File : s-secsta.ads
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-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S Y S T E M . S E C O N D A R Y _ S T A C K --
-- --
-- S p e c --
-- --
-- Copyright (C) 1992-2009, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. --
-- --
-- --
-- --
-- --
-- --
-- You should have received a copy of the GNU General Public License and --
-- a copy of the GCC Runtime Library Exception along with this program; --
-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
-- <http://www.gnu.org/licenses/>. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
pragma Compiler_Unit;
with System.Storage_Elements;
package System.Secondary_Stack is
package SSE renames System.Storage_Elements;
Default_Secondary_Stack_Size : Natural := 10 * 1024;
-- Default size of a secondary stack. May be modified by binder -D switch
-- which causes the binder to generate an appropriate assignment in the
-- binder generated file.
procedure SS_Init
(Stk : in out Address;
Size : Natural := Default_Secondary_Stack_Size);
-- Initialize the secondary stack with a main stack of the given Size.
--
-- If System.Parameters.Sec_Stack_Ratio equals Dynamic, Stk is really an
-- OUT parameter that will be allocated on the heap. Then all further
-- allocations which do not overflow the main stack will not generate
-- dynamic (de)allocation calls. If the main Stack overflows, a new
-- chuck of at least the same size will be allocated and linked to the
-- previous chunk.
--
-- Otherwise (Sec_Stack_Ratio between 0 and 100), Stk is an IN parameter
-- that is already pointing to a Stack_Id. The secondary stack in this case
-- is fixed, and any attempt to allocate more than the initial size will
-- result in a Storage_Error being raised.
--
-- Note: the reason that Stk is passed is that SS_Init is called before
-- the proper interface is established to obtain the address of the
-- stack using System.Soft_Links.Get_Sec_Stack_Addr.
procedure SS_Allocate
(Addr : out Address;
Storage_Size : SSE.Storage_Count);
-- Allocate enough space for a 'Storage_Size' bytes object with Maximum
-- alignment. The address of the allocated space is returned in Addr.
procedure SS_Free (Stk : in out Address);
-- Release the memory allocated for the Secondary Stack. That is
-- to say, all the allocated chunks. Upon return, Stk will be set
-- to System.Null_Address.
type Mark_Id is private;
-- Type used to mark the stack for mark/release processing
function SS_Mark return Mark_Id;
-- Return the Mark corresponding to the current state of the stack
procedure SS_Release (M : Mark_Id);
-- Restore the state of the stack corresponding to the mark M. If an
-- additional chunk have been allocated, it will never be freed during a
-- ??? missing comment here
function SS_Get_Max return Long_Long_Integer;
-- Return maximum used space in storage units for the current secondary
-- stack. For a dynamically allocated secondary stack, the returned
-- result is always -1. For a statically allocated secondary stack,
-- the returned value shows the largest amount of space allocated so
-- far during execution of the program to the current secondary stack,
-- i.e. the secondary stack for the current task.
generic
with procedure Put_Line (S : String);
procedure SS_Info;
-- Debugging procedure used to print out secondary Stack allocation
-- information. This procedure is generic in order to avoid a direct
-- dependance on a particular IO package.
private
SS_Pool : Integer;
-- Unused entity that is just present to ease the sharing of the pool
-- mechanism for specific allocation/deallocation in the compiler
type SS_Ptr is new SSE.Integer_Address;
-- Stack pointer value for secondary stack
type Mark_Id is record
Sstk : System.Address;
Sptr : SS_Ptr;
end record;
-- A mark value contains the address of the secondary stack structure,
-- as returned by System.Soft_Links.Get_Sec_Stack_Addr, and a stack
-- pointer value corresponding to the point of the mark call.
end System.Secondary_Stack;