michael@0: /******************************************************************************
michael@0:  *
michael@0:  * Copyright (C) 2002 Jason Evans <jasone@canonware.com>.
michael@0:  * All rights reserved.
michael@0:  *
michael@0:  * Redistribution and use in source and binary forms, with or without
michael@0:  * modification, are permitted provided that the following conditions
michael@0:  * are met:
michael@0:  * 1. Redistributions of source code must retain the above copyright
michael@0:  *    notice(s), this list of conditions and the following disclaimer
michael@0:  *    unmodified other than the allowable addition of one or more
michael@0:  *    copyright notices.
michael@0:  * 2. Redistributions in binary form must reproduce the above copyright
michael@0:  *    notice(s), this list of conditions and the following disclaimer in
michael@0:  *    the documentation and/or other materials provided with the
michael@0:  *    distribution.
michael@0:  *
michael@0:  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
michael@0:  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
michael@0:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
michael@0:  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
michael@0:  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
michael@0:  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
michael@0:  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
michael@0:  * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
michael@0:  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
michael@0:  * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
michael@0:  * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
michael@0:  *
michael@0:  ******************************************************************************/
michael@0: 
michael@0: /* Ring definitions. */
michael@0: #define qr(a_type)							\
michael@0: struct {								\
michael@0: 	a_type	*qre_next;						\
michael@0: 	a_type	*qre_prev;						\
michael@0: }
michael@0: 
michael@0: /* Ring functions. */
michael@0: #define qr_new(a_qr, a_field) do {					\
michael@0: 	(a_qr)->a_field.qre_next = (a_qr);				\
michael@0: 	(a_qr)->a_field.qre_prev = (a_qr);				\
michael@0: } while (0)
michael@0: 
michael@0: #define qr_next(a_qr, a_field) ((a_qr)->a_field.qre_next)
michael@0: 
michael@0: #define qr_prev(a_qr, a_field) ((a_qr)->a_field.qre_prev)
michael@0: 
michael@0: #define qr_before_insert(a_qrelm, a_qr, a_field) do {			\
michael@0: 	(a_qr)->a_field.qre_prev = (a_qrelm)->a_field.qre_prev;		\
michael@0: 	(a_qr)->a_field.qre_next = (a_qrelm);				\
michael@0: 	(a_qr)->a_field.qre_prev->a_field.qre_next = (a_qr);		\
michael@0: 	(a_qrelm)->a_field.qre_prev = (a_qr);				\
michael@0: } while (0)
michael@0: 
michael@0: #define qr_after_insert(a_qrelm, a_qr, a_field)				\
michael@0:     do									\
michael@0:     {									\
michael@0: 	(a_qr)->a_field.qre_next = (a_qrelm)->a_field.qre_next;		\
michael@0: 	(a_qr)->a_field.qre_prev = (a_qrelm);				\
michael@0: 	(a_qr)->a_field.qre_next->a_field.qre_prev = (a_qr);		\
michael@0: 	(a_qrelm)->a_field.qre_next = (a_qr);				\
michael@0:     } while (0)
michael@0: 
michael@0: #define qr_meld(a_qr_a, a_qr_b, a_field) do {				\
michael@0: 	void *t;							\
michael@0: 	(a_qr_a)->a_field.qre_prev->a_field.qre_next = (a_qr_b);	\
michael@0: 	(a_qr_b)->a_field.qre_prev->a_field.qre_next = (a_qr_a);	\
michael@0: 	t = (a_qr_a)->a_field.qre_prev;					\
michael@0: 	(a_qr_a)->a_field.qre_prev = (a_qr_b)->a_field.qre_prev;	\
michael@0: 	(a_qr_b)->a_field.qre_prev = t;					\
michael@0: } while (0)
michael@0: 
michael@0: /* qr_meld() and qr_split() are functionally equivalent, so there's no need to
michael@0:  * have two copies of the code. */
michael@0: #define qr_split(a_qr_a, a_qr_b, a_field)				\
michael@0: 	qr_meld((a_qr_a), (a_qr_b), a_field)
michael@0: 
michael@0: #define qr_remove(a_qr, a_field) do {					\
michael@0: 	(a_qr)->a_field.qre_prev->a_field.qre_next			\
michael@0: 	    = (a_qr)->a_field.qre_next;					\
michael@0: 	(a_qr)->a_field.qre_next->a_field.qre_prev			\
michael@0: 	    = (a_qr)->a_field.qre_prev;					\
michael@0: 	(a_qr)->a_field.qre_next = (a_qr);				\
michael@0: 	(a_qr)->a_field.qre_prev = (a_qr);				\
michael@0: } while (0)
michael@0: 
michael@0: #define qr_foreach(var, a_qr, a_field)					\
michael@0: 	for ((var) = (a_qr);						\
michael@0: 	    (var) != NULL;						\
michael@0: 	    (var) = (((var)->a_field.qre_next != (a_qr))		\
michael@0: 	    ? (var)->a_field.qre_next : NULL))
michael@0: 
michael@0: #define qr_reverse_foreach(var, a_qr, a_field)				\
michael@0: 	for ((var) = ((a_qr) != NULL) ? qr_prev(a_qr, a_field) : NULL;	\
michael@0: 	    (var) != NULL;						\
michael@0: 	    (var) = (((var) != (a_qr))					\
michael@0: 	    ? (var)->a_field.qre_prev : NULL))