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93 lines
2.7 KiB
C
93 lines
2.7 KiB
C
/*
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* Copyright (C) 2018 Kaspar Schleiser <kaspar@schleiser.de>
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* Copyright (C) 2018 Eistec AB
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*
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* This file is subject to the terms and conditions of the GNU Lesser General
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* Public License v2.1. See the file LICENSE in the top level directory for more
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* details.
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*/
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/**
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* @defgroup sys_ztimer_convert_frac ztimer_convert_frac frequency conversion layer
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* @ingroup sys_ztimer_convert
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* @brief Translates between clock tick rates
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*
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* Translates the ticks of an underlying clock into virtual ticks at a different
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* frequency.
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* This module makes use of frac for calculating fractions using multiplicative
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* inversions, avoiding integer divisions. frac trades accuracy for speed.
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* Please see the documentation of frac for more details.
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*
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* @{
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* @file
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* @brief ztimer_convert_frac interface definitions
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*
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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 ZTIMER_CONVERT_FRAC_H
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#define ZTIMER_CONVERT_FRAC_H
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#include <stdint.h>
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#include "ztimer.h"
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#include "ztimer/convert.h"
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#include "ztimer/convert_frac.h"
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#include "frac.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 ztimer_convert_frac frequency conversion layer class
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*/
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typedef struct {
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/**
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* @brief Superclass instance
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*/
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ztimer_convert_t super;
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/**
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* @brief Frequency conversion scaling constant from lower to self
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*/
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frac_t scale_now;
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/**
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* @brief Frequency conversion scaling constant from self to lower
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*/
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frac_t scale_set;
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/**
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* @brief Rounding value, will be added to all lower set().
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*
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* E.g., 1000000/32768== ~30.5. `round` will be set to 30.
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*/
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uint32_t round;
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} ztimer_convert_frac_t;
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/**
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* @brief @ref ztimer_convert_frac_t constructor
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*
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* @param[in] self pointer to instance being initialized
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* @param[in] lower pointer to underlying clock
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* @param[in] freq_self desired frequency of this clock
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* @param[in] freq_lower frequency of the underlying clock
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*/
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void ztimer_convert_frac_init(ztimer_convert_frac_t *self,
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ztimer_clock_t *lower,
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uint32_t freq_self, uint32_t freq_lower);
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/**
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* @brief Change the scaling without affecting the current count
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*
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* @param[in] self pointer to instance being initialized
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* @param[in] freq_self desired frequency of this clock
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* @param[in] freq_lower frequency of the underlying clock
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*/
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void ztimer_convert_frac_change_rate(ztimer_convert_frac_t *self,
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uint32_t freq_self, uint32_t freq_lower);
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#ifdef __cplusplus
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}
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#endif
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#endif /* ZTIMER_CONVERT_FRAC_H */
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/** @} */
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