/****************************************************************************
 * net/uip/uip_tcpwrbuffer.c
 *
 *   Copyright (C) 2007-2009, 2013-2014 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *           Jason Jiang  <jasonj@live.cn>
 *
 * 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 NuttX 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 OWNER 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.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/net/uip/uipopt.h>
#if defined(CONFIG_NET) && defined(CONFIG_NET_TCP) && defined(CONFIG_NET_TCP_WRITE_BUFFERS)

#include <queue.h>
#include <semaphore.h>
#include <debug.h>

#include "uip_internal.h"

/****************************************************************************
 * Private Types
 ****************************************************************************/

/* Package all globals used by this logic into a structure */

struct wrbuffer_s
{
  /* The semaphore to protect the buffers */

  sem_t sem;

  /* This is the list of available write buffers */

  sq_queue_t freebuffers;

  /* These are the pre-allocated write buffers */

  struct uip_wrbuffer_s buffers[CONFIG_NET_NTCP_WRITE_BUFFERS];
};

/****************************************************************************
 * Private Data
 ****************************************************************************/

/* This is the state of the global write buffer resource */

static struct wrbuffer_s g_wrbuffer;

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Function: uip_tcpwrbuffer_init
 *
 * Description:
 *   Initialize the list of free write buffers
 *
 * Assumptions:
 *   Called once early initialization.
 *
 ****************************************************************************/

void uip_tcpwrbuffer_init(void)
{
  int i;

  sq_init(&g_wrbuffer.freebuffers);

  for (i = 0; i < CONFIG_NET_NTCP_WRITE_BUFFERS; i++)
    {
      sq_addfirst(&g_wrbuffer.buffers[i].wb_node, &g_wrbuffer.freebuffers);
    }

  sem_init(&g_wrbuffer.sem, 0, CONFIG_NET_NTCP_WRITE_BUFFERS);
}

/****************************************************************************
 * Function: uip_tcpwrbuffer_alloc
 *
 * Description:
 *   Allocate a TCP write buffer by taking a pre-allocated buffer from
 *   the free list.  This function is called from TCP logic when a buffer
 *   of TCP data is about to sent
 *
 * Assumptions:
 *   Called from user logic with interrupts enabled.
 *
 ****************************************************************************/

FAR struct uip_wrbuffer_s *
uip_tcpwrbuffer_alloc(FAR const struct timespec *abstime)
{
  int ret;

  if (abstime)
    {
      ret = sem_timedwait(&g_wrbuffer.sem, abstime);
    }
  else
    {
      ret = sem_wait(&g_wrbuffer.sem);
    }

  if (ret != 0)
    {
      return NULL;
    }

  return (FAR struct uip_wrbuffer_s*)sq_remfirst(&g_wrbuffer.freebuffers);
}

/****************************************************************************
 * Function: uip_tcpwrbuffer_release
 *
 * Description:
 *   Release a TCP write buffer by returning the buffer to the free list.
 *   This function is called from user logic after it is consumed the
 *   buffered data.
 *
 * Assumptions:
 *   Called from interrupt level with interrupts disabled.
 *
 ****************************************************************************/

void uip_tcpwrbuffer_release(FAR struct uip_wrbuffer_s *wrbuffer)
{
  sq_addlast(&wrbuffer->wb_node, &g_wrbuffer.freebuffers);
  sem_post(&g_wrbuffer.sem);
}

#endif /* CONFIG_NET && CONFIG_NET_TCP && CONFIG_NET_TCP_WRITE_BUFFERS */