C++ (Cpp) FPTODの例

コード例 #1

void
offset_calculation (
	struct pkt *rpkt,
	int rpktl,
	struct timeval *tv_dst,
	double *offset,
	double *precision,
	double *root_dispersion
	)
{
	l_fp p_rec, p_xmt, p_ref, p_org, tmp, dst;
	u_fp p_rdly, p_rdsp;
	double t21, t34, delta;

	/* Convert timestamps from network to host byte order */
	p_rdly = NTOHS_FP(rpkt->rootdelay);
	p_rdsp = NTOHS_FP(rpkt->rootdisp);
	NTOHL_FP(&rpkt->reftime, &p_ref);
	NTOHL_FP(&rpkt->org, &p_org);
	NTOHL_FP(&rpkt->rec, &p_rec);
	NTOHL_FP(&rpkt->xmt, &p_xmt);

	*precision = LOGTOD(rpkt->precision);
#ifdef DEBUG
	printf("sntp precision: %f\n", *precision);
#endif /* DEBUG */

	*root_dispersion = FPTOD(p_rdsp);

#ifdef DEBUG
	printf("sntp rootdelay: %f\n", FPTOD(p_rdly));
	printf("sntp rootdisp: %f\n", *root_dispersion);

	pkt_output(rpkt, rpktl, stdout);

	printf("sntp offset_calculation: rpkt->reftime:\n");
	l_fp_output(&(rpkt->reftime), stdout);
	printf("sntp offset_calculation: rpkt->org:\n");
	l_fp_output(&(rpkt->org), stdout);
	printf("sntp offset_calculation: rpkt->rec:\n");
	l_fp_output(&(rpkt->rec), stdout);
	printf("sntp offset_calculation: rpkt->rec:\n");
	l_fp_output_bin(&(rpkt->rec), stdout);
	printf("sntp offset_calculation: rpkt->rec:\n");
	l_fp_output_dec(&(rpkt->rec), stdout);
	printf("sntp offset_calculation: rpkt->xmt:\n");
	l_fp_output(&(rpkt->xmt), stdout);
#endif

	/* Compute offset etc. */
	tmp = p_rec;
	L_SUB(&tmp, &p_org);
	LFPTOD(&tmp, t21);
	TVTOTS(tv_dst, &dst);
	dst.l_ui += JAN_1970;
	tmp = p_xmt;
	L_SUB(&tmp, &dst);
	LFPTOD(&tmp, t34);
	*offset = (t21 + t34) / 2.;
	delta = t21 - t34;

	if (ENABLED_OPT(NORMALVERBOSE))
		printf("sntp offset_calculation:\tt21: %.6f\t\t t34: %.6f\n\t\tdelta: %.6f\t offset: %.6f\n", 
			   t21, t34, delta, *offset);
}

コード例 #2

ファイル: main.c プロジェクト: cemeyer/freebsd-base-graphics

void
offset_calculation(
	struct pkt *rpkt,
	int rpktl,
	struct timeval *tv_dst,
	double *offset,
	double *precision,
	double *synch_distance
	)
{
	l_fp p_rec, p_xmt, p_ref, p_org, tmp, dst;
	u_fp p_rdly, p_rdsp;
	double t21, t34, delta;

	/* Convert timestamps from network to host byte order */
	p_rdly = NTOHS_FP(rpkt->rootdelay);
	p_rdsp = NTOHS_FP(rpkt->rootdisp);
	NTOHL_FP(&rpkt->reftime, &p_ref);
	NTOHL_FP(&rpkt->org, &p_org);
	NTOHL_FP(&rpkt->rec, &p_rec);
	NTOHL_FP(&rpkt->xmt, &p_xmt);

	*precision = LOGTOD(rpkt->precision);

	TRACE(3, ("offset_calculation: LOGTOD(rpkt->precision): %f\n", *precision));

	/* Compute offset etc. */
	tmp = p_rec;
	L_SUB(&tmp, &p_org);
	LFPTOD(&tmp, t21);
	TVTOTS(tv_dst, &dst);
	dst.l_ui += JAN_1970;
	tmp = p_xmt;
	L_SUB(&tmp, &dst);
	LFPTOD(&tmp, t34);
	*offset = (t21 + t34) / 2.;
	delta = t21 - t34;

	// synch_distance is:
	// (peer->delay + peer->rootdelay) / 2 + peer->disp
	// + peer->rootdisp + clock_phi * (current_time - peer->update)
	// + peer->jitter;
	//
	// and peer->delay = fabs(peer->offset - p_offset) * 2;
	// and peer->offset needs history, so we're left with
	// p_offset = (t21 + t34) / 2.;
	// peer->disp = 0; (we have no history to augment this)
	// clock_phi = 15e-6; 
	// peer->jitter = LOGTOD(sys_precision); (we have no history to augment this)
	// and ntp_proto.c:set_sys_tick_precision() should get us sys_precision.
	//
	// so our answer seems to be:
	//
	// (fabs(t21 + t34) + peer->rootdelay) / 3.
	// + 0 (peer->disp)
	// + peer->rootdisp
	// + 15e-6 (clock_phi)
	// + LOGTOD(sys_precision)

	INSIST( FPTOD(p_rdly) >= 0. );
#if 1
	*synch_distance = (fabs(t21 + t34) + FPTOD(p_rdly)) / 3.
		+ 0.
		+ FPTOD(p_rdsp)
		+ 15e-6
		+ 0.	/* LOGTOD(sys_precision) when we can get it */
		;
	INSIST( *synch_distance >= 0. );
#else
	*synch_distance = (FPTOD(p_rdly) + FPTOD(p_rdsp))/2.0;
#endif

#ifdef DEBUG
	if (debug > 3) {
		printf("sntp rootdelay: %f\n", FPTOD(p_rdly));
		printf("sntp rootdisp: %f\n", FPTOD(p_rdsp));
		printf("sntp syncdist: %f\n", *synch_distance);

		pkt_output(rpkt, rpktl, stdout);

		printf("sntp offset_calculation: rpkt->reftime:\n");
		l_fp_output(&p_ref, stdout);
		printf("sntp offset_calculation: rpkt->org:\n");
		l_fp_output(&p_org, stdout);
		printf("sntp offset_calculation: rpkt->rec:\n");
		l_fp_output(&p_rec, stdout);
		printf("sntp offset_calculation: rpkt->xmt:\n");
		l_fp_output(&p_xmt, stdout);
	}
#endif

	TRACE(3, ("sntp offset_calculation:\trec - org t21: %.6f\n"
		  "\txmt - dst t34: %.6f\tdelta: %.6f\toffset: %.6f\n",
		  t21, t34, delta, *offset));

	return;
}