Commit e416a8cc authored by Mike Hibler's avatar Mike Hibler

Forgot this one...

parent dd7a05ee
/*
* Mach Operating System
* Copyright (c) 1991,1990,1989,1988,1987 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.
*
* 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 FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie Mellon rights
* to redistribute these changes.
*/
/*
* File: queue.h
* Author: Avadis Tevanian, Jr.
* Date: 1985
*
* Type definitions for generic queues.
*
*/
#ifndef _KERN_QUEUE_H_
#define _KERN_QUEUE_H_
/*
* Queue of abstract objects. Queue is maintained
* within that object.
*
* Supports fast removal from within the queue.
*
* How to declare a queue of elements of type "foo_t":
* In the "*foo_t" type, you must have a field of
* type "queue_chain_t" to hold together this queue.
* There may be more than one chain through a
* "foo_t", for use by different queues.
*
* Declare the queue as a "queue_t" type.
*
* Elements of the queue (of type "foo_t", that is)
* are referred to by reference, and cast to type
* "queue_entry_t" within this module.
*/
/*
* A generic doubly-linked list (queue).
*/
struct queue_entry {
struct queue_entry *next; /* next element */
struct queue_entry *prev; /* previous element */
};
typedef struct queue_entry *queue_t;
typedef struct queue_entry queue_head_t;
typedef struct queue_entry queue_chain_t;
typedef struct queue_entry *queue_entry_t;
/*
* Macro: queue_init
* Function:
* Initialize the given queue.
* Header:
* void queue_init(q)
* queue_t q; *MODIFIED*
*/
#define queue_init(q) ((q)->next = (q)->prev = q)
/*
* Macro: queue_first
* Function:
* Returns the first entry in the queue,
* Header:
* queue_entry_t queue_first(q)
* queue_t q; *IN*
*/
#define queue_first(q) ((q)->next)
/*
* Macro: queue_next
* Function:
* Returns the entry after an item in the queue.
* Header:
* queue_entry_t queue_next(qc)
* queue_t qc;
*/
#define queue_next(qc) ((qc)->next)
/*
* Macro: queue_last
* Function:
* Returns the last entry in the queue.
* Header:
* queue_entry_t queue_last(q)
* queue_t q; *IN*
*/
#define queue_last(q) ((q)->prev)
/*
* Macro: queue_prev
* Function:
* Returns the entry before an item in the queue.
* Header:
* queue_entry_t queue_prev(qc)
* queue_t qc;
*/
#define queue_prev(qc) ((qc)->prev)
/*
* Macro: queue_end
* Function:
* Tests whether a new entry is really the end of
* the queue.
* Header:
* boolean_t queue_end(q, qe)
* queue_t q;
* queue_entry_t qe;
*/
#define queue_end(q, qe) ((q) == (qe))
/*
* Macro: queue_empty
* Function:
* Tests whether a queue is empty.
* Header:
* boolean_t queue_empty(q)
* queue_t q;
*/
#define queue_empty(q) queue_end((q), queue_first(q))
/*----------------------------------------------------------------*/
/*
* Macros that operate on generic structures. The queue
* chain may be at any location within the structure, and there
* may be more than one chain.
*/
/*
* Macro: queue_enter
* Function:
* Insert a new element at the tail of the queue.
* Header:
* void queue_enter(q, elt, type, field)
* queue_t q;
* <type> elt;
* <type> is what's in our queue
* <field> is the chain field in (*<type>)
*/
#define queue_enter(head, elt, type, field) \
{ \
register queue_entry_t prev; \
\
prev = (head)->prev; \
if ((head) == prev) { \
(head)->next = (queue_entry_t) (elt); \
} \
else { \
((type)prev)->field.next = (queue_entry_t)(elt);\
} \
(elt)->field.prev = prev; \
(elt)->field.next = head; \
(head)->prev = (queue_entry_t) elt; \
}
/*
* Macro: queue_enter_first
* Function:
* Insert a new element at the head of the queue.
* Header:
* void queue_enter_first(q, elt, type, field)
* queue_t q;
* <type> elt;
* <type> is what's in our queue
* <field> is the chain field in (*<type>)
*/
#define queue_enter_first(head, elt, type, field) \
{ \
register queue_entry_t next; \
\
next = (head)->next; \
if ((head) == next) { \
(head)->prev = (queue_entry_t) (elt); \
} \
else { \
((type)next)->field.prev = (queue_entry_t)(elt);\
} \
(elt)->field.next = next; \
(elt)->field.prev = head; \
(head)->next = (queue_entry_t) elt; \
}
/*
* Macro: queue_enter_before
* Function:
* Insert a new element before the indicated element.
