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/* Pseudo Random Sequence
* Copyright (C) 2010 Chris Hall (GMCH), Highwayman
*
* This file is part of GNU Zebra.
*
* GNU Zebra 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 2, or (at your
* option) any later version.
*
* GNU Zebra 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 GNU Zebra; see the file COPYING. If not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include "misc.h"
#include "qrand.h"
/*==============================================================================
* Simple 32 bit random sequence.
*/
/*------------------------------------------------------------------------------
* Return next in the given sequence.
*
* Returns value in range 0..range-1, or 0..0x7FFF_FFFF if range == 0
*
* If range == 1, returns 0 every time !
*/
extern int
qrand(qrand_seq seq, int range)
{
uint64_t r ;
r = seq->last ^ 3141592653 ;
r = ((r * 2650845021) + 5) & 0xFFFFFFFF ; /* see Knuth */
seq->last = r ;
if (range == 0)
return r >> 1 ;
else
return (r % range) ;
} ;
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