Return to queue.c CVS log

Up to [GnuMach] / OSKit-Mach / kern

Annotation of OSKit-Mach/kern/queue.c, revision 1.1.1.1

1.1       root        1: /* 
                      2:  * Mach Operating System
                      3:  * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
                      4:  * All Rights Reserved.
                      5:  * 
                      6:  * Permission to use, copy, modify and distribute this software and its
                      7:  * documentation is hereby granted, provided that both the copyright
                      8:  * notice and this permission notice appear in all copies of the
                      9:  * software, derivative works or modified versions, and any portions
                     10:  * thereof, and that both notices appear in supporting documentation.
                     11:  * 
                     12:  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
                     13:  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
                     14:  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
                     15:  * 
                     16:  * Carnegie Mellon requests users of this software to return to
                     17:  * 
                     18:  *  Software Distribution Coordinator  or  [email protected]
                     19:  *  School of Computer Science
                     20:  *  Carnegie Mellon University
                     21:  *  Pittsburgh PA 15213-3890
                     22:  * 
                     23:  * any improvements or extensions that they make and grant Carnegie Mellon
                     24:  * the rights to redistribute these changes.
                     25:  */
                     26: /*
                     27:  *     Routines to implement queue package.
                     28:  */
                     29: 
                     30: #include <kern/queue.h>
                     31: 
                     32: 
                     33: 
                     34: /*
                     35:  *     Insert element at head of queue.
                     36:  */
                     37: void enqueue_head(
                     38:        register queue_t        que,
                     39:        register queue_entry_t  elt)
                     40: {
                     41:        elt->next = que->next;
                     42:        elt->prev = que;
                     43:        elt->next->prev = elt;
                     44:        que->next = elt;
                     45: }
                     46: 
                     47: /*
                     48:  *     Insert element at tail of queue.
                     49:  */
                     50: void enqueue_tail(
                     51:        register queue_t        que,
                     52:        register queue_entry_t  elt)
                     53: {
                     54:        elt->next = que;
                     55:        elt->prev = que->prev;
                     56:        elt->prev->next = elt;
                     57:        que->prev = elt;
                     58: }
                     59: 
                     60: /*
                     61:  *     Remove and return element at head of queue.
                     62:  */
                     63: queue_entry_t dequeue_head(
                     64:        register queue_t        que)
                     65: {
                     66:        register queue_entry_t  elt;
                     67: 
                     68:        if (que->next == que)
                     69:                return((queue_entry_t)0);
                     70: 
                     71:        elt = que->next;
                     72:        elt->next->prev = que;
                     73:        que->next = elt->next;
                     74:        return(elt);
                     75: }
                     76: 
                     77: /*
                     78:  *     Remove and return element at tail of queue.
                     79:  */
                     80: queue_entry_t dequeue_tail(
                     81:        register queue_t        que)
                     82: {
                     83:        register queue_entry_t  elt;
                     84: 
                     85:        if (que->prev == que)
                     86:                return((queue_entry_t)0);
                     87: 
                     88:        elt = que->prev;
                     89:        elt->prev->next = que;
                     90:        que->prev = elt->prev;
                     91:        return(elt);
                     92: }
                     93: 
                     94: /*
                     95:  *     Remove arbitrary element from queue.
                     96:  *     Does not check whether element is on queue - the world
                     97:  *     will go haywire if it isn't.
                     98:  */
                     99: 
                    100: /*ARGSUSED*/
                    101: void remqueue(
                    102:        queue_t                 que,
                    103:        register queue_entry_t  elt)
                    104: {
                    105:        elt->next->prev = elt->prev;
                    106:        elt->prev->next = elt->next;
                    107: }
                    108: 
                    109: /*
                    110:  *     Routines to directly imitate the VAX hardware queue
                    111:  *     package.
                    112:  */
                    113: void insque(
                    114:        register struct queue_entry *entry,
                    115:        register struct queue_entry *pred)
                    116: {
                    117:        entry->next = pred->next;
                    118:        entry->prev = pred;
                    119:        (pred->next)->prev = entry;
                    120:        pred->next = entry;
                    121: }
                    122: 
                    123: struct queue_entry
                    124: *remque(
                    125:        register struct queue_entry *elt)
                    126: {
                    127:        (elt->next)->prev = elt->prev;
                    128:        (elt->prev)->next = elt->next;
                    129:        return(elt);
                    130: }
                    131: 

This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.