px4-firmware/nuttx/sched/clock_abstime2ticks.c

127 lines
4.7 KiB
C

/********************************************************************************
* clock_abstime2ticks.c
*
* Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
********************************************************************************/
/********************************************************************************
* Included Files
********************************************************************************/
#include <nuttx/config.h>
#include <time.h>
#include <errno.h>
#include <debug.h>
#include "clock_internal.h"
/********************************************************************************
* Definitions
********************************************************************************/
/********************************************************************************
* Private Type Declarations
********************************************************************************/
/********************************************************************************
* Global Variables
********************************************************************************/
/********************************************************************************
* Private Variables
********************************************************************************/
/********************************************************************************
* Private Functions
********************************************************************************/
/********************************************************************************
* Public Functions
********************************************************************************/
/********************************************************************************
* Name: clock_abstime2ticks
*
* Description:
* Convert an absolute timespec delay to system timer ticks.
*
* Parameters:
* clockid - The timing source to use in the conversion
* reltime - Convert this absolue time to system clock ticks.
* ticks - Return the converted number of ticks here.
*
* Return Value:
* OK on success; A non-zero error number on failure;
*
* Assumptions:
* Interrupts should be disabled so that the time is not changing during the
* calculation
*
********************************************************************************/
int clock_abstime2ticks(clockid_t clockid, FAR const struct timespec *abstime,
FAR int *ticks)
{
struct timespec currtime;
struct timespec reltime;
int ret;
/* Convert the timespec to clock ticks. NOTE: Here we use internal knowledge
* that CLOCK_REALTIME is defined to be zero!
*/
ret = clock_gettime(clockid, &currtime);
if (ret)
{
return EINVAL;
}
/* The relative time to wait is the absolute time minus the current time. */
reltime.tv_nsec = (abstime->tv_nsec - currtime.tv_nsec);
reltime.tv_sec = (abstime->tv_sec - currtime.tv_sec);
/* Check if we were supposed to borrow from the seconds to borrow from the
* seconds
*/
if (reltime.tv_nsec < 0)
{
reltime.tv_nsec += NSEC_PER_SEC;
reltime.tv_sec -= 1;
}
/* Convert this relative time into microseconds.*/
return clock_time2ticks(&reltime, ticks);
}