79 lines
3.3 KiB
C
79 lines
3.3 KiB
C
/****************************************************************************
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* sched/clock/clock.c
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*
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* Copyright (C) 2015, 2018-2019 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 <nuttx/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
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*
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* Description:
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* The clock() function returns the implementation's best approximation to
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* the processor time used by the process since the beginning of a
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* implementation-defined era related only to the process invocation.
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*
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* To determine the time in seconds, the value returned by clock() should
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* be divided by the value of the macro CLOCKS_PER_SEC as defined in <time.h>.
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*
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* NOTE: The current implementation does NOT return the processor time
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* used by the process. NuttX currently does not keep any record of
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* processing time. Instead the elapsed time since power up is returned.
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*
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* Input Parameters:
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* None
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*
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* Returned Value:
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* The system time in units of clock ticks is returned. If the processor
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* time used is not available or its value cannot be represented, the
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* function will return the value (clock_t)-1.
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*
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****************************************************************************/
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clock_t clock(void)
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{
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return (clock_t)clock_systimer();
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}
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