text: /**
   * @file
   * Stack-internal timers implementation.
   * This file includes timer callbacks for stack-internal timers as well as
   * functions to set up or stop timers and check for expired timers.
   *
   */
  
  /*
   * Copyright (c) 2001-2004 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. The name of the author may not be used to endorse or promote products
   *    derived from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
   *
   * This file is part of the lwIP TCP/IP stack.
   *
   * Author: Adam Dunkels <adam@sics.se>
   *         Simon Goldschmidt
   *
   */
  
  #include "lwip/opt.h"
  
  #include "lwip/timers.h"
  #include "lwip/tcp_impl.h"
  
  #if LWIP_TIMERS
  
  #include "lwip/def.h"
  #include "lwip/memp.h"
  #include "lwip/tcpip.h"
  
  #include "lwip/ip_frag.h"
  #include "netif/etharp.h"
  #include "lwip/dhcp.h"
  #include "lwip/autoip.h"
  #include "lwip/igmp.h"
  #include "lwip/dns.h"
  #include "lwip/sys.h"
  #include "lwip/pbuf.h"
  
  
  /** The one and only timeout list */
  static struct sys_timeo* next_timeout;
  #if NO_SYS
  	static u32_t timeouts_last_time;
  #endif /* NO_SYS */
  
  #if LWIP_TCP
  /** global variable that shows if the tcp timer is currently scheduled or not */
  static int tcpip_tcp_timer_active;
  
  /**
   * Timer callback function that calls tcp_tmr() and reschedules itself.
   *
   * @param arg unused argument
   */
  static void
  tcpip_tcp_timer(void* arg)
  {
  	LWIP_UNUSED_ARG(arg);
  
  	/* call TCP timer handler */
  	tcp_tmr();
  
  	/* timer still needed? */
  	if(tcp_active_pcbs || tcp_tw_pcbs) {
  		/* restart timer */
  		sys_timeout(TCP_TMR_INTERVAL, tcpip_tcp_timer, NULL);
  	} else {
  		/* disable timer */
  		tcpip_tcp_timer_active = 0;
  	}
  }
  
  /**
   * Called from TCP_REG when registering a new PCB:
   * the reason is to have the TCP timer only running when
   * there are active (or time-wait) PCBs.
   */
  void
  tcp_timer_needed(void)
  {
  	/* timer is off but needed again? */
  	if(!tcpip_tcp_timer_active && (tcp_active_pcbs || tcp_tw_pcbs)) {
  		/* enable and start timer */
  		tcpip_tcp_timer_active = 1;
  		sys_timeout(TCP_TMR_INTERVAL, tcpip_tcp_timer, NULL);
  	}
  }
  #endif /* LWIP_TCP */
  
  #if IP_REASSEMBLY
  /**
   * Timer callback function that calls ip_reass_tmr() and reschedules itself.
   *
   * @param arg unused argument
   */
  static void
  ip_reass_timer(void* arg)
  {
  	LWIP_UNUSED_ARG(arg);
  	LWIP_DEBUGF(TIMERS_DEBUG, ("tcpip: ip_reass_tmr()\n"));
  	ip_reass_tmr();
  	sys_timeout(IP_TMR_INTERVAL, ip_reass_timer, NULL);
  }
  #endif /* IP_REASSEMBLY */
  
  #if LWIP_ARP
  /**
   * Timer callback function that calls etharp_tmr() and reschedules itself.
   *
   * @param arg unused argument
   */
  static void
  arp_timer(void* arg)
  {
  	LWIP_UNUSED_ARG(arg);
  	LWIP_DEBUGF(TIMERS_DEBUG, ("tcpip: etharp_tmr()\n"));
  	etharp_tmr();
  	sys_timeout(ARP_TMR_INTERVAL, arp_timer, NULL);
  }
  #endif /* LWIP_ARP */
  
  #if LWIP_DHCP
  /**
   * Timer callback function that calls dhcp_coarse_tmr() and reschedules itself.
   *
   * @param arg unused argument
   */
  static void
  dhcp_timer_coarse(void* arg)
  {
  	LWIP_UNUSED_ARG(arg);
  	LWIP_DEBUGF(TIMERS_DEBUG, ("tcpip: dhcp_coarse_tmr()\n"));
  	dhcp_coarse_tmr();
  	sys_timeout(DHCP_COARSE_TIMER_MSECS, dhcp_timer_coarse, NULL);
  }
  
