+++ /dev/null
-------------------------------------------------------------------------------
--- --
--- GNAT COMPILER COMPONENTS --
--- --
--- S Y S T E M . S E C O N D A R Y _ S T A C K --
--- --
--- B o d y --
--- --
--- $Revision: 1.1.16.1 $
--- --
--- Copyright (C) 1992-2001 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 2, 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. See the GNU General Public License --
--- for more details. You should have received a copy of the GNU General --
--- Public License distributed with GNAT; see 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. --
--- --
--- GNAT was originally developed by the GNAT team at New York University. --
--- Extensive contributions were provided by Ada Core Technologies Inc. --
--- --
-------------------------------------------------------------------------------
-
-with System.Soft_Links;
-with System.Parameters;
-with Unchecked_Conversion;
-with Unchecked_Deallocation;
-
-package body System.Secondary_Stack is
-
- package SSL renames System.Soft_Links;
-
- use type SSE.Storage_Offset;
- use type System.Parameters.Size_Type;
-
- SS_Ratio_Dynamic : constant Boolean :=
- Parameters.Sec_Stack_Ratio = Parameters.Dynamic;
-
- -- +------------------+
- -- | Next |
- -- +------------------+
- -- | | Last (200)
- -- | |
- -- | |
- -- | |
- -- | |
- -- | |
- -- | | First (101)
- -- +------------------+
- -- +----------> | | |
- -- | +----------+-------+
- -- | | |
- -- | ^ V
- -- | | |
- -- | +-------+----------+
- -- | | | |
- -- | +------------------+
- -- | | | Last (100)
- -- | | C |
- -- | | H |
- -- +-----------------+ | +-------->| U |
- -- | Current_Chunk -|--+ | | N |
- -- +-----------------+ | | K |
- -- | Top -|-----+ | | First (1)
- -- +-----------------+ +------------------+
- -- | Default_Size | | Prev |
- -- +-----------------+ +------------------+
- --
- --
- type Memory is array (Mark_Id range <>) of SSE.Storage_Element;
-
- type Chunk_Id (First, Last : Mark_Id);
- type Chunk_Ptr is access all Chunk_Id;
-
- type Chunk_Id (First, Last : Mark_Id) is record
- Prev, Next : Chunk_Ptr;
- Mem : Memory (First .. Last);
- end record;
-
- type Stack_Id is record
- Top : Mark_Id;
- Default_Size : SSE.Storage_Count;
- Current_Chunk : Chunk_Ptr;
- end record;
-
- type Fixed_Stack_Id is record
- Top : Mark_Id;
- Last : Mark_Id;
- Mem : Memory (1 .. Mark_Id'Last / 2 - 1);
- -- This should really be 1 .. Mark_Id'Last, but there is a bug in gigi
- -- with this type, introduced Sep 2001, that causes gigi to reject this
- -- type because its size in bytes overflows ???
