1 /* $OpenBSD: drand48.c,v 1.7 2015年09月14日 13:30:17 guenther Exp $ */ 2 /* 3 * Copyright (c) 1993 Martin Birgmeier 4 * All rights reserved. 5 * 6 * You may redistribute unmodified or modified versions of this source 7 * code provided that the above copyright notice and this and the 8 * following conditions are retained. 9 * 10 * This software is provided ``as is'', and comes with no warranties 11 * of any kind. I shall in no event be liable for anything that happens 12 * to anyone/anything when using this software. 13 */ 14 15#include <math.h> 16#include "rand48.h" 17 18 double 19 drand48(void) 20{ 21 if (__rand48_deterministic == 0) { 22 unsigned short rseed[3]; 23 24 arc4random_buf(rseed, sizeof rseed); 25 return ldexp((double) rseed[0], -48) + 26 ldexp((double) rseed[1], -32) + 27 ldexp((double) rseed[2], -16); 28 } 29 return erand48(__rand48_seed); 30} 31