storage.def

<B>Digital的Unix操作系统VAX 4.2源码</B>

(*#@(#)Storage.def	4.1	Ultrix	7/17/90 *)
(* $Header: Storage.def,v 1.5 84/05/19 11:39:36 powell Exp $ *)

(* Definition module for standard memory allocation routines *)

(* The size of the storage allocated or deallocated is specified in bits *)
(*  (as returned by system.tsize) *)

(* The following note appears in Storage.def and memory.def *)

(* NOTE:
   Modula-2 generates code to validate pointers before dereferencing
   them.  Storage allocated by the New operation has an extra word at
   the beginning that points to the second word, which is where the
   pointer points.  Thus, the pointer validation looks like
	cmpl	rx,-4(rx)
   The word is set up by the New operation, which calls Storage.ALLOCATE
   asking for one more word than the user needs and sets things up.  Thus,
   New and the pointer check work correctly with any ALLOCATE.  This is set
   up whether compiling with -C or not, since some modules may do checking
   and others not.

   To avoid this check and eliminate the extra word, declare your pointers
   as follows:
    type
	UncheckedPointer = pointer @nocheck to Oblivion;

   If you need to call ALLOCATE instead of New, you must either declare the
   pointers to be @nocheck, or import ALLOCATE and DEALLOCATE from memory.
   ALLOCATE and DEALLOCATE in memory set up for the check.

   Remember, memory.allocate and memory.deallocate are for checked memory,
   Storage.ALLOCATE and Storage.DEALLOCATE are for @nocheck memory.
*)

DEFINITION MODULE Storage;

FROM SYSTEM IMPORT ADDRESS;

EXPORT QUALIFIED ALLOCATE, DEALLOCATE;

PROCEDURE ALLOCATE(VAR p : ADDRESS; n : CARDINAL);

PROCEDURE DEALLOCATE(VAR p : ADDRESS; n : CARDINAL);

END Storage.