- end record;
-
- type Stack_Ptr is access Stack_Id;
- type Fixed_Stack_Ptr is access Fixed_Stack_Id;
-
- function From_Addr is new Unchecked_Conversion (Address, Stack_Ptr);
- function To_Addr is new Unchecked_Conversion (Stack_Ptr, System.Address);
- function To_Stack is new Unchecked_Conversion (Fixed_Stack_Ptr, Stack_Ptr);
- function To_Fixed is new Unchecked_Conversion (Stack_Ptr, Fixed_Stack_Ptr);
-
- procedure Free is new Unchecked_Deallocation (Chunk_Id, Chunk_Ptr);
-
- --------------
- -- Allocate --
- --------------
-
- procedure SS_Allocate
- (Address : out System.Address;
- Storage_Size : SSE.Storage_Count)
- is
- Stack : constant Stack_Ptr :=
- From_Addr (SSL.Get_Sec_Stack_Addr.all);
- Fixed_Stack : Fixed_Stack_Ptr;
- Chunk : Chunk_Ptr;
- Max_Align : constant Mark_Id := Mark_Id (Standard'Maximum_Alignment);
- Max_Size : constant Mark_Id :=
- ((Mark_Id (Storage_Size) + Max_Align - 1) / Max_Align)
- * Max_Align;
-
- Count_Unreleased_Chunks : Natural;
- To_Be_Released_Chunk : Chunk_Ptr;
-
- begin
- -- If the secondary stack is fixed in the primary stack, then the
- -- handling becomes simple
-
- if not SS_Ratio_Dynamic then
- Fixed_Stack := To_Fixed (Stack);
-
- if Fixed_Stack.Top + Max_Size > Fixed_Stack.Last then
- raise Storage_Error;
- end if;
-
- Address := Fixed_Stack.Mem (Fixed_Stack.Top)'Address;
- Fixed_Stack.Top := Fixed_Stack.Top + Mark_Id (Max_Size);
- return;
- end if;
-
- Chunk := Stack.Current_Chunk;
-
- -- The Current_Chunk may not be the good one if a lot of release
- -- operations have taken place. So go down the stack if necessary
-
- while Chunk.First > Stack.Top loop
- Chunk := Chunk.Prev;
- end loop;
-
- -- Find out if the available memory in the current chunk is sufficient.
- -- if not, go to the next one and eventally create the necessary room
-
- Count_Unreleased_Chunks := 0;
-
- while Chunk.Last - Stack.Top + 1 < Max_Size loop
- if Chunk.Next /= null then
-
- -- Release unused non-first empty chunk
-
- if Chunk.Prev /= null and then Chunk.First = Stack.Top then
- To_Be_Released_Chunk := Chunk;
- Chunk := Chunk.Prev;
- Chunk.Next := To_Be_Released_Chunk.Next;
- To_Be_Released_Chunk.Next.Prev := Chunk;
- Free (To_Be_Released_Chunk);
- end if;
-
- -- Create new chunk of the default size unless it is not sufficient
-
- elsif SSE.Storage_Count (Max_Size) <= Stack.Default_Size then
- Chunk.Next := new Chunk_Id (
- First => Chunk.Last + 1,
- Last => Chunk.Last + Mark_Id (Stack.Default_Size));
-
- Chunk.Next.Prev := Chunk;
-
- else
- Chunk.Next := new Chunk_Id (
- First => Chunk.Last + 1,
- Last => Chunk.Last + Max_Size);
-
- Chunk.Next.Prev := Chunk;
- end if;
-
- Chunk := Chunk.Next;
- Stack.Top := Chunk.First;
- end loop;
-
- -- Resulting address is the address pointed by Stack.Top
-
- Address := Chunk.Mem (Stack.Top)'Address;
- Stack.Top := Stack.Top + Max_Size;
- Stack.Current_Chunk := Chunk;
- end SS_Allocate;
-
- -------------
- -- SS_Free --
- -------------
-
- procedure SS_Free (Stk : in out System.Address) is
- Stack : Stack_Ptr;
- Chunk : Chunk_Ptr;
-
- procedure Free is new Unchecked_Deallocation (Stack_Id, Stack_Ptr);
-
- begin
- if not SS_Ratio_Dynamic then
- return;
- end if;
-
- Stack := From_Addr (Stk);
- Chunk := Stack.Current_Chunk;
-
- while Chunk.Prev /= null loop
- Chunk := Chunk.Prev;
- end loop;
-
- while Chunk.Next /= null loop
