/* Copyright (C) 1995, 1997 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Ulrich Drepper <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 Library General Public License as published by the Free Software Foundation; either version 2 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 Library General Public License for more details. You should have received a copy of the GNU Library General Public License along with the GNU C 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. */ #include <ieee754.h> #include <stdlib.h> #include <limits.h> 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). */ #if USHRT_MAX == 65535 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); #elif USHRT_MAX == 2147483647 temp.ieee.negative = 0; temp.ieee.exponent = IEEE754_DOUBLE_BIAS; temp.ieee.mantissa0 = (xsubi[1] << 4) | (xsubi[0] >> 28); temp.ieee.mantissa1 = ((xsubi[0] & 0xfffffff) << 4); #else # error Unsupported size of short int #endif /* Please note the lower 4 bits of mantissa1 are always 0. */ *result = temp.d - 1.0; return 0; } weak_alias (__erand48_r, erand48_r)