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 *
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 * 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.
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 *    notice, this list of conditions and the following disclaimer in
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 *    used to endorse or promote products derived from this software
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/**
 * @file cpuload.c
 *
 * Measurement of CPU load of each individual task.
 *
 * @author Lorenz Meier <lorenz@px4.io>
 * @author Petri Tanskanen <petri.tanskanen@inf.ethz.ch>
 */
#include <px4_platform_common/px4_config.h>
#include <px4_platform_common/atomic.h>
#include <px4_platform/cpuload.h>

#include <drivers/drv_hrt.h>

#if defined(__PX4_NUTTX) && defined(CONFIG_SCHED_INSTRUMENTATION)
__BEGIN_DECLS
# include <nuttx/sched_note.h>

__EXPORT struct system_load_s system_load;

static px4::atomic_int cpuload_monitor_all_count{0};

void cpuload_monitor_start()
{
	if (cpuload_monitor_all_count.fetch_add(1) == 0) {
		// if the count was previously 0 (idle thread only) then clear any existing runtime data
		sched_lock();

		system_load.start_time = hrt_absolute_time();

		for (int i = 1; i < CONFIG_MAX_TASKS; i++) {
			system_load.tasks[i].total_runtime = 0;
			system_load.tasks[i].curr_start_time = 0;
		}

		sched_unlock();
	}
}

void cpuload_monitor_stop()
{
	if (cpuload_monitor_all_count.fetch_sub(1) <= 1) {
		// don't allow the count to go negative
		cpuload_monitor_all_count.store(0);
	}
}

void cpuload_initialize_once()
{
	for (auto &task : system_load.tasks) {
		task.valid = false;
	}

	int static_tasks_count = 2;	// there are at least 2 threads that should be initialized statically - "idle" and "init"

#ifdef CONFIG_PAGING
	static_tasks_count++;	// include paging thread in initialization
#endif /* CONFIG_PAGING */
#if CONFIG_SCHED_WORKQUEUE
	static_tasks_count++;	// include high priority work0 thread in initialization
#endif /* CONFIG_SCHED_WORKQUEUE */
#if CONFIG_SCHED_LPWORK
	static_tasks_count++;	// include low priority work1 thread in initialization
#endif /* CONFIG_SCHED_WORKQUEUE */

	// perform static initialization of "system" threads
	for (system_load.total_count = 0; system_load.total_count < static_tasks_count; system_load.total_count++) {
		system_load.tasks[system_load.total_count].total_runtime = 0;
		system_load.tasks[system_load.total_count].curr_start_time = 0;
		system_load.tasks[system_load.total_count].tcb = nxsched_get_tcb(
					system_load.total_count);	// it is assumed that these static threads have consecutive PIDs
		system_load.tasks[system_load.total_count].valid = true;
	}

	system_load.initialized = true;
}

void sched_note_start(FAR struct tcb_s *tcb)
{
	// find first free slot
	if (system_load.initialized) {
		for (auto &task : system_load.tasks) {
			if (!task.valid) {
				// slot is available
				task.total_runtime = 0;
				task.curr_start_time = 0;
				task.tcb = tcb;
				task.valid = true;
				system_load.total_count++;
				break;
			}
		}
	}
}

void sched_note_stop(FAR struct tcb_s *tcb)
{
	if (system_load.initialized) {
		for (auto &task : system_load.tasks) {
			if (task.tcb && task.tcb->pid == tcb->pid) {
				// mark slot as free
				task.valid = false;
				task.total_runtime = 0;
				task.curr_start_time = 0;
				task.tcb = nullptr;
				system_load.total_count--;
				break;
			}
		}
	}
}

void sched_note_suspend(FAR struct tcb_s *tcb)
{
	if (system_load.initialized) {
		if (tcb->pid == 0) {
			system_load.tasks[0].total_runtime += hrt_elapsed_time(&system_load.tasks[0].curr_start_time);
			return;

		} else {
			if (cpuload_monitor_all_count.load() == 0) {
				return;
			}
		}

		for (auto &task : system_load.tasks) {
			// Task ending its current scheduling run
			if (task.valid && (task.curr_start_time > 0)
			    && task.tcb && task.tcb->pid == tcb->pid) {

				task.total_runtime += hrt_elapsed_time(&task.curr_start_time);
				break;
			}
		}
	}
}

void sched_note_resume(FAR struct tcb_s *tcb)
{
	if (system_load.initialized) {
		if (tcb->pid == 0) {
			hrt_store_absolute_time(&system_load.tasks[0].curr_start_time);
			return;

		} else {
			if (cpuload_monitor_all_count.load() == 0) {
				return;
			}
		}

		for (auto &task : system_load.tasks) {
			if (task.valid && task.tcb && task.tcb->pid == tcb->pid) {
				// curr_start_time is accessed from an IRQ handler (in logger), so we need
				// to make the update atomic
				hrt_store_absolute_time(&task.curr_start_time);
				break;
			}
		}
	}
}
__END_DECLS
#endif // PX4_NUTTX && CONFIG_SCHED_INSTRUMENTATION