- Chunk := Chunk.Next;
- Free (Chunk.Prev);
- end loop;
-
- Free (Chunk);
- Free (Stack);
- Stk := Null_Address;
- end SS_Free;
-
- -------------
- -- SS_Info --
- -------------
-
- procedure SS_Info is
- Stack : constant Stack_Ptr :=
- From_Addr (SSL.Get_Sec_Stack_Addr.all);
- Fixed_Stack : Fixed_Stack_Ptr;
- Nb_Chunks : Integer := 1;
- Chunk : Chunk_Ptr := Stack.Current_Chunk;
-
- begin
- Put_Line ("Secondary Stack information:");
-
- if not SS_Ratio_Dynamic then
- Fixed_Stack := To_Fixed (Stack);
- Put_Line (
- " Total size : "
- & Mark_Id'Image (Fixed_Stack.Last)
- & " bytes");
- Put_Line (
- " Current allocated space : "
- & Mark_Id'Image (Fixed_Stack.Top - 1)
- & " bytes");
- return;
- end if;
-
- while Chunk.Prev /= null loop
- Chunk := Chunk.Prev;
- end loop;
-
- while Chunk.Next /= null loop
- Nb_Chunks := Nb_Chunks + 1;
- Chunk := Chunk.Next;
- end loop;
-
- -- Current Chunk information
-
- Put_Line (
- " Total size : "
- & Mark_Id'Image (Chunk.Last)
- & " bytes");
- Put_Line (
- " Current allocated space : "
- & Mark_Id'Image (Stack.Top - 1)
- & " bytes");
-
- Put_Line (
- " Number of Chunks : "
- & Integer'Image (Nb_Chunks));
-
- Put_Line (
- " Default size of Chunks : "
- & SSE.Storage_Count'Image (Stack.Default_Size));
- end SS_Info;
-
- -------------
- -- SS_Init --
- -------------
-
- procedure SS_Init
- (Stk : in out System.Address;
- Size : Natural := Default_Secondary_Stack_Size)
- is
- Stack : Stack_Ptr;
- Fixed_Stack : Fixed_Stack_Ptr;
-
- begin
- if not SS_Ratio_Dynamic then
- Fixed_Stack := To_Fixed (From_Addr (Stk));
- Fixed_Stack.Top := Fixed_Stack.Mem'First;
-
- if Size < 2 * Mark_Id'Max_Size_In_Storage_Elements then
- Fixed_Stack.Last := 0;
- else
- Fixed_Stack.Last := Mark_Id (Size) -
- 2 * Mark_Id'Max_Size_In_Storage_Elements;
- end if;
-
- return;
- end if;
-
- Stack := new Stack_Id;
- Stack.Current_Chunk := new Chunk_Id (1, Mark_Id (Size));
- Stack.Top := 1;
- Stack.Default_Size := SSE.Storage_Count (Size);
-
- Stk := To_Addr (Stack);
- end SS_Init;
-
- -------------
- -- SS_Mark --
- -------------
-
- function SS_Mark return Mark_Id is
- begin
- return From_Addr (SSL.Get_Sec_Stack_Addr.all).Top;
- end SS_Mark;
-
- ----------------
- -- SS_Release --
- ----------------
-
- procedure SS_Release (M : Mark_Id) is
- begin
- From_Addr (SSL.Get_Sec_Stack_Addr.all).Top := M;
- end SS_Release;
-
- -------------------------
- -- Package Elaboration --
- -------------------------
-
- -- Allocate a secondary stack for the main program to use.
- -- We make sure that the stack has maximum alignment. Some systems require
- -- this (e.g. Sun), and in any case it is a good idea for efficiency.
-
- Stack : aliased Stack_Id;
- for Stack'Alignment use Standard'Maximum_Alignment;
-
- Chunk : aliased Chunk_Id (1, Default_Secondary_Stack_Size);
- for Chunk'Alignment use Standard'Maximum_Alignment;
-
- Chunk_Address : System.Address;
-
-begin
- if SS_Ratio_Dynamic then
- Stack.Top := 1;
- Stack.Current_Chunk := Chunk'Access;
- Stack.Default_Size := Default_Secondary_Stack_Size;
- System.Soft_Links.Set_Sec_Stack_Addr_NT (Stack'Address);
-
- else
- Chunk_Address := Chunk'Address;
- SS_Init (Chunk_Address, Default_Secondary_Stack_Size);
- System.Soft_Links.Set_Sec_Stack_Addr_NT (Chunk_Address);
- end if;
-end System.Secondary_Stack;
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