mclink.cpp

Go to the documentation of this file.

//
// Copyright (c) 2021 Regents of the SIGNET lab, University of Padova.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
// 3. Neither the name of the University of Padova (SIGNET lab) nor the
//    names of its contributors may be used to endorse or promote products
//    derived from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
// OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
// WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
// OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
// ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
 
#include <string.h>
#include <rng.h>
#include <tclcl.h>
#include <iostream>
#include "mclink.h"
 
MCLink::MCLink() 
    : ber_good(0.0)
    , ber_bad(0.0)
    , p_gb(0.0)
    , p_bg(0.0)
    , last_update(NOW)
    , step_period(5.0)
    , ch_state(GOOD)
{   
}
 
 
MCLink::MCLink(double ber_good, double ber_bad,double p_gb, double p_bg, 
        double step_period,ChState ch_state)
    : ber_good(ber_good)
    , ber_bad(ber_bad)
    , p_gb(p_gb)
    , p_bg(p_bg)
    , last_update(NOW)
    , step_period(step_period)
    , ch_state(ch_state)
{
    assert(ber_good >=0.0 && ber_good <= 1.0 && 
            ber_bad >= 0.0 && ber_bad <= 1.0 &&
            p_gb >= 0.0 && p_gb <= 1.0 && p_bg >= 0.0 && p_bg <= 1.0);
}
 
MCLink::ChState
MCLink::updateChState()
{
    int n_step = floor((NOW - last_update) / step_period);
    if (n_step == 0) {
        return ch_state;
    }
 
    double c1 = 1.0 / (p_gb + p_bg);
    double c2 = pow(1.0 - p_gb - p_bg, n_step) / (p_gb + p_bg);
 
    if (ch_state == MCLink::GOOD) {
        double new_p_gg = c1 * p_bg + c2 * p_gb;
        if (RNG::defaultrng()->uniform_double() > new_p_gg) {
            ch_state = MCLink::BAD;
        }
    } else if (ch_state == MCLink::BAD) {
        double new_p_bb = c1 * p_gb + c2 * p_bg;
        if (RNG::defaultrng()->uniform_double() > new_p_bb) {
            ch_state = MCLink::GOOD;    
        }
    }
    last_update += n_step * step_period;
    return ch_state;
}
 
double 
MCLink::getBER()
{
    updateChState();
    if (ch_state == GOOD) {
        return ber_good;
    } else { 
        return ber_bad;
    }
}
 
int
MCLink::command(int argc, const char *const *argv)
{
    Tcl &tcl = Tcl::instance();
 
    if (argc == 2) {
        if (strcasecmp(argv[1], "getChState") == 0) {
            tcl.resultf("%d", getChState());
            return TCL_OK;
        } else if (strcasecmp(argv[1], "getBER") == 0) {
            tcl.resultf("%f", getBER());
            return TCL_OK;
        }
    }
 
    std::cerr << "TCL: unknown MCLink command" << std::endl;
    return TCL_ERROR;
}
 
static class MCLinkClass : public TclClass
{
public:
    MCLinkClass()
    : TclClass("Module/UW/HMMPHYSICAL/MCLINK")
    {
    }
    TclObject *
    create(int argc, const char *const * argv)
    {
        if (argc > 8) {
            if (argc == 9) {
                return (new MCLink(std::stod(argv[4]), std::stod(argv[5]), 
                        std::stod(argv[6]), std::stod(argv[7]),std::stod(argv[8])));
            }
            if (argc == 10) {
                MCLink::ChState ch_state;
                if (strcasecmp(argv[9], "GOOD") == 0) {
                    ch_state = MCLink::GOOD;
                } else if (strcasecmp(argv[9], "BAD") == 0) {
                    ch_state = MCLink::BAD;
                } else {
                    std::cerr << "TCL: MCLink state must be GOOD or BAD"
                    << std::endl;
                    exit(1);
                }
                return (new MCLink(std::stod(argv[4]), std::stod(argv[5]), 
                        std::stod(argv[6]), std::stod(argv[7]),std::stod(argv[8]),ch_state));
            }
            std::cerr << "TCL: check MCLink constructor args" << std::endl;
            exit(1);
        }
 
        return (new MCLink);
    }
} class_module_mclink;