/* 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 2000, 2001, 2002, 2003, 2004 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. */ #define MPFR_NEED_LONGLONG_H #include "mpfr-impl.h" int mpfr_urandomb (mpfr_ptr rop, gmp_randstate_t rstate) { mp_ptr rp; mp_prec_t nbits; mp_size_t nlimbs; mp_size_t k; /* number of high zero limbs */ mp_exp_t exp; int cnt; MPFR_CLEAR_FLAGS(rop); rp = MPFR_MANT(rop); nbits = MPFR_PREC(rop); nlimbs = MPFR_LIMB_SIZE(rop); /*(nbits + BITS_PER_MP_LIMB - 1) / BITS_PER_MP_LIMB;*/ _gmp_rand (rp, rstate, nlimbs * BITS_PER_MP_LIMB); /* If nbits isn't a multiple of BITS_PER_MP_LIMB, mask the low bits */ cnt = nlimbs * BITS_PER_MP_LIMB - nbits; if (cnt != 0) rp[0] &= ~((MP_LIMB_T_ONE << cnt) - MP_LIMB_T_ONE); exp = 0; k = 0; while (nlimbs != 0 && rp[nlimbs - 1] == 0) { k ++; nlimbs --; exp -= BITS_PER_MP_LIMB; } if (nlimbs != 0) /* otherwise value is zero */ { count_leading_zeros (cnt, rp[nlimbs - 1]); if (mpfr_set_exp (rop, exp - cnt)) { MPFR_SET_NAN (rop); __gmpfr_flags |= MPFR_FLAGS_NAN; return 1; } if (cnt != 0) mpn_lshift (rp + k, rp, nlimbs, cnt); if (k) MPN_ZERO (rp, k); } else MPFR_SET_ZERO(rop); MPFR_SET_POS (rop); return 0; }