358 lines
12 KiB
Ada
358 lines
12 KiB
Ada
------------------------------------------------------------------------------
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-- --
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-- GNAT RUN-TIME COMPONENTS --
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-- --
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-- S Y S T E M . P O O L _ S I Z E --
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-- --
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-- B o d y --
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-- --
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-- Copyright (C) 1992-2001 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 2, 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. See the GNU General Public License --
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-- for more details. You should have received a copy of the GNU General --
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-- Public License distributed with GNAT; see file COPYING. If not, write --
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-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
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-- MA 02111-1307, USA. --
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-- --
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-- As a special exception, if other files instantiate generics from this --
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-- unit, or you link this unit with other files to produce an executable, --
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-- this unit does not by itself cause the resulting executable to be --
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-- covered by the GNU General Public License. This exception does not --
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-- however invalidate any other reasons why the executable file might be --
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-- covered by the GNU Public License. --
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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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with System.Storage_Elements;
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with System.Address_To_Access_Conversions;
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package body System.Pool_Size is
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package SSE renames System.Storage_Elements;
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use type SSE.Storage_Offset;
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package SC is new Address_To_Access_Conversions (SSE.Storage_Count);
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SC_Size : constant
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:= SSE.Storage_Count'Object_Size / System.Storage_Unit;
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package Variable_Size_Management is
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-- Embedded pool that manages allocation of variable-size data.
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-- This pool is used as soon as the Elmt_sizS of the pool object is 0.
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-- Allocation is done on the first chunk long enough for the request.
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-- Deallocation just puts the freed chunk at the beginning of the list.
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procedure Initialize (Pool : in out Stack_Bounded_Pool);
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procedure Allocate
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(Pool : in out Stack_Bounded_Pool;
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Address : out System.Address;
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Storage_Size : SSE.Storage_Count;
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Alignment : SSE.Storage_Count);
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procedure Deallocate
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(Pool : in out Stack_Bounded_Pool;
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Address : System.Address;
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Storage_Size : SSE.Storage_Count;
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Alignment : SSE.Storage_Count);
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end Variable_Size_Management;
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package Vsize renames Variable_Size_Management;
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--------------
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-- Allocate --
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--------------
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procedure Allocate
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(Pool : in out Stack_Bounded_Pool;
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Address : out System.Address;
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Storage_Size : SSE.Storage_Count;
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Alignment : SSE.Storage_Count)
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is
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begin
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if Pool.Elmt_Size = 0 then
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Vsize.Allocate (Pool, Address, Storage_Size, Alignment);
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elsif Pool.First_Free /= 0 then
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Address := Pool.The_Pool (Pool.First_Free)'Address;
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Pool.First_Free := SC.To_Pointer (Address).all;
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elsif
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Pool.First_Empty <= (Pool.Pool_Size - Pool.Aligned_Elmt_Size + 1)
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then
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Address := Pool.The_Pool (Pool.First_Empty)'Address;
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Pool.First_Empty := Pool.First_Empty + Pool.Aligned_Elmt_Size;
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else
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raise Storage_Error;
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end if;
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end Allocate;
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----------------
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-- Deallocate --
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----------------
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procedure Deallocate
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(Pool : in out Stack_Bounded_Pool;
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Address : System.Address;
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Storage_Size : SSE.Storage_Count;
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Alignment : SSE.Storage_Count)
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is
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begin
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if Pool.Elmt_Size = 0 then
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Vsize.Deallocate (Pool, Address, Storage_Size, Alignment);
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else
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SC.To_Pointer (Address).all := Pool.First_Free;
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Pool.First_Free := Address - Pool.The_Pool'Address + 1;
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end if;
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end Deallocate;
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----------------
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-- Initialize --
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----------------
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procedure Initialize (Pool : in out Stack_Bounded_Pool) is
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Align : constant SSE.Storage_Count :=
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SSE.Storage_Count'Max (SSE.Storage_Count'Alignment, Pool.Alignment);
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begin
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if Pool.Elmt_Size = 0 then
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Vsize.Initialize (Pool);
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else
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Pool.First_Free := 0;
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Pool.First_Empty := 1;
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-- Compute the size to allocate given the size of the element and
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-- the possible Alignment clause
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Pool.Aligned_Elmt_Size :=
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SSE.Storage_Count'Max (SC_Size,
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((Pool.Elmt_Size + Align - 1) / Align) * Align);
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end if;
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end Initialize;
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------------------
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-- Storage_Size --
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------------------
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function Storage_Size
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(Pool : Stack_Bounded_Pool)
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return SSE.Storage_Count
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is
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begin
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return Pool.Pool_Size;
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end Storage_Size;
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------------------------------
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-- Variable_Size_Management --
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------------------------------
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package body Variable_Size_Management is
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Minimum_Size : constant := 2 * SC_Size;
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procedure Set_Size
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(Pool : Stack_Bounded_Pool;
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Chunk, Size : SSE.Storage_Count);
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-- Update the field 'size' of a chunk of available storage
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procedure Set_Next
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(Pool : Stack_Bounded_Pool;
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Chunk, Next : SSE.Storage_Count);
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-- Update the field 'next' of a chunk of available storage
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function Size
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(Pool : Stack_Bounded_Pool;
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Chunk : SSE.Storage_Count)
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return SSE.Storage_Count;
