5 POSIX specification:@* @url{http://www.opengroup.org/onlinepubs/9699919799/functions/log2.html}
9 Portability problems fixed by Gnulib:
13 Portability problems not fixed by Gnulib:
16 This function is missing on some platforms:
17 MacOS X 10.5, FreeBSD 6.0, NetBSD 3.0, OpenBSD 3.8, AIX 5.1, IRIX 6.5,
18 Solaris 9, Interix 3.5.
20 This function is only provided as a macro on some platforms: