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- /****************************************************************************
- * sched/clock/clock_systime_ticks.c
- *
- * Copyright (C) 2011, 2014-2016, 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 <stdint.h>
- #include <nuttx/irq.h>
- #include <nuttx/arch.h>
- #include <nuttx/clock.h>
- #include "clock/clock.h"
- /****************************************************************************
- * Pre-processor Definitions
- ****************************************************************************/
- /* See nuttx/clock.h */
- #undef clock_systime_ticks
- /* 32-bit mask for 64-bit timer values */
- #define TIMER_MASK32 0x00000000ffffffff
- /****************************************************************************
- * Public Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: clock_systime_ticks
- *
- * Description:
- * Return the current value of the 32/64-bit system timer counter.
- *
- * Indirect access to the system timer counter is required through this
- * function if the execution environment does not have direct access to
- * kernel global data.
- *
- * Use of this function is also required to assure atomic access to the
- * 64-bit system timer.
- *
- * NOTE: This is an internal OS interface and should not be called from
- * application code. Rather, the functionally equivalent, standard
- * interface clock() should be used.
- *
- * Input Parameters:
- * None
- *
- * Returned Value:
- * The current value of the system timer counter
- *
- ****************************************************************************/
- clock_t clock_systime_ticks(void)
- {
- #ifdef CONFIG_SCHED_TICKLESS
- # ifdef CONFIG_SYSTEM_TIME64
- struct timespec ts;
- /* Get the time from the platform specific hardware */
- clock_systime_timespec(&ts);
- /* Convert to a 64-bit value in microseconds, then in clock tick units */
- return USEC2TICK(1000000 * (uint64_t)ts.tv_sec + ts.tv_nsec / 1000);
- # else /* CONFIG_SYSTEM_TIME64 */
- struct timespec ts;
- uint64_t tmp;
- /* Get the time from the platform specific hardware */
- clock_systime_timespec(&ts);
- /* Convert to a 64- then a 32-bit value */
- tmp = USEC2TICK(1000000 * (uint64_t)ts.tv_sec + ts.tv_nsec / 1000);
- return (clock_t)(tmp & TIMER_MASK32);
- # endif /* CONFIG_SYSTEM_TIME64 */
- #else /* CONFIG_SCHED_TICKLESS */
- # ifdef CONFIG_SYSTEM_TIME64
- clock_t sample;
- clock_t verify;
- /* 64-bit accesses are not atomic on most architectures. The following
- * loop samples the 64-bit timer twice and loops in the rare event that
- * there was 32-bit rollover between samples.
- *
- * If there is no 32-bit rollover, then:
- *
- * - The MS 32-bits of each sample will be the same, and
- * - The LS 32-bits of the second sample will be greater than or equal to
- * the LS 32-bits for the first sample.
- */
- do
- {
- verify = g_system_timer;
- sample = g_system_timer;
- }
- while ((sample & TIMER_MASK32) < (verify & TIMER_MASK32) ||
- (sample & ~TIMER_MASK32) != (verify & ~TIMER_MASK32));
- return sample;
- # else /* CONFIG_SYSTEM_TIME64 */
- /* Return the current system time */
- return g_system_timer;
- # endif /* CONFIG_SYSTEM_TIME64 */
- #endif /* CONFIG_SCHED_TICKLESS */
- }
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