Add the best master clock algorithm.
This commit also introduces clock and port objects, but only with the minimal interface needed by the BMC. Signed-off-by: Richard Cochran <richardcochran@gmail.com>master
Richard Cochran
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c9a15e6094
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/**
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* @file bmc.c
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* @note Copyright (C) 2011 Richard Cochran <richardcochran@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include <string.h>
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#include "bmc.h"
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#include "ds.h"
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#define A_BETTER 1
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#define B_BETTER -1
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static int dscmp2(struct dataset *a, struct dataset *b)
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{
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int diff;
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unsigned int A = a->stepsRemoved, B = b->stepsRemoved;
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if (A + 1 < B)
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return A_BETTER;
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if (B + 1 < A)
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return B_BETTER;
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/*
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* We ignore the "error-1" conditions mentioned in the
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* standard, since there is nothing we can do about it anyway.
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*/
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if (A < B)
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return A_BETTER;
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if (A > B)
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return B_BETTER;
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diff = memcmp(&a->sender, &b->sender, sizeof(a->sender));
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if (diff < 0)
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return A_BETTER;
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if (diff > 0)
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return B_BETTER;
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if (a->receiver.portNumber < b->receiver.portNumber)
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return A_BETTER;
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if (a->receiver.portNumber > b->receiver.portNumber)
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return B_BETTER;
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/*
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* If we got this far, it means "error-2" has occured.
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*/
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return 0;
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}
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int dscmp(struct dataset *a, struct dataset *b)
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{
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int diff;
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if (a == b)
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return 0;
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if (a && !b)
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return A_BETTER;
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if (b && !a)
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return B_BETTER;
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diff = memcmp(&a->identity, &b->identity, sizeof(a->identity));
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if (!diff)
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return dscmp2(a, b);
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if (a->priority1 < b->priority1)
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return A_BETTER;
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if (a->priority1 > b->priority1)
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return B_BETTER;
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if (a->quality.clockClass < b->quality.clockClass)
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return A_BETTER;
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if (a->quality.clockClass > b->quality.clockClass)
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return B_BETTER;
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if (a->quality.clockAccuracy < b->quality.clockAccuracy)
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return A_BETTER;
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if (a->quality.clockAccuracy > b->quality.clockAccuracy)
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return B_BETTER;
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if (a->quality.offsetScaledLogVariance <
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b->quality.offsetScaledLogVariance)
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return A_BETTER;
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if (a->quality.offsetScaledLogVariance >
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b->quality.offsetScaledLogVariance)
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return B_BETTER;
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if (a->priority2 < b->priority2)
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return A_BETTER;
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if (a->priority2 > b->priority2)
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return B_BETTER;
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return diff < 0 ? A_BETTER : B_BETTER;
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}
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enum port_state bmc_state_decision(struct clock *c, struct port *r)
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{
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struct dataset *clock_ds, *clock_best, *port_best;
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enum port_state ps;
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clock_ds = clock_default_ds(c);
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clock_best = clock_best_foreign(c);
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port_best = port_best_foreign(r);
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ps = port_state(r);
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if (!port_best) {
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if (PS_LISTENING == ps)
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return ps;
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else
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return PS_FAULTY;
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}
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if (!clock_best)
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return PS_FAULTY;
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if (clock_class(c) <= 127) {
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if (dscmp(clock_ds, port_best) > 0) {
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return PS_GRAND_MASTER; /*M1*/
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} else {
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return PS_PASSIVE; /*P1*/
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}
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}
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if (dscmp(clock_ds, clock_best) > 0) {
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return PS_GRAND_MASTER; /*M2*/
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}
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if (clock_best_port(c) == r) {
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return PS_SLAVE; /*S1*/
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}
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if (dscmp(clock_best, port_best) > 0) {
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return PS_PASSIVE; /*P2*/
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} else {
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return PS_MASTER; /*M3*/
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}
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}
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@ -0,0 +1,45 @@
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/**
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* @file bmc.h
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* @brief Best master clock algorithm
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* @note Copyright (C) 2011 Richard Cochran <richardcochran@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#ifndef HAVE_BMC_H
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#define HAVE_BMC_H
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#include "clock.h"
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#include "port.h"
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#include "fsm.h"
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/**
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* BMC state decision algorithm.
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* @param c The local clock.
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* @param r The port in question.
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* @return A @ref port_state value as the recommended state.
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*/
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enum port_state bmc_state_decision(struct clock *c, struct port *r);
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/**
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* Compare two data sets.
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* @param a A dataset to compare.
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* @param b A dataset to compare.
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* @return An integer less than, equal to, or greater than zero
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* if the dataset @a a is found, respectively, to be
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* less than, to match, or be greater than @a b.
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*/
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int dscmp(struct dataset *a, struct dataset *b);
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#endif
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@ -0,0 +1,57 @@
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/**
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* @file clock.h
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* @note Copyright (C) 2011 Richard Cochran <richardcochran@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#ifndef HAVE_CLOCK_H
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#define HAVE_CLOCK_H
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#include "ds.h"
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/** Opaque type. */
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struct clock;
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/**
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* Obtains a reference to the best foreign master of a clock.
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* @param c The clock instance.
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* @return A pointer to the data set of the foreign master,
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* or NULL if none has been yet discovered.
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*/
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struct dataset *clock_best_foreign(struct clock *c);
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/**
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* Obtains a reference to the port with the best foreign master.
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* @param c The clock instance.
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* @return A pointer to the port with the best foreign master,
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* or NULL if none has been yet discovered.
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*/
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struct port *clock_best_port(struct clock *c);
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/**
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* Obtain the clockClass attribute from a clock.
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* @param c The clock instance.
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* @return The value of the clock's class.
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*/
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UInteger8 clock_class(struct clock *c);
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/**
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* Obtains a clock's default data set.
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* @param c The clock instance.
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* @return A pointer to the data set of the clock.
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*/
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struct dataset *clock_default_ds(struct clock *c);
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#endif
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2
makefile
2
makefile
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@ -24,7 +24,7 @@ CFLAGS = -Wall $(INC) $(DEBUG)
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LDFLAGS =
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LDLIBS = -lm -lrt
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PRG = linuxptp
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OBJ = fsm.o phc.o print.o
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OBJ = bmc.o fsm.o phc.o print.o
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SRC = $(OBJ:.o=.c)
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DEPEND = $(OBJ:.o=.d)
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@ -0,0 +1,41 @@
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/**
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* @file port.h
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* @note Copyright (C) 2011 Richard Cochran <richardcochran@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#ifndef HAVE_PORT_H
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#define HAVE_PORT_H
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/** Opaque type. */
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struct port;
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/**
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* Returns the dataset from a port's best foreign clock record, if any
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* has yet been discovered.
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*
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* @param port A port instance.
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* @return A pointer to a dataset, or NULL.
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*/
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struct dataset *port_best_foreign(struct port *port);
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/**
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* Returns a port's current state.
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* @param port A port instance.
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* @return One of the @ref port_state values.
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*/
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enum port_state port_state(struct port *port);
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#endif
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