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/**
* @file
*
* @brief Correct the Time to Synchronize the System Clock
* @ingroup POSIXAPI
*/
/*
* COPYRIGHT (c) 1989-2007.
* 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 <sys/time.h>
#include <errno.h>
#include <rtems/score/timespec.h>
#include <rtems/score/threaddispatch.h>
#include <rtems/score/todimpl.h>
#include <rtems/config.h>
#include <rtems/seterr.h>
/**
* This method was initially added as part of porting NTP to RTEMS.
* It is a BSD compatability function and now is available on
* GNU/Linux.
*
* At one point there was a static variable named adjustment
* used by this implementation. I don't see any reason for it
* to be here based upon the GNU/Linux documentation.
*/
int adjtime(
const struct timeval *delta,
struct timeval *olddelta
)
{
struct timespec ts;
long adjustment;
/*
* Simple validations
*/
if ( !delta )
rtems_set_errno_and_return_minus_one( EINVAL );
if ( delta->tv_usec >= TOD_MICROSECONDS_PER_SECOND )
rtems_set_errno_and_return_minus_one( EINVAL );
if ( olddelta ) {
olddelta->tv_sec = 0;
olddelta->tv_usec = 0;
}
/* convert delta to microseconds */
adjustment = (delta->tv_sec * TOD_MICROSECONDS_PER_SECOND);
adjustment += delta->tv_usec;
/* too small to account for */
if ( adjustment < rtems_configuration_get_microseconds_per_tick() )
return 0;
/*
* This prevents context switches while we are adjusting the TOD
*/
_Thread_Disable_dispatch();
_TOD_Get( &ts );
ts.tv_sec += delta->tv_sec;
ts.tv_nsec += delta->tv_usec * TOD_NANOSECONDS_PER_MICROSECOND;
/* if adjustment is too much positive */
while ( ts.tv_nsec >= TOD_NANOSECONDS_PER_SECOND ) {
ts.tv_nsec -= TOD_NANOSECONDS_PER_SECOND;
ts.tv_sec++;
}
/* if adjustment is too much negative */
while ( ts.tv_nsec <= (-1 * TOD_NANOSECONDS_PER_SECOND) ) {
ts.tv_nsec += TOD_NANOSECONDS_PER_SECOND;
ts.tv_sec--;
}
_TOD_Set( &ts );
_Thread_Enable_dispatch();
/* set the user's output */
if ( olddelta )
*olddelta = *delta;
return 0;
}
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