  /**
   * Timer callback function that calls dhcp_fine_tmr() and reschedules itself.
   *
   * @param arg unused argument
   */
  static void
  dhcp_timer_fine(void* arg)
  {
  	LWIP_UNUSED_ARG(arg);
  	LWIP_DEBUGF(TIMERS_DEBUG, ("tcpip: dhcp_fine_tmr()\n"));
  	dhcp_fine_tmr();
  	sys_timeout(DHCP_FINE_TIMER_MSECS, dhcp_timer_fine, NULL);
  }
  #endif /* LWIP_DHCP */
  
  #if LWIP_AUTOIP
  /**
   * Timer callback function that calls autoip_tmr() and reschedules itself.
   *
   * @param arg unused argument
   */
  static void
  autoip_timer(void* arg)
  {
  	LWIP_UNUSED_ARG(arg);
  	LWIP_DEBUGF(TIMERS_DEBUG, ("tcpip: autoip_tmr()\n"));
  	autoip_tmr();
  	sys_timeout(AUTOIP_TMR_INTERVAL, autoip_timer, NULL);
  }
  #endif /* LWIP_AUTOIP */
  
  #if LWIP_IGMP
  /**
   * Timer callback function that calls igmp_tmr() and reschedules itself.
   *
   * @param arg unused argument
   */
  static void
  igmp_timer(void* arg)
  {
  	LWIP_UNUSED_ARG(arg);
  	LWIP_DEBUGF(TIMERS_DEBUG, ("tcpip: igmp_tmr()\n"));
  	igmp_tmr();
  	sys_timeout(IGMP_TMR_INTERVAL, igmp_timer, NULL);
  }
  #endif /* LWIP_IGMP */
  
  #if LWIP_DNS
  /**
   * Timer callback function that calls dns_tmr() and reschedules itself.
   *
   * @param arg unused argument
   */
  static void
  dns_timer(void* arg)
  {
  	LWIP_UNUSED_ARG(arg);
  	LWIP_DEBUGF(TIMERS_DEBUG, ("tcpip: dns_tmr()\n"));
  	dns_tmr();
  	sys_timeout(DNS_TMR_INTERVAL, dns_timer, NULL);
  }
  #endif /* LWIP_DNS */
  
  /** Initialize this module */
  void sys_timeouts_init(void)
  {
  #if IP_REASSEMBLY
  	sys_timeout(IP_TMR_INTERVAL, ip_reass_timer, NULL);
  #endif /* IP_REASSEMBLY */
  #if LWIP_ARP
  	sys_timeout(ARP_TMR_INTERVAL, arp_timer, NULL);
  #endif /* LWIP_ARP */
  #if LWIP_DHCP
  	sys_timeout(DHCP_COARSE_TIMER_MSECS, dhcp_timer_coarse, NULL);
  	sys_timeout(DHCP_FINE_TIMER_MSECS, dhcp_timer_fine, NULL);
  #endif /* LWIP_DHCP */
  #if LWIP_AUTOIP
  	sys_timeout(AUTOIP_TMR_INTERVAL, autoip_timer, NULL);
  #endif /* LWIP_AUTOIP */
  #if LWIP_IGMP
  	sys_timeout(IGMP_TMR_INTERVAL, igmp_timer, NULL);
  #endif /* LWIP_IGMP */
  #if LWIP_DNS
  	sys_timeout(DNS_TMR_INTERVAL, dns_timer, NULL);
  #endif /* LWIP_DNS */
  
  #if NO_SYS
  	/* Initialise timestamp for sys_check_timeouts */
  	timeouts_last_time = sys_now();
  #endif
  }
  
