mirror of
https://github.com/RIOT-OS/RIOT.git
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05f114d0af
- most were trivial
- missing group close or open
- extra space
- no doxygen comment
- name commad might open an implicit group
this hould also be implicit cosed but does not happen somtimes
- crazy: internal declared groups have to be closed internal
140 lines
4.4 KiB
C
140 lines
4.4 KiB
C
/*
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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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* @{
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* @file
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* @brief xtimer tick <-> seconds conversions for different values of XTIMER_HZ
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* @author Joakim Nohlgård <joakim.nohlgard@eistec.se>
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*/
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#ifndef XTIMER_TICK_CONVERSION_H
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#define XTIMER_TICK_CONVERSION_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 "div.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* Some optimizations for common timer frequencies */
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#if (XTIMER_SHIFT != 0)
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#if (XTIMER_HZ % 15625 != 0)
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#error XTIMER_HZ must be a multiple of 15625 (5^6) when using XTIMER_SHIFT
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#endif
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#if (XTIMER_HZ > 1000000ul)
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#if (XTIMER_HZ != (1000000ul << XTIMER_SHIFT))
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#error XTIMER_HZ != (1000000ul << XTIMER_SHIFT)
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#endif
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/* XTIMER_HZ is a power-of-two multiple of 1 MHz */
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/* e.g. cc2538 uses a 16 MHz timer */
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static inline uint32_t _xtimer_ticks_from_usec(uint32_t usec) {
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return (usec << XTIMER_SHIFT); /* multiply by power of two */
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}
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static inline uint64_t _xtimer_ticks_from_usec64(uint64_t usec) {
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return (usec << XTIMER_SHIFT); /* multiply by power of two */
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}
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static inline uint32_t _xtimer_usec_from_ticks(uint32_t ticks) {
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return (ticks >> XTIMER_SHIFT); /* divide by power of two */
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}
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static inline uint64_t _xtimer_usec_from_ticks64(uint64_t ticks) {
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return (ticks >> XTIMER_SHIFT); /* divide by power of two */
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}
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#else /* !(XTIMER_HZ > 1000000ul) */
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#if ((XTIMER_HZ << XTIMER_SHIFT) != 1000000ul)
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#error (XTIMER_HZ << XTIMER_SHIFT) != 1000000ul
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#endif
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/* 1 MHz is a power-of-two multiple of XTIMER_HZ */
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/* e.g. ATmega2560 uses a 250 kHz timer */
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static inline uint32_t _xtimer_ticks_from_usec(uint32_t usec) {
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return (usec >> XTIMER_SHIFT); /* divide by power of two */
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}
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static inline uint64_t _xtimer_ticks_from_usec64(uint64_t usec) {
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return (usec >> XTIMER_SHIFT); /* divide by power of two */
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}
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static inline uint32_t _xtimer_usec_from_ticks(uint32_t ticks) {
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return (ticks << XTIMER_SHIFT); /* multiply by power of two */
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}
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static inline uint64_t _xtimer_usec_from_ticks64(uint64_t ticks) {
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return (ticks << XTIMER_SHIFT); /* multiply by power of two */
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}
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#endif /* defined(XTIMER_SHIFT) && (XTIMER_SHIFT != 0) */
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#elif (XTIMER_HZ == (1000000ul)) || defined(MODULE_XTIMER_ON_ZTIMER)
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/* This is the most straightforward as the xtimer API is based around
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* microseconds for representing time values. */
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static inline uint32_t _xtimer_usec_from_ticks(uint32_t ticks) {
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return ticks; /* no-op */
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}
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static inline uint64_t _xtimer_usec_from_ticks64(uint64_t ticks) {
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return ticks; /* no-op */
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}
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static inline uint32_t _xtimer_ticks_from_usec(uint32_t usec) {
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return usec; /* no-op */
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}
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static inline uint64_t _xtimer_ticks_from_usec64(uint64_t usec) {
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return usec; /* no-op */
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}
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#elif XTIMER_HZ == (32768ul)
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/* This is a common frequency for RTC crystals. We use the fact that the
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* greatest common divisor between 32768 and 1000000 is 64, so instead of
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* multiplying by the fraction (32768 / 1000000), we will instead use
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* (512 / 15625), which reduces the truncation caused by the integer widths */
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static inline uint32_t _xtimer_ticks_from_usec(uint32_t usec) {
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return div_u32_by_15625div512(usec);
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}
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static inline uint64_t _xtimer_ticks_from_usec64(uint64_t usec) {
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return div_u64_by_15625div512(usec);
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}
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static inline uint32_t _xtimer_usec_from_ticks(uint32_t ticks) {
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/* return (usec * 15625) / 512; */
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/* Using 64 bit multiplication to avoid truncating the top 9 bits */
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uint64_t usec = (uint64_t)ticks * 15625ul;
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return (usec >> 9); /* equivalent to (usec / 512) */
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}
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static inline uint64_t _xtimer_usec_from_ticks64(uint64_t ticks) {
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/* return (usec * 15625) / 512; */
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uint64_t usec = (uint64_t)ticks * 15625ul;
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return (usec >> 9); /* equivalent to (usec / 512) */
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}
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#else
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/* No matching implementation found, try to give meaningful error messages */
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#if ((XTIMER_HZ % 15625) == 0)
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#error Unsupported hardware timer frequency (XTIMER_HZ), missing XTIMER_SHIFT in board.h? See xtimer.h documentation for more info
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#else
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#error Unknown hardware timer frequency (XTIMER_HZ), check board.h and/or add an implementation in sys/include/xtimer/tick_conversion.h
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#endif
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#endif
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#ifdef __cplusplus
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}
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#endif
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#endif /* XTIMER_TICK_CONVERSION_H */
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/** @} */
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