tcptimer.c

用于嵌入式系统的TCP/IP协议栈

/***********************************************************************/
/*                                                                     */
/*   Module:  tcp_ip/tcptimer.c                                        */
/*   Release: 2001.3                                                   */
/*   Version: 99.0                                                     */
/*   Purpose: TCP/IP Timer Routines                                    */
/*                                                                     */
/*---------------------------------------------------------------------*/
/*                                                                     */
/*               Copyright 1999, Blunk Microsystems                    */
/*                      ALL RIGHTS RESERVED                            */
/*                                                                     */
/*   Licensees have the non-exclusive right to use, modify, or extract */
/*   this computer program for software development at a single site.  */
/*   This program may be resold or disseminated in executable format   */
/*   only. The source code may not be redistributed or resold.         */
/*                                                                     */
/***********************************************************************/
#include "tcp_ipp.h"

/***********************************************************************/
/* Global Variable Definitions                                         */
/***********************************************************************/
ui32 NetTickCount;
static CircLink TimeoutList;

/***********************************************************************/
/* Global Function Definitions                                         */
/***********************************************************************/

/***********************************************************************/
/* NetTimerInit: Initialize TCP/IP timer processing                    */
/*                                                                     */
/***********************************************************************/
void NetTimerInit(void)
{
  TimeoutList.next_fwd = TimeoutList.next_bck = &TimeoutList;
}

/***********************************************************************/
/* NetTimerStart: Start or restart TCP/IP timer                        */
/*                                                                     */
/*      Inputs: timer = pointer to timer control block                 */
/*              timeout = number of ticks before expiration            */
/*                                                                     */
/***********************************************************************/
void NetTimerStart(TcpTmr *timer, uint timeout)
{
  CircLink *link;

  /*-------------------------------------------------------------------*/
  /* Ensure timer has expiration routine.                              */
  /*-------------------------------------------------------------------*/
  TcpAssert(timer->action);

  /*-------------------------------------------------------------------*/
  /* If we are restarting, stop timer first.                           */
  /*-------------------------------------------------------------------*/
  if (timer->running)
    NetTimerStop(timer);

  /*-------------------------------------------------------------------*/
  /* Assign timer's expiration tick count.                             */
  /*-------------------------------------------------------------------*/
  timer->time_due = NetTickCount + timeout;

  /*-------------------------------------------------------------------*/
  /* Search timeout list for timer with later expiration date.         */
  /*-------------------------------------------------------------------*/
  for (link = TimeoutList.next_bck;; link = link->next_bck)
  {
    /*-----------------------------------------------------------------*/
    /* If end of sorted list is reached, append to end.                */
    /*-----------------------------------------------------------------*/
    if (link == &TimeoutList)
    {
      /*---------------------------------------------------------------*/
      /* Append timer to end of sorted list and break.                 */
      /*---------------------------------------------------------------*/
      timer->link.next_fwd = TimeoutList.next_fwd;
      timer->link.next_bck = &TimeoutList;
      TimeoutList.next_fwd->next_bck = &timer->link;
      TimeoutList.next_fwd = &timer->link;
      break;
    }

    /*-----------------------------------------------------------------*/
    /* If later expiration found, insert into sorted list and break.   */
    /*-----------------------------------------------------------------*/
    else if (SEQ_LT(timer->time_due, ((TcpTmr *)link)->time_due))
    {
      timer->link.next_fwd = link->next_fwd;
      timer->link.next_bck = link;
      link->next_fwd->next_bck = &timer->link;
      link->next_fwd = &timer->link;
      break;
    }
  }

  /*-------------------------------------------------------------------*/
  /* Flag that timer is running.                                       */
  /*-------------------------------------------------------------------*/
  timer->running = TRUE;
}

/***********************************************************************/
/* NetTimerStop: Stop selected timer                                   */
/*                                                                     */
/*       Input: timer = pointer to timer control block to process      */
/*                                                                     */
/***********************************************************************/
void NetTimerStop(TcpTmr *timer)
{
  /*-------------------------------------------------------------------*/
  /* If running, remove from active timers list and mark as stopped.   */
  /*-------------------------------------------------------------------*/
  if (timer->running)
  {
    timer->link.next_bck->next_fwd = timer->link.next_fwd;
    timer->link.next_fwd->next_bck = timer->link.next_bck;
    timer->running = FALSE;
  }
}

/***********************************************************************/
/* NetTimerTick: Process TCP/IP timer tick                             */
/*                                                                     */
/***********************************************************************/
void NetTimerTick(void)
{
  /*-------------------------------------------------------------------*/
  /* Increment TCP initial segment sequence number.                    */
  /*-------------------------------------------------------------------*/
  Net.ISN += 125000;

  /*-------------------------------------------------------------------*/
  /* Whip through timeout list, processing expired timers.             */
  /*-------------------------------------------------------------------*/
  while (TimeoutList.next_bck != &TimeoutList)
  {
    TcpTmr *timer = (TcpTmr *)TimeoutList.next_bck;

    /*-----------------------------------------------------------------*/
    /* Break upon reaching non-expired timer.                          */
    /*-----------------------------------------------------------------*/
    if (timer->time_due != NetTickCount)
      break;

    /*-----------------------------------------------------------------*/
    /* Remove from head of timeout list and mark as stopped.           */
    /*-----------------------------------------------------------------*/
    TimeoutList.next_bck = TimeoutList.next_bck->next_bck;
    TimeoutList.next_bck->next_fwd = &TimeoutList;
    timer->running = FALSE;

    /*-----------------------------------------------------------------*/
    /* Call timer action routine.                                      */
    /*-----------------------------------------------------------------*/
    timer->action(timer->object);
  }

  /*-------------------------------------------------------------------*/
  /* Increment tick counter.                                           */
  /*-------------------------------------------------------------------*/
  ++NetTickCount;
}