1 /* Linuxthreads - a simple clone()-based implementation of Posix        */
2 /* threads for Linux.                                                   */
3 /* Copyright (C) 1996 Xavier Leroy (Xavier.Leroy@inria.fr)              */
4 /*                                                                      */
5 /* This program is free software; you can redistribute it and/or        */
6 /* modify it under the terms of the GNU Library General Public License  */
7 /* as published by the Free Software Foundation; either version 2       */
8 /* of the License, or (at your option) any later version.               */
9 /*                                                                      */
10 /* This program is distributed in the hope that it will be useful,      */
11 /* but WITHOUT ANY WARRANTY; without even the implied warranty of       */
12 /* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the        */
13 /* GNU Library General Public License for more details.                 */
14 
15 /* Waiting queues */
16 
17 /* Waiting queues are represented by lists of thread descriptors
18    linked through their p_nextwaiting field.  The lists are kept
19    sorted by decreasing priority, and then decreasing waiting time. */
20 
enqueue(pthread_descr * q,pthread_descr th)21 static __inline__ void enqueue(pthread_descr * q, pthread_descr th)
22 {
23   int prio = th->p_priority;
24   for (; *q != NULL; q = &((*q)->p_nextwaiting)) {
25     if (prio > (*q)->p_priority) {
26       th->p_nextwaiting = *q;
27       *q = th;
28       return;
29     }
30   }
31   *q = th;
32 }
33 
dequeue(pthread_descr * q)34 static __inline__ pthread_descr dequeue(pthread_descr * q)
35 {
36   pthread_descr th;
37   th = *q;
38   if (th != NULL) {
39     *q = th->p_nextwaiting;
40     th->p_nextwaiting = NULL;
41   }
42   return th;
43 }
44 
remove_from_queue(pthread_descr * q,pthread_descr th)45 static __inline__ int remove_from_queue(pthread_descr * q, pthread_descr th)
46 {
47   for (; *q != NULL; q = &((*q)->p_nextwaiting)) {
48     if (*q == th) {
49       *q = th->p_nextwaiting;
50       th->p_nextwaiting = NULL;
51       return 1;
52     }
53   }
54   return 0;
55 }
56 
queue_is_empty(pthread_descr * q)57 static __inline__ int queue_is_empty(pthread_descr * q)
58 {
59     return *q == NULL;
60 }
61