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/* -*- c++ -*- */
/*
* Copyright 2002,2015,2018 Free Software Foundation, Inc.
*
* This file is part of GNU Radio
*
* SPDX-License-Identifier: GPL-3.0-or-later
*
*/
/*
* 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 <chrono>
#include <cmath>
namespace gr {
random::random(uint64_t seed, int64_t min_integer, int64_t max_integer)
: d_rng(seed), d_integer_dis(0, 1)
{
d_gauss_stored = false; // set gasdev (gauss distributed numbers) on calculation state
// Setup random number generators
set_integer_limits(min_integer, max_integer);
}
random::~random() {}
/*
* 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(uint64_t seed)
{
d_seed = seed;
if (d_seed == 0) {
auto now = std::chrono::system_clock::now().time_since_epoch();
auto ns = std::chrono::duration_cast<std::chrono::nanoseconds>(now).count();
d_rng.seed(ns);
} else {
d_rng.seed(d_seed);
}
}
void random::set_integer_limits(int64_t minimum, int64_t maximum)
{
// boost expects integer limits defined as [minimum, maximum] which is unintuitive.
// use the expected half open interval behavior! [minimum, maximum)!
d_integer_dis = std::uniform_int_distribution<int64_t>(minimum, maximum - 1);
}
/*!
* Uniform random integers in the range set by 'set_integer_limits' [min, max).
*/
int64_t random::ran_int() { return d_integer_dis(d_rng); }
/*
* Returns uniformly distributed numbers in [0,1) taken from boost.random using a Mersenne
* twister
*/
float random::ran1() { return d_uniform(d_rng); }
/*
* 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 */
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