| lh | 9ed821d | 2023-04-07 01:36:19 -0700 | [diff] [blame] | 1 | /* Copyright (C) 1995, 1997, 2001 Free Software Foundation, Inc. |
| 2 | This file is part of the GNU C Library. |
| 3 | Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu <mailto:drepper@gnu.ai.mit.edu>>, August 1995. |
| 4 | |
| 5 | The GNU C Library is free software; you can redistribute it and/or |
| 6 | modify it under the terms of the GNU Lesser General Public |
| 7 | License as published by the Free Software Foundation; either |
| 8 | version 2.1 of the License, or (at your option) any later version. |
| 9 | |
| 10 | The GNU C Library is distributed in the hope that it will be useful, |
| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 13 | Lesser General Public License for more details. |
| 14 | |
| 15 | You should have received a copy of the GNU Lesser General Public |
| 16 | License along with the GNU C Library; if not, write to the Free |
| 17 | Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 18 | 02111-1307 USA. */ |
| 19 | |
| 20 | #include <ieee754.h> |
| 21 | #include <stdlib.h> |
| 22 | #include <limits.h> |
| 23 | |
| 24 | int erand48_r (unsigned short int xsubi[3], struct drand48_data *buffer, double *result) |
| 25 | { |
| 26 | union ieee754_double temp; |
| 27 | |
| 28 | /* Compute next state. */ |
| 29 | if (__drand48_iterate (xsubi, buffer) < 0) |
| 30 | return -1; |
| 31 | |
| 32 | /* Construct a positive double with the 48 random bits distributed over |
| 33 | its fractional part so the resulting FP number is [0.0,1.0). */ |
| 34 | |
| 35 | temp.ieee.negative = 0; |
| 36 | temp.ieee.exponent = IEEE754_DOUBLE_BIAS; |
| 37 | temp.ieee.mantissa0 = (xsubi[2] << 4) | (xsubi[1] >> 12); |
| 38 | temp.ieee.mantissa1 = ((xsubi[1] & 0xfff) << 20) | (xsubi[0] << 4); |
| 39 | |
| 40 | /* Please note the lower 4 bits of mantissa1 are always 0. */ |
| 41 | *result = temp.d - 1.0; |
| 42 | |
| 43 | return 0; |
| 44 | } |
| 45 | libc_hidden_def(erand48_r) |