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/* mpfr_random -- generate a random floating-point number
Copyright (C) 1999 PolKA project, Inria Lorraine and Loria
This file is part of the MPFR Library.
The MPFR Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Library General Public License as published by
the Free Software Foundation; either version 2 of the License, or (at your
option) any later version.
The MPFR Library 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 Library General Public
License for more details.
You should have received a copy of the GNU Library General Public License
along with the MPFR Library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA. */
#include <stdio.h>
#include "gmp.h"
#include "gmp-impl.h"
#include "longlong.h"
#include "mpfr.h"
/* Computes a random mpfr in [0, 1[ with precision PREC */
extern long random _PROTO((void));
extern int srandom _PROTO((unsigned int));
/* extracted from GNU mpf */
#if defined (__hpux) || defined (__alpha)
/* HPUX lacks random(). DEC OSF/1 1.2 random() returns a double. */
#define random mrand48
#define srandom srand48
#endif
void
#if __STDC__
mpfr_random(mpfr_ptr x)
#else
mpfr_random(x)
mpfr_ptr x;
#endif
{
mp_limb_t *xp; unsigned long xn, i, cnt, prec=PREC(x);
xp = MANT(x);
xn = (prec-1)/BITS_PER_MP_LIMB + 1;
for (i = 0; i < xn; i++)
{
/* random() c/sh/ould be replaced by a homemade random number generator.
Indeed, if on Linux random is a good RNG, this is definitely not
the case in most Un*xes. */
xp[i] = random();
}
count_leading_zeros(cnt, xp[xn - 1]);
if (cnt) mpn_lshift(xp, xp, xn, cnt);
EXP(x) = -cnt;
cnt = xn*BITS_PER_MP_LIMB - prec;
/* cnt is the number of non significant bits in the low limb */
xp[0] &= ~((((mp_limb_t)1)<<cnt) - 1);
}
void
mpfr_srandom(unsigned long seed)
{
srandom(seed);
}
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