Subversion Repositories openrisc

-- C954A03.A

--

--                             Grant of Unlimited Rights

--

--     Under contracts F33600-87-D-0337, F33600-84-D-0280, MDA903-79-C-0687,

--     F08630-91-C-0015, and DCA100-97-D-0025, the U.S. Government obtained

--     unlimited rights in the software and documentation contained herein.

--     Unlimited rights are defined in DFAR 252.227-7013(a)(19).  By making

--     this public release, the Government intends to confer upon all

--     recipients unlimited rights  equal to those held by the Government.

--     These rights include rights to use, duplicate, release or disclose the

--     released technical data and computer software in whole or in part, in

--     any manner and for any purpose whatsoever, and to have or permit others

--     to do so.

--

--                                    DISCLAIMER

--

--     ALL MATERIALS OR INFORMATION HEREIN RELEASED, MADE AVAILABLE OR

--     DISCLOSED ARE AS IS.  THE GOVERNMENT MAKES NO EXPRESS OR IMPLIED

--     WARRANTY AS TO ANY MATTER WHATSOEVER, INCLUDING THE CONDITIONS OF THE

--     SOFTWARE, DOCUMENTATION OR OTHER INFORMATION RELEASED, MADE AVAILABLE

--     OR DISCLOSED, OR THE OWNERSHIP, MERCHANTABILITY, OR FITNESS FOR A

--     PARTICULAR PURPOSE OF SAID MATERIAL.

--*

--

-- OBJECTIVE:

--      Check that a requeue statement in an accept_statement with

--      parameters may requeue the entry call to a protected entry with no

--      parameters. Check that, if the call is queued on the new entry's

--      queue, the original caller remains blocked after the requeue, but

--      the accept_statement containing the requeue is completed.

--

--      Note that this test uses a requeue "with abort," although it does not

--      check that such a requeued caller can be aborted; that feature is

--      tested elsewhere.

--

-- TEST DESCRIPTION:

--      Declare a protected type which simulates a printer device driver

--      (foundation code).

--

--      Declare a task which simulates a printer server for multiple printers.

--

--      For the protected type, declare an entry with a barrier that is set

--      false by a protected procedure (which simulates starting a print job

--      on the printer), and is set true by a second protected procedure (which

--      simulates a handler called when the printer interrupts, indicating

--      that printing is done).

--

--      For the task, declare an entry whose corresponding accept statement

--      contains a call to first protected procedure of the protected type

--      (which sets the barrier of the protected entry to false), followed by

--      a requeue with abort to the protected entry. Declare a second entry

--      which does nothing.

--

--      Declare a "requesting" task which calls the printer server task entry

--      (and thus executes the requeue). Verify that, following the requeue,

--      the requesting task remains blocked. Call the second entry of the

--      printer server task (the acceptance of this entry call verifies that

--      the requeue statement completed the entry call by the requesting task.

--      Call the second protected procedure of the protected type (the

--      interrupt handler) and verify that the protected entry completes for

--      the requesting task (which verifies that the requeue statement queued

--      the first task object to the protected entry).

--

-- TEST FILES:

--      This test depends on the following foundation code:

--

--         F954A00.A

--

--

-- CHANGE HISTORY:

--      06 Dec 94   SAIC    ACVC 2.0

--      10 Oct 96   SAIC    Added pragma elaborate.

--

--!

package C954A03_0 is  -- Printer server abstraction.

   -- Simulate a system with multiple printers. The entry Print requests

   -- that data be printed on the next available printer. The entry call

   -- is accepted when a printer is available, and completes when printing

   -- is done.

   task Printer_Server is

      entry Print (File_Name : String);        -- Test the requeue statement.

      entry Verify_Results;                    -- Artifice for test purposes.

   end Printer_Server;

end C954A03_0;

     --==================================================================--

with Report;

with ImpDef;

with F954A00;              -- Printer device abstraction.

use  F954A00;

pragma Elaborate(F954a00);

package body C954A03_0 is  -- Printer server abstraction.

   task body Printer_Server is

      Printers_Busy  : Boolean    := True;

      Index          : Printer_ID := 1;

      Print_Accepted : Boolean    := False;

   begin

      loop

         -- Wait for a printer to become available:

         while Printers_Busy loop

            Printers_Busy := False;                        -- Exit loop if

                                                           -- entry accepted.

            select

               Printer(Index).Done_Printing;               -- Accepted immed.

                                                           -- when printer is

                                                           -- available.

            else

               Index := 1 + (Index mod Number_Of_Printers);-- Entry not immed.

               Printers_Busy := True;                      -- accepted; keep

            end select;                                    -- looping.

            -- Allow other tasks to get control

            delay ImpDef.Minimum_Task_Switch;

         end loop;

                                                           -- Value of Index

                                                           -- at loop exit

                                                           -- identifies the

                                                           -- avail. printer.

         -- Wait for a print request or terminate:

         select

            accept Print (File_Name : String) do

               Print_Accepted := True;                     -- Allow

                                                           -- Verify_Results

                                                           -- to be accepted.

