Added GSM timer handling routines. GSM timer is the same as osmo_timer, but it uses frame numbers instead of seconds.
This commit is contained in:
Ivan Kluchnikov
parent
4277f0cdbc
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657856279b
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/* gsm_timer.cpp
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*
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* Copyright (C) 2012 Ivan Klyuchnikov
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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/* These store the amount of frame number that we wait until next timer expires. */
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static int nearest;
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static int *nearest_p;
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/*! \addtogroup gsm_timer
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* @{
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*/
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/*! \file gsm_timer.cpp
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*/
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#include <assert.h>
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#include <string.h>
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#include <limits.h>
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#include <gsm_timer.h>
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#include <pcu_l1_if.h>
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static struct rb_root timer_root = RB_ROOT;
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static void __add_gsm_timer(struct osmo_gsm_timer_list *timer)
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{
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struct rb_node **new_node = &(timer_root.rb_node);
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struct rb_node *parent = NULL;
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while (*new_node) {
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struct osmo_gsm_timer_list *this_timer;
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this_timer = container_of(*new_node, struct osmo_gsm_timer_list, node);
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parent = *new_node;
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if (timer->fn < this_timer->fn)
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new_node = &((*new_node)->rb_left);
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else
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new_node = &((*new_node)->rb_right);
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}
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rb_link_node(&timer->node, parent, new_node);
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rb_insert_color(&timer->node, &timer_root);
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}
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/*! \brief add a new timer to the timer management
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* \param[in] timer the timer that should be added
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*/
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void osmo_gsm_timer_add(struct osmo_gsm_timer_list *timer)
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{
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osmo_gsm_timer_del(timer);
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timer->active = 1;
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INIT_LLIST_HEAD(&timer->list);
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__add_gsm_timer(timer);
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}
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/*! \brief schedule a gsm timer at a given future relative time
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* \param[in] timer the to-be-added timer
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* \param[in] number of frames from now
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*
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* This function can be used to (re-)schedule a given timer at a
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* specified number of frames in the future. It will
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* internally add it to the timer management data structures, thus
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* osmo_timer_add() is automatically called.
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*/
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void
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osmo_gsm_timer_schedule(struct osmo_gsm_timer_list *timer, int fn)
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{
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int current_fn;
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current_fn = get_current_fn();
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timer->fn = current_fn + fn;
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osmo_gsm_timer_add(timer);
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}
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/*! \brief delete a gsm timer from timer management
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* \param[in] timer the to-be-deleted timer
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*
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* This function can be used to delete a previously added/scheduled
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* timer from the timer management code.
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*/
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void osmo_gsm_timer_del(struct osmo_gsm_timer_list *timer)
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{
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if (timer->active) {
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timer->active = 0;
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rb_erase(&timer->node, &timer_root);
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/* make sure this is not already scheduled for removal. */
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if (!llist_empty(&timer->list))
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llist_del_init(&timer->list);
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}
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}
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/*! \brief check if given timer is still pending
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* \param[in] timer the to-be-checked timer
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* \return 1 if pending, 0 otherwise
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*
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* This function can be used to determine whether a given timer
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* has alredy expired (returns 0) or is still pending (returns 1)
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*/
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int osmo_gsm_timer_pending(struct osmo_gsm_timer_list *timer)
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{
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return timer->active;
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}
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/*
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* if we have a nearest frame number return the delta between the current
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* FN and the FN of the nearest timer.
