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#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#ifdef NEED_HPUX_ADJTIME
/*************************************************************************/
/* (c) Copyright Tai Jin, 1988. All Rights Reserved. */
/* Hewlett-Packard Laboratories. */
/* */
/* Permission is hereby granted for unlimited modification, use, and */
/* distribution. This software is made available with no warranty of */
/* any kind, express or implied. This copyright notice must remain */
/* intact in all versions of this software. */
/* */
/* The author would appreciate it if any bug fixes and enhancements were */
/* to be sent back to him for incorporation into future versions of this */
/* software. Please send changes to tai@iag.hp.com or ken@sdd.hp.com. */
/*************************************************************************/
/*
* Revision history
*
* 9 Jul 94 David L. Mills, Unibergity of Delabunch
* Implemented variable threshold to limit age of
* corrections; reformatted code for readability.
*/
#ifndef lint
static char RCSid[] = "adjtime.c,v 3.1 1993/07/06 01:04:42 jbj Exp";
#endif
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>
#include <time.h>
#include <signal.h>
#include "adjtime.h"
#define abs(x) ((x) < 0 ? -(x) : (x))
/*
* The following paramters are appropriate for an NTP adjustment
* interval of one second.
*/
#define ADJ_THRESH 200 /* initial threshold */
#define ADJ_DELTA 4 /* threshold decrement */
static long adjthresh; /* adjustment threshold */
static long saveup; /* corrections accumulator */
/*
* clear_adjtime - reset accumulator and threshold variables
*/
void
_clear_adjtime()
{
saveup = 0;
adjthresh = ADJ_THRESH;
}
/*
* adjtime - hp-ux copout of the standard Unix adjtime() system call
*/
int
adjtime(delta, olddelta)
register struct timeval *delta;
register struct timeval *olddelta;
{
struct timeval newdelta;
/*
* Corrections greater than one second are done immediately.
*/
if (delta->tv_sec) {
adjthresh = ADJ_THRESH;
saveup = 0;
return(_adjtime(delta, olddelta));
}
/*
* Corrections less than one second are accumulated until
* tripping a threshold, which is initially set at ADJ_THESH and
* reduced in ADJ_DELTA steps to zero. The idea here is to
* introduce large corrections quickly, while making sure that
* small corrections are introduced without excessive delay. The
* idea comes from the ARPAnet routing update algorithm.
*/
saveup += delta->tv_usec;
if (abs(saveup) >= adjthresh) {
adjthresh = ADJ_THRESH;
newdelta.tv_sec = 0;
newdelta.tv_usec = saveup;
saveup = 0;
return(_adjtime(&newdelta, olddelta));
} else {
adjthresh -= ADJ_DELTA;
}
/*
* While nobody uses it, return the residual before correction,
* as per Unix convention.
*/
if (olddelta)
olddelta->tv_sec = olddelta->tv_usec = 0;
return(0);
}
/*
* _adjtime - does the actual work
*/
int
_adjtime(delta, olddelta)
register struct timeval *delta;
register struct timeval *olddelta;
{
register int mqid;
MsgBuf msg;
register MsgBuf *msgp = &msg;
/*
* Get the key to the adjtime message queue (note that we must
* get it every time because the queue might have been removed
* and recreated)
*/
if ((mqid = msgget(KEY, 0)) == -1)
return (-1);
msgp->msgb.mtype = CLIENT;
msgp->msgb.tv = *delta;
if (olddelta)
msgp->msgb.code = DELTA2;
else
msgp->msgb.code = DELTA1;
/*
* Tickle adjtimed and snatch residual, if indicated. Lots of
* fanatic error checking here.
*/
if (msgsnd(mqid, &msgp->msgp, MSGSIZE, 0) == -1)
return (-1);
if (olddelta) {
if (msgrcv(mqid, &msgp->msgp, MSGSIZE, SERVER, 0) == -1)
return (-1);
*olddelta = msgp->msgb.tv;
}
return (0);
}
#else /* not NEED_HPUX_ADJTIME */
int adjtime_bs;
#endif /* not NEED_HPUX_ADJTIME */
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