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-- Fetch the field 'size' of a chunk of available storage
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function Next
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(Pool : Stack_Bounded_Pool;
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Chunk : SSE.Storage_Count)
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return SSE.Storage_Count;
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-- Fetch the field 'next' of a chunk of available storage
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function Chunk_Of
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(Pool : Stack_Bounded_Pool;
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Addr : System.Address)
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return SSE.Storage_Count;
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-- Give the chunk number in the pool from its Address
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--------------
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-- Allocate --
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--------------
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procedure Allocate
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(Pool : in out Stack_Bounded_Pool;
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Address : out System.Address;
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Storage_Size : SSE.Storage_Count;
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Alignment : SSE.Storage_Count)
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is
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Chunk : SSE.Storage_Count;
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New_Chunk : SSE.Storage_Count;
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Prev_Chunk : SSE.Storage_Count;
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Our_Align : constant SSE.Storage_Count :=
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SSE.Storage_Count'Max (SSE.Storage_Count'Alignment,
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Alignment);
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Align_Size : constant SSE.Storage_Count :=
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SSE.Storage_Count'Max (
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Minimum_Size,
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((Storage_Size + Our_Align - 1) / Our_Align) *
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Our_Align);
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begin
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-- Look for the first big enough chunk
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Prev_Chunk := Pool.First_Free;
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Chunk := Next (Pool, Prev_Chunk);
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while Chunk /= 0 and then Size (Pool, Chunk) < Align_Size loop
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Prev_Chunk := Chunk;
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Chunk := Next (Pool, Chunk);
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end loop;
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-- Raise storage_error if no big enough chunk available
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if Chunk = 0 then
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raise Storage_Error;
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end if;
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-- When the chunk is bigger than what is needed, take appropraite
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-- amount and build a new shrinked chunk with the remainder.
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if Size (Pool, Chunk) - Align_Size > Minimum_Size then
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New_Chunk := Chunk + Align_Size;
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Set_Size (Pool, New_Chunk, Size (Pool, Chunk) - Align_Size);
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Set_Next (Pool, New_Chunk, Next (Pool, Chunk));
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Set_Next (Pool, Prev_Chunk, New_Chunk);
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-- If the chunk is the right size, just delete it from the chain
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else
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Set_Next (Pool, Prev_Chunk, Next (Pool, Chunk));
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end if;
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Address := Pool.The_Pool (Chunk)'Address;
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end Allocate;
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--------------
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-- Chunk_Of --
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--------------
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function Chunk_Of
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(Pool : Stack_Bounded_Pool;
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Addr : System.Address)
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return SSE.Storage_Count
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is
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begin
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return 1 + abs (Addr - Pool.The_Pool (1)'Address);
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end Chunk_Of;
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----------------
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-- Deallocate --
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----------------
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procedure Deallocate
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(Pool : in out Stack_Bounded_Pool;
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Address : System.Address;
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Storage_Size : SSE.Storage_Count;
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Alignment : SSE.Storage_Count)
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is
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Align_Size : constant SSE.Storage_Count :=
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((Storage_Size + Alignment - 1) / Alignment) *
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Alignment;
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Chunk : SSE.Storage_Count := Chunk_Of (Pool, Address);
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begin
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-- Attach the freed chunk to the chain
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Set_Size (Pool, Chunk,
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SSE.Storage_Count'Max (Align_Size, Minimum_Size));
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Set_Next (Pool, Chunk, Next (Pool, Pool.First_Free));
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Set_Next (Pool, Pool.First_Free, Chunk);
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end Deallocate;
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----------------
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-- Initialize --
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----------------
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procedure Initialize (Pool : in out Stack_Bounded_Pool) is
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begin
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Pool.First_Free := 1;
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if Pool.Pool_Size > Minimum_Size then
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Set_Next (Pool, Pool.First_Free, Pool.First_Free + Minimum_Size);
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Set_Size (Pool, Pool.First_Free, 0);
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Set_Size (Pool, Pool.First_Free + Minimum_Size,
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Pool.Pool_Size - Minimum_Size);
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Set_Next (Pool, Pool.First_Free + Minimum_Size, 0);
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end if;
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end Initialize;
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----------
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-- Next --
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----------
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function Next
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(Pool : Stack_Bounded_Pool;
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Chunk : SSE.Storage_Count)
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return SSE.Storage_Count
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is
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begin
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return SC.To_Pointer (Pool.The_Pool (Chunk + SC_Size)'Address).all;
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end Next;
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--------------
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-- Set_Next --
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--------------
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procedure Set_Next
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(Pool : Stack_Bounded_Pool;
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Chunk, Next : SSE.Storage_Count)
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is
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begin
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SC.To_Pointer (Pool.The_Pool (Chunk + SC_Size)'Address).all := Next;
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end Set_Next;
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--------------
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-- Set_Size --
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--------------
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procedure Set_Size
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(Pool : Stack_Bounded_Pool;
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Chunk, Size : SSE.Storage_Count)
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is
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begin
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SC.To_Pointer (Pool.The_Pool (Chunk)'Address).all := Size;
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end Set_Size;
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----------
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-- Size --
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----------
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function Size
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(Pool : Stack_Bounded_Pool;
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Chunk : SSE.Storage_Count)
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return SSE.Storage_Count
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is
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begin
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return SC.To_Pointer (Pool.The_Pool (Chunk)'Address).all;
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end Size;
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end Variable_Size_Management;
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end System.Pool_Size;
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