/*
 * 
 *             Coda: an Experimental Distributed File System
 *                              Release 3.1
 * 
 *           Copyright (c) 1987-1998 Carnegie Mellon University
 *                          All Rights Reserved
 * 
 * Permission  to  use, copy, modify and distribute this software and its
 * documentation is hereby granted,  provided  that  both  the  copyright
 * notice  and  this  permission  notice  appear  in  all  copies  of the
 * software, derivative works or  modified  versions,  and  any  portions
 * thereof, and that both notices appear in supporting documentation, and
 * that credit is given to Carnegie Mellon University  in  all  documents
 * and publicity pertaining to direct or indirect use of this code or its
 * derivatives.
 * 
 * CODA IS AN EXPERIMENTAL SOFTWARE SYSTEM AND IS  KNOWN  TO  HAVE  BUGS,
 * SOME  OF  WHICH MAY HAVE SERIOUS CONSEQUENCES.  CARNEGIE MELLON ALLOWS
 * FREE USE OF THIS SOFTWARE IN ITS "AS IS" CONDITION.   CARNEGIE  MELLON
 * DISCLAIMS  ANY  LIABILITY  OF  ANY  KIND  FOR  ANY  DAMAGES WHATSOEVER
 * RESULTING DIRECTLY OR INDIRECTLY FROM THE USE OF THIS SOFTWARE  OR  OF
 * ANY DERIVATIVE WORK.
 * 
 * Carnegie  Mellon  encourages  users  of  this  software  to return any
 * improvements or extensions that  they  make,  and  to  grant  Carnegie
 * Mellon the rights to redistribute these changes without encumbrance.
 * 
 * 	@(#) src/sys/coda/coda_kernel.h,v 1.1.1.1 1998/08/29 21:14:52 rvb Exp $ 
 *  $Id: coda_kernel.h,v 1.2 1998/09/02 19:09:53 rvb Exp $
 * 
 */

/* Macros to manipulate the queue */
#ifndef INIT_QUEUE
struct queue {
    struct queue *forw, *back;
};

#define INIT_QUEUE(head)                     \
do {                                         \
    (head).forw = (struct queue *)&(head);   \
    (head).back = (struct queue *)&(head);   \
} while (0)

#define GETNEXT(head) (head).forw

#define EMPTY(head) ((head).forw == &(head))

#define EOQ(el, head) ((struct queue *)(el) == (struct queue *)&(head))
		   
#define INSQUE(el, head)                             \
do {                                                 \
	(el).forw = ((head).back)->forw;             \
	(el).back = (head).back;                     \
	((head).back)->forw = (struct queue *)&(el); \
	(head).back = (struct queue *)&(el);         \
} while (0)

#define REMQUE(el)                         \
do {                                       \
	((el).forw)->back = (el).back;     \
	(el).back->forw = (el).forw;       \
}  while (0)

#endif