integer-length
integer-length Function
Syntax:
integer-length integer → number-of-bits
Arguments and Values:
integer—an integer .
number-of-bits—a non-negative integer .
Description:
Returns the number of bits needed to represent integer in binary two’s-complement format.
Examples:
(integer-length 0) → 0
(integer-length 1) → 1
(integer-length 3) → 2
(integer-length 4) → 3
(integer-length 7) → 3
(integer-length -1) → 0
(integer-length -4) → 2
(integer-length -7) → 3
(integer-length -8) → 3
(integer-length (expt 2 9)) → 10
(integer-length (1- (expt 2 9))) → 9
(integer-length (- (expt 2 9))) → 9
(integer-length (- (1+ (expt 2 9)))) → 10
Exceptional Situations:
Should signal an error of type type-error if integer is not an integer .
Notes:
This function could have been defined by:
(defun integer-length (integer)
(ceiling (log (if (minusp integer)
(- integer)
(1+ integer))
2)))
If integer is non-negative, then its value can be represented in unsigned binary form in a field whose width in bits is no smaller than (integer-length integer). Regardless of the sign of integer, its value can be represented in signed binary two’s-complement form in a field whose width in bits is no smaller than (+ (integer-length integer) 1).
Expanded Reference: integer-length
TODO: Please contribute to this page by adding explanations and examples
(integer-length )