1*16dce513Schristos /* insque(3C) routines 2*16dce513Schristos This file is in the public domain. */ 3*16dce513Schristos 4*16dce513Schristos /* 5*16dce513Schristos 6*16dce513Schristos @deftypefn Supplemental void insque (struct qelem *@var{elem}, @ 7*16dce513Schristos struct qelem *@var{pred}) 8*16dce513Schristos @deftypefnx Supplemental void remque (struct qelem *@var{elem}) 9*16dce513Schristos 10*16dce513Schristos Routines to manipulate queues built from doubly linked lists. The 11*16dce513Schristos @code{insque} routine inserts @var{elem} in the queue immediately 12*16dce513Schristos after @var{pred}. The @code{remque} routine removes @var{elem} from 13*16dce513Schristos its containing queue. These routines expect to be passed pointers to 14*16dce513Schristos structures which have as their first members a forward pointer and a 15*16dce513Schristos back pointer, like this prototype (although no prototype is provided): 16*16dce513Schristos 17*16dce513Schristos @example 18*16dce513Schristos struct qelem @{ 19*16dce513Schristos struct qelem *q_forw; 20*16dce513Schristos struct qelem *q_back; 21*16dce513Schristos char q_data[]; 22*16dce513Schristos @}; 23*16dce513Schristos @end example 24*16dce513Schristos 25*16dce513Schristos @end deftypefn 26*16dce513Schristos 27*16dce513Schristos */ 28*16dce513Schristos 29*16dce513Schristos 30*16dce513Schristos struct qelem { 31*16dce513Schristos struct qelem *q_forw; 32*16dce513Schristos struct qelem *q_back; 33*16dce513Schristos }; 34*16dce513Schristos 35*16dce513Schristos 36*16dce513Schristos void insque(struct qelem * elem,struct qelem * pred)37*16dce513Schristosinsque (struct qelem *elem, struct qelem *pred) 38*16dce513Schristos { 39*16dce513Schristos elem -> q_forw = pred -> q_forw; 40*16dce513Schristos pred -> q_forw -> q_back = elem; 41*16dce513Schristos elem -> q_back = pred; 42*16dce513Schristos pred -> q_forw = elem; 43*16dce513Schristos } 44*16dce513Schristos 45*16dce513Schristos 46*16dce513Schristos void remque(struct qelem * elem)47*16dce513Schristosremque (struct qelem *elem) 48*16dce513Schristos { 49*16dce513Schristos elem -> q_forw -> q_back = elem -> q_back; 50*16dce513Schristos elem -> q_back -> q_forw = elem -> q_forw; 51*16dce513Schristos } 52