| ILOG2(3) | Library Functions Manual | ILOG2(3) |
ilog2 —
#include <sys/bitops.h>
int
ilog2(size
x);
ilog2() macro
returns the integer part of the base-2 logarithm of x;
that is,
floor(log_2(x));.
If n =
ilog2(x), then
n is the largest integer such that
2**n
<= x; in other words,
ilog2() returns the largest integer to which 2 can be
raised to obtain a value at most x.
The type of the input parameter must be unsigned.
If x is a constant expression, then so is
ilog2(x).
ilog2() returns -1 when x is zero.
ilog2() macro first appeared in
NetBSD 5.0.
| November 5, 2021 | NetBSD 10.0 |