incubator-nuttx/sched/clock/clock.c

75 lines
3.0 KiB
C

/****************************************************************************
* sched/clock/clock.c
*
* Copyright (C) 2015, 2018 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 <nuttx/clock.h>
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: clock
*
* Description:
* The clock() function returns the implementation's best approximation to
* the processor time used by the process since the beginning of a
* implementation-defined era related only to the process invocation.
*
* To determine the time in seconds, the value returned by clock() should
* be divided by the value of the macro CLOCKS_PER_SEC as defined in <time.h>.
*
* Input Parameters:
* None
*
* Returned Value:
* The system time in units of clock ticks is returend. If the processor
* time used is not available or its value cannot be represented, the
* function will return the value (clock_t)-1.
*
****************************************************************************/
clock_t clock(void)
{
return (clock_t)clock_systimer();
}