142 lines
3.7 KiB
C
142 lines
3.7 KiB
C
/*
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* $Id$
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*/
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/*
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* xHarbour Project source code:
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* Random number generator routine
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*
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* Copyright 2003 Giancarlo Niccolai <gian@niccolai.ws>
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* www - http://www.harbour-project.org
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this software; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
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* Boston, MA 02111-1307 USA (or visit the web site http://www.gnu.org/).
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*
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* As a special exception, the Harbour Project gives permission for
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* additional uses of the text contained in its release of Harbour.
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*
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* The exception is that, if you link the Harbour libraries with other
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* files to produce an executable, this does not by itself cause the
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* resulting executable to be covered by the GNU General Public License.
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* Your use of that executable is in no way restricted on account of
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* linking the Harbour library code into it.
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*
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* This exception does not however invalidate any other reasons why
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* the executable file might be covered by the GNU General Public License.
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*
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* This exception applies only to the code released by the Harbour
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* Project under the name Harbour. If you copy code from other
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* Harbour Project or Free Software Foundation releases into a copy of
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* Harbour, as the General Public License permits, the exception does
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* not apply to the code that you add in this way. To avoid misleading
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* anyone as to the status of such modified files, you must delete
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* this exception notice from them.
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*
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* If you write modifications of your own for Harbour, it is your choice
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* whether to permit this exception to apply to your modifications.
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* If you do not wish that, delete this exception notice.
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*
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*/
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#include <hbmath.h>
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#include <stdlib.h>
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#include <time.h>
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#ifndef HB_OS_WIN_32
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#include <float.h>
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#endif
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/* Globally available data, no need to MT it */
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volatile static int s_bInit = 0;
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/*
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* HB_RANDOM
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*
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* HB_RANDOM() --> returns a real value n so that 0 <= n < 1
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* HB_RANDOM( x ) --> returns a real number n so that 0 <= n < x
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* HB_RANDOM( x, y) --> Returns a real number n so that x <= n < y
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*/
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HB_FUNC( HB_RANDOM )
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{
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double dRnd;
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double dX, dY;
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dRnd = hb_random_num();
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if( ! ISNUM( 1 ) )
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{
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hb_retnd( dRnd );
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}
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else if( ! ISNUM(2) )
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{
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hb_retnd( dRnd * hb_parnd(1) );
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}
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else
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{
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dX = hb_parnd( 2 );
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dY = hb_parnd( 1 );
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if ( dX > dY )
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{
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double dZ = dY;
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dY = dX;
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dX = dZ;
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}
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hb_retnd( dRnd * (dY - dX ) + dX );
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}
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}
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HB_FUNC( HB_RANDOMSEED )
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{
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if( ! ISNUM( 1 ) )
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{
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srand( (unsigned)time( NULL ) );
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}
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else
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{
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srand( hb_parni(1) );
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}
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s_bInit = 1;
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}
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/* Returns a double value between 0 and 1 */
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double hb_random_num()
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{
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double d1, d2;
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if( s_bInit == 0 )
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{
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srand( (unsigned)time( NULL ) );
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s_bInit = 1;
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}
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d1 = (double) rand();
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d2 = (double) RAND_MAX;
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#ifdef HB_OS_WIN_32
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/* It seems that on win32 platform there some weirdness about EPSILON value so
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that a float division using an epsilon smaller than 1e-10 may be rounded.
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Must dig if it's a borland lib bug or a windows problem.
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*/
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d2 += 0.001;
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#else
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d2 += DBL_EPSILON;
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#endif
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return d1 / d2;
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}
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