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Diffstat (limited to 'serverboot/queue.h')
| -rw-r--r-- | serverboot/queue.h | 316 |
1 files changed, 316 insertions, 0 deletions
diff --git a/serverboot/queue.h b/serverboot/queue.h new file mode 100644 index 00000000..3e93476f --- /dev/null +++ b/serverboot/queue.h @@ -0,0 +1,316 @@ +/* + * 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 _QUEUE_H_ +#define _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_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 _QUEUE_H_ |