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-- GHDL Run Time (GRT) - Callbacks.
-- Copyright (C) 2015 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>.
--
-- 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.
package body Grt.Callbacks is
Recycled_Handles : Callback_Handle := null;
procedure Free_Handle (Hand : Callback_Handle) is
begin
Hand.Next := Recycled_Handles;
Recycled_Handles := Hand;
end Free_Handle;
function Allocate_Handle return Callback_Handle
is
Res : Callback_Handle;
begin
Res := Recycled_Handles;
if Res = null then
return new Cb_Cell;
else
Recycled_Handles := Res.Next;
return Res;
end if;
end Allocate_Handle;
procedure Register_Callback_At
(List : in out Callback_Time_List;
Handle : out Callback_Handle;
T : Std_Time;
Proc : Callback_Acc;
Arg : System.Address := System.Null_Address)
is
Last, Cur : Callback_Handle;
begin
Handle := Allocate_Handle;
Handle.all := (T => T, Mode => Timed,
Proc => Proc, Arg => Arg, Next => null);
Last := null;
Cur := List.First;
-- Insert after timeouts before (<=) T.
while Cur /= null loop
exit when Cur.T > T;
Last := Cur;
Cur := Cur.Next;
end loop;
if Last = null then
-- At head.
Handle.Next := List.First;
List.First := Handle;
List.First_Timeout := T;
else
pragma Assert (Cur = Last.Next);
Handle.Next := Cur;
Last.Next := Handle;
end if;
end Register_Callback_At;
procedure Call_Time_Callbacks (List : in out Callback_Time_List)
is
C : Callback_Handle;
begin
pragma Assert (List.First_Timeout = Current_Time);
loop
C := List.First;
if C = null then
-- No more callback.
List.First_Timeout := Std_Time'Last;
exit;
elsif C.T > Current_Time then
-- No more callbacks for current time.
List.First_Timeout := C.T;
exit;
end if;
List.First := C.Next;
-- Calling the callback may have side effects, like adding a new
-- callback. They should be in the future.
declare
Proc : constant Callback_Acc := C.Proc;
Arg : constant System.Address := C.Arg;
begin
Free_Handle (C);
Proc.all (Arg);
end;
end loop;
end Call_Time_Callbacks;
procedure Register_Callback
(List : in out Callback_List;
Handle : out Callback_Handle;
Mode : Callback_Mode;
Proc : Callback_Acc;
Arg : System.Address := System.Null_Address) is
begin
Handle := Allocate_Handle;
Handle.all := (T => 0, Mode => Mode,
Proc => Proc, Arg => Arg, Next => null);
-- Append.
if List.First = null then
pragma Assert (List.Last = null);
List.First := Handle;
else
pragma Assert (List.Last /= null);
List.Last.Next := Handle;
end if;
List.Last := Handle;
end Register_Callback;
procedure Call_Callbacks (List : in out Callback_List)
is
-- Last cell to call. Newly appended cells are not executed.
Last : constant Callback_Handle := List.Last;
Cell, Next_Cell, Prev_Cell : Callback_Handle;
begin
Cell := List.First;
if Cell = null then
return;
end if;
Prev_Cell := null;
loop
-- First, call the callback. This may change the queue (for example
-- append a new callback and therefore change the next link of that
-- cell).
declare
Proc : constant Callback_Acc := Cell.Proc;
Arg : constant System.Address := Cell.Arg;
begin
Proc.all (Arg);
end;
Next_Cell := Cell.Next;
if Cell.Mode = Oneshot then
if Prev_Cell = null then
-- First cell of the list, update head.
List.First := Next_Cell;
else
Prev_Cell.Next := Next_Cell;
end if;
if Next_Cell = null then
List.Last := Prev_Cell;
end if;
Free_Handle (Cell);
else
Prev_Cell := Cell;
end if;
exit when Cell = Last;
Cell := Next_Cell;
end loop;
end Call_Callbacks;
procedure Nop_Callback (Arg : System.Address) is
begin
null;
end Nop_Callback;
procedure Delete_Callback (Handle : Callback_Handle) is
begin
Handle.Proc := Nop_Callback'Access;
if Handle.Mode = Repeat then
-- Be sure the callback will be removed at the next call.
Handle.Mode := Oneshot;
end if;
end Delete_Callback;
function Get_First_Time (List : Callback_Time_List) return Std_Time is
begin
return List.First_Timeout;
end Get_First_Time;
function Has_Callbacks (List : Callback_List) return Boolean is
begin
return List.First /= null;
end Has_Callbacks;
end Grt.Callbacks;
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