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/**
* @file
*
* @brief Suspends Execution of calling thread until Time elapses
* @ingroup POSIXAPI
*/
/*
* COPYRIGHT (c) 1989-2015.
* On-Line Applications Research Corporation (OAR).
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include <time.h>
#include <errno.h>
#include <rtems/seterr.h>
#include <rtems/score/threadimpl.h>
#include <rtems/score/threadqimpl.h>
#include <rtems/score/timespec.h>
#include <rtems/score/watchdogimpl.h>
static Thread_queue_Control _Nanosleep_Pseudo_queue =
THREAD_QUEUE_INITIALIZER( "Nanosleep" );
/*
* 14.2.5 High Resolution Sleep, P1003.1b-1993, p. 269
*/
int nanosleep(
const struct timespec *rqtp,
struct timespec *rmtp
)
{
/*
* It is critical to obtain the executing thread after thread dispatching is
* disabled on SMP configurations.
*/
Thread_Control *executing;
Per_CPU_Control *cpu_self;
Watchdog_Interval ticks;
Watchdog_Interval start;
Watchdog_Interval elapsed;
/*
* Return EINVAL if the delay interval is negative.
*
* NOTE: This behavior is beyond the POSIX specification.
* FSU and GNU/Linux pthreads shares this behavior.
*/
if ( !_Timespec_Is_valid( rqtp ) )
rtems_set_errno_and_return_minus_one( EINVAL );
/*
* Convert the timespec delay into the appropriate number of clock ticks.
*/
ticks = _Timespec_To_ticks( rqtp );
executing = _Thread_Get_executing();
/*
* A nanosleep for zero time is implemented as a yield.
* This behavior is also beyond the POSIX specification but is
* consistent with the RTEMS API and yields desirable behavior.
*/
if ( !ticks ) {
cpu_self = _Thread_Dispatch_disable();
_Thread_Yield( executing );
_Thread_Dispatch_enable( cpu_self );
if ( rmtp ) {
rmtp->tv_sec = 0;
rmtp->tv_nsec = 0;
}
return 0;
}
start = _Watchdog_Ticks_since_boot;
/*
* Block for the desired amount of time
*/
_Thread_queue_Enqueue(
&_Nanosleep_Pseudo_queue,
&_Thread_queue_Operations_FIFO,
executing,
STATES_DELAYING | STATES_INTERRUPTIBLE_BY_SIGNAL,
ticks,
0
);
/*
* Calculate the time that passed while we were sleeping and how
* much remains from what we requested.
*/
elapsed = _Watchdog_Ticks_since_boot - start;
if ( elapsed >= ticks )
ticks = 0;
else
ticks -= elapsed;
/*
* If the user wants the time remaining, do the conversion.
*/
if ( rmtp ) {
_Timespec_From_ticks( ticks, rmtp );
}
/*
* Only when POSIX is enabled, can a sleep be interrupted.
*/
#if defined(RTEMS_POSIX_API)
/*
* If there is time remaining, then we were interrupted by a signal.
*/
if ( ticks )
rtems_set_errno_and_return_minus_one( EINTR );
#endif
return 0;
}
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