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-- Area based memory manager
-- Copyright (C) 2014 Tristan Gingold
--
-- This program is free software: you can redistribute it and/or modify
-- it under the terms of the GNU General Public License as published by
-- the Free Software Foundation, either version 2 of the License, or
-- (at your option) any later version.
--
-- This program is distributed in the hope that it will be useful,
-- but WITHOUT 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
-- along with this program. If not, see <gnu.org/licenses>.
with Ada.Unchecked_Deallocation;
package body Areapools is
procedure Deallocate is new Ada.Unchecked_Deallocation
(Chunk_Type, Chunk_Acc);
Free_Chunks : Chunk_Acc;
function Get_Chunk return Chunk_Acc is
Res : Chunk_Acc;
begin
if Free_Chunks /= null then
Res := Free_Chunks;
Free_Chunks := Res.Prev;
return Res;
else
return new Chunk_Type (Default_Chunk_Size - 1);
end if;
end Get_Chunk;
procedure Free_Chunk (Chunk : Chunk_Acc) is
begin
Chunk.Prev := Free_Chunks;
Free_Chunks := Chunk;
end Free_Chunk;
procedure Allocate (Pool : in out Areapool;
Res : out Address;
Size : Size_Type;
Align : Size_Type)
is
Align_M1 : constant Size_Type := Align - 1;
function Do_Align (X : Size_Type) return Size_Type is
begin
return (X + Align_M1) and not Align_M1;
end Do_Align;
Chunk : Chunk_Acc;
begin
-- Need to allocate a new chunk if there is no current chunk, or not
-- enough room in the current chunk.
if Pool.Last = null
or else Do_Align (Pool.Next_Use) + Size > Pool.Last.Last
then
if Size > Default_Chunk_Size then
Chunk := new Chunk_Type (Size - 1);
else
Chunk := Get_Chunk;
end if;
Chunk.Prev := Pool.Last;
Pool.Next_Use := 0;
if Pool.First = null then
Pool.First := Chunk;
end if;
Pool.Last := Chunk;
else
Chunk := Pool.Last;
Pool.Next_Use := Do_Align (Pool.Next_Use);
end if;
Res := Chunk.Data (Pool.Next_Use)'Address;
Pool.Next_Use := Pool.Next_Use + Size;
end Allocate;
procedure Mark (M : out Mark_Type; Pool : Areapool) is
begin
M := (Last => Pool.Last, Next_Use => Pool.Next_Use);
end Mark;
procedure Release (M : Mark_Type; Pool : in out Areapool)
is
Chunk : Chunk_Acc;
Prev : Chunk_Acc;
begin
Chunk := Pool.Last;
while Chunk /= M.Last loop
if Erase_When_Released then
Chunk.Data := (others => 16#DE#);
end if;
Prev := Chunk.Prev;
if Chunk.Last = Default_Chunk_Size - 1 then
Free_Chunk (Chunk);
else
Deallocate (Chunk);
end if;
Chunk := Prev;
end loop;
if Erase_When_Released
and then M.Last /= null
and then M.Next_Use /= 0
then
declare
Last : Size_Type;
begin
if Pool.Last = M.Last then
Last := Pool.Next_Use - 1;
else
Last := Chunk.Data'Last;
end if;
Chunk.Data (M.Next_Use .. Last) := (others => 16#DE#);
end;
end if;
Pool.Last := M.Last;
Pool.Next_Use := M.Next_Use;
end Release;
function Is_Empty (Pool : Areapool) return Boolean is
begin
return Pool.Last = null;
end Is_Empty;
function Is_At_Mark (Pool : Areapool; M : Mark_Type) return Boolean is
begin
return Pool.Last = M.Last and Pool.Next_Use = M.Next_Use;
end Is_At_Mark;
function Alloc_On_Pool_Addr (Pool : Areapool_Acc; Val : T)
return System.Address
is
Res : Address;
begin
Allocate (Pool.all, Res, T'Size / Storage_Unit, T'Alignment);
declare
Addr1 : constant Address := Res;
Init : T := Val;
for Init'Address use Addr1;
begin
null;
end;
return Res;
end Alloc_On_Pool_Addr;
end Areapools;
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