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ILOG2(3) NetBSD Library Functions Manual ILOG2(3)
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by Kimmo Suominen.
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ilog2 -- integer base-2 logarithm
For positive x, the 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.
bitops(3), ffs(3), ilogb(3), log2(3), imax(9), powerof2(9)
The ilog2() macro first appeared in NetBSD 5.0.
NetBSD 10.99 November 5, 2021 NetBSD 10.99