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/*
ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
2011,2012,2013 Giovanni Di Sirio.
This file is part of ChibiOS/RT.
ChibiOS/RT is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
ChibiOS/RT is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* @file chrt.h
* @brief Real Time Counter and Measurement module macros and structures.
*
* @addtogroup rt_measurement
* @{
*/
#ifndef _CHRT_H_
#define _CHRT_H_
#if CH_CFG_USE_RT || defined(__DOXYGEN__)
#define port_rt_get_counter_value() 0
/*===========================================================================*/
/* Module constants. */
/*===========================================================================*/
/*===========================================================================*/
/* Module pre-compile time settings. */
/*===========================================================================*/
/*===========================================================================*/
/* Derived constants and error checks. */
/*===========================================================================*/
#if !CH_PORT_SUPPORTS_RT
#error "the port layer does not support the realtime counter functionality"
#endif
/*===========================================================================*/
/* Module data structures and types. */
/*===========================================================================*/
/*===========================================================================*/
/* Module macros. */
/*===========================================================================*/
/**
* @name Time conversion utilities for the realtime counter
* @{
*/
/**
* @brief Seconds to realtime counter.
* @details Converts from seconds to realtime counter cycles.
* @note The result is rounded upward to the next tick boundary.
*
* @param[in] sec number of seconds
* @return The number of cycles.
*
* @api
*/
#define S2RTV(freq, sec) ((freq) * (sec))
/**
* @brief Milliseconds to realtime counter.
* @details Converts from milliseconds to realtime counter cycles.
* @note The result is rounded upward to the next tick boundary.
*
* @param[in] msec number of milliseconds
* @return The number of cycles.
*
* @api
*/
#define MS2RTC(freq, msec) (rtcnt_t)((((freq) + 999UL) / 1000UL) * (msec))
/**
* @brief Microseconds to realtime counter.
* @details Converts from microseconds to realtime counter cycles.
* @note The result is rounded upward to the next tick boundary.
*
* @param[in] usec number of microseconds
* @return The number of cycles.
*
* @api
*/
#define US2RTC(freq, usec) (rtcnt_t)((((freq) + 999999UL) / 1000000UL) * (usec))
/**
* @brief Realtime counter cycles to seconds.
* @details Converts from realtime counter cycles number to seconds.
*
* @param[in] n number of cycles
* @return The number of seconds.
*
* @api
*/
#define RTC2S(freq, n) (rtcnt_t)((n) / (freq))
/**
* @brief Realtime counter cycles to milliseconds.
* @details Converts from realtime counter cycles number to milliseconds.
*
* @param[in] n number of cycles
* @return The number of milliseconds.
*
* @api
*/
#define RTC2MS(freq, n) ((n) / ((freq) / 1000UL))
/**
* @brief Realtime counter cycles to microseconds.
* @details Converts from realtime counter cycles number to microseconds.
*
* @param[in] n number of cycles
* @return The number of microseconds.
*
* @api
*/
#define RTC2US(freq, n) ((n) / ((freq) / 1000000UL))
/** @} */
/*===========================================================================*/
/* External declarations. */
/*===========================================================================*/
#ifdef __cplusplus
extern "C" {
#endif
#ifdef __cplusplus
}
#endif
/*===========================================================================*/
/* Module inline functions. */
/*===========================================================================*/
/**
* @brief Returns the current value of the system real time counter.
* @note This function can be called from any context.
*
* @return The value of the system free running counter of
* type rtcnt_t.
*
* @special
*/
static inline rtcnt_t chRTGetCounterValue(void) {
return port_rt_get_counter_value();
}
/**
* @brief Realtime window test.
* @details This function verifies if the current realtime counter value
* lies within the specified range or not. The test takes care
* of the realtime counter wrapping to zero on overflow.
* @note When start==end then the function returns always true because the
* whole time range is specified.
* @note This function can be called from any context.
*
* @par Example 1
* Example of a guarded loop using the realtime counter. The loop implements
* a timeout after one second.
* @code
* rtcnt_t start = chRTGetCounterValue();
* rtcnt_t timeout = start + S2RTC(1);
* while (my_condition) {
* if (!chRTIsCounterWithin(start, timeout)
* return TIMEOUT;
* // Do something.
* }
* // Continue.
* @endcode
*
* @par Example 2
* Example of a loop that lasts exactly 50 microseconds.
* @code
* rtcnt_t start = chRTGetCounterValue();
* rtcnt_t timeout = start + US2RTC(50);
* while (chRTIsCounterWithin(start, timeout)) {
* // Do something.
* }
* // Continue.
* @endcode
*
* @param[in] start the start of the time window (inclusive)
* @param[in] end the end of the time window (non inclusive)
* @retval true current time within the specified time window.
* @retval false current time not within the specified time window.
*
* @special
*/
static inline bool chRTIsCounterWithin(rtcnt_t start, rtcnt_t end) {
rtcnt_t now = chRTGetCounterValue();
return end > start ? (now >= start) && (now < end) :
(now >= start) || (now < end);
}
/**
* @brief Polled delay.
* @note The real delay is always few cycles in excess of the specified
* value.
* @note This function can be called from any context.
*
* @param[in] ticks number of ticks
*
* @special
*/
static inline void chRTPolledDelay(rtcnt_t ticks) {
rtcnt_t start = chRTGetCounterValue();
rtcnt_t timeout = start + (ticks);
while (chRTIsCounterWithin(start, timeout))
;
}
#endif /* CH_CFG_USE_RT */
#endif /* _CHRT_H_ */
/** @} */
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