oldXMenu/insque.c

   1 /*
   2 Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 2001, 2002, 2003,
   3   2004, 2005, 2006, 2007, 2008, 2009, 2010  Free Software Foundation, Inc.
   4
   5 This program is free software: you can redistribute it and/or modify
   6 it under the terms of the GNU General Public License as published by
   7 the Free Software Foundation, either version 3 of the License, or
   8 (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 General Public License for more details.
  14
  15 You should have received a copy of the GNU General Public License
  16 along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  17
  18 /* This file implements the emacs_insque and emacs_remque functions,
  19    clones of the insque and remque functions of BSD.  They and all
  20    their callers have been renamed to emacs_mumble to allow us to
  21    include this file in the menu library on all systems.  */
  22
  23
  24 struct qelem {
  25   struct    qelem *q_forw;
  26   struct    qelem *q_back;
  27   char q_data[1];
  28 };
  29
  30 /* Insert ELEM into a doubly-linked list, after PREV.  */
  31
  32 void
  33 emacs_insque (elem, prev)
  34      struct qelem *elem, *prev;
  35 {
  36   struct qelem *next = prev->q_forw;
  37   prev->q_forw = elem;
  38   if (next)
  39     next->q_back = elem;
  40   elem->q_forw = next;
  41   elem->q_back = prev;
  42 }
  43
  44 /* Unlink ELEM from the doubly-linked list that it is in.  */
  45
  46 emacs_remque (elem)
  47      struct qelem *elem;
  48 {
  49   struct qelem *next = elem->q_forw;
  50   struct qelem *prev = elem->q_back;
  51   if (next)
  52     next->q_back = prev;
  53   if (prev)
  54     prev->q_forw = next;
  55 }
  56
  57 /* arch-tag: a8719d1a-5c3f-4bce-b36b-173106d36165
  58    (do not change this comment) */