  /**
   * Create a one-shot timer (aka timeout). Timeouts are processed in the
   * following cases:
   * - while waiting for a message using sys_timeouts_mbox_fetch()
   * - by calling sys_check_timeouts() (NO_SYS==1 only)
   *
   * @param msecs time in milliseconds after that the timer should expire
   * @param handler callback function to call when msecs have elapsed
   * @param arg argument to pass to the callback function
   */
  #if LWIP_DEBUG_TIMERNAMES
  	void
  	sys_timeout_debug(u32_t msecs, sys_timeout_handler handler, void* arg, const char* handler_name)
  #else /* LWIP_DEBUG_TIMERNAMES */
  	void
  	sys_timeout(u32_t msecs, sys_timeout_handler handler, void* arg)
  #endif /* LWIP_DEBUG_TIMERNAMES */
  {
  	struct sys_timeo* timeout, *t;
  
  	timeout = (struct sys_timeo*)memp_malloc(MEMP_SYS_TIMEOUT);
  
  	if(timeout == NULL) {
  		LWIP_ASSERT("sys_timeout: timeout != NULL, pool MEMP_SYS_TIMEOUT is empty", timeout != NULL);
  		return;
  	}
  
  	timeout->next = NULL;
  	timeout->h = handler;
  	timeout->arg = arg;
  	timeout->time = msecs;
  #if LWIP_DEBUG_TIMERNAMES
  	timeout->handler_name = handler_name;
  	LWIP_DEBUGF(TIMERS_DEBUG, ("sys_timeout: %p msecs=%"U32_F" handler=%s arg=%p\n",
  	                           (void*)timeout, msecs, handler_name, (void*)arg));
  #endif /* LWIP_DEBUG_TIMERNAMES */
  
  	if(next_timeout == NULL) {
  		next_timeout = timeout;
  		return;
  	}
  
  	if(next_timeout->time > msecs) {
  		next_timeout->time -= msecs;
  		timeout->next = next_timeout;
  		next_timeout = timeout;
  	} else {
  		for(t = next_timeout; t != NULL; t = t->next) {
  			timeout->time -= t->time;
  
  			if(t->next == NULL || t->next->time > timeout->time) {
  				if(t->next != NULL) {
  					t->next->time -= timeout->time;
  				}
  
  				timeout->next = t->next;
  				t->next = timeout;
  				break;
  			}
  		}
  	}
  }
  
  /**
   * Go through timeout list (for this task only) and remove the first matching
   * entry, even though the timeout has not triggered yet.
   *
   * @note This function only works as expected if there is only one timeout
   * calling 'handler' in the list of timeouts.
   *
   * @param handler callback function that would be called by the timeout
   * @param arg callback argument that would be passed to handler
  */
  void
  sys_untimeout(sys_timeout_handler handler, void* arg)
  {
  	struct sys_timeo* prev_t, *t;
  
  	if(next_timeout == NULL) {
  		return;
  	}
  
  	for(t = next_timeout, prev_t = NULL; t != NULL; prev_t = t, t = t->next) {
  		if((t->h == handler) && (t->arg == arg)) {
  			/* We have a match */
  			/* Unlink from previous in list */
  			if(prev_t == NULL) {
  				next_timeout = t->next;
  			} else {
  				prev_t->next = t->next;
  			}
  
  			/* If not the last one, add time of this one back to next */
  			if(t->next != NULL) {
  				t->next->time += t->time;
  			}
  
  			memp_free(MEMP_SYS_TIMEOUT, t);
  			return;
  		}
  	}
  
  	return;
  }
  
  #if NO_SYS
  
  /** Handle timeouts for NO_SYS==1 (i.e. without using
   * tcpip_thread/sys_timeouts_mbox_fetch(). Uses sys_now() to call timeout
   * handler functions when timeouts expire.
   *
   * Must be called periodically from your main loop.
   */
  void
  sys_check_timeouts(void)
  {
  	if(next_timeout) {
  		struct sys_timeo* tmptimeout;
  		u32_t diff;
  		sys_timeout_handler handler;
  		void* arg;
  		u8_t had_one;
  		u32_t now;
  
  		now = sys_now();
  		/* this cares for wraparounds */
  		diff = now - timeouts_last_time;
  
  		do {
  #if PBUF_POOL_FREE_OOSEQ
  			PBUF_CHECK_FREE_OOSEQ();
  #endif /* PBUF_POOL_FREE_OOSEQ */
  			had_one = 0;
  			tmptimeout = next_timeout;
  
