1 /*
2 * Empire - A multi-player, client/server Internet based war game.
3 * Copyright (C) 1986-2021, Dave Pare, Jeff Bailey, Thomas Ruschak,
4 * Ken Stevens, Steve McClure, Markus Armbruster
5 *
6 * Empire is free software: you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation, either version 3 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
18 *
19 * ---
20 *
21 * See files README, COPYING and CREDITS in the root of the source
22 * tree for related information and legal notices. It is expected
23 * that future projects/authors will amend these files as needed.
24 *
25 * ---
26 *
27 * queue.c: Various queue routines (for lists)
28 *
29 * Known contributors to this file:
30 * Markus Armbruster, 2014
31 */
32
33 #include <config.h>
34
35 #include <stddef.h>
36 #include "queue.h"
37
38 void
emp_insque(struct emp_qelem * elem,struct emp_qelem * queue)39 emp_insque(struct emp_qelem *elem, struct emp_qelem *queue)
40 {
41 struct emp_qelem *next;
42
43 next = queue->q_forw;
44 queue->q_forw = elem;
45 elem->q_forw = next;
46 elem->q_back = queue;
47 next->q_back = elem;
48 }
49
50 void
emp_remque(struct emp_qelem * elem)51 emp_remque(struct emp_qelem *elem)
52 {
53 if (!elem)
54 return;
55 if (elem->q_forw)
56 elem->q_forw->q_back = elem->q_back;
57 if (elem->q_back)
58 elem->q_back->q_forw = elem->q_forw;
59 }
60
61 int
emp_quelen(struct emp_qelem * queue)62 emp_quelen(struct emp_qelem *queue)
63 {
64 struct emp_qelem *qp;
65 int len;
66
67 for (qp = queue->q_forw, len = 0; qp != queue; qp = qp->q_forw, len++)
68 ;
69 return len;
70 }
71
72 struct emp_qelem *
emp_searchque(struct emp_qelem * queue,void * key,int (* test)(struct emp_qelem *,void *))73 emp_searchque(struct emp_qelem *queue, void *key,
74 int (*test)(struct emp_qelem *, void *))
75 {
76 struct emp_qelem *qp;
77
78 for (qp = queue->q_forw; qp != queue; qp = qp->q_forw) {
79 if (test(qp, key))
80 return qp;
81 }
82 return NULL;
83 }
84
85 void
emp_initque(struct emp_qelem * elem)86 emp_initque(struct emp_qelem *elem)
87 {
88 elem->q_forw = elem;
89 elem->q_back = elem;
90 }
91