/*
** AreaEditor - a program for editing SMAUG and ROM area files.
** Author: Nick Gammon
** http://www.gammon.com.au/
** See Copyright Notice at the end of AreaEditor.h
*/

#include "stdafx.h"

/*
 * Stick a little fuzz on a number.
 */
int number_fuzzy( int number )
{
    switch ( number_bits( 2 ) )
    {
	case 0:  number -= 1; break;
	case 3:  number += 1; break;
    }

    return UMAX( 1, number );
}



/*
 * Generate a random number.
 */
int number_range( int from, int to )
{

  if ( ( to = to - from + 1 ) <= 1 )
  	return from;

  return (number_mm() % to) + from;
}



/*
 * Generate a percentile roll.
 */
int number_percent( void )
{
  return number_mm() % 100;
}



/*
 * Generate a random door.
 */
int number_door( void )
{
  int door;

  while ( ( door = number_mm( ) & (16-1) ) > 9 )
  	;

  return door;
}



int number_bits( int width )
{
    return number_mm( ) & ( ( 1 << width ) - 1 );
}



/*
 * I've gotten too many bad reports on OS-supplied random number generators.
 * This is the Mitchell-Moore algorithm from Knuth Volume II.
 * Best to leave the constants alone unless you've read Knuth.
 * -- Furey
 */
static	int	rgiState[2+55];

void init_mm( void)
{
    int *piState;
    int iState;
    time_t		    current_time = time (0);	/* Time of this pulse		*/

    piState	= &rgiState[2];

    piState[-2]	= 55 - 55;
    piState[-1]	= 55 - 24;

    piState[0]	= ((int) current_time) & ((1 << 30) - 1);
    piState[1]	= 1;
    for ( iState = 2; iState < 55; iState++ )
    {
    	piState[iState] = (piState[iState-1] + piState[iState-2])
			& ((1 << 30) - 1);
    }
    return;
}



int number_mm( void )
{
    int *piState;
    int iState1;
    int iState2;
    int iRand;

    piState		= &rgiState[2];
    iState1	 	= piState[-2];
    iState2	 	= piState[-1];
    iRand	 	= (piState[iState1] + piState[iState2])
			& ((1 << 30) - 1);
    piState[iState1]	= iRand;
    if ( ++iState1 == 55 )
	iState1 = 0;
    if ( ++iState2 == 55 )
	iState2 = 0;
    piState[-2]		= iState1;
    piState[-1]		= iState2;
    return iRand >> 6;
}



/*
 * Roll some dice.						-Thoric
 */
int dice( int number, int size )
{
    int idice;
    int sum;

    switch ( size )
    {
      case 0: return 0;
      case 1: return number;
    }

  for ( idice = 0, sum = 0; idice < number; idice++ )
	  sum += number_range( 1, size );

  return sum;
}



/*
 * Simple linear interpolation.
 */
int interpolate( int level, int value_00, int value_32 )
{
  return value_00 + level * (value_32 - value_00) / 32;
}