157 lines
5.0 KiB
C
157 lines
5.0 KiB
C
/****************************************************************************
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* sched/clock/clock_systime_ticks.c
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*
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* Copyright (C) 2011, 2014-2016, 2018 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 <nuttx/irq.h>
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#include <nuttx/arch.h>
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#include <nuttx/clock.h>
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#include "clock/clock.h"
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/* See nuttx/clock.h */
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#undef clock_systime_ticks
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/* 32-bit mask for 64-bit timer values */
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#define TIMER_MASK32 0x00000000ffffffff
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: clock_systime_ticks
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*
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* Description:
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* Return the current value of the 32/64-bit system timer counter.
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*
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* Indirect access to the system timer counter is required through this
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* function if the execution environment does not have direct access to
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* kernel global data.
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*
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* Use of this function is also required to assure atomic access to the
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* 64-bit system timer.
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*
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* NOTE: This is an internal OS interface and should not be called from
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* application code. Rather, the functionally equivalent, standard
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* interface clock() should be used.
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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 current value of the system timer counter
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*
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****************************************************************************/
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clock_t clock_systime_ticks(void)
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{
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#ifdef CONFIG_SCHED_TICKLESS
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# ifdef CONFIG_SYSTEM_TIME64
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struct timespec ts;
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/* Get the time from the platform specific hardware */
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clock_systime_timespec(&ts);
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/* Convert to a 64-bit value in microseconds, then in clock tick units */
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return USEC2TICK(1000000 * (uint64_t)ts.tv_sec + ts.tv_nsec / 1000);
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# else /* CONFIG_SYSTEM_TIME64 */
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struct timespec ts;
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uint64_t tmp;
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/* Get the time from the platform specific hardware */
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clock_systime_timespec(&ts);
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/* Convert to a 64- then a 32-bit value */
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tmp = USEC2TICK(1000000 * (uint64_t)ts.tv_sec + ts.tv_nsec / 1000);
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return (clock_t)(tmp & TIMER_MASK32);
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# endif /* CONFIG_SYSTEM_TIME64 */
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#else /* CONFIG_SCHED_TICKLESS */
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# ifdef CONFIG_SYSTEM_TIME64
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clock_t sample;
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clock_t verify;
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/* 64-bit accesses are not atomic on most architectures. The following
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* loop samples the 64-bit timer twice and loops in the rare event that
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* there was 32-bit rollover between samples.
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*
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* If there is no 32-bit rollover, then:
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*
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* - The MS 32-bits of each sample will be the same, and
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* - The LS 32-bits of the second sample will be greater than or equal to
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* the LS 32-bits for the first sample.
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*/
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do
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{
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verify = g_system_timer;
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sample = g_system_timer;
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}
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while ((sample & TIMER_MASK32) < (verify & TIMER_MASK32) ||
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(sample & ~TIMER_MASK32) != (verify & ~TIMER_MASK32));
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return sample;
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# else /* CONFIG_SYSTEM_TIME64 */
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/* Return the current system time */
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return g_system_timer;
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# endif /* CONFIG_SYSTEM_TIME64 */
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#endif /* CONFIG_SCHED_TICKLESS */
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}
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