129 lines
3.9 KiB
C
129 lines
3.9 KiB
C
/****************************************************************************
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* sched/clock/clock_abstime2ticks.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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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 <errno.h>
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#include <debug.h>
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#include "clock/clock.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: clock_timespec_compare
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*
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* Description:
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* Return < 0 if time a is before time b
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* Return > 0 if time b is before time a
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* Return 0 if time a is the same as time b
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*
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****************************************************************************/
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int clock_timespec_compare(FAR const struct timespec *a,
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FAR const struct timespec *b)
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{
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if (a->tv_sec < b->tv_sec)
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{
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return -1;
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}
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if (a->tv_sec > b->tv_sec)
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{
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return 1;
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}
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return a->tv_nsec - b->tv_nsec;
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}
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/****************************************************************************
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* Name: clock_abstime2ticks
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*
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* Description:
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* Convert an absolute timespec delay to system timer ticks.
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*
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* Input Parameters:
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* clockid - The timing source to use in the conversion
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* reltime - Convert this absolute time to system clock ticks.
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* ticks - Return the converted number of ticks here.
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*
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* Returned Value:
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* OK on success; A non-zero error number on failure
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*
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* Assumptions:
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* Interrupts should be disabled so that the time is not changing during
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* the calculation
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*
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****************************************************************************/
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int clock_abstime2ticks(clockid_t clockid,
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FAR const struct timespec *abstime,
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FAR sclock_t *ticks)
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{
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struct timespec currtime;
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struct timespec reltime;
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int ret;
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/* Convert the timespec to clock ticks.
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* NOTE: Here we use internal knowledge
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* that CLOCK_REALTIME is defined to be zero!
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*/
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ret = clock_gettime(clockid, &currtime);
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if (ret != OK)
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{
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return ret;
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}
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if (clock_timespec_compare(abstime, &currtime) < 0)
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{
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/* Every caller of clock_abstime2ticks check 'ticks < 0' to see if
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* absolute time is in the past. So lets just return negative tick
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* here.
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*/
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*ticks = -1;
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return OK;
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}
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/* The relative time to wait is the absolute time minus the current time. */
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reltime.tv_nsec = (abstime->tv_nsec - currtime.tv_nsec);
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reltime.tv_sec = (abstime->tv_sec - currtime.tv_sec);
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/* Check if we were supposed to borrow from the seconds. */
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if (reltime.tv_nsec < 0)
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{
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reltime.tv_nsec += NSEC_PER_SEC;
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reltime.tv_sec -= 1;
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}
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/* Convert this relative time into clock ticks. */
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return clock_time2ticks(&reltime, ticks);
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}
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