------------------------------------------------------------------------
-- Howard Eng                                                    2/94 --
-- Unixpros, Inc.                                                     --
--                                                                    --
-- This package implements a semaphore.  It is used for mutexes and   --
-- condition variables.                                               --
------------------------------------------------------------------------

with SYSTEM;
with TEXT_IO;

package body DCE_ADA_SEMAPHORE is

     task body SEMAPHORE_TASK_TYPE is

          FINISHED      : BOOLEAN := FALSE;
          WAIT_TIME     : DURATION;
          CURR_TIME     : CALENDAR.TIME;

          use CALENDAR;

     begin

          loop

               select
                    accept WAKE_ONE;

                    select 
                         accept WAIT;

                    else
                         NULL;

                    end select;

               or
                    accept WAKE_ALL;

                    loop
                         select
                              accept WAIT;
                         else
                              exit;

                         end select;

                    end loop;

               or
--
-- For the timed wait, T_OUT is the clock time that the thread should
-- be released.  The "accept" takes the difference between T_OUT and
-- the current time to derive the maximum delay time.
--
                    accept TIMED_WAIT( T_OUT : in CALENDAR.TIME ) do

                         CURR_TIME := CALENDAR.CLOCK;

                         if( CURR_TIME > T_OUT ) then
                              WAIT_TIME := DURATION( 0 );
                         else

                              WAIT_TIME := T_OUT - CURR_TIME;
                         end if;

                         select

                              accept WAKE_ONE;
                         or
                              accept WAKE_ALL;

                              loop
                                   select
                                        accept WAIT;
                                   else
                                        exit;

                                   end select;

                              end loop;
                         or
                              delay WAIT_TIME;

                         end select;

                    end TIMED_WAIT;

               or
                    accept STOP do

                         loop
                              select
                                   accept WAIT;
                              else
                                   exit;

                              end select;

                         end loop;

                    end STOP;

                    FINISHED := TRUE;

               or
--                    when FINISHED =>
                    terminate;

               end select;

          end loop;

     end SEMAPHORE_TASK_TYPE;

end DCE_ADA_SEMAPHORE;