* Header:
* void queue_enter_before(q, nelt, elt, type, field)
* queue_t q;
* <type> nelt, elt;
* <type> is what's in our queue
* <field> is the chain field in (*<type>)
*/
#define queue_enter_before(head, nelt, elt, type, field) \
{ \
register queue_entry_t prev; \
\
(elt)->field.next = (queue_entry_t)(nelt); \
if ((head) == (queue_entry_t)(nelt)) { \
(elt)->field.prev = (head)->prev; \
prev = (head)->prev; \
(head)->prev = (queue_entry_t)(elt); \
} else { \
(elt)->field.prev = (nelt)->field.prev; \
prev = (nelt)->field.prev; \
(nelt)->field.prev = (queue_entry_t)(elt); \
} \
if ((head) == prev) \
(head)->next = (queue_entry_t)(elt); \
else \
((type)prev)->field.next = (queue_entry_t)(elt);\
}
/*
* Macro: queue_enter_after
* Function:
* Insert a new element after the indicated element.
* Header:
* void queue_enter_after(q, pelt, elt, type, field)
* queue_t q;
* <type> pelt, elt;
* <type> is what's in our queue
* <field> is the chain field in (*<type>)
*/
#define queue_enter_after(head, pelt, elt, type, field) \
{ \
register queue_entry_t next; \
\
(elt)->field.prev = (queue_entry_t)(pelt); \
if ((head) == (queue_entry_t)(pelt)) { \
(elt)->field.next = (head)->next; \
next = (head)->next; \
(head)->next = (queue_entry_t)(elt); \
} else { \
(elt)->field.next = (pelt)->field.next; \
next = (pelt)->field.next; \
(pelt)->field.next = (queue_entry_t)(elt); \
} \
if ((head) == next) \
(head)->prev = (queue_entry_t)(elt); \
else \
((type)next)->field.prev = (queue_entry_t)(elt);\
}
/*
* Macro: queue_field [internal use only]
* Function:
* Find the queue_chain_t (or queue_t) for the
* given element (thing) in the given queue (head)
*/
#define queue_field(head, thing, type, field) \
(((head) == (thing)) ? (head) : &((type)(thing))->field)
/*
* Macro: queue_remove
* Function:
* Remove an arbitrary item from the queue.
* Header:
* void queue_remove(q, qe, type, field)
* arguments as in queue_enter
*/
#define queue_remove(head, elt, type, field) \
{ \
register queue_entry_t next, prev; \
\
next = (elt)->field.next; \
prev = (elt)->field.prev; \
\
if ((head) == next) \
(head)->prev = prev; \
else \
((type)next)->field.prev = prev; \
\
if ((head) == prev) \
(head)->next = next; \
else \
((type)prev)->field.next = next; \
}
/*
* Macro: queue_remove_first
* Function:
* Remove and return the entry at the head of
* the queue.
* Header:
* queue_remove_first(head, entry, type, field)
* entry is returned by reference
*/
#define queue_remove_first(head, entry, type, field) \
{ \
register queue_entry_t next; \
\
(entry) = (type) ((head)->next); \
next = (entry)->field.next; \
\
if ((head) == next) \
(head)->prev = (head); \
else \
((type)(next))->field.prev = (head); \
(head)->next = next; \
}
/*
* Macro: queue_remove_last
* Function:
* Remove and return the entry at the tail of
* the queue.
* Header:
* queue_remove_last(head, entry, type, field)
* entry is returned by reference
*/
#define queue_remove_last(head, entry, type, field) \
{ \
register queue_entry_t prev; \
\
(entry) = (type) ((head)->prev); \
prev = (entry)->field.prev; \
\
if ((head) == prev) \
(head)->next = (head); \
else \
((type)(prev))->field.next = (head); \
(head)->prev = prev; \
}
/*
* Macro: queue_assign
*/
#define queue_assign(to, from, type, field) \
{ \
((type)((from)->prev))->field.next = (to); \
((type)((from)->next))->field.prev = (to); \
*to = *from; \
}
/*
* Macro: queue_iterate
* Function:
* iterate over each item in the queue.
* Generates a 'for' loop, setting elt to
* each item in turn (by reference).
* Header:
* queue_iterate(q, elt, type, field)
* queue_t q;
* <type> elt;
* <type> is what's in our queue
* <field> is the chain field in (*<type>)
*/
#define queue_iterate(head, elt, type, field) \
for ((elt) = (type) queue_first(head); \
!queue_end((head), (queue_entry_t)(elt)); \
(elt) = (type) queue_next(&(elt)->field))
#endif /* _KERN_QUEUE_H_ */
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