src/Random.cpp

/*
 *   This file is part of the Standard Portable Library (SPL).
 *
 *   SPL 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 of the License, or
 *   (at your option) any later version.
 *
 *   SPL 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 SPL.  If not, see <http://www.gnu.org/licenses/>.
 */
#include <spl/types.h>

#ifdef _WINDOWS
#include <spl/configwin32.h>
#else
#include <spl/autoconf/config.h>
#endif

#ifdef HAVE_TIME_H
#include <time.h>
#endif
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#include <math.h>

#include <spl/math/Random.h>

#define RAND_MAX_COMBO (4294967295.0/2)

Random::Random()
{
        combo_x = 3;
        combo_y = 1;
        combo_z = 1;
        combo_v = 0;

        uint32 seed;

        time_t _t;
        time (&_t);
        seed = ((long)_t) & (((long)_t) << 16) & ((long)_t) & (((long)_t) << 16);
    combo_x = seed * 8 + 3;
    combo_y = seed * 2 + 1;
    combo_z = seed | 1;
    combo_v = 0;
}

Random::Random(int seed)
{
    combo_x = seed * 8 + 3;
    combo_y = seed * 2 + 1;
    combo_z = seed | 1;
    combo_v = 0;
}

int Random::Next()
{
    combo_v = combo_x * combo_y;
    combo_x = combo_y;
    combo_y = combo_v;
    combo_z = (combo_z & 65535L) * 30903 + (combo_z >> 16);
        int rnd = combo_y + combo_z;
        if ( rnd < 0 )
        {
                return -1 * rnd;
        }
        return rnd;
}

int Random::Next(int max)
{
        return Next() % max;
}

int Random::Next(int min, int max)
{
        return (int)(NextDouble() * (max - min) + min);
}

double Random::NextDouble()
{
        double val = fabs((double)Next()/(double)RAND_MAX_COMBO);
        ASSERT( val <= 1.0 );
        return val;
}

void Random::NextBytes(byte *data, int len)
{
        for ( int x = 0; x < len; x++ )
        {
                int next = Next(256);
                ASSERT (next < 256);
                data[x] = (byte)next;
        }
}

int Random::NextInt()
{
    combo_v = combo_x * combo_y;
    combo_x = combo_y;
    combo_y = combo_v;
    combo_z = (combo_z & 65535L) * 30903 + (combo_z >> 16);
        return combo_y + combo_z;
}