331 lines
10 KiB
C
331 lines
10 KiB
C
/****************************************************************************
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* arch/sim/src/up_tickless.c
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*
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* Copyright (C) 2014 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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* Tickless OS Support.
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*
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* When CONFIG_SCHED_TICKLESS is enabled, all support for timer interrupts
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* is suppressed and the platform specific code is expected to provide the
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* following custom functions.
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*
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* void sim_timer_initialize(void): Initializes the timer facilities. Called
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* early in the intialization sequence (by up_intialize()).
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* int up_timer_gettime(FAR struct timespec *ts): Returns the current
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* time from the platform specific time source.
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* int up_timer_cancel(void): Cancels the interval timer.
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* int up_timer_start(FAR const struct timespec *ts): Start (or re-starts)
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* the interval timer.
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*
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* The RTOS will provide the following interfaces for use by the platform-
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* specific interval timer implementation:
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*
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* void sched_timer_expiration(void): Called by the platform-specific
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* logic when the interval timer expires.
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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 <stdbool.h>
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#include <time.h>
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#include <nuttx/arch.h>
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#include <nuttx/clock.h>
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#ifdef CONFIG_SCHED_TICKLESS
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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#if defined(CONFIG_SIM_WALLTIME) || defined(CONFIG_SIM_X11FB)
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# define TICK_USEC (USEC_PER_SEC / CLK_TCK)
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# define TICK_SEC (TICK_USEC / USEC_PER_SEC)
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# define TICK_NSEC ((TICK_USEC % NSEC_PER_USEC) * NSEC_PER_USEC)
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#else
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# define TICK_SEC 0
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# define TICK_NSEC NSEC_PER_TICK
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#endif
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/****************************************************************************
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* Private Data
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****************************************************************************/
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static struct timespec g_elapsed_time;
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static struct timespec g_interval_delay;
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static bool g_timer_active;
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: sim_timer_initialize
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*
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* Description:
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* Initializes all platform-specific timer facilities. This function is
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* called early in the initialization sequence by up_intialize().
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* On return, the current up-time should be available from
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* up_timer_gettime() and the interval timer is ready for use (but not
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* actively timing.
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*
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* Provided by platform-specific code and called from the architecture-
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* specific logic.
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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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* None
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*
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* Assumptions:
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* Called early in the initialization sequence before any special
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* concurrency protections are required.
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*
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****************************************************************************/
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void sim_timer_initialize(void)
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{
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}
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/****************************************************************************
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* Name: up_timer_gettime
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*
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* Description:
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* Return the elapsed time since power-up (or, more correctly, since
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* sim_timer_initialize() was called). This function is functionally
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* equivalent to:
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*
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* int clock_gettime(clockid_t clockid, FAR struct timespec *ts);
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*
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* when clockid is CLOCK_MONOTONIC.
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*
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* This function provides the basis for reporting the current time and
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* also is used to eliminate error build-up from small erros in interval
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* time calculations.
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*
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* Provided by platform-specific code and called from the RTOS base code.
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*
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* Input Parameters:
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* ts - Provides the location in which to return the up-time.
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*
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* Returned Value:
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* Zero (OK) is returned on success; a negated errno value is returned on
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* any failure.
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*
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* Assumptions:
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* Called from the normal tasking context. The implementation must
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* provide whatever mutual exclusion is necessary for correct operation.
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* This can include disabling interrupts in order to assure atomic register
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* operations.
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*
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****************************************************************************/
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int up_timer_gettime(FAR struct timespec *ts)
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{
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ts->tv_sec = g_elapsed_time.tv_sec;
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ts->tv_nsec = g_elapsed_time.tv_nsec;
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return OK;
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}
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/****************************************************************************
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* Name: up_timer_cancel
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*
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* Description:
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* Cancel the interval timer and return the time remaining on the timer.
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* These two steps need to be as nearly atomic as possible.
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* sched_timer_expiration() will not be called unless the timer is
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* restarted with up_timer_start().
