(* Copyright (C) 1987 Jensen & Partners International *)
DEFINITION MODULE Storage;

TYPE
  HeapRecPtr = POINTER TO HeapRec;
  HeapRec    = RECORD
                 size : CARDINAL;
                 next : HeapRecPtr;
               END;

VAR
  MainHeap : HeapRecPtr;
  ClearOnAllocate : BOOLEAN;


(* Main heap procedures *)

PROCEDURE ALLOCATE  (VAR a: ADDRESS; size: CARDINAL);

PROCEDURE DEALLOCATE(VAR a: ADDRESS; size: CARDINAL);

PROCEDURE Available (size : CARDINAL) : BOOLEAN;


(* Other heap procedures *)

PROCEDURE MakeHeap( Source  : CARDINAL;           (* base segment of heap *)
                    Size    : CARDINAL            (* size in paragraphs   *)
                   ) : HeapRecPtr;

PROCEDURE HeapAllocate  ( Source : HeapRecPtr;     (* source heap         *)
                          VAR A  : ADDRESS;        (* result              *)
                          Size   : CARDINAL);      (* size in paragraphs  *)

PROCEDURE HeapDeallocate( Source : HeapRecPtr;     (* source heap         *)
                          VAR A  : ADDRESS;        (* block to deallocate *)
                          Size   : CARDINAL);      (* size in paragraphs  *)



PROCEDURE HeapAvail(Source: HeapRecPtr) : CARDINAL;
(* returns the largest block size available for allocation in paragraphs *)

PROCEDURE HeapTotalAvail(Source: HeapRecPtr) : CARDINAL;
(* returns the total size available for allocation in paragraphs *)


PROCEDURE HeapChangeSize( Source : HeapRecPtr;     (* source heap        *)
                          VAR A  : ADDRESS;        (* block to change    *)
                          OldSize,                 (* old size of block  *)
                          NewSize: CARDINAL);      (* new size of block  *)
                                                   (* in paragraphs      *)

(*
   This procedure will change the size of an allocated block
   avoiding any copy of data if possible. Calls HeapChangeAlloc
*)

PROCEDURE HeapChangeAlloc(Source : HeapRecPtr;     (* source heap        *)
                          A      : ADDRESS;        (* block to change    *)
                          OldSize,                 (* old size of block  *)
                          NewSize: CARDINAL)       (* new size of block  *)
                                                   (* in paragraphs      *)
                          : BOOLEAN ;              (* If sucessful       *)

(*
   This procedure attempts to change the size of an allocated block.
   It returns TRUE if succeeded (only expansion can fail).
   If it fails no action is taken.
*)


END Storage.