/* -*- c++ -*- */
/*
 * Copyright 2002,2015,2018 Free Software Foundation, Inc.
 *
 * This file is part of GNU Radio
 *
 * GNU Radio 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 3, or (at your option)
 * any later version.
 *
 * GNU Radio 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 GNU Radio; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street,
 * Boston, MA 02110-1301, USA.
 */

/*
 *  Copyright 1997 Massachusetts Institute of Technology
 *
 *  Permission to use, copy, modify, distribute, and sell this software and its
 *  documentation for any purpose is hereby granted without fee, provided that
 *  the above copyright notice appear in all copies and that both that
 *  copyright notice and this permission notice appear in supporting
 *  documentation, and that the name of M.I.T. not be used in advertising or
 *  publicity pertaining to distribution of the software without specific,
 *  written prior permission.  M.I.T. makes no representations about the
 *  suitability of this software for any purpose.  It is provided "as is"
 *  without express or implied warranty.
 *
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <gnuradio/math.h>
#include <gnuradio/random.h>

#include <cmath>

namespace gr {

random::random(unsigned int seed, int min_integer, int max_integer)
{
    d_gauss_stored = false; // set gasdev (gauss distributed numbers) on calculation state

    // Setup random number generators
    d_rng = new boost::mt19937;                     // random numbers are generated here.
    d_uniform = new boost::uniform_real<float>;     // map random number to distribution
    d_integer_dis = new boost::uniform_int<>(0, 1); // another "mapper"
    d_generator = NULL; // MUST be reinstantiated on every call to reseed.
    d_integer_generator =
        NULL; // MUST be reinstantiated on everytime d_rng or d_integer_dis is changed.
    reseed(seed); // set seed for random number generator
    set_integer_limits(min_integer, max_integer);
}

random::~random()
{
    delete d_rng;
    delete d_uniform;
    delete d_integer_dis;
    delete d_generator;
    delete d_integer_generator;
}

/*
 * Seed is initialized with time if the given seed is 0. Otherwise the seed is taken
 * directly. Sets the seed for the random number generator.
 */
void random::reseed(unsigned int seed)
{
    d_seed = seed;
    if (d_seed == 0) {
        d_rng->seed();
    } else {
        d_rng->seed(d_seed);
    }
    // reinstantiate generators. Otherwise reseed doesn't take effect.
    delete d_generator;
    d_generator =
        new boost::variate_generator<boost::mt19937&, boost::uniform_real<float>>(
            *d_rng, *d_uniform); // create number generator in [0,1) from boost.random
    delete d_integer_generator;
    d_integer_generator =
        new boost::variate_generator<boost::mt19937&, boost::uniform_int<>>(
            *d_rng, *d_integer_dis);
}

void random::set_integer_limits(const int minimum, const int maximum)
{
    // boost expects integer limits defined as [minimum, maximum] which is unintuitive.
    // use the expected half open interval behavior! [minimum, maximum)!
    delete d_integer_generator;
    delete d_integer_dis;
    d_integer_dis = new boost::uniform_int<>(minimum, maximum - 1);
    d_integer_generator =
        new boost::variate_generator<boost::mt19937&, boost::uniform_int<>>(
            *d_rng, *d_integer_dis);
}

/*!
 * Uniform random integers in the range set by 'set_integer_limits' [min, max).
 */
int random::ran_int() { return (*d_integer_generator)(); }

/*
 * Returns uniformly distributed numbers in [0,1) taken from boost.random using a Mersenne
 * twister
 */
float random::ran1() { return (*d_generator)(); }

/*
 * Returns a normally distributed deviate with zero mean and variance 1.
 * Used is the Marsaglia polar method.
 * Every second call a number is stored because the transformation works only in pairs.
 * Otherwise half calculation is thrown away.
 */
float random::gasdev()
{
    if (d_gauss_stored) { // just return the stored value if available
        d_gauss_stored = false;
        return d_gauss_value;
    } else { // generate a pair of gaussian distributed numbers
        float x, y, s;
        do {
            x = 2.0 * ran1() - 1.0;
            y = 2.0 * ran1() - 1.0;
            s = x * x + y * y;
        } while (s >= 1.0f || s == 0.0f);
        d_gauss_stored = true;
        d_gauss_value = x * sqrtf(-2.0 * logf(s) / s);
        return y * sqrtf(-2.0 * logf(s) / s);
    }
}

float random::laplacian()
{
    float z = ran1();
    if (z > 0.5f) {
        return -logf(2.0f * (1.0f - z));
    }
    return logf(2 * z);
}
/*
 * Copied from The KC7WW / OH2BNS Channel Simulator
 * FIXME Need to check how good this is at some point
 */
// 5 => scratchy, 8 => Geiger
float random::impulse(float factor = 5)
{
    float z = -GR_M_SQRT2 * logf(ran1());
    if (fabsf(z) <= factor)
        return 0.0;
    else
        return z;
}

gr_complex random::rayleigh_complex() { return gr_complex(gasdev(), gasdev()); }

float random::rayleigh() { return sqrtf(-2.0 * logf(ran1())); }

} /* namespace gr */
