1 /* $NetBSD: erand48_ieee754.c,v 1.2 2006/03/31 11:42:31 drochner Exp $ */ 2 3 /* 4 * Copyright (c) 1993 Martin Birgmeier 5 * All rights reserved. 6 * 7 * You may redistribute unmodified or modified versions of this source 8 * code provided that the above copyright notice and this and the 9 * following conditions are retained. 10 * 11 * This software is provided ``as is'', and comes with no warranties 12 * of any kind. I shall in no event be liable for anything that happens 13 * to anyone/anything when using this software. 14 */ 15 16 #include <sys/cdefs.h> 17 #if defined(LIBC_SCCS) && !defined(lint) 18 __RCSID("$NetBSD: erand48_ieee754.c,v 1.2 2006/03/31 11:42:31 drochner Exp $"); 19 #endif /* LIBC_SCCS and not lint */ 20 21 #include "namespace.h" 22 23 #include <assert.h> 24 #include <machine/ieee.h> 25 26 #include "rand48.h" 27 28 #ifdef __weak_alias 29 __weak_alias(erand48,_erand48) 30 #endif 31 32 double 33 erand48(unsigned short xseed[3]) 34 { 35 union ieee_double_u u; 36 37 _DIAGASSERT(xseed != NULL); 38 39 __dorand48(xseed); 40 u.dblu_dbl.dbl_sign = 0; 41 u.dblu_dbl.dbl_exp = DBL_EXP_BIAS; /* so we get [1,2) */ 42 u.dblu_dbl.dbl_frach = ((unsigned int)xseed[2] << 4) 43 | ((unsigned int)xseed[1] >> 12); 44 u.dblu_dbl.dbl_fracl = (((unsigned int)xseed[1] & 0x0fff) << 20) 45 | ((unsigned int)xseed[0] << 4); 46 return (u.dblu_d - 1); 47 } 48