code.delx.au - gnu-emacs/blob - oldXMenu/insque.c

   1 /* This file implements the emacs_insque and emacs_remque functions,
   2    copies of the insque and remque functions of BSD.  They and all
   3    their callers have been renamed to emacs_mumble to allow us to
   4    include this file in the menu library on all systems.  */
   5
   6
   7 struct qelem {
   8   struct    qelem *q_forw;
   9   struct    qelem *q_back;
  10   char q_data[1];
  11 };
  12
  13 /* Insert ELEM into a doubly-linked list, after PREV.  */
  14
  15 void
  16 emacs_insque (elem, prev)
  17      struct qelem *elem, *prev;
  18 {
  19   struct qelem *next = prev->q_forw;
  20   prev->q_forw = elem;
  21   if (next)
  22     next->q_back = elem;
  23   elem->q_forw = next;
  24   elem->q_back = prev;
  25 }
  26
  27 /* Unlink ELEM from the doubly-linked list that it is in.  */
  28
  29 emacs_remque (elem)
  30      struct qelem *elem;
  31 {
  32   struct qelem *next = elem->q_forw;
  33   struct qelem *prev = elem->q_back;
  34   if (next)
  35     next->q_back = prev;
  36   if (prev)
  37     prev->q_forw = next;
  38 }