/* $NetBSD: ranny.c,v 1.1.1.1 2000/03/29 12:38:50 simonb Exp $ */ /* * Random number generator is: * * Copyright 1988 by Rayan S. Zachariassen, all rights reserved. * This will be free software, but only when it is finished. * * Used in ntp by permission of the author. If copyright is * annoying to you, read no further. Instead, look up the reference, * write me an equivalent to this and send it back to me. */ /* * Random number generator; see Knuth Vol 2. 2nd ed. p.27 (section 3.2.2) */ #include "ntp_stdlib.h" extern time_t time P((time_t *loc)); /* * 55 random numbers, not all even. Note we don't initialize ran_y * directly since I have had thoughts of putting this in an EPROM */ static time_t ran_y[55]; static time_t init_ran_y[55] = { 1860909544, 231033423, 437666411, 1349655137, 2014584962, 504613712, 656256107, 1246027206, 573713775, 643466871, 540235388, 1630565153, 443649364, 729302839, 1933991552, 944681982, 949111118, 406212522, 1065063137, 1712954727, 73280612, 787623973, 1874130997, 801658492, 73395958, 739165367, 596047144, 490055249, 1131094323, 662727104, 483614097, 844520219, 893760527, 921280508, 46691708, 760861842, 1425894220, 702947816, 2006889048, 1999607995, 1346414687, 399640789, 1482689501, 1790064052, 1128943628, 1269197405, 587262386, 2078054746, 1675409928, 1652325524, 1643525825, 1748690540, 292465849, 1370173174, 402865384 }; static int ran_j; static int ran_k; /* * ranp2 - return a random integer in the range 0 .. (1 << m) - 1 */ u_long ranp2( int m ) { time_t r; ran_y[ran_k] += ran_y[ran_j]; /* overflow does a mod */ r = ran_y[ran_k]; if (ran_k-- == 0) ran_k = 54; if (ran_j-- == 0) ran_j = 54; return (u_long)(r & ((1 << m ) - 1)); } /* * init_random - do initialization of random number routine */ void init_random(void) { register int i; register time_t now; ran_j = 23; ran_k = 54; /* * Randomize the seed array some more. The time of day * should be initialized by now. */ now = time((time_t *)0) | 01; for (i = 0; i < 55; ++i) ran_y[i] = now * init_ran_y[i]; /* overflow does a mod */ }