132 lines
5.0 KiB
C
132 lines
5.0 KiB
C
/****************************************************************************
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* libs/libc/unistd/lib_sleep.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 <unistd.h>
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#include <signal.h>
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#include <nuttx/clock.h>
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#include <arch/irq.h>
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: sleep
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*
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* Description:
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* The sleep() function will cause the calling thread to be suspended from
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* execution until either the number of real-time seconds specified by the
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* argument 'seconds' has elapsed or a signal is delivered to the calling
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* thread and its action is to invoke a signal-catching function or to
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* terminate the process. The suspension time may be longer than requested
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* due to the scheduling of other activity by the system.
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*
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* If a SIGALRM signal is generated for the calling process during
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* execution of sleep() and if the SIGALRM signal is being ignored or
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* blocked from delivery, it is unspecified whether sleep() returns
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* when the SIGALRM signal is scheduled. If the signal is being blocked, it
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* is also unspecified whether it remains pending after sleep() returns or
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* it is discarded.
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*
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* If a SIGALRM signal is generated for the calling process during
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* execution of sleep(), except as a result of a prior call to alarm(),
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* and if the SIGALRM signal is not being ignored or blocked from delivery,
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* it is unspecified whether that signal has any effect other than causing
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* sleep() to return.
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*
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* If a signal-catching function interrupts sleep() and examines or changes
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* either the time a SIGALRM is scheduled to be generated, the action
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* associated with the SIGALRM signal, or whether the SIGALRM signal is
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* blocked from delivery, the results are unspecified.
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*
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* If a signal-catching function interrupts sleep() and calls siglongjmp()
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* or longjmp() to restore an environment saved prior to the sleep() call,
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* the action associated with the SIGALRM signal and the time at which a
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* SIGALRM signal is scheduled to be generated are unspecified. It is also
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* unspecified whether the SIGALRM signal is blocked, unless the process'
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* signal mask is restored as part of the environment.
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*
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* Implementations may place limitations on the granularity of timer
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* values. For each interval timer, if the requested timer value requires a
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* finer granularity than the implementation supports, the actual timer
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* value will be rounded up to the next supported value.
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*
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* Interactions between sleep() and any of setitimer(), ualarm() or sleep()
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* are unspecified.
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*
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* Input Parameters:
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* seconds - The number of seconds to sleep
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*
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* Returned Value:
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* If sleep() returns because the requested time has elapsed, the value
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* returned will be 0. If sleep() returns because of premature arousal due
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* to delivery of a signal, the return value will be the "unslept" amount
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* (the requested time minus the time actually slept) in seconds.
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*
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* Assumptions:
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*
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****************************************************************************/
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unsigned int sleep(unsigned int seconds)
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{
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struct timespec rqtp;
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struct timespec rmtp;
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unsigned int remaining = 0;
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int ret;
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/* Don't sleep if seconds == 0 */
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if (seconds > 0)
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{
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/* Let clock_nanosleep() do all of the work. */
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rqtp.tv_sec = seconds;
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rqtp.tv_nsec = 0;
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ret = clock_nanosleep(CLOCK_REALTIME, 0, &rqtp, &rmtp);
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/* clock_nanosleep() should only fail if it was interrupted by a
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* signal, but we treat all errors the same,
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*/
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if (ret < 0)
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{
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remaining = rmtp.tv_sec;
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if (remaining < seconds && rmtp.tv_nsec >= 500000000)
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{
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/* Round up */
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remaining++;
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}
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}
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return remaining;
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}
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return 0;
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}
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