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

1.1       maekawa     1: /* mpfr_random -- generate a random floating-point number
                      2:
                      3: Copyright (C) 1999 PolKA project, Inria Lorraine and Loria
                      4:
                      5: This file is part of the MPFR Library.
                      6:
                      7: The MPFR Library is free software; you can redistribute it and/or modify
                      8: it under the terms of the GNU Library General Public License as published by
                      9: the Free Software Foundation; either version 2 of the License, or (at your
                     10: option) any later version.
                     11:
                     12: The MPFR Library is distributed in the hope that it will be useful, but
                     13: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
                     14: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
                     15: License for more details.
                     16:
                     17: You should have received a copy of the GNU Library General Public License
                     18: along with the MPFR Library; see the file COPYING.LIB.  If not, write to
                     19: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
                     20: MA 02111-1307, USA. */
                     21:
                     22: #include <stdio.h>
                     23: #include "gmp.h"
                     24: #include "gmp-impl.h"
                     25: #include "longlong.h"
                     26: #include "mpfr.h"
                     27:
                     28: /* Computes a random mpfr in [0, 1[ with precision PREC */
                     29:
                     30: extern long random _PROTO((void));
                     31: extern int srandom _PROTO((unsigned int));
                     32:
                     33: /* extracted from GNU mpf */
                     34: #if defined (__hpux) || defined (__alpha)
                     35: /* HPUX lacks random().  DEC OSF/1 1.2 random() returns a double.  */
                     36: #define random mrand48
                     37: #define srandom srand48
                     38: #endif
                     39:
                     40: void
                     41: #if __STDC__
                     42: mpfr_random(mpfr_ptr x)
                     43: #else
                     44: mpfr_random(x)
                     45:      mpfr_ptr x;
                     46: #endif
                     47: {
                     48:   mp_limb_t *xp; unsigned long xn, i, cnt, prec=PREC(x);
                     49:
                     50:   xp = MANT(x);
                     51:   xn = (prec-1)/BITS_PER_MP_LIMB + 1;
                     52:
                     53:   for (i = 0; i < xn; i++)
                     54:     {
                     55:       /* random() c/sh/ould be replaced by a homemade random number generator.
                     56:         Indeed, if on Linux random is a good RNG, this is definitely not
                     57:         the case in most Un*xes. */
                     58:       xp[i] = random();
                     59:     }
                     60:
                     61:   count_leading_zeros(cnt, xp[xn - 1]);
                     62:   if (cnt) mpn_lshift(xp, xp, xn, cnt);
                     63:   EXP(x) = -cnt;
                     64:
                     65:   cnt = xn*BITS_PER_MP_LIMB - prec;
                     66:   /* cnt is the number of non significant bits in the low limb */
                     67:   xp[0] &= ~((((mp_limb_t)1)<<cnt) - 1);
                     68: }
                     69:
                     70: void
                     71: mpfr_srandom(unsigned long seed)
                     72: {
                     73:   srandom(seed);
                     74: }