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/*
* ntpshmwrite.c - put time information in SHM segment for ntpd
*
* This file is Copyright (c) 2010 by the GPSD project BSD terms apply:
* see the file COPYING in the distribution root for details.
*/
#include <string.h>
#include <libgen.h>
#include <stdbool.h>
#include <math.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#ifndef S_SPLINT_S
#include <sys/wait.h>
#include <sys/socket.h>
#include <unistd.h>
#endif /* S_SPLINT_S */
#include "ntpshm.h"
#include "compiler.h"
void ntp_write(volatile struct shmTime *shmseg,
struct timedelta_t *td, int precision, int leap_notify)
/* put a received fix time into shared memory for NTP */
{
/* we use the shmTime mode 1 protocol
*
* ntpd does this:
*
* reads valid.
* IFF valid is 1
* reads count
* reads values
* reads count
* IFF count unchanged
* use values
* clear valid
*
*/
shmseg->valid = 0;
shmseg->count++;
/* We need a memory barrier here to prevent write reordering by
* the compiler or CPU cache */
memory_barrier();
/*@-type@*/ /* splint is confused about struct timespec */
shmseg->clockTimeStampSec = (time_t)td->real.tv_sec;
shmseg->clockTimeStampUSec = (int)(td->real.tv_nsec/1000);
shmseg->clockTimeStampNSec = (unsigned)td->real.tv_nsec;
shmseg->receiveTimeStampSec = (time_t)td->clock.tv_sec;
shmseg->receiveTimeStampUSec = (int)(td->clock.tv_nsec/1000);
shmseg->receiveTimeStampNSec = (unsigned)td->clock.tv_nsec;
/*@+type@*/
shmseg->leap = leap_notify;
shmseg->precision = precision;
memory_barrier();
shmseg->count++;
shmseg->valid = 1;
}
/* end */
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