sched/hrtimer/hrtimer_gettime.c

/****************************************************************************
 * sched/hrtimer/hrtimer_gettime.c
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.  The
 * ASF licenses this file under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the
 * License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include "hrtimer/hrtimer.h"

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: hrtimer_gettime
 *
 * Description:
 *   Get the rest of the delay time of the hrtimer in nanoseconds.
 *
 * Input Parameters:
 *   timer - The hrtimer to be queried.
 *
 * Returned Value
 *   The time until next expiration in nanoseconds.
 *
 * Assumption:
 *   The timer should not be NULL.
 *
 ****************************************************************************/

uint64_t hrtimer_gettime(FAR hrtimer_t *timer)
{
  uint64_t expire = hrtimer_read_64(&timer->expired);
  int64_t  remain = expire - clock_systime_nsec();

  return remain < 0 ? 0u : remain;
}