/*--------------------------------------------- * TwoTasks.c * * DUAL TASK Demo in 16-bit Manx C * * Brian Jackson (B.J. on GEnie) * * This is just a toy that I wrote to learn how to spawn a child * task from a parent. This simply creates a second task that opens * a window and draws lines in that window (just like the parent task). * In fact, it uses the same NewWindow structure for both tasks. There * is some sharing of global variables. You can turn on/off the rendering * of the graphics in the child task with Function keys 1 & 2. This is * accomplished via message passing (as is the notification that it is * time to shut down.) Note that you cannot use any AmigaDOS calls in the * child (ie., Delay()) so the timing of things gets a bit tricky. * * I found that the main hassle is the debugging of the child. * Since a spawned task cannot use DOS calls (printf(), puts(), etc.), * it's hard to find out why things crashed. * * Like I said, this was just my own personal toy but, now that it (appears) * to work ok, I thought y'all might find it useful as an example. * * The header files listed in the program may not be complete. I use the * Manx pre-compiled headers so the compiler automatically finds ANY thing * it might need regardless of what I have listed as header files. You may * need to add some. * * This has been coded to run from the CLI. What with the numerous calls * to puts() some minor adjustments would be needed for WB use. * * compile with: cc TwoTasks.c * link with: ln TwoTasks.o -lc * * Nov 21, 1988 *-------------------------------------------------- */ #include #include #include #include #include #include #include #include #include #include #define RN 33L /* the current library revision # */ #define ACTION_START_GRAPHICS 1L #define ACTION_STOP_GRAPHICS 2L #define ACTION_CLEANUP 3L #define FKEY_1 0x50 /* IDCMP Rawkey 'code' values */ #define FKEY_2 0x51 struct IntuitionBase *IntuitionBase = NULL ; struct GfxBase *GfxBase = NULL ; struct Window *MW = NULL ; struct IntuiMessage *message = NULL ; struct Task *secondtask = NULL ; struct RastPort *rp = NULL ; struct RastPort *rp2 = NULL ; VOID TaskTwo() ; LONG errorval ; struct MyMessage { struct Message msg ; LONG Action ; } ; struct MyMessage *T2Msg ; struct NewWindow newwindow = { 0,0, 320,199, 0,1, CLOSEWINDOW| RAWKEY, WINDOWDEPTH | WINDOWDRAG | SMART_REFRESH | ACTIVATE | NOCAREREFRESH | WINDOWCLOSE, NULL, NULL, (UBYTE *)" PARENT ", NULL, NULL, 320,199, 320,199, WBENCHSCREEN }; struct MsgPort *replyport, *task2port ; VOID _cli_parse() {} /* make stubs of these */ VOID _wb_parse() {} main() { ULONG class; USHORT code ; LONG left = 20L, right = 300L, ypos = 20L, pen = 1L ; errorval = 0L ; IntuitionBase = (struct IntuitionBase *)OpenLibrary("intuition.library",RN) ; if( ! IntuitionBase ) GetOut ("Error: No Intuition"); GfxBase = (struct GfxBase *)OpenLibrary("graphics.library",RN) ; if( ! GfxBase ) GetOut ("Error: No Graphics.lib"); T2Msg = (struct MyMessage *)AllocMem((LONG)sizeof(*T2Msg), MEMF_PUBLIC) ; if( ! T2Msg ) GetOut("Couldn't alloc memory for T2Msg" ) ; replyport = (struct MsgPort *)CreatePort( 0L , 0L ) ; if( ! replyport ) GetOut( "Error: no reply port" ) ; MW = (struct Window *)OpenWindow(&newwindow) ; if( ! MW ) GetOut ("Error: No Window"); rp = MW->RPort ; secondtask = (struct Task *)CreateTask( "tasktwo", 0L, TaskTwo, 2000L) ; if( ! secondtask ) GetOut( "Can't spawn child" ) ; Delay( 20L ) ; task2port = (struct MsgPort *)FindPort( "childport" ) ; if( !task2port ) GetOut( "can't find child port" ) ; task2port->mp_Node.ln_Type = NT_MSGPORT ; task2port->mp_Flags = PA_IGNORE ; T2Msg -> msg.mn_Node.ln_Type = NT_MESSAGE ; T2Msg -> msg.mn_Length = (LONG)sizeof( struct MyMessage ) ; T2Msg -> msg.mn_ReplyPort = replyport ; SetAPen( rp, 1L ) ; Move( rp, 40L, 194L ) ; Text( rp, "F1 Stops Child Graphics", 23L ) ; FOREVER { if( errorval ) { DeleteTask( secondtask ) ; Delay( 30L ) ; GetOut( "Error: child task didn't start up properly" ) ; } while(message = (struct IntuiMessage *)GetMsg(MW->UserPort)) { class = message->Class; code = message->Code ; ReplyMsg(message); if (class == CLOSEWINDOW) { T2Msg->Action = ACTION_CLEANUP ; PutMsg( task2port, T2Msg ) ; WaitPort( replyport ) ; Delay( 20L ) ; /* wait for exec to kill child */ GetOut(NULL); } else if ( class == RAWKEY ) { if( code == FKEY_1 ) T2Msg->Action = ACTION_STOP_GRAPHICS ; else if( code == FKEY_2 ) T2Msg->Action = ACTION_START_GRAPHICS ; else break ; PutMsg( task2port, T2Msg ) ; WaitPort( replyport ) ; } } if( ++ypos > 180L) { ypos = 20L ; if( ++pen > 3L ) pen = 1L ; SetAPen( rp, pen ) ; } Move( rp, left, ypos ) ; Draw( rp, right, ypos++ ) ; Delay( 1L ) ; /* can't use this in the child! */ } /* end forever */ } /* end main */ GetOut( lastword ) TEXT *lastword ; /* Close things in REVERSE order!! */ { if(MW) CloseWindow(MW); if( replyport ) DeletePort( replyport ) ; if( T2Msg ) FreeMem( T2Msg, (LONG)sizeof( *T2Msg ) ) ; if(GfxBase) CloseLibrary(GfxBase); if(IntuitionBase) CloseLibrary(IntuitionBase); if( lastword ) puts(lastword) ; exit(0) ; } /* end function */ UBYTE blockaddress[20] ; UBYTE *title ; /* -------------------------------------------------------- * This is the child task. It's mostly just like any other * stand alone program except that you have to be careful not * to use any calls to AmigaDOS functions. (Trust me! :-)) * * The variable 'errorval' is a globals one that both tasks * know about. It's the way I let the parent know if problems * occurred during the spawning process. If an error occurs, * the child sets this variable to non-null and then goes into * an infinite Wait(), waiting for the parent to Delete the task. * * I use the same NewWindow structure except that I kill the * CloseWindow and Activate flags as well as adjust the location * of it's opening. * * One other thing to note. Because the child is always busy doing * something we just loop and check for messages as we work. If, on * the other hand, the child was to be one that was waiting for a * message before it did a single act and then waited again, I would * replace the FOREVER with a WaitPort() and do "the act" when a * message arrived. * * Also note that before I call DeleteTask() I call Forbid() but never * call Permit(). The DeleteTask() function deals with that for you. *----------------------------------------------------------- */ VOID TaskTwo() { LONG left = 20L, right = 300L, ypos = 40L, pen = 1L ; struct MsgPort *port ; struct Window *window ; struct IntuiMessage *mess ; struct MyMessage *MyMess ; LONG what_to_do, x ; BOOL do_graphics = TRUE ; geta4 () ; /* Manx mandatory for use of small code/data ! */ port = (struct MsgPort *)CreatePort( "childport", 0L ) ; if( ! port ) { errorval == 1L ; Wait( 0L ) ; } newwindow.LeftEdge = 315 ; /* fiddle with the window defs */ newwindow.Title = (UBYTE *)" CHILD " ; newwindow.Flags &= ~(WINDOWCLOSE|ACTIVATE) ; window = (struct Window *)OpenWindow(&newwindow) ; if( ! window ) { errorval = 2L ; DeletePort( port ) ; Wait( 0L ) ; } rp2 = window->RPort ; SetAPen( rp2, 1L ) ; Move( rp2, 40L, 194L ) ; Text( rp2, "F2 Starts Child Graphics", 24L ) ; FOREVER { while( MyMess = (struct MyMessage *)GetMsg( port )) { what_to_do = MyMess->Action ; ReplyMsg( MyMess ) ; if( what_to_do == ACTION_CLEANUP) { CloseWindow( window ) ; /* Forbid() will prevent any new */ /* messages from being posted to */ /* the port until we can close it */ Forbid() ; /* Make sure to empty the port */ while( MyMess = (struct MyMessage *)GetMsg( port ) ) { Remove( MyMess ) ; ReplyMsg( MyMess ) ; } DeletePort( port ) ; DeleteTask((struct Task *)FindTask(0L)) ; } else if( what_to_do == ACTION_START_GRAPHICS ) do_graphics = TRUE ; else if( what_to_do == ACTION_STOP_GRAPHICS ) do_graphics = FALSE ; } /* end while MyMess */ if( do_graphics ) { if( ++ypos > 180L) { ypos = 20L ; if( ++pen > 3L ) pen = 1L ; SetAPen( rp2, pen ) ; } Move( rp2, left, ypos ) ; Draw( rp2, right, ypos++ ) ; } } /* end forever */ }