1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
5 -- S Y S T E M . S E C O N D A R Y _ S T A C K --
10 -- Copyright (C) 1992-1999 Free Software Foundation, Inc. --
12 -- GNAT is free software; you can redistribute it and/or modify it under --
13 -- terms of the GNU General Public License as published by the Free Soft- --
14 -- ware Foundation; either version 2, or (at your option) any later ver- --
15 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
16 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
17 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
18 -- for more details. You should have received a copy of the GNU General --
19 -- Public License distributed with GNAT; see file COPYING. If not, write --
20 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
21 -- MA 02111-1307, USA. --
23 -- As a special exception, if other files instantiate generics from this --
24 -- unit, or you link this unit with other files to produce an executable, --
25 -- this unit does not by itself cause the resulting executable to be --
26 -- covered by the GNU General Public License. This exception does not --
27 -- however invalidate any other reasons why the executable file might be --
28 -- covered by the GNU Public License. --
30 -- GNAT was originally developed by the GNAT team at New York University. --
31 -- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
33 ------------------------------------------------------------------------------
35 with System
.Storage_Elements
;
37 package System
.Secondary_Stack
is
39 package SSE
renames System
.Storage_Elements
;
41 Default_Secondary_Stack_Size
: constant := 10 * 1024;
42 -- Default size of a secondary stack
45 (Stk
: in out System
.Address
;
46 Size
: Natural := Default_Secondary_Stack_Size
);
47 -- Initialize the secondary stack with a main stack of the given Size.
49 -- If System.Parameters.Sec_Stack_Ratio equals Dynamic, Stk is really an
50 -- "out" parameter that will be allocated on the heap. Then all further
51 -- allocations which do not overflow the main stack will not generate
52 -- dynamic (de)allocation calls. If the main Stack overflows, a new
53 -- chuck of at least the same size will be allocated and linked to the
56 -- Otherwise (Sec_Stack_Ratio between 0 and 100), Stk is an "in" parameter
57 -- that is already pointing to a Stack_Id. The secondary stack in this case
58 -- is fixed, and any attempt to allocated more than the initial size will
59 -- result in a Storage_Error being raised.
61 -- Note: the reason that Stk is passed is that SS_Init is called before
62 -- the proper interface is established to obtain the address of the
63 -- stack using System.Soft_Links.Get_Sec_Stack_Addr.
66 (Address
: out System
.Address
;
67 Storage_Size
: SSE
.Storage_Count
);
68 -- Allocate enough space for a 'Storage_Size' bytes object with Maximum
69 -- alignment. The address of the allocated space is returned in 'Address'
71 procedure SS_Free
(Stk
: in out System
.Address
);
72 -- Release the memory allocated for the Secondary Stack. That is to say,
73 -- all the allocated chuncks.
74 -- Upon return, Stk will be set to System.Null_Address
76 type Mark_Id
is private;
77 -- Type used to mark the stack.
79 function SS_Mark
return Mark_Id
;
80 -- Return the Mark corresponding to the current state of the stack
82 procedure SS_Release
(M
: Mark_Id
);
83 -- Restore the state of the stack corresponding to the mark M. If an
84 -- additional chunk have been allocated, it will never be freed during a
87 with procedure Put_Line
(S
: String);
89 -- Debugging procedure used to print out secondary Stack allocation
90 -- information. This procedure is generic in order to avoid a direct
91 -- dependence on a particular IO package.
96 -- Unused entity that is just present to ease the sharing of the pool
97 -- mechanism for specific allocation/deallocation in the compiler
99 type Mark_Id
is new SSE
.Integer_Address
;
101 end System
.Secondary_Stack
;