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-- Efficient expandable one dimensional array.
-- Copyright (C) 2015 Tristan Gingold
--
-- GHDL 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, or (at your option) any later
-- version.
--
-- GHDL 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 GHDL; see the file COPYING. If not, write to the Free
-- Software Foundation, 59 Temple Place - Suite 330, Boston, MA
-- 02111-1307, USA.
with Interfaces.C; use Interfaces.C;
with System;
package body Tables is
-- Number of allocated elements in the table.
Length : Natural := 0;
-- Number of used elements in the table.
Last_Pos : Natural := 0;
-- Size of an element in storage units (bytes).
El_Size : constant size_t :=
size_t (Table_Type'Component_Size / System.Storage_Unit);
-- Expand the table by doubling its size. The table must have been
-- initialized.
procedure Expand (Num : Natural)
is
-- For efficiency, directly call realloc.
function Crealloc (Ptr : Table_Thin_Ptr; Size : size_t)
return Table_Thin_Ptr;
pragma Import (C, Crealloc, "realloc");
begin
pragma Assert (Length /= 0);
pragma Assert (Table /= null);
-- Expand the bound.
Last_Pos := Last_Pos + Num;
-- Check if need to reallocate.
if Last_Pos < Length then
return;
else
-- Double the length.
loop
Length := Length * 2;
exit when Length > Last_Pos;
end loop;
end if;
-- Realloc and check result.
Table := Crealloc (Table, size_t (Length) * El_Size);
if Table = null then
raise Storage_Error;
end if;
end Expand;
function Allocate (Num : Natural := 1) return Table_Index_Type
is
Res : constant Table_Index_Type := Table_Index_Type'Val
(Table_Index_Type'Pos (Table_Low_Bound) + Last_Pos);
begin
Expand (Num);
return Res;
end Allocate;
procedure Increment_Last is
begin
-- Increase by 1.
Expand (1);
end Increment_Last;
procedure Decrement_Last is
begin
Last_Pos := Last_Pos - 1;
end Decrement_Last;
procedure Set_Last (Index : Table_Index_Type)
is
New_Last : constant Natural :=
(Table_Index_Type'Pos (Index)
- Table_Index_Type'Pos (Table_Low_Bound) + 1);
begin
if New_Last < Last_Pos then
-- Decrease length.
Last_Pos := New_Last;
else
-- Increase length.
Expand (New_Last - Last_Pos);
end if;
end Set_Last;
procedure Init
is
-- Direct interface to malloc.
function Cmalloc (Size : size_t) return Table_Thin_Ptr;
pragma Import (C, Cmalloc, "malloc");
begin
if Table = null then
-- Allocate memory if not already allocated.
Length := Table_Initial;
Table := Cmalloc (size_t (Length) * El_Size);
end if;
-- Table is initially empty.
Last_Pos := 0;
end Init;
function Last return Table_Index_Type is
begin
return Table_Index_Type'Val
(Table_Index_Type'Pos (Table_Low_Bound) + Last_Pos - 1);
end Last;
procedure Free is
-- Direct interface to free.
procedure Cfree (Ptr : Table_Thin_Ptr);
pragma Import (C, Cfree, "free");
begin
Cfree (Table);
Table := null;
Length := 0;
Last_Pos := 0;
end Free;
procedure Append (Val : Table_Component_Type) is
begin
Increment_Last;
Table (Last) := Val;
end Append;
begin
Init;
end Tables;
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