* libguile/foreign.c (make_cif): New procedure, with code formerly in
`scm_make_foreign_function'.
(scm_make_foreign_function): Use it.
(invoke_closure, scm_procedure_to_pointer)[FFI_CLOSURES]: New
functions.
* libguile/foreign.h (scm_procedure_to_pointer): New declaration.
* module/system/foreign.scm: Export `procedure->pointer' when available.
* test-suite/standalone/test-ffi (f-callback-1, f-callback-2): New
procedures and related tests.
* test-suite/standalone/test-ffi-lib.c (test_ffi_callback_1,
test_ffi_callback_2): New functions.
* test-suite/tests/foreign.test ("procedure->pointer"): New test prefix.
* doc/ref/api-foreign.texi (Dynamic FFI): Document `procedure->pointer'.
* libguile/foreign.c (scm_string_to_pointer, scm_pointer_to_string): New
functions.
* libguile/foreign.h (scm_string_to_pointer, scm_pointer_to_string): New
declarations.
* module/system/foreign.scm: Export `string->pointer' and
`pointer->string'.
* test-suite/tests/foreign.test ("pointer<->string"): New test prefix.
* doc/ref/api-foreign.texi (Void Pointers and Byte Access): Add
`string->pointer' and `pointer->string'.
* libguile/foreign.c (scm_i_pointer_print): Print in hexadecimal.
* doc/ref/api-foreign.texi (Modules and Extensions): Update for
"extensiondir", and a discussion of Guile versions.
(Foreign Variables): Fix discussion of types.
(Void Pointers and Byte Access): Fix typo.
* doc/ref/api-foreign.texi (Foreign Types): Remove bits about typed
foreign pointers. Add `void'.
(Foreign Variables): Update the doc of `dynamic-pointer' and the
`numptob' example. Remove `foreign-set!' and `foreign-ref'. Add
`pointer-address', `make-pointer', `%null-pointer', and
`null-pointer?'
(Void Pointers and Byte Access): Make it clear that wrapped pointers
are untyped. Remove `void' from here. Replace `foreign->bytevector'
and `bytevector->foreign' by `pointer->bytevector' and
`bytevector->pointer'. Add `dereference-pointer' and the rest of the
`numptob' example.
(Dynamic FFI): Update examples. Remove `%null-pointer' from here.
* libguile/dynl.c (scm_dynamic_pointer): Update docstring.
* libguile/foreign.c (scm_dereference_pointer,
scm_pointer_to_bytevector): Likewise.
* module/system/foreign.scm (null-pointer?): Add docstring.
* doc/ref/api-foreign.texi: New file.
* doc/ref/api-modules.texi: Reorganize bits about dynamic linking into
api-foreign.
* doc/ref/guile.texi:
* doc/ref/Makefile.am: Adapt to api-foreign.texi.