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Annotation of OpenXM_contrib/gmp/mpfr/random2.c, Revision 1.1

1.1     ! ohara       1: /* mpf_random2 -- Generate a positive random mpf_t of specified size, with
        !             2:    long runs of consecutive ones and zeros in the binary representation.
        !             3:    Intended for testing of other MP routines.
        !             4:
        !             5: Copyright 1999, 2001 Free Software Foundation, Inc.
        !             6: (Copied from the GNU MP Library.)
        !             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_random2 (mpfr_ptr x, mp_size_t size, mp_exp_t exp)
        !            34: {
        !            35:   mp_size_t xn;
        !            36:   unsigned long cnt;
        !            37:   mp_ptr xp = MPFR_MANT(x), yp[1];
        !            38:   mp_size_t prec = (MPFR_PREC(x) - 1)/BITS_PER_MP_LIMB;
        !            39:
        !            40:   MPFR_CLEAR_FLAGS(x);
        !            41:   xn = ABS (size);
        !            42:   if (xn != 0)
        !            43:     {
        !            44:       if (xn > prec + 1)
        !            45:        xn = prec + 1;
        !            46:
        !            47:       mpn_random2 (xp, xn);
        !            48:     }
        !            49:
        !            50:   if (exp != 0) {
        !            51:     /* use mpn_random instead of random since that function is not
        !            52:        available on all platforms (for example HPUX, DEC OSF, ...) */
        !            53:     mpn_random ((mp_limb_t*) yp, 1);
        !            54:     exp = (mp_exp_t) yp[0] % (2 * exp) - exp;
        !            55:   }
        !            56:
        !            57:   count_leading_zeros(cnt, xp[xn - 1]);
        !            58:   if (cnt) mpn_lshift(xp, xp, xn, cnt);
        !            59:   MPFR_EXP(x) = exp-cnt;
        !            60:   cnt = xn*BITS_PER_MP_LIMB - prec;
        !            61:   /* cnt is the number of non significant bits in the low limb */
        !            62:   xp[0] &= ~((MP_LIMB_T_ONE << cnt) - MP_LIMB_T_ONE);
        !            63: }