LibrePilot/flight/pios/posix/pios_delay.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 /* if defined(PIOS_INCLUDE_DELAY) */