ffi: allow ptr-in-out passing of cptr.

* ffi.c (ffi_ptr_alloc): New static function.
(ffi_type_compile): Give the cptr type alloc and free
functions: alloc just retrives the address of the pointer
inside the cptr object (pointer to pointer); free is a noop.
(cptr_make): New static function.
(ffi_init): Register cptr_make as cptr intrinsic. Register
cptr-null intrinsic variable denoting a ready-made null
pointer.

* lib.c (cptr_addr_of): New function.

* lib.h (cptr_addr_of): Declared.

1 files changed, 1 insertions, 0 deletions

diff --git a/lib.h b/lib.h
index 943fd3ac..5c74abf5 100644
--- a/lib.h
+++ b/lib.h
@@ -936,6 +936,7 @@ mem_t *cobj_handle(val cobj, val cls_sym);
 struct cobj_ops *cobj_ops(val cobj, val cls_sym);
 val cptr(mem_t *ptr);
 mem_t *cptr_get(val cptr);
+mem_t **cptr_addr_of(val cptr);
 val assoc(val key, val list);
 val assql(val key, val list);
 val rassoc(val key, val list);