ztimer: add ztimer_stopwatch convenience functions

sys/include/ztimer/stopwatch.h

@@ -0,0 +1,102 @@
+/*
+ * Copyright (C) 2023 ML!PA Consulting GmbH
+ *
+ * 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.
+ */
+
+/**
+ * @defgroup    sys_ztimer_stopwatch ztimer stop watch
+ * @ingroup     sys_ztimer
+ * @brief       Measure time with ztimer
+ *
+ * @author      Benjamin Valentin <benjamin.valentin@ml-pa.com>
+ * @{
+ */
+#ifndef ZTIMER_STOPWATCH_H
+#define ZTIMER_STOPWATCH_H
+
+#include "ztimer.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief   ztimer stop watch struct
+ */
+typedef struct {
+    ztimer_clock_t *clock;  /**< the clock to use     */
+    uint32_t start_time;    /**< start of measurement */
+} ztimer_stopwatch_t;
+
+/**
+ * @brief   Initialize a ztimer stop watch
+ *          The stop watch is not running yet.
+ *
+ * @param[in]  clock    The clock to use for the stopwatch
+ * @param[out] timer    The stop watch clock to initialize
+ */
+static inline void ztimer_stopwatch_init(ztimer_clock_t *clock, ztimer_stopwatch_t *timer)
+{
+    timer->clock = clock;
+}
+
+/**
+ * @brief   Start the stop watch timer
+ *
+ * @param[in] timer     The stop watch timer to start
+ */
+static inline void ztimer_stopwatch_start(ztimer_stopwatch_t *timer)
+{
+    ztimer_acquire(timer->clock);
+    timer->start_time = ztimer_now(timer->clock);
+}
+
+/**
+ * @brief   Take a measurement from the stop watch timer
+ *
+ * @param[in] timer     The stop watch timer to take a measurement of
+ *
+ * @return  Timer ticks since the stop watch was started / reset
+ */
+static inline uint32_t ztimer_stopwatch_measure(ztimer_stopwatch_t *timer)
+{
+    return ztimer_now(timer->clock) - timer->start_time;
+}
+
+/**
+ * @brief   Reset the stop watch start time.
+ *          The Stop Watch will start counting from 0 again.
+ *
+ * @param[in] timer     The stop watch timer to reset
+ *
+ * @return Timer ticks since the last reset / start of the watch
+ */
+static inline uint32_t ztimer_stopwatch_reset(ztimer_stopwatch_t *timer)
+{
+    uint32_t now = ztimer_now(timer->clock);
+    uint32_t diff = now - timer->start_time;
+
+    timer->start_time = now;
+    return diff;
+}
+
+/**
+ * @brief   Stop the stop watch.
+ *          The stop watch will no longer run.
+ *
+ * @param[in] timer     The stop watch timer to stop
+ */
+static inline void ztimer_stopwatch_stop(ztimer_stopwatch_t *timer)
+{
+    ztimer_release(timer->clock);
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ZTIMER_STOPWATCH_H */
+/** @} */