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161 lines
3.6 KiB
C
161 lines
3.6 KiB
C
/*
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* Copyright (C) 2015 Kaspar Schleiser <kaspar@schleiser.de>
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* Copyright (C) 2016 Eistec AB
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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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* @ingroup sys_xtimer
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* @{
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* @file
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* @brief xtimer implementation
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* @author Kaspar Schleiser <kaspar@schleiser.de>
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* @author Joakim Nohlgård <joakim.nohlgard@eistec.se>
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*/
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#ifndef XTIMER_IMPLEMENTATION_H_
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#define XTIMER_IMPLEMENTATION_H_
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#ifndef XTIMER_H
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#error "Do not include this file directly! Use xtimer.h instead"
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#endif
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#include "periph/timer.h"
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/**
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* @brief internal define to allow using variables instead of defines
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*/
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#ifdef XTIMER_TRACE
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#include "xtimer_trace.h"
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#endif
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#ifdef __cplusplus
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extern "C" {
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#endif
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#if XTIMER_MASK
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extern volatile uint32_t _high_cnt;
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#endif
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#if (XTIMER_SHIFT < 0)
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#define XTIMER_USEC_TO_TICKS(value) ( (value) << -XTIMER_SHIFT )
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#define XTIMER_TICKS_TO_USEC(value) ( (value) >> -XTIMER_SHIFT )
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#else
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#define XTIMER_USEC_TO_TICKS(value) ( (value) >> XTIMER_SHIFT )
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#define XTIMER_TICKS_TO_USEC(value) ( (value) << XTIMER_SHIFT )
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#endif
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/**
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* @brief IPC message type for xtimer msg callback
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*/
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#define MSG_XTIMER 12345
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/**
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* @brief returns the (masked) low-level timer counter value.
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*/
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static inline uint32_t _lltimer_now(void)
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{
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#if XTIMER_SHIFT
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return XTIMER_TICKS_TO_USEC((uint32_t)timer_read(XTIMER));
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#else
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return timer_read(XTIMER);
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#endif
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}
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/**
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* @brief drop bits of a value that don't fit into the low-level timer.
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*/
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static inline uint32_t _lltimer_mask(uint32_t val)
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{
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return val & ~XTIMER_MASK_SHIFTED;
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}
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/**
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* @{
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* @brief xtimer internal stuff
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* @internal
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*/
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int _xtimer_set_absolute(xtimer_t *timer, uint32_t target);
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void _xtimer_set64(xtimer_t *timer, uint32_t offset, uint32_t long_offset);
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void _xtimer_sleep(uint32_t offset, uint32_t long_offset);
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/** @} */
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#ifndef XTIMER_MIN_SPIN
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/**
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* @brief Minimal value xtimer_spin() can spin
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*/
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#define XTIMER_MIN_SPIN XTIMER_TICKS_TO_USEC(1)
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#endif
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#ifndef DOXYGEN
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/* Doxygen warns that these are undocumented, but the documentation can be found in xtimer.h */
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static inline uint32_t xtimer_now(void)
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{
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#if XTIMER_MASK
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uint32_t latched_high_cnt, now;
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/* _high_cnt can change at any time, so check the value before
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* and after reading the low-level timer. If it hasn't changed,
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* then it can be safely applied to the timer count. */
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do {
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latched_high_cnt = _high_cnt;
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now = _lltimer_now();
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} while (_high_cnt != latched_high_cnt);
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return latched_high_cnt | now;
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#else
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return _lltimer_now();
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#endif
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}
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static inline void xtimer_spin_until(uint32_t target) {
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#if XTIMER_MASK
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target = _lltimer_mask(target);
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#endif
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while (_lltimer_now() > target);
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while (_lltimer_now() < target);
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}
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static inline void xtimer_spin(uint32_t offset) {
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uint32_t start = _lltimer_now();
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#if XTIMER_MASK
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offset = _lltimer_mask(offset);
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while (_lltimer_mask(_lltimer_now() - start) < offset);
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#else
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while ((_lltimer_now() - start) < offset);
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#endif
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}
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static inline void xtimer_usleep(uint32_t microseconds)
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{
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_xtimer_sleep(microseconds, 0);
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}
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static inline void xtimer_usleep64(uint64_t microseconds)
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{
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_xtimer_sleep((uint32_t) microseconds, (uint32_t) (microseconds >> 32));
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}
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static inline void xtimer_sleep(uint32_t seconds)
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{
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xtimer_usleep64((uint64_t)seconds * SEC_IN_USEC);
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}
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static inline void xtimer_nanosleep(uint32_t nanoseconds)
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{
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_xtimer_sleep(nanoseconds / USEC_IN_NS, 0);
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}
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#endif /* !defined(DOXYGEN) */
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#ifdef __cplusplus
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}
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#endif
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#endif
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