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