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Allegro CL version 9.0
Unrevised from 8.2 to 9.0.
8.2 version


Arguments: name arglist &rest body

This macro is obsolete and has been replaced by defun-foreign-callable. Please use that macro in all new code. This macro is maintained for backward compatibility only.

This macro defines a function in Lisp that can be called from foreign (traditionally C) code.

The argument list can be restated as:

lisp-function-name ({arg | (arg type)}*) body-form+ 

Thus arglist (the second argument in the argument list) is a list of arguments each of which is either a symbol (as in the usual function definition), or it is a list of length two, a symbol and its type. If a symbol only is present, then it has the default type (:signed-natural). Each is an argument which C passes to Lisp. This macro does not allow &rest or &optional arguments in the argument list. The type corresponds to a memref type (see memref and memref-int) and is limited to be one of the following:

:signed-byte 8 bits
:unsigned-byte 8 bits
:signed-word 16 bits
:unsigned-word 16 bits
:fixnum 30 bits
:signed-long 32 bits
:unsigned-long 32 bits
:signed-natural (the default)
:single-float, single-float 32 bits
:double-float, double-float 64 bits
:lisp (Assumes that C passes an actual Lisp value)

Warning for users of 64-bit Lisps: :signed-long and :unsigned-long are treated as 32-bit values, even on a 64-bit port. Contrast this to defun-foreign-callable, where :long and :unsigned-long match the precise meaning in C on the architecture in question. But note further that that does not mean they follow the 32/64-bit nature of the Lisp; for example, a :long foreign type on Compaq Alphas is always 64-bits, even for a 32-bit lisp. But this is consistent with C.

Warning about backward compatibility with release 5.0.1 and earlier: The default argument type is changed from :signed-long to :signed-natural. If a user has pre-6.0 code that explicitly specifies :signed-long, it is likely not to work on 64-bit ports, because :signed-long always specifies 32 bit values. If the user instead takes the default argument type, then the code will work in all 6.0 and pre-6.0 versions. If 32-bits is explicitly desired, however, then the :signed-long (or :unsigned-long) should be explicitly specified.

See memref and memref-int and foreign-functions.htm for general information on foreign functions in Allegro CL.

Copyright (c) 1998-2012, Franz Inc. Oakland, CA., USA. All rights reserved.
Documentation for Allegro CL version 9.0. This page was not revised from the 8.2 page.
Created 2012.5.30.

Allegro CL version 9.0
Unrevised from 8.2 to 9.0.
8.2 version