netbsd man page for ilog2

ILOG2(3)						   BSD Library Functions Manual 						  ILOG2(3)

NAME
     ilog2 -- integer logarithm

SYNOPSIS
     #include <sys/bitops.h>

     size
     ilog2(size x);

DESCRIPTION
     The ilog2() macro returns an integer (binary) logarithm of x.  It is the logarithm for base 2; the binary logarithm of x is the power to
     which the number 2 must be raised to obtain the value x.

     The type of the input parameter should be either uint32_t or uint64_t.

ERRORS
     A value -1 is returned on error.

SEE ALSO
     bitops(3), ilogb(3), log2(3), imax(9), powerof2(9)

HISTORY
     The ilog2() macro first appeared in NetBSD 5.0.

BSD
								   May 10, 2011 							       BSD