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/* Copyright (C) 1995, 1997, 2001 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu <mailto:drepper@gnu.ai.mit.edu>>, August 1995.

   The GNU C 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 GNU C 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 GNU C Library; if not, write to the Free

   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA

   02111-1307 USA.  */

#include <ieee754.h>

#include <stdlib.h>

#include <limits.h>

extern int __drand48_iterate(unsigned short xsubi[3],

        struct drand48_data *buffer);

int erand48_r (xsubi, buffer, result)

     unsigned short int xsubi[3];

     struct drand48_data *buffer;

     double *result;

{

    union ieee754_double temp;

    /* Compute next state.  */

    if (__drand48_iterate (xsubi, buffer) < 0)

        return -1;

    /* Construct a positive double with the 48 random bits distributed over

       its fractional part so the resulting FP number is [0.0,1.0).  */

    temp.ieee.negative = 0;

    temp.ieee.exponent = IEEE754_DOUBLE_BIAS;

    temp.ieee.mantissa0 = (xsubi[2] << 4) | (xsubi[1] >> 12);

    temp.ieee.mantissa1 = ((xsubi[1] & 0xfff) << 20) | (xsubi[0] << 4);

    /* Please note the lower 4 bits of mantissa1 are always 0.  */

    *result = temp.d - 1.0;

    return 0;

}