diff options
Diffstat (limited to 'libc/stdlib/erand48_r.c')
-rw-r--r-- | libc/stdlib/erand48_r.c | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/libc/stdlib/erand48_r.c b/libc/stdlib/erand48_r.c new file mode 100644 index 000000000..fb48304fa --- /dev/null +++ b/libc/stdlib/erand48_r.c @@ -0,0 +1,48 @@ +/* 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> + + +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; +} |