nuttx/libs/libc/sched/clock_time2ticks.c
Jukka Laitinen c79d2067c7 Move timespec calculations from sched into libc/sched
Allow using these functions also outside sched, where systick
related calculations are performed

Signed-off-by: Jukka Laitinen <jukkax@ssrc.tii.ae>
2021-11-04 13:19:01 -05:00

104 lines
3.5 KiB
C

/****************************************************************************
* libs/libc/sched/clock_time2ticks.c
*
* 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 to you 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 <stdint.h>
#include <time.h>
#include <assert.h>
#include <nuttx/clock.h>
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: clock_time2ticks
*
* Description:
* Convert a timespec delay to system timer ticks. This function is
* suitable for calculating relative time delays and does not depend on
* the other clock_* logic.
*
* Input Parameters:
* reltime - Convert this relative time to system clock ticks.
* ticks - Return the converted number of ticks here.
*
* Returned Value:
* Always returns OK
*
* Assumptions:
*
****************************************************************************/
int clock_time2ticks(FAR const struct timespec *reltime,
FAR sclock_t *ticks)
{
#ifdef CONFIG_HAVE_LONG_LONG
int64_t relnsec;
/* Convert the relative time into nanoseconds. The range of the int64_t
* is sufficiently large that there is no real need for range checking.
*/
relnsec = (int64_t)reltime->tv_sec * NSEC_PER_SEC +
(int64_t)reltime->tv_nsec;
/* Convert nanoseconds to clock ticks, rounding up to the smallest integer
* that is greater than or equal to the exact number of tick.
*/
*ticks = (sclock_t)((relnsec + NSEC_PER_TICK - 1) / NSEC_PER_TICK);
return OK;
#else
int32_t relusec;
/* This function uses an int32_t to only the relative time in microseconds.
* that means that the maximum supported relative time is 2,147,487.647
* seconds
*/
#if 0 // overkill
DEBUGASSERT(reltime->tv_sec < 2147487 ||
reltime->tv_sec == 2147487 &&
reltime->tv_nsec <= 647 * NSEC_PER_MSEC);
#endif
/* Convert the relative time into microseconds, rounding up to the smallest
* value that is greater than or equal to the exact number of microseconds.
*/
relusec = reltime->tv_sec * USEC_PER_SEC +
(reltime->tv_nsec + NSEC_PER_USEC - 1) / NSEC_PER_USEC;
/* Convert microseconds to clock ticks, rounding up to the smallest integer
* that is greater than or equal to the exact number of tick.
*/
*ticks = (sclock_t)((relusec + USEC_PER_TICK - 1) / USEC_PER_TICK);
return OK;
#endif
}