101 lines
3.4 KiB
C
101 lines
3.4 KiB
C
/****************************************************************************
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* sched/clock/clock_timespec_subtract.c
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*
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* Copyright (C) 2015 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdint.h>
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#include <time.h>
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#include "clock/clock.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: clock_timespec_subtract
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*
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* Description:
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* Subtract timespec ts2 from to1 and return the result in ts3.
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* Zero is returned if the time difference is negative.
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*
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* Input Parameters:
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* ts1 and ts2: The two timespecs to be subtracted (ts1 - ts2)
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* ts3: The location to return the result (may be ts1 or ts2)
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*
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* Returned Value:
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* None
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*
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****************************************************************************/
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void clock_timespec_subtract(FAR const struct timespec *ts1,
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FAR const struct timespec *ts2,
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FAR struct timespec *ts3)
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{
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time_t sec;
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long nsec;
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if (ts1->tv_sec < ts2->tv_sec)
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{
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sec = 0;
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nsec = 0;
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}
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else if (ts1->tv_sec == ts2->tv_sec && ts1->tv_nsec <= ts2->tv_nsec)
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{
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sec = 0;
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nsec = 0;
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}
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else
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{
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sec = ts1->tv_sec - ts2->tv_sec;
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if (ts1->tv_nsec < ts2->tv_nsec)
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{
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nsec = (ts1->tv_nsec + NSEC_PER_SEC) - ts2->tv_nsec;
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sec--;
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}
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else
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{
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nsec = ts1->tv_nsec - ts2->tv_nsec;
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}
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}
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ts3->tv_sec = sec;
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ts3->tv_nsec = nsec;
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}
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