(*
 * Copyright (c) 2013 Jeremy Yallop.
 *
 * This file is distributed under the terms of the MIT License.
 * See the file LICENSE for details.
 *)

(** High-level bindings for C functions and values *)

val foreign :
  ?abi:Libffi_abi.abi ->
  ?from:Dl.library ->
  ?stub:bool -> 
  ?check_errno:bool ->
  ?release_runtime_lock:bool ->
  string ->
  ('a -> 'b) Ctypes.fn ->
  ('a -> 'b)
(** [foreign name typ] exposes the C function of type [typ] named by [name] as
    an OCaml value.

    The argument [?from], if supplied, is a library handle returned by
    {!Dl.dlopen}.

    The argument [?stub], if [true] (defaults to [false]), indicates that the
    function should not raise an exception if [name] is not found but return
    an OCaml value that raises an exception when called.

    The value [?check_errno], which defaults to [false], indicates whether
    {!Unix.Unix_error} should be raised if the C function modifies [errno].
    Please note that a function that succeeds is allowed to change errno. So
    use this option with caution.

    The value [?release_runtime_lock], which defaults to [false], indicates
    whether the OCaml runtime lock should be released during the call to the C
    function, allowing other threads to run.  If the runtime lock is released
    then the C function must not access OCaml heap objects, such as arguments
    passed using {!Ctypes.ocaml_string} and {!Ctypes.ocaml_bytes}, and must not
    call back into OCaml.

    @raise Dl.DL_error if [name] is not found in [?from] and [?stub] is
    [false]. *)

val foreign_value : ?from:Dl.library -> string -> 'a Ctypes.typ -> 'a Ctypes.ptr
(** [foreign_value name typ] exposes the C value of type [typ] named by [name]
    as an OCaml value.  The argument [?from], if supplied, is a library handle
    returned by {!Dl.dlopen}.  *)

val funptr :
  ?abi:Libffi_abi.abi ->
  ?name:string ->
  ?check_errno:bool ->
  ?runtime_lock:bool ->
  ?thread_registration:bool ->
  ('a -> 'b) Ctypes.fn ->
  ('a -> 'b) Ctypes.typ
(** Construct a function pointer type from a function type.

    The ctypes library, like C itself, distinguishes functions and function
    pointers.  Functions are not first class: it is not possible to use them
    as arguments or return values of calls, or store them in addressable
    memory.  Function pointers are first class, and so have none of these
    restrictions.

    The value [?check_errno], which defaults to [false], indicates whether
    {!Unix.Unix_error} should be raised if the C function modifies [errno].

    The value [?runtime_lock], which defaults to [false], indicates whether
    the OCaml runtime lock should be released during the call to the C
    function, allowing other threads to run.  If the runtime lock is released
    then the C function must not access OCaml heap objects, such as arguments
    passed using {!Ctypes.ocaml_string} and {!Ctypes.ocaml_bytes}, and must
    not call back into OCaml.  If the function pointer is used to call into
    OCaml from C then the [?runtime_lock] argument indicates whether the lock
    should be acquired and held during the call.

    @raise Dl.DL_error if [name] is not found in [?from] and [?stub] is
    [false]. *)

val funptr_opt :
  ?abi:Libffi_abi.abi ->
  ?name:string ->
  ?check_errno:bool ->
  ?runtime_lock:bool ->
  ?thread_registration:bool ->
  ('a -> 'b) Ctypes.fn ->
  ('a -> 'b) option Ctypes.typ
(** Construct a function pointer type from a function type.

    This behaves like {!funptr}, except that null pointers appear in OCaml as
    [None]. *)

exception CallToExpiredClosure
(** A closure passed to C was collected by the OCaml garbage collector before
    it was called. *)
