148 lines
4.8 KiB
C
148 lines
4.8 KiB
C
/****************************************************************************
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* sched/clock/clock_abstime2ticks.c
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*
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* Copyright (C) 2007, 2008, 2013-2014, 2016 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 <time.h>
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#include <errno.h>
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#include <debug.h>
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#include "clock/clock.h"
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: compare_timespec
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*
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* Description:
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* Return < 0 if time a is before time b
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* Return > 0 if time b is before time a
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* Return 0 if time a is the same as time b
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*
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****************************************************************************/
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static long compare_timespec(FAR const struct timespec *a,
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FAR const struct timespec *b)
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{
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if (a->tv_sec < b->tv_sec)
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{
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return -1;
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}
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if (a->tv_sec > b->tv_sec)
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{
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return 1;
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}
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return (long)a->tv_nsec -(long)b->tv_nsec;
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: clock_abstime2ticks
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*
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* Description:
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* Convert an absolute timespec delay to system timer ticks.
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*
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* Parameters:
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* clockid - The timing source to use in the conversion
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* reltime - Convert this absolue time to system clock ticks.
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* ticks - Return the converted number of ticks here.
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*
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* Return Value:
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* OK on success; A non-zero error number on failure;
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*
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* Assumptions:
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* Interrupts should be disabled so that the time is not changing during
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* the calculation
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*
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****************************************************************************/
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int clock_abstime2ticks(clockid_t clockid, FAR const struct timespec *abstime,
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FAR int *ticks)
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{
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struct timespec currtime;
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struct timespec reltime;
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int ret;
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/* Convert the timespec to clock ticks. NOTE: Here we use internal knowledge
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* that CLOCK_REALTIME is defined to be zero!
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*/
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ret = clock_gettime(clockid, &currtime);
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if (ret != OK)
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{
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return EINVAL;
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}
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if (compare_timespec(abstime, &currtime) < 0)
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{
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/* Every caller of clock_abstime2ticks check 'ticks < 0' to see if
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* absolute time is in the past. So lets just return negative tick
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* here.
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*/
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*ticks = -1;
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return OK;
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}
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/* The relative time to wait is the absolute time minus the current time. */
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reltime.tv_nsec = (abstime->tv_nsec - currtime.tv_nsec);
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reltime.tv_sec = (abstime->tv_sec - currtime.tv_sec);
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/* Check if we were supposed to borrow from the seconds to borrow from the
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* seconds
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*/
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if (reltime.tv_nsec < 0)
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{
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reltime.tv_nsec += NSEC_PER_SEC;
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reltime.tv_sec -= 1;
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}
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/* Convert this relative time into clock ticks. */
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return clock_time2ticks(&reltime, ticks);
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}
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