Function

Summary

Accesses a typed aref vector efficiently.

Package

system

Signature

typed-aref type vector byte-index => value

(setf typed-aref) value type vector byte-index => value

Arguments

type

A type specifier.

vector

A vector created by make-typed-aref-vector.

byte-index

A non-negative fixnum.

Values

value

An object of type type.

Description

The function typed-aref allows efficient access to a typed aref vector.

The following values of type are accepted:

• double-float
• float
• single-float
• sys:int32
• (unsigned-byte 32)
• (signed-byte 32)
• (unsigned-byte 16)
• (signed-byte 16)
• (unsigned-byte 8)
• (signed-byte 8)

Additionally in 64-bit LispWorks only, the following values of type are also accepted:

• sys:int64
• (unsigned-byte 64)
• (signed-byte 64)

vector must be an object returned by make-typed-aref-vector.

byte-index specifies the index in 8-bit bytes from the start of the data in the vector. It must be a non-negative fixnum which is less than the byte-length argument passed to make-typed-aref-vector.

typed-aref and (setf typed-aref) will be inlined to code which is as efficient as possible when compiled with (optimize (safety 0)) and a constant type. As usual, you need to add (optimize (float 0)) to remove boxing for the float types.

Notes

Efficient access to foreign arrays is also available. See fli:foreign-typed-aref in the LispWorks Foreign Language Interface User Guide and Reference Manual

Example

(defun double-float-typed-aref-incf (x y z)

  (declare (optimize (float 0) (safety 0)))

  (incf (sys:typed-aref 'double-float x y)

        (the double-float z))

  x)

See also

make-typed-aref-vector
Optimized integer arithmetic and integer vector access