1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
|
/* mpfr_urandomb (rop, state, nbits) -- Generate a uniform pseudorandom
real number between 0 (inclusive) and 1 (exclusive) of size NBITS,
using STATE as the random state previously initialized by a call to
gmp_randinit().
Copyright (C) 2000, 2001 Free Software Foundation, Inc.
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 Lesser General Public License as published by
the Free Software Foundation; either version 2.1 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 Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser 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"
#include "mpfr-impl.h"
void
mpfr_urandomb (mpfr_ptr rop, gmp_randstate_t rstate)
{
mp_ptr rp;
mp_size_t nlimbs;
mp_exp_t exp;
unsigned long cnt, nbits;
MPFR_CLEAR_FLAGS(rop);
rp = MPFR_MANT(rop);
nbits = MPFR_PREC(rop);
nlimbs = (nbits + BITS_PER_MP_LIMB - 1) / BITS_PER_MP_LIMB;
_gmp_rand (rp, rstate, nbits);
/* If nbits isn't a multiple of BITS_PER_MP_LIMB, shift up. */
if (nlimbs != 0)
{
if (nbits % BITS_PER_MP_LIMB != 0)
mpn_lshift (rp, rp, nlimbs,
BITS_PER_MP_LIMB - nbits % BITS_PER_MP_LIMB);
}
exp = 0;
while (nlimbs != 0 && rp[nlimbs - 1] == 0)
{
nlimbs--;
exp--;
}
count_leading_zeros (cnt, rp[nlimbs - 1]);
if (cnt) mpn_lshift (rp, rp, nlimbs, cnt);
exp -= cnt;
cnt = nlimbs*BITS_PER_MP_LIMB - nbits;
/* cnt is the number of non significant bits in the low limb */
rp[0] &= ~((MP_LIMB_T_ONE << cnt) - 1);
MPFR_EXP (rop) = exp;
}
|
