1/* mpf_urandomb (rop, state, nbits) -- Generate a uniform pseudorandom
2   real number between 0 (inclusive) and 1 (exclusive) of size NBITS,
3   using STATE as the random state previously initialized by a call to
4   gmp_randinit().
5
6Copyright 1999, 2000, 2001, 2002  Free Software Foundation, Inc.
7
8This file is part of the GNU MP Library.
9
10The GNU MP Library is free software; you can redistribute it and/or modify
11it under the terms of the GNU Lesser General Public License as published by
12the Free Software Foundation; either version 3 of the License, or (at your
13option) any later version.
14
15The GNU MP Library is distributed in the hope that it will be useful, but
16WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
17or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
18License for more details.
19
20You should have received a copy of the GNU Lesser General Public License
21along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */
22
23#include "gmp.h"
24#include "gmp-impl.h"
25
26void
27mpf_urandomb (mpf_t rop, gmp_randstate_t rstate, mp_bitcnt_t nbits)
28{
29  mp_ptr rp;
30  mp_size_t nlimbs;
31  mp_exp_t exp;
32  mp_size_t prec;
33
34  rp = PTR (rop);
35  nlimbs = BITS_TO_LIMBS (nbits);
36  prec = PREC (rop);
37
38  if (nlimbs > prec + 1 || nlimbs == 0)
39    {
40      nlimbs = prec + 1;
41      nbits = nlimbs * GMP_NUMB_BITS;
42    }
43
44  _gmp_rand (rp, rstate, nbits);
45
46  /* If nbits isn't a multiple of GMP_NUMB_BITS, shift up.  */
47  if (nbits % GMP_NUMB_BITS != 0)
48    mpn_lshift (rp, rp, nlimbs, GMP_NUMB_BITS - nbits % GMP_NUMB_BITS);
49
50  exp = 0;
51  while (nlimbs != 0 && rp[nlimbs - 1] == 0)
52    {
53      nlimbs--;
54      exp--;
55    }
56  EXP (rop) = exp;
57  SIZ (rop) = nlimbs;
58}
59