md->md_mtx);
  
        return 0;
  }
  
  struct packet *
  medium_get_next_packet(struct wtap_medium *md)
  {
  	struct packet *p;
  
  	mtx_lock(&md->md_mtx);
  	p = STAILQ_FIRST(&md->md_pktbuf);
  	if (p == NULL){
  		mtx_unlock(&md->md_mtx);
  		return NULL;
  	}
  
  	STAILQ_REMOVE_HEAD(&md->md_pktbuf, pf_list);
  	mtx_unlock(&md->md_mtx);
  	return p;
  }
  
  void
  medium_open(struct wtap_medium *md)
  {
  
  	mtx_lock(&md->md_mtx);
  	md->open = 1;
  	mtx_unlock(&md->md_mtx);
  }
  
  void
  medium_close(struct wtap_medium *md)
  {
  
  	mtx_lock(&md->md_mtx);
  	md->open = 0;
  	mtx_unlock(&md->md_mtx);
  }
  