               Printer(Index).Start_Printing (File_Name);  -- Begin printing on

                                                           -- the available

               --                        --                -- printer.

               -- Requeue is tested here --

               --                        --

                                                           -- Requeue caller so

               requeue Printer(Index).Done_Printing        -- server task free

                 with abort;                               -- to accept other

            end Print;                                     -- requests.

         or

            -- Guard ensures that Verify_Results cannot be accepted

            -- until after Print has been accepted. This avoids a

            -- race condition in the main program.

            when Print_Accepted => accept Verify_Results;  -- Artifice for

                                                           -- testing purposes.

         or

            terminate;

         end select;

      end loop;

   exception

      when others =>

         Report.Failed ("Exception raised in Printer_Server task");

   end Printer_Server;

end C954A03_0;

     --==================================================================--

with Report;

with ImpDef;

with F954A00;    -- Printer device abstraction.

with C954A03_0;  -- Printer server abstraction.

use  C954A03_0;

use  F954A00;

procedure C954A03 is

   Long_Enough : constant Duration := ImpDef.Clear_Ready_Queue;

               --==============================================--

   Task_Completed : Boolean := False;          -- Testing flag.

   protected Interlock is                      -- Artifice for test purposes.

      entry Wait;                              -- Wait for lock to be released.

      procedure Release;                       -- Release the lock.

   private

      Locked : Boolean := True;

   end Interlock;

   protected body Interlock is

      entry Wait when not Locked is            -- Calls are queued until after

      --                                       -- Release is called.

      begin

         Task_Completed := True;

      end Wait;

      procedure Release is                     -- Called by Print_Request.

      begin

         Locked := False;

      end Release;

   end Interlock;

               --==============================================--

   task Print_Request is                       -- Send a print request.

   end Print_Request;

   task body Print_Request is

      My_File : constant String := "MYFILE.DAT";

   begin

      Printer_Server.Print (My_File);          -- Invoke requeue statement.

      Interlock.Release;                       -- Allow main to continue.

   exception

      when others =>

         Report.Failed ("Exception raised in Print_Request task");

   end Print_Request;

               --==============================================--

begin  -- Main program.

   Report.Test ("C954A03", "Requeue from an Accept with parameters" &

                              " to a Protected Entry without parameters");

   -- To pass this test, the following must be true:

   --

   --    (A) The Print entry call made by the task Print_Request must be

   --        completed by the requeue statement.

   --    (B) Print_Request must remain blocked following the requeue.

   --    (C) Print_Request must be queued on the Done_Printing queue of

   --        Printer(1).

   --    (D) Print_Request must continue execution after Done_Printing is

   --        complete.

   --

   -- First, verify (A): that the Print entry call is complete.

   --

   -- Call the entry Verify_Results. If the requeue statement completed the

   -- entry call to Print, the entry call to Verify_Results should be

   -- accepted. Since the main will hang if this is NOT the case, make this

   -- a timed entry call.

   select

      Printer_Server.Verify_Results;        -- Accepted if requeue completed

                                            -- entry call to Print.

   or

      delay Long_Enough;                    -- Time out otherwise.

      Report.Failed ("Requeue did not complete entry call");

   end select;

   -- Now verify (B): that Print_Request remains blocked following the

   -- requeue. Also verify that Done_Printing (the entry to which

   -- Print_Request should have been queued) has not yet executed.

   if Printer(1).Is_Done then

      Report.Failed ("Target entry of requeue executed prematurely");

   elsif Print_Request'Terminated then

      Report.Failed ("Caller did not remain blocked after the requeue");

   else

      -- Verify (C): that Print_Request is queued on the

      -- Done_Printing queue of Printer(1).

      --

      -- Set the barrier for Printer(1).Done_Printing to true. Check

      -- that the Done flag is updated and that Print_Request terminates.

      Printer(1).Handle_Interrupt;             -- Simulate a printer interrupt,

                                               -- signaling that printing is

                                               -- done.

      -- The Done_Printing entry body will complete before the next

      -- protected action is called (Printer(1).Is_Done).

      if not Printer(1).Is_Done then

         Report.Failed ("Caller was not requeued on target entry");

      end if;

      -- Finally, verify (D): that Print_Request continues after Done_Printing

      -- completes.

      --

      -- After Done_Printing completes, there is a potential race condition

      -- between the main program and Print_Request. The protected object

      -- Interlock is provided to ensure that the check of whether

      -- Print_Request continued is made *after* it has had a chance to do so.

      -- The main program waits until the statement in Print_Request following

      -- the requeue-causing statement has executed, then checks to see

      -- whether Print_Request did in fact continue executing.

      --

      -- Note that the test will hang here if Print_Request does not continue

      -- executing following the completion of the requeued entry call.

      Interlock.Wait;                          -- Wait until Print_Request is

                                               -- done.

      if not Task_Completed then

         Report.Failed ("Caller remained blocked after target " &

                        "entry released");

      end if;

      -- Wait for Print_Request to finish before calling Report.Result.

      while not Print_Request'Terminated loop

         delay ImpDef.Minimum_Task_Switch;

      end loop;

   end if;

   Report.Result;

end C954A03;