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7 Unexported Primitive Functions

Parts of the ffi/unsafe library are implemented by the Racket built-in '#%foreign module. The '#%foreign module is not intended for direct use, but it exports the following procedures. If you find any of these useful, please let us know.

(ffi-obj objname lib)  any
  objname : (or/c string? bytes? symbol?)
  lib : (or/c ffi-lib? path-string? #f)
Pulls out a foreign object from a library, returning a Racket value that can be used as a pointer. If a name is provided instead of a foreign-library value, ffi-lib is used to create a library object.

(ffi-obj? x)  boolean?
  x : any/c
(ffi-obj-lib obj)  ffi-lib?
  obj : ffi-obj?
(ffi-obj-name obj)  string?
  obj : ffi-obj?
A predicate for objects returned by ffi-obj, and accessor functions that return its corresponding library object and name. These values can also be used as C pointer objects.

(ctype-basetype type)  (or/c ctype? #f)
  type : ctype?
(ctype-scheme->c type)  procedure?
  type : ctype?
(ctype-c->scheme type)  procedure?
  type : ctype?
Accessors for the components of a C type object, made by make-ctype. The ctype-basetype selector returns a symbol for primitive types that names the type, a list of ctypes for cstructs, and another ctype for user-defined ctypes.

(ffi-call ptr in-types out-type [abi])  any
  ptr : any/c
  in-types : (listof ctype?)
  out-type : ctype?
  abi : (or/c symbol/c #f) = #f
The primitive mechanism that creates Racket “callout” values. The given ptr (any pointer value, including ffi-obj values) is wrapped in a Racket-callable primitive function that uses the types to specify how values are marshaled.

The optional abi argument determines the foreign ABI that is used. #f or 'default will use a platform-dependent default; other possible values are 'stdcall and 'sysv (the latter corresponds to “cdecl”). This is especially important on Windows, where most system functions are 'stdcall, which is not the default.

(ffi-callback proc    
  atomic?])  ffi-callback?
  proc : any/c
  in-types : any/c
  out-type : any/c
  abi : (or/c symbol/c #f) = #f
  atomic? : any/c = #f
The symmetric counterpart of ffi-call. It receives a Racket procedure and creates a callback object, which can also be used as a pointer. This object can be used as a C-callable function, which invokes proc using the types to specify how values are marshaled.

(ffi-callback? x)  boolean?
  x : any/c
A predicate for callback values that are created by ffi-callback.