/*
   $Id: yarg.cc,v 1.8 2002/04/12 15:35:40 ksterker Exp $

   (C) Copyright 1998/2002 Kai Sterker <kaisterker@linuxgames.com>
   Part of the Adonthell Project http://adonthell.linuxgames.com

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License.
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY.

   See the COPYING file for more details
*/

/**
 * @file   yarg.cc
 * @author Kai Sterker <kaisterker@linuxgames.com>
 * 
 * @brief  Yet Another Random Number Genarator.
 * 
 * 
 */

#include <time.h>
#include "yarg.h"

unsigned char yarg::schieberegister[16];// Here the random numbers are created
int yarg::min;                          // Smallest possible numbe
int yarg::max;                          // Largest possible number

// Init the generator with a seed and a range 
void yarg::init (std::string str, int mn, int mx)
{
	int s = str.length ();

	for (int i = 0; i < 16; i++)
   		schieberegister[i] = str[i%s];

    range (mn, mx);
}

// change the range of the generator
void yarg::range (int mn, int mx)
{
	min = (mx < mn ? mx : mn);
	max = (mn > mx ? mn : mx);
}

// Apply the time to get a bit extra variation
void yarg::randomize ()
{
    long int clk = clock ();
  
	int	s = sizeof (clk);

	for (int i = 0; i < 16; i++)
   		schieberegister[i] = schieberegister[i]^(clk >> (8+i)%s);
}

// Retrieve the next/nth random number
int yarg::get (int steps)
{
	for (int i = 0; i < steps; i++)
	folgezustand();

	return zufallszahl();
}

// Here the dice get rolled
void yarg::folgezustand ()
{
	unsigned char tmp = schieberegister[0];

	for (int i = 0; i < 15; i++)
   	{
		if (i%3 == 0) schieberegister[i] = schieberegister[i+1]^tmp;
		else schieberegister[i] = schieberegister[i+1];
	}

    schieberegister[15] = tmp;
}

// Here we generate the actual random number
int yarg::zufallszahl ()
{
    unsigned int zahl = 0;

	for (int i = 0; i < 16; i++)
   	    zahl += schieberegister[i] << (i*8)%(sizeof(zahl)*8);

    zahl = zahl >> 1;

    return (zahl%(max - min + 1)) + min;
}