text: /****************************************************************************
   * libc/wqueue/work_thread.c
   *
   *   Copyright (C) 2009-2013 Gregory Nutt. All rights reserved.
   *   Author: Gregory Nutt <gnutt@nuttx.org>
   *   Modified by: Mark Charlebois to use hrt compatible times
   *
   * 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 <px4_config.h>
  #include <px4_defines.h>
  #include <px4_posix.h>
  #include <px4_tasks.h>
  #include <px4_time.h>
  #include <stdint.h>
  #include <signal.h>
  #include <stdio.h>
  #include <unistd.h>
  #include <queue.h>
  #include <px4_workqueue.h>
  #include <drivers/drv_hrt.h>
  #include "hrt_work.h"
  
  #include <string.h>
  
  /****************************************************************************
   * Pre-processor Definitions
   ****************************************************************************/
  
  /****************************************************************************
   * Private Type Declarations
   ****************************************************************************/
  
  /****************************************************************************
   * Public Variables
   ****************************************************************************/
  
  /* The state of each work queue. */
  struct wqueue_s g_hrt_work;
  
  /****************************************************************************
   * Private Variables
   ****************************************************************************/
  px4_sem_t _hrt_work_lock;
  
  /****************************************************************************
   * Private Functions
   ****************************************************************************/
  static void hrt_work_process(void);
  
  static void _sighandler(int sig_num);
  
  /****************************************************************************
   * Name: _sighandler
   *
   * Description:
   *   This is the handler for the signal to wake the queue processing thread
   *
   * Input parameters:
   *   sig_num - the received signal
   *
   * Returned Value:
   *   None
   *
   ****************************************************************************/
  static void _sighandler(int sig_num)
  {
  	PX4_DEBUG("RECEIVED SIGNAL %d", sig_num);
  }
  
  /****************************************************************************
   * Name: work_process
   *
   * Description:
   *   This is the logic that performs actions placed on any work list.
   *
   * Input parameters:
   *   wqueue - Describes the work queue to be processed
   *
   * Returned Value:
   *   None
   *
   ****************************************************************************/
  
  static void hrt_work_process()
  {
  	struct wqueue_s *wqueue = &g_hrt_work;
  	volatile struct work_s *work;
  	worker_t  worker;
  	void *arg;
  	uint64_t elapsed;
  	uint32_t remaining;
  	uint32_t next;
  
  	// set the threads name
  #ifdef __PX4_DARWIN
  	pthread_setname_np("HRT");
  #else
  	// The Linux headers do not actually contain this
  	//rv = pthread_setname_np(pthread_self(), "HRT");
  #endif
  
  	/* Then process queued work.  We need to keep interrupts disabled while
  	 * we process items in the work list.
  	 */
  
  	/* Default to sleeping for 1 sec */
  	next  = 1000000;
  
  	hrt_work_lock();
  
  	work  = (struct work_s *)wqueue->q.head;
  
  	while (work) {
  		/* Is this work ready?  It is ready if there is no delay or if
  		 * the delay has elapsed. qtime is the time that the work was added
  		 * to the work queue.  It will always be greater than or equal to
  		 * zero.  Therefore a delay of zero will always execute immediately.
  		 */
  
  		elapsed = hrt_absolute_time() - work->qtime;
  
  		//PX4_INFO("hrt work_process: in usec elapsed=%lu delay=%u work=%p", elapsed, work->delay, work);
  		if (elapsed >= work->delay) {
  			/* Remove the ready-to-execute work from the list */
  
  			(void)dq_rem((struct dq_entry_s *) & (work->dq), &(wqueue->q));
  			//PX4_INFO("Dequeued work=%p", work);
  
  			/* Extract the work description from the entry (in case the work
  			 * instance by the re-used after it has been de-queued).
  			 */
  
  			worker = work->worker;
  			arg    = work->arg;
  
  			/* Mark the work as no longer being queued */
  
  			work->worker = NULL;
  
  			/* Do the work.  Re-enable interrupts while the work is being
  			 * performed... we don't have any idea how long that will take!
  			 */
  
  			hrt_work_unlock();
  
  			if (!worker) {
  				PX4_ERR("MESSED UP: worker = 0");
  				PX4_BACKTRACE();
  
  			} else {
  				worker(arg);
  			}
  
  			/* Now, unfortunately, since we re-enabled interrupts we don't
  			 * know the state of the work list and we will have to start
  			 * back at the head of the list.
  			 */
  
  			hrt_work_lock();
  			work  = (struct work_s *)wqueue->q.head;
  
  		} else {
  			/* This one is not ready.. will it be ready before the next
  			 * scheduled wakeup interval?
  			 */
  
  			/* Here: elapsed < work->delay */
  			remaining = work->delay - elapsed;
  
  			//PX4_INFO("remaining=%u delay=%u elapsed=%lu", remaining, work->delay, elapsed);
  			if (remaining < next) {
  				/* Yes.. Then schedule to wake up when the work is ready */
  
  				next = remaining;
  			}
  
  			/* Then try the next in the list. */
  
  			work = (struct work_s *)work->dq.flink;
  			//PX4_INFO("next %u work %p", next, work);
  		}
  	}
  
  	/* Wait awhile to check the work list.  We will wait here until either
  	 * the time elapses or until we are awakened by a signal.
  	 */
  	hrt_work_unlock();
  
  	/* might sleep less if a signal received and new item was queued */
  	//PX4_INFO("Sleeping for %u usec", next);
  	px4_usleep(next);
  }
  
  /****************************************************************************
   * Name: work_hrtthread
   *
   * Description:
   *   This is the worker threads that performs actions placed on the ISR work
   *   list.
   *
   *   work_hpthread and work_lpthread:  These are the kernel mode work queues
   *     (also build in the flat build).  One of these threads also performs
   *     periodic garbage collection (that is otherwise performed by the idle
   *     thread if CONFIG_SCHED_WORKQUEUE is not defined).
   *
   *     These worker threads are started by the OS during normal bringup.
   *
   *   All of these entrypoints are referenced by OS internally and should not
   *   not be accessed by application logic.
   *
   * Input parameters:
   *   argc, argv (not used)
   *
   * Returned Value:
   *   Does not return
   *
   ****************************************************************************/
  
  static int work_hrtthread(int argc, char *argv[])
  {
  	/* Loop forever */
  
  	for (;;) {
  		/* First, perform garbage collection.  This cleans-up memory de-allocations
  		 * that were queued because they could not be freed in that execution
  		 * context (for example, if the memory was freed from an interrupt handler).
  		 * NOTE: If the work thread is disabled, this clean-up is performed by
  		 * the IDLE thread (at a very, very low priority).
  		 */
  
  		/* Then process queued work.  We need to keep interrupts disabled while
  		 * we process items in the work list.
  		 */
  
  		hrt_work_process();
  	}
  
  	return PX4_OK; /* To keep some compilers happy */
  }
  
  /****************************************************************************
   * Public Functions
   ****************************************************************************/
  
  void hrt_work_queue_init(void)
  {
  	px4_sem_init(&_hrt_work_lock, 0, 1);
  	memset(&g_hrt_work, 0, sizeof(g_hrt_work));
  
  	// Create high priority worker thread
  	g_hrt_work.pid = px4_task_spawn_cmd("wkr_hrt",
  					    SCHED_DEFAULT,
  					    SCHED_PRIORITY_MAX,
  					    2000,
  					    work_hrtthread,
  					    (char *const *)NULL);
  
  
  #ifdef __PX4_QURT
  	signal(SIGALRM, _sighandler);
  #else
  	signal(SIGCONT, _sighandler);
  #endif
  }
  
  