Return to urandomb.c CVS log

Up to [local] / OpenXM_contrib / gmp / mpfr

Annotation of OpenXM_contrib/gmp/mpfr/urandomb.c, Revision 1.1.1.1

1.1       ohara       1: /* mpfr_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:
                      6: Copyright 2000, 2001 Free Software Foundation, Inc.
                      7:
                      8: This file is part of the MPFR Library.
                      9:
                     10: The MPFR Library is free software; you can redistribute it and/or modify
                     11: it under the terms of the GNU Lesser General Public License as published by
                     12: the Free Software Foundation; either version 2.1 of the License, or (at your
                     13: option) any later version.
                     14:
                     15: The MPFR Library is distributed in the hope that it will be useful, but
                     16: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
                     17: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
                     18: License for more details.
                     19:
                     20: You should have received a copy of the GNU Lesser General Public License
                     21: along with the MPFR Library; see the file COPYING.LIB.  If not, write to
                     22: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
                     23: MA 02111-1307, USA. */
                     24:
                     25: #include <stdio.h>
                     26: #include "gmp.h"
                     27: #include "gmp-impl.h"
                     28: #include "longlong.h"
                     29: #include "mpfr.h"
                     30: #include "mpfr-impl.h"
                     31:
                     32: void
                     33: mpfr_urandomb (mpfr_ptr rop, gmp_randstate_t rstate)
                     34: {
                     35:   mp_ptr rp;
                     36:   mp_size_t nlimbs;
                     37:   mp_exp_t exp;
                     38:   unsigned long cnt, nbits;
                     39:
                     40:   MPFR_CLEAR_FLAGS(rop);
                     41:
                     42:   rp = MPFR_MANT(rop);
                     43:   nbits = MPFR_PREC(rop);
                     44:   nlimbs = (nbits + BITS_PER_MP_LIMB - 1) / BITS_PER_MP_LIMB;
                     45:
                     46:   _gmp_rand (rp, rstate, nbits);
                     47:
                     48:   /* If nbits isn't a multiple of BITS_PER_MP_LIMB, shift up.  */
                     49:   if (nlimbs != 0)
                     50:     {
                     51:       if (nbits % BITS_PER_MP_LIMB != 0)
                     52:        mpn_lshift (rp, rp, nlimbs,
                     53:                    BITS_PER_MP_LIMB - nbits % BITS_PER_MP_LIMB);
                     54:     }
                     55:
                     56:   exp = 0;
                     57:   while (nlimbs != 0 && rp[nlimbs - 1] == 0)
                     58:     {
                     59:       nlimbs--;
                     60:       exp--;
                     61:     }
                     62:
                     63:   count_leading_zeros (cnt, rp[nlimbs - 1]);
                     64:   if (cnt) mpn_lshift (rp, rp, nlimbs, cnt);
                     65:   exp -= cnt;
                     66:
                     67:   cnt = nlimbs*BITS_PER_MP_LIMB - nbits;
                     68:   /* cnt is the number of non significant bits in the low limb */
                     69:   rp[0] &= ~((MP_LIMB_T_ONE << cnt) - 1);
                     70:
                     71:   MPFR_EXP (rop) = exp;
                     72: }