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LibrePilot/flight/PiOS/posix/pios_delay.c
2013-04-07 09:49:13 +03:00

143 lines
3.3 KiB
C

/**
******************************************************************************
*
* @file pios_delay.c
* @author The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
* Parts by Thorsten Klose (tk@midibox.org) (tk@midibox.org)
* @brief Delay Functions
* - Provides a micro-second granular delay using a TIM
* @see The GNU Public License (GPL) Version 3
* @defgroup PIOS_DELAY Delay Functions
* @{
*
*****************************************************************************/
/*
* This program 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.
*
* This program 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, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/* Project Includes */
#include "pios.h"
#if defined(PIOS_INCLUDE_DELAY)
/**
* Initialises the Timer used by PIOS_DELAY functions<BR>
* This is called from pios.c as part of the main() function
* at system start up.
* \return < 0 if initialisation failed
*/
#include <time.h>
int32_t PIOS_DELAY_Init(void)
{
// stub
/* No error */
return 0;
}
/**
* Waits for a specific number of uS<BR>
* Example:<BR>
* \code
* // Wait for 500 uS
* PIOS_DELAY_Wait_uS(500);
* \endcode
* \param[in] uS delay (1..65535 microseconds)
* \return < 0 on errors
*/
int32_t PIOS_DELAY_WaituS(uint32_t uS)
{
static struct timespec wait,rest;
wait.tv_sec=0;
wait.tv_nsec=1000*uS;
while (nanosleep(&wait,&rest)!=0) {
wait=rest;
}
/* No error */
return 0;
}
/**
* Waits for a specific number of mS<BR>
* Example:<BR>
* \code
* // Wait for 500 mS
* PIOS_DELAY_Wait_mS(500);
* \endcode
* \param[in] mS delay (1..65535 milliseconds)
* \return < 0 on errors
*/
int32_t PIOS_DELAY_WaitmS(uint32_t mS)
{
//for(int i = 0; i < mS; i++) {
// PIOS_DELAY_WaituS(1000);
static struct timespec wait,rest;
wait.tv_sec=mS/1000;
wait.tv_nsec=(mS%1000)*1000000;
while (nanosleep(&wait,&rest)!=0) {
wait=rest;
}
//}
/* No error */
return 0;
}
/**
* @brief Query the Delay timer for the current uS
* @return A microsecond value
*/
uint32_t PIOS_DELAY_GetuS()
{
static struct timespec current;
clock_gettime(CLOCK_REALTIME, &current);
return ((current.tv_sec * 1000000) + (current.tv_nsec / 1000));
}
/**
* @brief Calculate time in microseconds since a previous time
* @param[in] t previous time
* @return time in us since previous time t.
*/
uint32_t PIOS_DELAY_GetuSSince(uint32_t t)
{
return (PIOS_DELAY_GetuS() - t);
}
/**
* @brief Get the raw delay timer, useful for timing
* @return Unitless value (uint32 wrap around)
*/
uint32_t PIOS_DELAY_GetRaw()
{
return (PIOS_DELAY_GetuS());
}
/**
* @brief Compare to raw times to and convert to us
* @return A microsecond value
*/
uint32_t PIOS_DELAY_DiffuS(uint32_t raw)
{
return ( PIOS_DELAY_GetuS() - raw );
}
#endif