| 1 | /* insque(3C) routines |
| 2 | This file is in the public domain. */ |
| 3 | |
| 4 | /* |
| 5 | NAME |
| 6 | insque, remque -- insert, remove an element from a queue |
| 7 | |
| 8 | SYNOPSIS |
| 9 | struct qelem { |
| 10 | struct qelem *q_forw; |
| 11 | struct qelem *q_back; |
| 12 | char q_data[]; |
| 13 | }; |
| 14 | |
| 15 | void insque (struct qelem *elem, struct qelem *pred) |
| 16 | |
| 17 | void remque (struct qelem *elem) |
| 18 | |
| 19 | DESCRIPTION |
| 20 | Routines to manipulate queues built from doubly linked lists. |
| 21 | The insque routine inserts ELEM in the queue immediately after |
| 22 | PRED. The remque routine removes ELEM from its containing queue. |
| 23 | */ |
| 24 | |
| 25 | |
| 26 | struct qelem { |
| 27 | struct qelem *q_forw; |
| 28 | struct qelem *q_back; |
| 29 | }; |
| 30 | |
| 31 | |
| 32 | void |
| 33 | insque (elem, pred) |
| 34 | struct qelem *elem; |
| 35 | struct qelem *pred; |
| 36 | { |
| 37 | elem -> q_forw = pred -> q_forw; |
| 38 | pred -> q_forw -> q_back = elem; |
| 39 | elem -> q_back = pred; |
| 40 | pred -> q_forw = elem; |
| 41 | } |
| 42 | |
| 43 | |
| 44 | void |
| 45 | remque (elem) |
| 46 | struct qelem *elem; |
| 47 | { |
| 48 | elem -> q_forw -> q_back = elem -> q_back; |
| 49 | elem -> q_back -> q_forw = elem -> q_forw; |
| 50 | } |