Added GSM timer handling routines. GSM timer is the same as osmo_timer, but it uses frame numbers instead of seconds.
diff --git a/gsm_timer.cpp b/gsm_timer.cpp
new file mode 100644
index 0000000..95513b4
--- /dev/null
+++ b/gsm_timer.cpp
@@ -0,0 +1,226 @@
+/* gsm_timer.cpp
+ *
+ * Copyright (C) 2012 Ivan Klyuchnikov
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+/* These store the amount of frame number that we wait until next timer expires. */
+static int nearest;
+static int *nearest_p;
+
+/*! \addtogroup gsm_timer
+ * @{
+ */
+
+/*! \file gsm_timer.cpp
+ */
+
+#include <assert.h>
+#include <string.h>
+#include <limits.h>
+#include <gsm_timer.h>
+#include <pcu_l1_if.h>
+
+static struct rb_root timer_root = RB_ROOT;
+
+static void __add_gsm_timer(struct osmo_gsm_timer_list *timer)
+{
+ struct rb_node **new_node = &(timer_root.rb_node);
+ struct rb_node *parent = NULL;
+
+ while (*new_node) {
+ struct osmo_gsm_timer_list *this_timer;
+
+ this_timer = container_of(*new_node, struct osmo_gsm_timer_list, node);
+
+ parent = *new_node;
+ if (timer->fn < this_timer->fn)
+ new_node = &((*new_node)->rb_left);
+ else
+ new_node = &((*new_node)->rb_right);
+ }
+
+ rb_link_node(&timer->node, parent, new_node);
+ rb_insert_color(&timer->node, &timer_root);
+}
+
+/*! \brief add a new timer to the timer management
+ * \param[in] timer the timer that should be added
+ */
+void osmo_gsm_timer_add(struct osmo_gsm_timer_list *timer)
+{
+ osmo_gsm_timer_del(timer);
+ timer->active = 1;
+ INIT_LLIST_HEAD(&timer->list);
+ __add_gsm_timer(timer);
+}
+
+/*! \brief schedule a gsm timer at a given future relative time
+ * \param[in] timer the to-be-added timer
+ * \param[in] number of frames from now
+ *
+ * This function can be used to (re-)schedule a given timer at a
+ * specified number of frames in the future. It will
+ * internally add it to the timer management data structures, thus
+ * osmo_timer_add() is automatically called.
+ */
+void
+osmo_gsm_timer_schedule(struct osmo_gsm_timer_list *timer, int fn)
+{
+ int current_fn;
+
+ current_fn = get_current_fn();
+ timer->fn = current_fn + fn;
+ osmo_gsm_timer_add(timer);
+}
+
+/*! \brief delete a gsm timer from timer management
+ * \param[in] timer the to-be-deleted timer
+ *
+ * This function can be used to delete a previously added/scheduled
+ * timer from the timer management code.
+ */
+void osmo_gsm_timer_del(struct osmo_gsm_timer_list *timer)
+{
+ if (timer->active) {
+ timer->active = 0;
+ rb_erase(&timer->node, &timer_root);
+ /* make sure this is not already scheduled for removal. */
+ if (!llist_empty(&timer->list))
+ llist_del_init(&timer->list);
+ }
+}
+
+/*! \brief check if given timer is still pending
+ * \param[in] timer the to-be-checked timer
+ * \return 1 if pending, 0 otherwise
+ *
+ * This function can be used to determine whether a given timer
+ * has alredy expired (returns 0) or is still pending (returns 1)
+ */
+int osmo_gsm_timer_pending(struct osmo_gsm_timer_list *timer)
+{
+ return timer->active;
+}
+
+/*
+ * if we have a nearest frame number return the delta between the current
+ * FN and the FN of the nearest timer.
+ * If the nearest timer timed out return NULL and then we will
+ * dispatch everything after the select
+ */
+int *osmo_gsm_timers_nearest(void)
+{
+ /* nearest_p is exactly what we need already: NULL if nothing is
+ * waiting, {0,0} if we must dispatch immediately, and the correct
+ * delay if we need to wait */
+ return nearest_p;
+}
+
+static void update_nearest(int *cand, int *current)
+{
+ if (*cand != LONG_MAX) {
+ if (*cand > *current)
+ nearest = *cand - *current;
+ else {
+ /* loop again inmediately */
+ nearest = 0;
+ }
+ nearest_p = &nearest;
+ } else {
+ nearest_p = NULL;
+ }
+}
+
+/*
+ * Find the nearest FN and update s_nearest_time
+ */
+void osmo_gsm_timers_prepare(void)
+{
+ struct rb_node *node;
+ int current_fn;
+
+ current_fn = get_current_fn();
+
+ node = rb_first(&timer_root);
+ if (node) {
+ struct osmo_gsm_timer_list *this_timer;
+ this_timer = container_of(node, struct osmo_gsm_timer_list, node);
+ update_nearest(&this_timer->fn, ¤t_fn);
+ } else {
+ nearest_p = NULL;
+ }
+}
+
+/*
+ * fire all timers... and remove them
+ */
+int osmo_gsm_timers_update(void)
+{
+ int current_fn;
+ struct rb_node *node;
+ struct llist_head timer_eviction_list;
+ struct osmo_gsm_timer_list *this_timer;
+ int work = 0;
+
+ current_fn = get_current_fn();
+
+ INIT_LLIST_HEAD(&timer_eviction_list);
+ for (node = rb_first(&timer_root); node; node = rb_next(node)) {
+ this_timer = container_of(node, struct osmo_gsm_timer_list, node);
+
+ if (this_timer->fn > current_fn)
+ break;
+
+ llist_add(&this_timer->list, &timer_eviction_list);
+ }
+
+ /*
+ * The callbacks might mess with our list and in this case
+ * even llist_for_each_entry_safe is not safe to use. To allow
+ * osmo_gsm_timer_del to be called from within the callback we need
+ * to restart the iteration for each element scheduled for removal.
+ *
+ * The problematic scenario is the following: Given two timers A
+ * and B that have expired at the same time. Thus, they are both
+ * in the eviction list in this order: A, then B. If we remove
+ * timer B from the A's callback, we continue with B in the next
+ * iteration step, leading to an access-after-release.
+ */
+restart:
+ llist_for_each_entry(this_timer, &timer_eviction_list, list) {
+ osmo_gsm_timer_del(this_timer);
+ this_timer->cb(this_timer->data);
+ work = 1;
+ goto restart;
+ }
+
+ return work;
+}
+
+int osmo_gsm_timers_check(void)
+{
+ struct rb_node *node;
+ int i = 0;
+
+ for (node = rb_first(&timer_root); node; node = rb_next(node)) {
+ i++;
+ }
+ return i;
+}
+
+/*! }@ */
+