queue.c

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/*
 *  queue.cc
 *  Copyright (C) 1998,1999 SAKAI Katsuya
 *
 *  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; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <stdio.h> // #include <iostream.h>
#include "queue.h"

inline u_long EventQueue::NextTime()
{
  return (item==0) ? (~0UL) : queue[1]->Time;
}

Event *EventQueue::store(Event *aEvent)
{
  if(item>=Max) return aEvent;

  register u_long j, k;
  item++;
  j = item;
  queue[item]=aEvent;

  while(j>1)
	{
	  k = (int)j/2;
	  if(queue[j]->Time < queue[k]->Time)
		{
		  queue[0] = queue[j];
		  queue[j] = queue[k];
		  queue[k] = queue[0];
		}
	  else
		break;
	  j = k;
	}
  return NULL;
}

Event *EventQueue::retrieve()
{
  if(item==0) return NULL;
  Event *rtn;
  rtn = queue[1];
  queue[1] = queue[item];
  item--;
  register u_long j=1, k;
  while(j*2 <= item)
	{
	  if(j*2+1 <= item )
		{
		  queue[0] = min(queue[j], queue[j*2], queue[j*2+1]);
		  if(queue[0]==queue[j]) break;
		  else if(queue[0]==queue[j*2]) k=j*2;
		  else k=j*2+1;
		  queue[0] = queue[k];
		  queue[k] = queue[j];
		  queue[j] = queue[0];
		  j = k;
		}
	  else
		{
		  if( queue[j]->Time < queue[j*2]->Time ) break;
		  queue[0] = queue[j];
		  queue[j] = queue[j*2];
		  queue[j*2] = queue[0];
		  j = j*2;
		}
	}
  return rtn;
}

Event *EventQueue::min(Event *a, Event *b, Event *c)
{
  return ( a->Time < b->Time ) ?
	(( a->Time < c->Time )? a : c)
	  : (( b->Time < c->Time )? b : c);
}
/*
   {
  if( a->Time < b->Time )
	if( a->Time < c->Time ) return a;
	else return c;
  else if( b->Time < c->Time ) return b;
  else return c;
  }
*/