reservationtable.cpp

/*
 * StarSim - the NoC Simulator
 *
 * (C) 2005-2010 by the University of Catania
 * For the complete list of authors refer to file ../doc/AUTHORS.txt
 * For the license applied to these sources refer to file ../doc/LICENSE.txt
 *
 * This file contains the implementation of the switch reservation table
 */

#include "reservationtable.h"

reservationtable::reservationtable()
{
    clear();
}

void reservationtable::clear()
{
    rtable.resize(DIRECTIONS + 1);

    // note that NOT_VALID entries should remain untouched
    for (int i = 0; i < DIRECTIONS + 1; i++)
	if (rtable[i] != NOT_VALID)
	    rtable[i] = NOT_RESERVED;
}

bool reservationtable::isAvailable(const int port_out) const
{
    assert(port_out >= 0 && port_out < DIRECTIONS + 1);

    return ((rtable[port_out] == NOT_RESERVED));
}

void reservationtable::reserve(const int port_in, const int port_out)
{
    // reservation of reserved/not valid ports is illegal. Correctness
    // should be assured by StarSimReservationTable users
    assert(isAvailable(port_out));

    // check for previous reservation to be released
    int port = getOutputPort(port_in);

    if (port != NOT_RESERVED)
	release(port);

    rtable[port_out] = port_in;
}

void reservationtable::release(const int port_out)
{
    assert(port_out >= 0 && port_out < DIRECTIONS + 1);
    // there is a valid reservation on port_out
    assert(rtable[port_out] >= 0 && rtable[port_out] < DIRECTIONS + 1);

    rtable[port_out] = NOT_RESERVED;
}

int reservationtable::getOutputPort(const int port_in) const
{
    assert(port_in >= 0 && port_in < DIRECTIONS + 1);

    for (int i = 0; i < DIRECTIONS + 1; i++)
	if (rtable[i] == port_in)
	    return i;		// port_in reserved outport i

    // semantic: port_in currently doesn't reserve any out port
    return NOT_RESERVED;
}

// makes port_out no longer available for reservation/release
void reservationtable::invalidate(const int port_out)
{
    rtable[port_out] = NOT_VALID;
}