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alarm.c

/*
 *  acm : an aerial combat simulator for X
 *  Copyright (C) 1991-1994  Riley Rainey
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; version 2 dated June, 1991.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program;  if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave., Cambridge, MA 02139, USA.
 */
#include "alarm.h"
#include <sys/param.h>
#if defined(__STDC__) || defined(HAVE_STDLIB_H)
#include <stdlib.h>
#else
#include <malloc.h>
#endif

static alarm_descriptor_t *alarm_list = NULL;
static alarm_id_t next_alarm_id = 0;

void
alarmCheck (delta)
double      delta;
{
      double d = delta;
      alarm_descriptor_t *p, *list = NULL, *list1;

      while (alarm_list != (alarm_descriptor_t *) NULL && d > 0.0) {
            if ((d = alarm_list->delta - d) <= 0.0) {
                p = alarm_list;
                alarm_list = alarm_list->next;
                if (list) {
                  p->next = list;
                  list = p;
                }
                else {
                  p->next = NULL;
                  list = p;
                }
                d = (d < 0.0) ? -d : 0.0;
            }
            else {
                  alarm_list->delta = d;
                  break;
            }
      }

      while (list) {
            (*list->proc) (list->arg1, list->arg2);
            list1 = list->next;
            free ((char *) list);
            list = list1;
      }

}

alarm_id_t
addAlarm (delta, proc, arg1, arg2)
double      delta;
void  (*proc)();
char  *arg1, *arg2;
{
      alarm_descriptor_t *n, *prev, *p;

      n = (alarm_descriptor_t *) malloc (sizeof(alarm_descriptor_t));
      n->alarm_id = next_alarm_id ++;
      n->delta = delta;
      n->proc = proc;
      n->arg1 = arg1;
      n->arg2 = arg2;
      n->next = NULL;

      if ((p = alarm_list) == NULL) {
            alarm_list = n;
      }
      else {
            prev = NULL;

            while (n->delta > p->delta) {
                  n->delta -= p->delta;
                  prev = p;
                  if ((p = p->next) == NULL) {
                        prev->next = n;
                        return n->alarm_id;
                  }
            }

            if (prev == NULL) {
                  n->next = alarm_list;
                  n->next->delta -= n->delta;
                  alarm_list = n;
            }
            else {
                  n->next = prev->next;
                  n->next->delta -= n->delta;
                  prev->next = n;
            }
      }

      return n->alarm_id;
}

/*
 *  cancelAlarm returns the amount of time remaining until the cancelled
 *  alarm would have "gone-off" (or -1.0, if the alarm was not found).
 */

double
cancelAlarm (id)
alarm_id_t id;
{
      alarm_descriptor_t *p, *last = NULL;
      double      result = 0.0;

/*
 *  Attempt to locate the specified alarm by its alarm_id.
 */
 
      for (p=alarm_list; p; ) {
            if (p->alarm_id == id) {

/*
 *  Unlink this alarm descriptor
 */
 
                  if (last) {
                        last->next = p->next;
                  }
                  else {
                        alarm_list = p->next;
                  }

/*
 *  Correct the next decriptor's delta value, free this descriptor and return.
 */

                  if (p->next) {
                        p->next->delta += p->delta;
                  }
                  result += p->delta;
                  free ((char *) p);
                  return result;
            }

            result += p->delta;
            last = p;
            p = p->next;
      }

/*
 *  Alarm not found, return -1.0.
 */

      return -1.0;
}

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