forked from Archive/PX4-Autopilot
137 lines
5.2 KiB
C
137 lines
5.2 KiB
C
/********************************************************************************
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* sched/clock_time2ticks.c
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*
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* Copyright (C) 2007, 2009 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_internal.h"
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/********************************************************************************
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* Definitions
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********************************************************************************/
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/********************************************************************************
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* Private Type Declarations
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********************************************************************************/
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/********************************************************************************
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* Global Variables
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********************************************************************************/
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/********************************************************************************
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* Private Variables
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********************************************************************************/
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/********************************************************************************
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* Private Functions
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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_time2ticks
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*
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* Description:
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* Convert a timespec delay to system timer ticks. This function is suitable
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* for calculating relative time delays and does not depend on the other
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* clock_* logic.
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*
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* Parameters:
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* reltime - Convert this relative 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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* Always returns OK
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*
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* Assumptions:
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*
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********************************************************************************/
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int clock_time2ticks(FAR const struct timespec *reltime, FAR int *ticks)
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{
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#ifdef CONFIG_HAVE_LONG_LONG
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int64_t relnsec;
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/* Convert the relative time into nanoseconds. The range of the int64_t is
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* sufficiently large that there is no real need for range checking.
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*/
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relnsec = (int64_t)reltime->tv_sec * NSEC_PER_SEC +
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(int64_t)reltime->tv_nsec;
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/* Convert nanoseconds to clock ticks, rounding up to the smallest integer
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* that is greater than or equal to the exact number of tick.
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*/
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*ticks = (int)((relnsec + NSEC_PER_TICK - 1) / NSEC_PER_TICK);
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return OK;
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#else
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int32_t relusec;
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/* This function uses an int32_t to only the relative time in microseconds.
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* that means that the maximum supported relative time is 2,147,487.647
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* seconds
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*/
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#if 0 // overkill
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DEBUGASSERT(reltime->tv_sec < 2147487 ||
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reltime->tv_sec == 2147487 &&
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reltime->tv_nsec <= 647 * NSEC_PER_MSEC);
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#endif
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/* Convert the relative time into microseconds, rounding up to the smallest
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* value that is greater than or equal to the exact number of microseconds.
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*/
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relusec = reltime->tv_sec * USEC_PER_SEC +
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(reltime->tv_nsec + NSEC_PER_USEC - 1) / NSEC_PER_USEC;
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/* Convert microseconds to clock ticks, rounding up to the smallest integer
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* that is greater than or equal to the exact number of tick.
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*/
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*ticks = (int)((relusec + USEC_PER_TICK - 1) / USEC_PER_TICK);
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return OK;
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#endif
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}
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