Index: lib/libc/gen/arc4random.c =================================================================== --- lib/libc/gen/arc4random.c (revision 243718) +++ lib/libc/gen/arc4random.c (working copy) @@ -1,4 +1,4 @@ -/* $OpenBSD: arc4random.c,v 1.22 2010/12/22 08:23:42 otto Exp $ */ +/* $OpenBSD: arc4random.c,v 1.23 2012/06/24 18:25:12 matthew Exp $ */ /* * Copyright (c) 1996, David Mazieres @@ -276,17 +278,8 @@ arc4random_uniform(u_int32_t upper_bound) if (upper_bound < 2) return 0; -#if (ULONG_MAX > 0xffffffffUL) - min = 0x100000000UL % upper_bound; -#else - /* Calculate (2**32 % upper_bound) avoiding 64-bit math */ - if (upper_bound > 0x80000000) - min = 1 + ~upper_bound; /* 2**32 - upper_bound */ - else { - /* (2**32 - (x * 2)) % x == 2**32 % x when x <= 2**31 */ - min = ((0xffffffff - (upper_bound * 2)) + 1) % upper_bound; - } -#endif + /* 2**32 % x == (2**32 - x) % x */ + min = -upper_bound % upper_bound; /* * This could theoretically loop forever but each retry has