path: root/cpukit/posix/src/alarm.c

/**
 * @file
 *
 * @brief System Generates Signal for process after realtime seconds elapsed
 * @ingroup POSIXAPI
 */

/*
 *  3.4.1 Schedule Alarm, P1003.1b-1993, p. 79
 */

/*  COPYRIGHT (c) 1989-2007.
 *  On-Line Applications Research Corporation (OAR).
 *
 *  The license and distribution terms for this file may be
 *  found in the file LICENSE in this distribution or at
 *  http://www.rtems.com/license/LICENSE.
 */

#if HAVE_CONFIG_H
#include "config.h"
#endif

#include <pthread.h>

#include <rtems/system.h>
#include <rtems/posix/pthread.h>
#include <rtems/posix/psignalimpl.h>

/*
 *  _POSIX_signals_Alarm_TSR
 */

static void _POSIX_signals_Alarm_TSR(
  Objects_Id      id __attribute__((unused)),
  void           *argument __attribute__((unused))
)
{
  kill( getpid(), SIGALRM );
  /* XXX can't print from an ISR, should this be fatal? */
}

unsigned int alarm(
  unsigned int seconds
)
{
  unsigned int      remaining = 0;
  Watchdog_Control *the_timer;

  the_timer = &_POSIX_signals_Alarm_timer;

  /*
   *  Initialize the timer used to implement alarm().
   */

  if ( !the_timer->routine ) {
    _Watchdog_Initialize( the_timer, _POSIX_signals_Alarm_TSR, 0, NULL );
  } else {
    Watchdog_States state;

    state = _Watchdog_Remove( the_timer );
    if ( (state == WATCHDOG_ACTIVE) || (state == WATCHDOG_REMOVE_IT) ) {
      /*
       *  The stop_time and start_time fields are snapshots of ticks since
       *  boot.  Since alarm() is dealing in seconds, we must account for
       *  this.
       */

      remaining = the_timer->initial -
        ((the_timer->stop_time - the_timer->start_time) / TOD_TICKS_PER_SECOND);
    }
  }

  if ( seconds )
    _Watchdog_Insert_seconds( the_timer, seconds );

  return remaining;
}