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.