287 lines
8.7 KiB
C
287 lines
8.7 KiB
C
/****************************************************************************
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* sched/sched/sched_cpuload_oneshot.c
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*
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* Copyright (C) 2016 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 <assert.h>
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#include <debug.h>
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#include <nuttx/arch.h>
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#include <nuttx/clock.h>
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#include <nuttx/lib/xorshift128.h>
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#include <nuttx/timers/oneshot.h>
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#include "clock/clock.h"
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#ifdef CONFIG_CPULOAD_ONESHOT
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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#if !defined(CONFIG_SCHED_CPULOAD) || !defined(CONFIG_SCHED_CPULOAD_EXTCLK)
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# error CONFIG_SCHED_CPULOAD and CONFIG_SCHED_CPULOAD_EXTCLK must be defined
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#endif
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#ifndef CONFIG_SCHED_CPULOAD_TICKSPERSEC
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# error CONFIG_SCHED_CPULOAD_TICKSPERSEC not defined
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#endif
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#define CPULOAD_ONESHOT_NOMINAL (CONFIG_SCHED_CPULOAD_TICKSPERSEC * 1000)
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#if CPULOAD_ONESHOT_NOMINAL < 1 || CPULOAD_ONESHOT_NOMINAL > 0x7fffffff
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# error CPULOAD_ONESHOT_NOMINAL is out of range
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#endif
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#ifndef CONFIG_CPULOAD_ONESHOT_ENTROPY
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# warning CONFIG_CPULOAD_ONESHOT_ENTROPY not defined
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# define CONFIG_CPULOAD_ONESHOT_ENTROPY 0
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#endif
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#define CPULOAD_ONESHOT_ENTROPY (1 << CONFIG_CPULOAD_ONESHOT_ENTROPY)
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#if CPULOAD_ONESHOT_NOMINAL < CPULOAD_ONESHOT_ENTROPY
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# error CPULOAD_ONESHOT_NOMINAL too small for CONFIG_CPULOAD_ONESHOT_ENTROPY
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#endif
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#define CPULOAD_ONESHOT_ENTROPY_MASK (CPULOAD_ONESHOT_ENTROPY - 1)
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/****************************************************************************
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* Private Types
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****************************************************************************/
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struct sched_oneshot_s
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{
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FAR struct oneshot_lowerhalf_s *oneshot;
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#if CONFIG_CPULOAD_ONESHOT_ENTROPY > 0
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struct xorshift128_state_s prng;
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int32_t maxdelay;
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int32_t error;
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#endif
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};
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/****************************************************************************
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* Private Function Prototypes
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****************************************************************************/
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static void sched_oneshot_start(void);
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static void sched_oneshot_callback(FAR struct oneshot_lowerhalf_s *lower,
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FAR void *arg);
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/****************************************************************************
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* Private Data
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****************************************************************************/
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static struct sched_oneshot_s g_sched_oneshot;
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: sched_oneshot_start
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*
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* Description:
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* [Re-]start the oneshot timer, applying entropy as configured
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*
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* Input Parameters:
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* None
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* lower - An instance of the lower half driver
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* arg - The opaque argument provided when the interrupt was registered
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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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static void sched_oneshot_start(void)
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{
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#if CONFIG_CPULOAD_ONESHOT_ENTROPY > 0
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struct timespec ts;
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uint32_t entropy;
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int32_t secs;
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#endif
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int32_t usecs;
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/* Get the next delay */
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#if CONFIG_CPULOAD_ONESHOT_ENTROPY > 0
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/* The one shot will be set to this interval:
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*
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* CPULOAD_ONESHOT_NOMINAL - (CPULOAD_ONESHOT_ENTROPY / 2) + error
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* + nrand(CPULOAD_ONESHOT_ENTROPY)
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*/
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usecs = (CPULOAD_ONESHOT_NOMINAL - CPULOAD_ONESHOT_ENTROPY / 2) +
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g_sched_oneshot.error;
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/* Add the random value in the range 0..(CPULOAD_ONESHOT_ENTRY - 1) */
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entropy = xorshift128(&g_sched_oneshot.prng);