  			if(tmptimeout && (tmptimeout->time <= diff)) {
  				/* timeout has expired */
  				had_one = 1;
  				timeouts_last_time = now;
  				diff -= tmptimeout->time;
  				next_timeout = tmptimeout->next;
  				handler = tmptimeout->h;
  				arg = tmptimeout->arg;
  #if LWIP_DEBUG_TIMERNAMES
  
  				if(handler != NULL) {
  					LWIP_DEBUGF(TIMERS_DEBUG, ("sct calling h=%s arg=%p\n",
  					                           tmptimeout->handler_name, arg));
  				}
  
  #endif /* LWIP_DEBUG_TIMERNAMES */
  				memp_free(MEMP_SYS_TIMEOUT, tmptimeout);
  
  				if(handler != NULL) {
  					handler(arg);
  				}
  			}
  
  			/* repeat until all expired timers have been called */
  		} while(had_one);
  	}
  }
  
  /** Set back the timestamp of the last call to sys_check_timeouts()
   * This is necessary if sys_check_timeouts() hasn't been called for a long
   * time (e.g. while saving energy) to prevent all timer functions of that
   * period being called.
   */
  void
  sys_restart_timeouts(void)
  {
  	timeouts_last_time = sys_now();
  }
  
  #else /* NO_SYS */
  
  /**
   * Wait (forever) for a message to arrive in an mbox.
   * While waiting, timeouts are processed.
   *
   * @param mbox the mbox to fetch the message from
   * @param msg the place to store the message
   */
  void
  sys_timeouts_mbox_fetch(sys_mbox_t* mbox, void** msg)
  {
  	u32_t time_needed;
  	struct sys_timeo* tmptimeout;
  	sys_timeout_handler handler;
  	void* arg;
  
  again:
  
  	if(!next_timeout) {
  		time_needed = sys_arch_mbox_fetch(mbox, msg, 0);
  	} else {
  		if(next_timeout->time > 0) {
  			time_needed = sys_arch_mbox_fetch(mbox, msg, next_timeout->time);
  		} else {
  			time_needed = SYS_ARCH_TIMEOUT;
  		}
  
  		if(time_needed == SYS_ARCH_TIMEOUT) {
  			/* If time == SYS_ARCH_TIMEOUT, a timeout occured before a message
  			   could be fetched. We should now call the timeout handler and
  			   deallocate the memory allocated for the timeout. */
  			tmptimeout = next_timeout;
  			next_timeout = tmptimeout->next;
  			handler = tmptimeout->h;
  			arg = tmptimeout->arg;
  #if LWIP_DEBUG_TIMERNAMES
  
  			if(handler != NULL) {
  				LWIP_DEBUGF(TIMERS_DEBUG, ("stmf calling h=%s arg=%p\n",
  				                           tmptimeout->handler_name, arg));
  			}
  
  #endif /* LWIP_DEBUG_TIMERNAMES */
  			memp_free(MEMP_SYS_TIMEOUT, tmptimeout);
  
  			if(handler != NULL) {
  				/* For LWIP_TCPIP_CORE_LOCKING, lock the core before calling the
  				   timeout handler function. */
  				LOCK_TCPIP_CORE();
  				handler(arg);
  				UNLOCK_TCPIP_CORE();
  			}
  
  			LWIP_TCPIP_THREAD_ALIVE();
  
  			/* We try again to fetch a message from the mbox. */
  			goto again;
  		} else {
  			/* If time != SYS_ARCH_TIMEOUT, a message was received before the timeout
  			   occured. The time variable is set to the number of
  			   milliseconds we waited for the message. */
  			if(time_needed < next_timeout->time) {
  				next_timeout->time -= time_needed;
  			} else {
  				next_timeout->time = 0;
  			}
  		}
  	}
  }
  
  #endif /* NO_SYS */
  
  #else /* LWIP_TIMERS */
  /* Satisfy the TCP code which calls this function */
  void
  tcp_timer_needed(void)
  {
  }
  #endif /* LWIP_TIMERS */
  