From 4ddbac3be37a84cc75c2775ba80d4e1e1245cae4 Mon Sep 17 00:00:00 2001
From: Francisco Molina <femolina@uc.cl>
Date: Thu, 3 Jun 2021 17:53:44 +0200
Subject: [PATCH] sys/event: add periodic event

---
 sys/Makefile.dep             |   5 ++
 sys/event/periodic.c         |  42 ++++++++++++++
 sys/include/event/periodic.h | 105 +++++++++++++++++++++++++++++++++++
 3 files changed, 152 insertions(+)
 create mode 100644 sys/event/periodic.c
 create mode 100644 sys/include/event/periodic.h

diff --git a/sys/Makefile.dep b/sys/Makefile.dep
index f6de237113..e08fbb6499 100644
--- a/sys/Makefile.dep
+++ b/sys/Makefile.dep
@@ -478,6 +478,11 @@ ifneq (,$(filter event_timeout_ztimer,$(USEMODULE)))
   USEMODULE += event_timeout
 endif
 
+ifneq (,$(filter event_periodic_timeout,$(USEMODULE)))
+  USEMODULE += event_timeout
+  USEMODULE += ztimer_periodic
+endif
+
 ifneq (,$(filter event_timeout,$(USEMODULE)))
   ifneq (,$(filter event_timeout_ztimer,$(USEMODULE)))
     USEMODULE += ztimer_usec
diff --git a/sys/event/periodic.c b/sys/event/periodic.c
new file mode 100644
index 0000000000..e493b0ee33
--- /dev/null
+++ b/sys/event/periodic.c
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2021 Inria
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     sys_event
+ * @{
+ *
+ * @file
+ * @brief       Periodic Event Implementation
+ *
+ * @author      Francisco Molina <francois-xavier.molina@inria.fr>
+ *
+ * @}
+ */
+#include "kernel_defines.h"
+#include "ztimer.h"
+#include "ztimer/periodic.h"
+#include "event/periodic.h"
+
+static int _event_periodic_callback(void *arg)
+{
+    event_periodic_t *event_periodic = (event_periodic_t *)arg;
+
+    event_post(event_periodic->queue, event_periodic->event);
+
+    return 0;
+}
+
+void event_periodic_init(event_periodic_t *event_periodic,
+                         ztimer_clock_t *clock,
+                         event_queue_t *queue, event_t *event)
+{
+    ztimer_periodic_init(clock, &event_periodic->timer, _event_periodic_callback,
+                         event_periodic, 0);
+    event_periodic->queue = queue;
+    event_periodic->event = event;
+}
diff --git a/sys/include/event/periodic.h b/sys/include/event/periodic.h
new file mode 100644
index 0000000000..408e8f0eef
--- /dev/null
+++ b/sys/include/event/periodic.h
@@ -0,0 +1,105 @@
+/*
+ * Copyright (C) 2021 Inria
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     sys_event
+ * @brief       Provides functionality to trigger periodic events
+ *
+ * event_periodic intentionally doesn't extend event structures in order to
+ * support events that are integrated in larger structs intrusively.
+ *
+ * Example:
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~ {.c}
+ * event_periodic_t event_periodic;
+ *
+ * printf("posting timed callback every 1sec\n");
+ * event_periodic_init(&event_periodic, ZTIMER_USEC, &queue, (event_t*)&event);
+ * event_periodic_start(&event_periodic, 1000000);
+ * [...]
+ * ~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ * @{
+ *
+ * @file
+ * @brief       Event Periodic API
+ *
+ * @author      Francisco Molina <francois-xavier.molina@inria.fr>
+ *
+ */
+
+#ifndef EVENT_PERIODIC_H
+#define EVENT_PERIODIC_H
+
+#include "event.h"
+#include "ztimer/periodic.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief   Timeout Event structure
+ */
+typedef struct {
+    ztimer_periodic_t timer;    /**< ztimer object used for timeout */
+    event_queue_t *queue;       /**< event queue to post event to */
+    event_t *event;             /**< event to post after timeout */
+} event_periodic_t;
+
+/**
+ * @brief    Initialize a periodic event timeout
+ *
+ * @param[in]       event_periodic  event_periodic object to initialize
+ * @param[in]       clock           the clock to configure this timer on
+ * @param[in]       queue           queue that the timed-out event will be
+ *                                  added to
+ * @param[in]       event           event to add to queue after timeout
+ */
+void event_periodic_init(event_periodic_t *event_periodic, ztimer_clock_t *clock,
+                         event_queue_t *queue, event_t *event);
+
+/**
+ * @brief   Starts a periodic timeout
+ *
+ * This will make the event as configured in @p event_periodic be triggered
+ * at every interval ticks (based on event_periodic->clock).
+ *
+ * @note: the used event_periodic struct must stay valid until after the timeout
+ *        event has been processed!
+ *
+ * @param[in]   event_periodic   event_timout context object to use
+ * @param[in]   interval         period length for the event
+ */
+static inline void event_periodic_start(event_periodic_t *event_periodic,
+                                        uint32_t interval)
+{
+    event_periodic->timer.interval = interval;
+    ztimer_periodic_start(&event_periodic->timer);
+}
+
+/**
+ * @brief   Stop a periodic timeout event
+ *
+ * Calling this function will cancel the timeout by removing its underlying
+ * timer. If the timer has already fired before calling this function, the
+ * connected event will be put already into the given event queue and this
+ * function does not have any effect.
+ *
+ * @param[in]   event_periodic  event_periodic_timeout context object to use
+ */
+static inline void event_periodic_stop(event_periodic_t *event_periodic)
+{
+    ztimer_periodic_stop(&event_periodic->timer);
+}
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* EVENT_PERIODIC_H */
+/** @} */