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diff --git a/src/translate/grt/grt-stacks.ads b/src/translate/grt/grt-stacks.ads
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+--  GHDL Run Time (GRT) - process stacks.
+--  Copyright (C) 2002 - 2014 Tristan Gingold
+--
+--  GHDL is free software; you can redistribute it and/or modify it under
+--  the terms of the GNU General Public License as published by the Free
+--  Software Foundation; either version 2, or (at your option) any later
+--  version.
+--
+--  GHDL is distributed in the hope that it will be useful, but WITHOUT ANY
+--  WARRANTY; without even the implied warranty of MERCHANTABILITY or
+--  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+--  for more details.
+--
+--  You should have received a copy of the GNU General Public License
+--  along with GCC; see the file COPYING.  If not, write to the Free
+--  Software Foundation, 59 Temple Place - Suite 330, Boston, MA
+--  02111-1307, USA.
+--
+--  As a special exception, if other files instantiate generics from this
+--  unit, or you link this unit with other files to produce an executable,
+--  this unit does not by itself cause the resulting executable to be
+--  covered by the GNU General Public License. This exception does not
+--  however invalidate any other reasons why the executable file might be
+--  covered by the GNU Public License.
+with System; use System;
+with Ada.Unchecked_Conversion;
+
+package Grt.Stacks is
+   --  Instance is the parameter of the process procedure.
+   --  This is in fact a fully opaque type whose content is private to the
+   --  process.
+   type Instance is limited private;
+   type Instance_Acc is access all Instance;
+   pragma Convention (C, Instance_Acc);
+
+   --  A process is identified by a procedure having a single private
+   --  parameter (its instance).
+   type Proc_Acc is access procedure (Self : Instance_Acc);
+   pragma Convention (C, Proc_Acc);
+
+   function To_Address is new Ada.Unchecked_Conversion
+     (Instance_Acc, System.Address);
+
+   type Stack_Type is new Address;
+   Null_Stack : constant Stack_Type := Stack_Type (Null_Address);
+
+   --  Initialize the stacks package.
+   --  This may adjust stack sizes.
+   --  Must be called after grt.options.decode.
+   procedure Stack_Init;
+
+   --  Create a new stack, which on first execution will call FUNC with
+   --  an argument ARG.
+   function Stack_Create (Func : Proc_Acc; Arg : Instance_Acc)
+                         return Stack_Type;
+
+   --  Resume stack TO and save the current context to the stack pointed by
+   --  CUR.
+   procedure Stack_Switch (To : Stack_Type; From : Stack_Type);
+
+   --  Delete stack STACK, which must not be currently executed.
+   procedure Stack_Delete (Stack : Stack_Type);
+
+   --  Error during stack handling:
+   --  Cannot grow the stack.
+   procedure Error_Grow_Failed;
+   pragma No_Return (Error_Grow_Failed);
+
+   --  Invalid memory access detected (other than dereferencing a NULL access).
+   procedure Error_Memory_Access;
+   pragma No_Return (Error_Memory_Access);
+
+   --  A NULL access is dereferenced.
+   procedure Error_Null_Access;
+   pragma No_Return (Error_Null_Access);
+private
+   type Instance is null record;
+
+   pragma Import (C, Stack_Init, "grt_stack_init");
+   pragma Import (C, Stack_Create, "grt_stack_create");
+   pragma Import (C, Stack_Switch, "grt_stack_switch");
+   pragma Import (C, Stack_Delete, "grt_stack_delete");
+
+   pragma Export (C, Error_Grow_Failed, "grt_stack_error_grow_failed");
+   pragma Export (C, Error_Memory_Access, "grt_stack_error_memory_access");
+   pragma Export (C, Error_Null_Access, "grt_stack_error_null_access");
+end Grt.Stacks;