ilog2(3) - NetBSD Manual Pages

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ILOG2(3)                NetBSD 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.

NetBSD 6.1.5                     May 10, 2011                     NetBSD 6.1.5