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usecs += (int32_t)(entropy & CPULOAD_ONESHOT_ENTROPY_MASK);
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DEBUGASSERT(usecs > 0); /* Check for overflow to negative or zero */
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/* Make sure that the accumulated value does not exceed the maximum delay */
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if (usecs > g_sched_oneshot.maxdelay)
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{
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tmrwarn("WARNING: Truncating\n");
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usecs = g_sched_oneshot.maxdelay;
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}
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/* Save the new error value */
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g_sched_oneshot.error = CPULOAD_ONESHOT_NOMINAL +
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g_sched_oneshot.error - usecs;
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#else
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/* No entropy */
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usecs = CPULOAD_ONESHOT_NOMINAL;
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#endif
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/* Then re-start the oneshot timer */
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secs = usecs / 1000000;
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usecs -= 100000 * secs;
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ts.tv_sec = secs;
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ts.tv_nsec = 1000 * usecs;
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DEBUGVERIFY(ONESHOT_START(g_sched_oneshot.oneshot, sched_oneshot_callback,
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NULL, &ts));
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}
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/****************************************************************************
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* Name: sched_oneshot_callback
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*
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* Description:
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* This is the callback function that will be invoked when the oneshot
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* timer expires.
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*
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* Input Parameters:
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* lower - An instance of the lower half driver
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* arg - The opaque argument provided when the interrupt was registered
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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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static void sched_oneshot_callback(FAR struct oneshot_lowerhalf_s *lower,
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FAR void *arg)
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{
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/* Perform CPU load measurements */
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#ifdef CONFIG_HAVE_WEAKFUNCTIONS
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if (sched_process_cpuload != NULL)
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#endif
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{
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sched_process_cpuload();
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}
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#endif
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/* Then restart the oneshot */
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sched_oneshot_start();
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: sched_oneshot_extclk
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*
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* Description:
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* Configure to use a oneshot timer as described in
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* include/nuttx/timers/oneshot.h to provid external clocking to assess
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* the CPU load.
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*
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* Input Parameters:
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* lower - An instance of the oneshot timer interface as defined in
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* include/nuttx/timers/oneshot.h
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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 sched_oneshot_extclk(FAR struct oneshot_lowerhalf_s *lower)
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{
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#if CONFIG_CPULOAD_ONESHOT_ENTROPY > 0
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struct timespec ts;
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#endif
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DEBUGASSERT(lower != NULL && lower->ops != NULL);
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DEBUGASSERT(lower->ops->start != NULL);
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#if CONFIG_CPULOAD_ONESHOT_ENTROPY > 0
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DEBUGASSERT(lower->ops->max_delay != NULL);
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/* Get the maximum delay */
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DEBUGVERIFY(ONESHOT_MAX_DELAY(lower, &ts));
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if (ts.tv_sec >= 0)
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{
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g_sched_oneshot.maxdelay = INT32_MAX;
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}
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else
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{
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g_sched_oneshot.maxdelay = ts.tv_nsec / 1000;
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}
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tmrinfo("madelay = %ld usec\n", (long)g_sched_oneshot.maxdelay);
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DEBUGASSERT(CPULOAD_ONESHOT_NOMINAL < g_sched_oneshot.maxdelay);
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/* Seed the PRNG */
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g_sched_oneshot.prng.w = 97;
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g_sched_oneshot.prng.x = 101;
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g_sched_oneshot.prng.y = g_sched_oneshot.prng.w << 17;
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g_sched_oneshot.prng.z = g_sched_oneshot.prng.x << 25;
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#endif
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/* Then start the oneshot */
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g_sched_oneshot.oneshot = lower;
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sched_oneshot_start();
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}
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