120 lines
5.9 KiB
Ada
120 lines
5.9 KiB
Ada
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------------------------------------------------------------------------------
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-- --
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-- GNAT COMPILER COMPONENTS --
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-- --
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-- S Y S T E M . S E C O N D A R Y _ S T A C K --
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-- --
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-- S p e c --
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-- --
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-- Copyright (C) 1992-2013, Free Software Foundation, Inc. --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 3, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. --
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-- --
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-- As a special exception under Section 7 of GPL version 3, you are granted --
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-- additional permissions described in the GCC Runtime Library Exception, --
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-- version 3.1, as published by the Free Software Foundation. --
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-- --
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-- You should have received a copy of the GNU General Public License and --
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-- a copy of the GCC Runtime Library Exception along with this program; --
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-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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-- <http://www.gnu.org/licenses/>. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- Extensive contributions were provided by Ada Core Technologies Inc. --
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-- --
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------------------------------------------------------------------------------
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pragma Compiler_Unit_Warning;
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with System.Storage_Elements;
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package System.Secondary_Stack is
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package SSE renames System.Storage_Elements;
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Default_Secondary_Stack_Size : Natural := 10 * 1024;
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-- Default size of a secondary stack. May be modified by binder -D switch
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-- which causes the binder to generate an appropriate assignment in the
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-- binder generated file.
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procedure SS_Init
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(Stk : in out Address;
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Size : Natural := Default_Secondary_Stack_Size);
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-- Initialize the secondary stack with a main stack of the given Size.
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--
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-- If System.Parameters.Sec_Stack_Percentage equals Dynamic, Stk is really
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-- an OUT parameter that will be allocated on the heap. Then all further
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-- allocations which do not overflow the main stack will not generate
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-- dynamic (de)allocation calls. If the main Stack overflows, a new
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-- chuck of at least the same size will be allocated and linked to the
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-- previous chunk.
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--
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-- Otherwise (Sec_Stack_Percentage between 0 and 100), Stk is an IN
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-- parameter that is already pointing to a Stack_Id. The secondary stack
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-- in this case is fixed, and any attempt to allocate more than the initial
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-- size will result in a Storage_Error being raised.
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--
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-- Note: the reason that Stk is passed is that SS_Init is called before
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-- the proper interface is established to obtain the address of the
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-- stack using System.Soft_Links.Get_Sec_Stack_Addr.
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procedure SS_Allocate
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(Addr : out Address;
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Storage_Size : SSE.Storage_Count);
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-- Allocate enough space for a 'Storage_Size' bytes object with Maximum
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-- alignment. The address of the allocated space is returned in Addr.
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procedure SS_Free (Stk : in out Address);
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-- Release the memory allocated for the Secondary Stack. That is
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-- to say, all the allocated chunks. Upon return, Stk will be set
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-- to System.Null_Address.
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type Mark_Id is private;
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-- Type used to mark the stack for mark/release processing
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function SS_Mark return Mark_Id;
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-- Return the Mark corresponding to the current state of the stack
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procedure SS_Release (M : Mark_Id);
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-- Restore the state of the stack corresponding to the mark M. If an
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-- additional chunk have been allocated, it will never be freed during a
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-- ??? missing comment here
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function SS_Get_Max return Long_Long_Integer;
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-- Return maximum used space in storage units for the current secondary
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-- stack. For a dynamically allocated secondary stack, the returned
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-- result is always -1. For a statically allocated secondary stack,
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-- the returned value shows the largest amount of space allocated so
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-- far during execution of the program to the current secondary stack,
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-- i.e. the secondary stack for the current task.
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generic
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with procedure Put_Line (S : String);
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procedure SS_Info;
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-- Debugging procedure used to print out secondary Stack allocation
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-- information. This procedure is generic in order to avoid a direct
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-- dependance on a particular IO package.
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private
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SS_Pool : Integer;
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-- Unused entity that is just present to ease the sharing of the pool
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-- mechanism for specific allocation/deallocation in the compiler
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type SS_Ptr is new SSE.Integer_Address;
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-- Stack pointer value for secondary stack
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type Mark_Id is record
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Sstk : System.Address;
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Sptr : SS_Ptr;
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end record;
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-- A mark value contains the address of the secondary stack structure,
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-- as returned by System.Soft_Links.Get_Sec_Stack_Addr, and a stack
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-- pointer value corresponding to the point of the mark call.
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end System.Secondary_Stack;
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