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bb2b6adb7e
Callbacks from evtimer are still executed in interrupt context. While xtimer warns about this, evtimer leaves the user unsuspecting. Copy the warning from xtimer to keep users vigilant.
135 lines
3.5 KiB
C
135 lines
3.5 KiB
C
/*
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* Copyright (C) 2016-17 Kaspar Schleiser <kaspar@schleiser.de>
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* 2017 Freie Universität Berlin
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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/**
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* @defgroup sys_evtimer Millisecond interval event timers
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* @ingroup sys
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* @brief Provides timers for events up to @$2^{32}@$ milliseconds in the
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* future
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*
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* @note Experimental and likely to replaced with unified timer API
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*
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* RIOT's main timer subsystem is @ref sys_xtimer "xtimer", but for many
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* applications @ref sys_xtimer "xtimer's" 64-bit absolute time values are
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* wasteful or clumsy to use.
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*
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* Compared to @ref sys_xtimer "xtimer", evtimer offers:
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*
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* - only relative 32-bit millisecond timer values
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* Events can be scheduled with a relative offset of up to ~49.7 days in the
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* future.
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* **For time-critical stuff, use @ref sys_xtimer "xtimer"!**
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* - more flexible, "intrusive" timer type @ref evtimer_event_t only contains
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* the necessary fields, which can be extended as needed, and handlers define
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* actions taken on timer triggers. Check out @ref evtimer_msg_event_t as
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* example.
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* - uses @ref sys_xtimer "xtimer" as backend
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*
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* @{
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*
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* @file
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* @brief evtimer API definitions
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*
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* @author Kaspar Schleiser <kaspar@schleiser.de>
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* @author Martine Lenders <m.lenders@fu-berlin.de>
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*/
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#ifndef EVTIMER_H
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#define EVTIMER_H
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#include <stdint.h>
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#include "xtimer.h"
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#include "timex.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* @brief Generic event
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*/
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typedef struct evtimer_event {
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struct evtimer_event *next; /**< the next event in the queue */
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uint32_t offset; /**< offset in milliseconds from previous event */
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} evtimer_event_t;
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/**
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* @brief Event timer callback type
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*/
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typedef void(*evtimer_callback_t)(evtimer_event_t* event);
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/**
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* @brief Event timer
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*/
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typedef struct {
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xtimer_t timer; /**< Timer */
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evtimer_callback_t callback; /**< Handler function for this evtimer's
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event type */
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evtimer_event_t *events; /**< Event queue */
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} evtimer_t;
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/**
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* @brief Initializes an event timer
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*
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* @warning BEWARE! Callbacks from evtimer_init() are being executed
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* in interrupt context.
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* DON'T USE THIS FUNCTION unless you know *exactly* what that means.
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*
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* @param[in] evtimer An event timer
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* @param[in] handler An event handler function
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*/
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void evtimer_init(evtimer_t *evtimer, evtimer_callback_t handler);
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/**
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* @brief Adds event to an event timer
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*
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* @param[in] evtimer An event timer
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* @param[in] event An event
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*/
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void evtimer_add(evtimer_t *evtimer, evtimer_event_t *event);
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/**
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* @brief Removes an event from an event timer
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*
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* @param[in] evtimer An event timer
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* @param[in] event An event
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*/
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void evtimer_del(evtimer_t *evtimer, evtimer_event_t *event);
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/**
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* @brief Print overview of current state of an event timer
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*
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* @param[in] evtimer An event timer
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*/
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void evtimer_print(const evtimer_t *evtimer);
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/**
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* @brief Return the current system time in msec
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*/
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static inline uint32_t evtimer_now_msec(void)
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{
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return xtimer_now_usec64() / US_PER_MS;
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}
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/**
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* @brief Return the current system time in minutes
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*/
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static inline uint32_t evtimer_now_min(void)
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{
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return xtimer_now_usec64() / (US_PER_SEC * SEC_PER_MIN);
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}
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#ifdef __cplusplus
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}
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#endif
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#endif /* EVTIMER_H */
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/** @} */
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