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emacs/oldXMenu/insque.c

58 lines
1.6 KiB
C

/*
Copyright (C) 1993-1998, 2001-2014 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
/* This file implements the emacs_insque and emacs_remque functions,
clones of the insque and remque functions of BSD. They and all
their callers have been renamed to emacs_mumble to allow us to
include this file in the menu library on all systems. */
#include "XMenuInt.h"
struct qelem {
struct qelem *q_forw;
struct qelem *q_back;
char q_data[1];
};
/* Insert ELEM into a doubly-linked list, after PREV. */
void
emacs_insque (void *velem, void *vprev)
{
struct qelem *elem = velem;
struct qelem *prev = vprev;
struct qelem *next = prev->q_forw;
prev->q_forw = elem;
if (next)
next->q_back = elem;
elem->q_forw = next;
elem->q_back = prev;
}
/* Unlink ELEM from the doubly-linked list that it is in. */
void
emacs_remque (void *velem)
{
struct qelem *elem = velem;
struct qelem *next = elem->q_forw;
struct qelem *prev = elem->q_back;
if (next)
next->q_back = prev;
if (prev)
prev->q_forw = next;
}