Re: Device file not closing on close command

["Pat Rogers" <progers@classwide.com>]

Procedure access_dev is the master of task TtyS2.  Since you never told
TtyS2 to quit it is still running, so access_dev can not complete.  Call the
"quit" entry after you call the "close" entry.

---
Patrick Rogers                       Consulting and Training in:
http://www.classwide.com          Real-Time/OO Languages
progers@classwide.com               Hard Deadline Schedulability Analysis
(281)648-3165                                 Software Fault Tolerance


"Tilman Gloetzner" <Tilman.Gloetzner@uundz.de> wrote in message
news:3B0D5544.ED114B7E@uundz.de...
> Hi,
>
> the program below controls a task handeling a serial device. The task
> opens the device file, and 5 secs later the device file should be
> closed. When running the program below, the device is opened, but when
> the time comes to close the device the task just blocks on the
> closecommand. If I open and close the device from the main procedure it
> just works fine. The device is connected to a GPS receiver which is
> constantly sending data. I am using gnat 3.13 onlinux (2.1.18) and linux
> native threads.
>
> Why does the task block(is it because there is still unread data in the
> device -- but why would it work then if I open and close the device from
> the main procedure rather than from the task ?) ? How can I make the
> task close the file right away ?
>
>
> Thank you,
>
> Tilman
>
>
>
> ================== main =====================
> with Text_IO;use Text_IO;
> with Device;use Device;
>
> procedure access_dev is
>    TtyS2:   DevTask;
>    In_Stream: File_Type;
> begin
>    TtyS2.Open("/dev/ttyS2");
>    delay(5.0);
>    Put_Line("waited for 5 secs");
>    TtyS2.Close;
>
> end access_dev;
>
> =============== package specification ==============
> package Device is
>    task type DevTask is
>       entry Open(Dev:String);
>       entry Close;
>       entry Quit;
>    end DevTask;
> end Device;
> ============== package body =======================
> with Text_Io;use Text_Io;
> with Device; use Device;
> package body Device is
>       task body DevTask is
>          Exit_Flag: Boolean := False;
>          In_Stream: File_Type;
>          Buf:       String(1..82);
>          Noc:       Integer := 0;
>       begin
>          while (Exit_Flag = False) loop
>             select
>                accept Open(Dev:String) do
>                   Put_Line("Openening Device " & Dev );
>                   Open(In_Stream,IN_FILE, "/dev/ttyS2");
>                   Put_Line("Device opened");
>                end Open;
>             or
>                accept Close do
>                   --if (Is_Open(In_Stream)) then
>                      Put_Line("Closing Device");
>                      Close(In_Stream);
>                      Put_Line("Device closed");
>             --      end if;
>                end Close;
>             or
>                accept Quit do
>                   Exit_Flag := True;
>                end Quit;
>             or
>                delay(0.0);
> --               if (Is_Open(In_Stream)) then
>                    Get_Line(In_Stream,Buf,Noc);
>                    Put_Line(Buf(1..Noc));
> --               end if;
>             end select;
>          end loop;
>        Put_line("Task terminated");
>       end DevTask;
> end Device;
>