Home | History | Annotate | Line # | Download | only in libiberty 
      1 /* insque(3C) routines
      2    This file is in the public domain.  */
      3 
      4 /*
      5 
      6 @deftypefn Supplemental void insque (struct qelem *@var{elem}, @
      7   struct qelem *@var{pred})
      8 @deftypefnx Supplemental void remque (struct qelem *@var{elem})
      9 
     10 Routines to manipulate queues built from doubly linked lists.  The
     11 @code{insque} routine inserts @var{elem} in the queue immediately
     12 after @var{pred}.  The @code{remque} routine removes @var{elem} from
     13 its containing queue.  These routines expect to be passed pointers to
     14 structures which have as their first members a forward pointer and a
     15 back pointer, like this prototype (although no prototype is provided):
     16 
     17 @example
     18 struct qelem @{
     19   struct qelem *q_forw;
     20   struct qelem *q_back;
     21   char q_data[];
     22 @};
     23 @end example
     24 
     25 @end deftypefn
     26 
     27 */
     28 
     29 
     30 struct qelem {
     31   struct qelem *q_forw;
     32   struct qelem *q_back;
     33 };
     34 
     35 
     36 void
     37 insque (struct qelem *elem, struct qelem *pred)
     38 {
     39   elem -> q_forw = pred -> q_forw;
     40   pred -> q_forw -> q_back = elem;
     41   elem -> q_back = pred;
     42   pred -> q_forw = elem;
     43 }
     44 
     45 
     46 void
     47 remque (struct qelem *elem)
     48 {
     49   elem -> q_forw -> q_back = elem -> q_back;
     50   elem -> q_back -> q_forw = elem -> q_forw;
     51 }
     52