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*
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* If, as a race condition, the timer has already expired when this
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* function is called, then that pending interrupt must be cleared so
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* that up_timer_start() and the remaining time of zero should be
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* returned.
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*
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* Provided by platform-specific code and called from the RTOS base code.
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*
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* Input Parameters:
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* ts - Location to return the remaining time. Zero should be returned
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* if the timer is not active.
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*
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* Returned Value:
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* Zero (OK) is returned on success; a negated errno value is returned on
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* any failure.
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*
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* Assumptions:
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* May be called from interrupt level handling or from the normal tasking
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* level. Interrupts may need to be disabled internally to assure
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* non-reentrancy.
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*
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****************************************************************************/
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#ifdef CONFIG_SCHED_TICKLESS
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int up_timer_cancel(FAR struct timespec *ts)
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{
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/* Return the time remaining on the simulated timer */
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if (g_timer_active)
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{
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ts->tv_sec = g_interval_delay.tv_sec;
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ts->tv_nsec = g_interval_delay.tv_nsec;
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}
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else
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{
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ts->tv_sec = 0;
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ts->tv_nsec = 0;
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}
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/* Disable and reset the simulated timer */
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g_interval_delay.tv_sec = 0;
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g_interval_delay.tv_nsec = 0;
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g_timer_active = false;
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}
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#endif
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/****************************************************************************
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* Name: up_timer_start
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*
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* Description:
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* Start the interval timer. sched_timer_expiration() will be
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* called at the completion of the timeout (unless up_timer_cancel
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* is called to stop the timing.
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*
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* Provided by platform-specific code and called from the RTOS base code.
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*
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* Input Parameters:
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* ts - Provides the time interval until sched_timer_expiration() is
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* called.
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*
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* Returned Value:
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* Zero (OK) is returned on success; a negated errno value is returned on
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* any failure.
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*
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* Assumptions:
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* May be called from interrupt level handling or from the normal tasking
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* level. Interrupts may need to be disabled internally to assure
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* non-reentrancy.
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*
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****************************************************************************/
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#ifdef CONFIG_SCHED_TICKLESS
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int up_timer_start(FAR const struct timespec *ts)
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{
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g_interval_delay.tv_sec = ts->tv_sec;
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g_interval_delay.tv_nsec = ts->tv_nsec;
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g_timer_active = true;
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}
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#endif
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/****************************************************************************
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* Name: up_timer_update
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*
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* Description:
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* Called from the IDLE loop to fake one timer tick.
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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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* None
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*
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****************************************************************************/
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void up_timer_update(void)
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{
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/* Increment the elapsed time */
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g_elapsed_time.tv_nsec += TICK_NSEC;
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if (g_elapsed_time.tv_nsec >= NSEC_PER_SEC)
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{
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g_elapsed_time.tv_sec++;
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g_elapsed_time.tv_nsec -= NSEC_PER_SEC;
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}
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g_elapsed_time.tv_sec += TICK_SEC;
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/* Is the interval timer active? */
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if (g_timer_active)
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{
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/* Yes... decrement the interval timer */
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if (g_interval_delay.tv_sec < TICK_SEC)
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{
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/* No more seconds left... the timer has expired */
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g_timer_active = false;
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sched_timer_expiration();
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}
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else
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{
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/* Decrement seconds. May decrement to zero */
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g_interval_delay.tv_sec -= TICK_SEC;
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/* Decrement nanoseconds */
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if (g_interval_delay.tv_nsec >= TICK_NSEC)
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{
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g_interval_delay.tv_nsec -= TICK_NSEC;
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}
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/* Handle borrow from seconds */
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else if (g_interval_delay.tv_sec > 0)
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{
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g_interval_delay.tv_nsec += NSEC_PER_SEC;
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g_interval_delay.tv_sec--;
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g_interval_delay.tv_nsec -= TICK_NSEC;
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}
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/* Otherwise the timer has expired */
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else
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{
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g_timer_active = false;
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sched_timer_expiration();
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}
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}
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}
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}
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#endif /* CONFIG_SCHED_TICKLESS */
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