5.2.5 Operations on 16–bit integers

Procedure: bytevector-u16-ref bytevector k endianness

Procedure: bytevector-s16-ref bytevector k endianness

Procedure: bytevector-u16-native-ref bytevector k

Procedure: bytevector-s16-native-ref bytevector k

Procedure: bytevector-u16-set! bytevector k n endianness

Procedure: bytevector-s16-set! bytevector k n endianness

Procedure: bytevector-u16-native-set! bytevector k n

Procedure: bytevector-s16-native-set! bytevector k n

k must be a valid index of bytevector; so must k+1.

For bytevector-u16-set! and bytevector-u16-native-set!, n must be an exact integer object in the interval 0 <= n <= 2^{16}-1.

For bytevector-s16-set! and bytevector-s16-native-set!, n must be an exact integer object in the interval -2^{15} <= n <= 2^{15}-1.

These procedures retrieve and set two–byte representations of numbers at indices k and k+1 according to the endianness specified by endianness. The procedures with u16 in their names deal with the unsigned representation; those with s16 in their names deal with the two’s–complement representation.

The procedures with native in their names employ the native endianness, and work only at aligned indices: k must be a multiple of 2.

The ...-set! procedures return unspecified values.

(define b
  (u8-list->bytevector
    '(255 255 255 255 255 255 255 255
      255 255 255 255 255 255 255 253)))

(bytevector-u16-ref b 14 (endianness little))           ⇒ 65023
(bytevector-s16-ref b 14 (endianness little))           ⇒ -513
(bytevector-u16-ref b 14 (endianness big))              ⇒ 65533
(bytevector-s16-ref b 14 (endianness big))              ⇒ -3

(bytevector-u16-set! b 0 12345 (endianness little))
(bytevector-u16-ref b 0 (endianness little))            ⇒ 12345

(bytevector-u16-native-set! b 0 12345)
(bytevector-u16-native-ref b 0)                         ⇒ 12345

(bytevector-u16-ref b 0 (endianness little))            ⇒ unspecified