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* If the nearest timer timed out return NULL and then we will
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* dispatch everything after the select
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*/
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int *osmo_gsm_timers_nearest(void)
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{
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/* nearest_p is exactly what we need already: NULL if nothing is
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* waiting, {0,0} if we must dispatch immediately, and the correct
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* delay if we need to wait */
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return nearest_p;
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}
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static void update_nearest(int *cand, int *current)
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{
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if (*cand != LONG_MAX) {
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if (*cand > *current)
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nearest = *cand - *current;
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else {
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/* loop again inmediately */
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nearest = 0;
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}
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nearest_p = &nearest;
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} else {
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nearest_p = NULL;
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}
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}
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/*
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* Find the nearest FN and update s_nearest_time
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*/
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void osmo_gsm_timers_prepare(void)
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{
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struct rb_node *node;
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int current_fn;
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current_fn = get_current_fn();
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node = rb_first(&timer_root);
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if (node) {
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struct osmo_gsm_timer_list *this_timer;
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this_timer = container_of(node, struct osmo_gsm_timer_list, node);
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update_nearest(&this_timer->fn, ¤t_fn);
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} else {
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nearest_p = NULL;
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}
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}
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/*
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* fire all timers... and remove them
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*/
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int osmo_gsm_timers_update(void)
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{
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int current_fn;
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struct rb_node *node;
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struct llist_head timer_eviction_list;
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struct osmo_gsm_timer_list *this_timer;
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int work = 0;
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current_fn = get_current_fn();
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INIT_LLIST_HEAD(&timer_eviction_list);
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for (node = rb_first(&timer_root); node; node = rb_next(node)) {
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this_timer = container_of(node, struct osmo_gsm_timer_list, node);
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if (this_timer->fn > current_fn)
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break;
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llist_add(&this_timer->list, &timer_eviction_list);
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}
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/*
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* The callbacks might mess with our list and in this case
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* even llist_for_each_entry_safe is not safe to use. To allow
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* osmo_gsm_timer_del to be called from within the callback we need
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* to restart the iteration for each element scheduled for removal.
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*
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* The problematic scenario is the following: Given two timers A
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* and B that have expired at the same time. Thus, they are both
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* in the eviction list in this order: A, then B. If we remove
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* timer B from the A's callback, we continue with B in the next
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* iteration step, leading to an access-after-release.
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*/
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restart:
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llist_for_each_entry(this_timer, &timer_eviction_list, list) {
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osmo_gsm_timer_del(this_timer);
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this_timer->cb(this_timer->data);
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work = 1;
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goto restart;
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}
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return work;
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}
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int osmo_gsm_timers_check(void)
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{
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struct rb_node *node;
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int i = 0;
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for (node = rb_first(&timer_root); node; node = rb_next(node)) {
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i++;
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}
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return i;
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}
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/*! }@ */
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@ -0,0 +1,84 @@
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/* gsm_timer.h
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*
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* Copyright (C) 2012 Ivan Klyuchnikov
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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/*! \defgroup timer GSM timers
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* @{
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*/
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/*! \file gsm_timer.h
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* \brief GSM timer handling routines
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*/
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#ifndef GSM_TIMER_H
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#define GSM_TIMER_H
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extern "C" {
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#include <osmocom/core/linuxlist.h>
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#include <osmocom/core/linuxrbtree.h>
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}
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/**
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* Timer management:
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* - Create a struct osmo_gsm_timer_list
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* - Fill out timeout and use add_gsm_timer or
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* use schedule_gsm_timer to schedule a timer in
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* x frames from now...
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* - Use del_gsm_timer to remove the timer
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*
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* Internally:
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* - We hook into select.c to give a frame number of the
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* nearest timer. On already passed timers we give
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* it a 0 to immediately fire after the select.
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* - update_gsm_timers will call the callbacks and remove
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* the timers.
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*
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*/
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/*! \brief A structure representing a single instance of a gsm timer */
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struct osmo_gsm_timer_list {
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struct rb_node node; /*!< \brief rb-tree node header */
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struct llist_head list; /*!< \brief internal list header */
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int fn; /*!< \brief expiration frame number */
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unsigned int active : 1; /*!< \brief is it active? */
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void (*cb)(void*); /*!< \brief call-back called at timeout */
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void *data; /*!< \brief user data for callback */
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};
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/**
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* timer management
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*/
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void osmo_gsm_timer_add(struct osmo_gsm_timer_list *timer);
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void osmo_gsm_timer_schedule(struct osmo_gsm_timer_list *timer, int fn);
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void osmo_gsm_timer_del(struct osmo_gsm_timer_list *timer);
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int osmo_gsm_timer_pending(struct osmo_gsm_timer_list *timer);
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/*
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* internal timer list management
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*/
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int *osmo_gsm_timers_nearest(void);
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void osmo_gsm_timers_prepare(void);
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int osmo_gsm_timers_update(void);
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int osmo_gsm_timers_check(void);
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/*! }@ */
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#endif // GSM_TIMER_H
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