12.7 Functions That Operate on Bit Vectors

Here are some functions that relate to bit vectors:

Function: bit-vector-p object

This function returns t if object is a bit vector.

(bit-vector-p #*01)
     ⇒ t
(bit-vector-p [0 1])
     ⇒ nil
(bit-vector-p "01")
     ⇒ nil

Function: bitp object

This function returns t if object is either 0 or 1.

Function: bit-vector &rest bits

This function creates and returns a bit vector whose elements are the arguments bits. Each argument must be a bit, i.e. one of the two integers 0 or 1.

(bit-vector 0 0 0 1 0 0 0 0 1 0)
     ⇒ #*0001000010
(bit-vector)
     ⇒ #*

Function: make-bit-vector length bit

This function creates and returns a bit vector consisting of length elements, each initialized to bit, which must be one of the two integers 0 or 1.

(setq picket-fence (make-bit-vector 9 1))
     ⇒ #*111111111

Function: bvconcat &rest sequences

This function returns a new bit vector containing all the elements of the sequences. The arguments sequences may be lists, vectors, or bit vectors, all of whose elements are the integers 0 or 1. If no sequences are given, an empty bit vector is returned.

The value is a newly constructed bit vector that is not eq to any existing bit vector.

(setq a (bvconcat '(1 1 0) '(0 0 1)))
     ⇒ #*110001
(eq a (bvconcat a))
     ⇒ nil

(bvconcat)
     ⇒ #*
(bvconcat [1 0 0 0 0] #*111 '(0 0 0 0 1))
     ⇒ #*1000011100001

For other concatenation functions, see mapconcat in Mapping Functions, concat in Creating Strings, vconcat in Vector Functions, and append in Building Lists.

The append function provides a way to convert a bit vector into a list with the same elements (see Building Lists):

(setq bv #*00001110)
     ⇒ #*00001110
(append bv nil)
     ⇒ (0 0 0 0 1 1 1 0)