148 lines
6.2 KiB
C
148 lines
6.2 KiB
C
/****************************************************************************
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* lib/lib_usleep.c
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*
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* Copyright (C) 2007, 2009, 2012-2013 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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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 <sys/types.h>
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#include <unistd.h>
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#include <signal.h>
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#include <assert.h>
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#include <errno.h>
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/****************************************************************************
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* Private Type Declarations
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****************************************************************************/
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/****************************************************************************
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* Public Data
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****************************************************************************/
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/****************************************************************************
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* Private Data
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****************************************************************************/
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/****************************************************************************
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* Private Function Prototypes
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****************************************************************************/
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: usleep
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*
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* Description:
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* The usleep() function will cause the calling thread to be suspended
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* from execution until either the number of real-time microseconds
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* specified by the argument 'usec' has elapsed or a signal is delivered
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* to the calling thread. 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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* The 'usec' argument must be less than 1,000,000. If the value of
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* 'usec' is 0, then the call has no effect.
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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 usleep() and if the SIGALRM signal is being ignored or
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* blocked from delivery, it is unspecified whether usleep() 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 usleep() 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 usleep(), 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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* usleep() to return.
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*
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* If a signal-catching function interrupts usleep() 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 usleep() and calls siglongjmp()
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* or longjmp() to restore an environment saved prior to the usleep() 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 values.
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* For each interval timer, if the requested timer value requires a finer
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* granularity than the implementation supports, the actual timer value will
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* be rounded up to the next supported value.
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*
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* Interactions between usleep() and any of the following are unspecified:
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*
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* nanosleep(), setitimer(), timer_create(), timer_delete(), timer_getoverrun(),
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* timer_gettime(), timer_settime(), ualarm(), sleep()
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*
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* Parameters:
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* usec - the number of microseconds to wait.
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*
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* Returned Value:
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* On successful completion, usleep() returns 0. Otherwise, it returns -1
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* and sets errno to indicate the error.
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*
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* Assumptions:
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*
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****************************************************************************/
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int usleep(useconds_t usec)
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{
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struct timespec rqtp;
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time_t sec;
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int ret = 0;
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if (usec)
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{
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/* Let nanosleep() do all of the work. */
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sec = usec / 1000000;
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rqtp.tv_sec = sec;
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rqtp.tv_nsec = (usec - (sec * 1000000)) * 1000;
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ret = nanosleep(&rqtp, NULL);
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}
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return ret;
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}
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