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/**
* @file bmc.c
* @note Copyright (C) 2011 Richard Cochran <richardcochran@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <string.h>
#include "bmc.h"
#include "ds.h"
static int portid_cmp(struct PortIdentity *a, struct PortIdentity *b)
{
int diff = memcmp(&a->clockIdentity, &b->clockIdentity, sizeof(a->clockIdentity));
if (diff == 0) {
diff = a->portNumber - b->portNumber;
}
return diff;
}
int dscmp2(struct dataset *a, struct dataset *b)
{
int diff;
unsigned int A = a->stepsRemoved, B = b->stepsRemoved;
if (A + 1 < B)
return A_BETTER;
if (B + 1 < A)
return B_BETTER;
/*
* We ignore the "error-1" conditions mentioned in the
* standard, since there is nothing we can do about it anyway.
*/
if (A < B) {
diff = portid_cmp(&b->receiver, &b->sender);
if (diff < 0)
return A_BETTER;
if (diff > 0)
return A_BETTER_TOPO;
/* error-1 */
return 0;
}
if (A > B) {
diff = portid_cmp(&a->receiver, &a->sender);
if (diff < 0)
return B_BETTER;
if (diff > 0)
return B_BETTER_TOPO;
/* error-1 */
return 0;
}
diff = portid_cmp(&a->sender, &b->sender);
if (diff < 0)
return A_BETTER_TOPO;
if (diff > 0)
return B_BETTER_TOPO;
if (a->receiver.portNumber < b->receiver.portNumber)
return A_BETTER_TOPO;
if (a->receiver.portNumber > b->receiver.portNumber)
return B_BETTER_TOPO;
/*
* If we got this far, it means "error-2" has occured.
*/
return 0;
}
int dscmp(struct dataset *a, struct dataset *b)
{
int diff;
if (a == b)
return 0;
if (a && !b)
return A_BETTER;
if (b && !a)
return B_BETTER;
diff = memcmp(&a->identity, &b->identity, sizeof(a->identity));
if (!diff)
return dscmp2(a, b);
if (a->priority1 < b->priority1)
return A_BETTER;
if (a->priority1 > b->priority1)
return B_BETTER;
if (a->quality.clockClass < b->quality.clockClass)
return A_BETTER;
if (a->quality.clockClass > b->quality.clockClass)
return B_BETTER;
if (a->quality.clockAccuracy < b->quality.clockAccuracy)
return A_BETTER;
if (a->quality.clockAccuracy > b->quality.clockAccuracy)
return B_BETTER;
if (a->quality.offsetScaledLogVariance <
b->quality.offsetScaledLogVariance)
return A_BETTER;
if (a->quality.offsetScaledLogVariance >
b->quality.offsetScaledLogVariance)
return B_BETTER;
if (a->priority2 < b->priority2)
return A_BETTER;
if (a->priority2 > b->priority2)
return B_BETTER;
return diff < 0 ? A_BETTER : B_BETTER;
}
enum port_state bmc_state_decision(struct clock *c, struct port *r,
int (*compare)(struct dataset *a, struct dataset *b))
{
struct dataset *clock_ds, *clock_best, *port_best;
enum port_state ps;
clock_ds = clock_default_ds(c);
clock_best = clock_best_foreign(c);
port_best = port_best_foreign(r);
ps = port_state(r);
/*
* This scenario is particularly important in the designated_slave_fsm
* when it is in PS_SLAVE state. In this scenario, there is no other
* foreign master and it will elect itself as master ultimately
* resulting in printing out some unnecessary warnings (see
* port_slave_priority_warning()).
*/
if (!port_best && port_bmca(r) == BMCA_NOOP) {
return ps;
}
if (!port_best && PS_LISTENING == ps)
return ps;
if (clock_class(c) <= 127) {
if (compare(clock_ds, port_best) > 0) {
return PS_GRAND_MASTER; /*M1*/
} else {
return PS_PASSIVE; /*P1*/
}
}
if (compare(clock_ds, clock_best) > 0) {
return PS_GRAND_MASTER; /*M2*/
}
if (clock_best_port(c) == r) {
return PS_SLAVE; /*S1*/
}
if (compare(clock_best, port_best) == A_BETTER_TOPO) {
return PS_PASSIVE; /*P2*/
} else {
return PS_MASTER; /*M3*/
}
}
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