From b7c15c31519dc44c1f691e0466badd556ffe9423 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 18:18:56 +0200 Subject: Adding upstream version 3.7.10. Signed-off-by: Daniel Baumann --- src/util/ring.c | 121 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 121 insertions(+) create mode 100644 src/util/ring.c (limited to 'src/util/ring.c') diff --git a/src/util/ring.c b/src/util/ring.c new file mode 100644 index 0000000..d4c5f82 --- /dev/null +++ b/src/util/ring.c @@ -0,0 +1,121 @@ +/*++ +/* NAME +/* ring 3 +/* SUMMARY +/* circular list management +/* SYNOPSIS +/* #include +/* +/* void ring_init(list) +/* RING *list; +/* +/* void ring_prepend(list, element) +/* RING *list; +/* RING *element; +/* +/* void ring_append(list, element) +/* RING *list; +/* RING *element; +/* +/* RING *ring_pred(element) +/* RING *element; +/* +/* RING *ring_succ(element) +/* RING *element; +/* +/* void ring_detach(element) +/* RING *element; +/* +/* RING_FOREACH(RING *element, RING *head) +/* DESCRIPTION +/* This module manages circular, doubly-linked, lists. It provides +/* operations to initialize a list, to add or remove an element, +/* and to iterate over a list. Although the documentation appears +/* to emphasize the special role of the list head, each operation +/* can be applied to each list member. +/* +/* Examples of applications: any sequence of objects such as queue, +/* unordered list, or stack. Typically, an application embeds a RING +/* structure into its own data structure, and uses the RING primitives +/* to maintain the linkage between application-specific data objects. +/* +/* ring_init() initializes its argument to a list of just one element. +/* +/* ring_append() appends the named element to the named list head. +/* +/* ring_prepend() prepends the named element to the named list head. +/* +/* ring_succ() returns the list element that follows its argument. +/* +/* ring_pred() returns the list element that precedes its argument. +/* +/* ring_detach() disconnects a list element from its neighbors +/* and closes the hole. This routine performs no implicit ring_init() +/* on the removed element. +/* +/* RING_FOREACH() is a macro that expands to a for (... ; ... ; ...) +/* statement that iterates over each list element in forward order. +/* Upon completion, the \fIelement\fR variable is set equal to +/* \fIhead\fR. The list head itself is not treated as a list member. +/* LICENSE +/* .ad +/* .fi +/* The Secure Mailer license must be distributed with this software. +/* AUTHOR(S) +/* Wietse Venema +/* IBM T.J. Watson Research +/* P.O. Box 704 +/* Yorktown Heights, NY 10598, USA +/*--*/ + +/* System libraries. */ + +/* Application-specific. */ + +#include "ring.h" + +/* ring_init - initialize ring head */ + +void ring_init(ring) +RING *ring; +{ + ring->pred = ring->succ = ring; +} + +/* ring_append - insert entry after ring head */ + +void ring_append(ring, entry) +RING *ring; +RING *entry; +{ + entry->succ = ring->succ; + entry->pred = ring; + ring->succ->pred = entry; + ring->succ = entry; +} + +/* ring_prepend - insert new entry before ring head */ + +void ring_prepend(ring, entry) +RING *ring; +RING *entry; +{ + entry->pred = ring->pred; + entry->succ = ring; + ring->pred->succ = entry; + ring->pred = entry; +} + +/* ring_detach - remove entry from ring */ + +void ring_detach(entry) +RING *entry; +{ + RING *succ = entry->succ; + RING *pred = entry->pred; + + pred->succ = succ; + succ->pred = pred; + + entry->succ = entry->pred = 0; +} -- cgit v1.2.3