5.2.3 Operations on bytes and octets

Procedure: bytevector-u8-ref bytevector k

Procedure: bytevector-s8-ref bytevector k

k must be a valid index of bytevector.

The bytevector-u8-ref procedure returns the byte at index k of bytevector, as an octet.

The bytevector-s8-ref procedure returns the byte at index k of bytevector, as a (signed) byte.

(let ((b1 (make-bytevector 16 -127))
      (b2 (make-bytevector 16 255)))
  (list
    (bytevector-s8-ref b1 0)
    (bytevector-u8-ref b1 0)
    (bytevector-s8-ref b2 0)
    (bytevector-u8-ref b2 0)))
⇒ (-127 129 -1 255)

Procedure: bytevector-u8-set! bytevector k octet

Procedure: bytevector-s8-set! bytevector k byte

k must be a valid index of bytevector.

The bytevector-u8-set! procedure stores octet in element k of bytevector.

The bytevector-s8-set! procedure stores the two’s–complement representation of byte in element k of bytevector.

Both procedures return unspecified values.

(let ((b (make-bytevector 16 -127)))

  (bytevector-s8-set! b 0 -126)
  (bytevector-u8-set! b 1 246)

  (list
    (bytevector-s8-ref b 0)
    (bytevector-u8-ref b 0)
    (bytevector-s8-ref b 1)
    (bytevector-u8-ref b 1)))
⇒ (-126 130 -10 246)

Procedure: bytevector->u8-list bytevector

Procedure: u8-list->bytevector list

list must be a list of octets.

The bytevector->u8-list procedure returns a newly allocated list of the octets of bytevector in the same order.

The u8-list->bytevector procedure returns a newly allocated bytevector whose elements are the elements of list list, in the same order. It is analogous to list->vector.