1/* gmp_urandomb_ui -- random bits returned in a ulong.
2
3Copyright 2003, 2004 Free Software Foundation, Inc.
4
5This file is part of the GNU MP Library.
6
7The GNU MP Library is free software; you can redistribute it and/or modify
8it under the terms of the GNU Lesser General Public License as published by
9the Free Software Foundation; either version 3 of the License, or (at your
10option) any later version.
11
12The GNU MP Library is distributed in the hope that it will be useful, but
13WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
15License for more details.
16
17You should have received a copy of the GNU Lesser General Public License
18along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */
19
20#include "gmp.h"
21#include "gmp-impl.h"
22
23
24/* Currently bits>=BITS_PER_ULONG is quietly truncated to BITS_PER_ULONG,
25   maybe this should raise an exception or something.  */
26
27unsigned long
28gmp_urandomb_ui (gmp_randstate_ptr rstate, unsigned long bits)
29{
30  mp_limb_t  a[LIMBS_PER_ULONG];
31
32  /* start with zeros, since if bits==0 then _gmp_rand will store nothing at
33     all, or if bits <= GMP_NUMB_BITS then it will store only a[0] */
34  a[0] = 0;
35#if LIMBS_PER_ULONG > 1
36  a[1] = 0;
37#endif
38
39  _gmp_rand (a, rstate, MIN (bits, BITS_PER_ULONG));
40
41#if LIMBS_PER_ULONG == 1
42  return a[0];
43#else
44  return a[0] | (a[1] << GMP_NUMB_BITS);
45#endif
46}
47