chickadee » srfi-151 » integer-length

The number of bits needed to represent i, i.e.

   (ceiling (/ (log (if (negative? integer)
                             (- integer)
                             (+ 1 integer)))
                    (log 2)))

The result is always non-negative.

For non-negative i, this is the number of bits needed to represent i in an unsigned binary representation. For all i, (+ 1 (integer-length i)) is the number of bits needed to represent i in a signed twos-complement representation.

    (integer-length  0) => 0
    (integer-length  1) => 1
    (integer-length -1) => 0
    (integer-length  7) => 3
    (integer-length -7) => 3
    (integer-length  8) => 4
    (integer-length -8) => 3