10      !+ 
        !This VAX BASIC program creates three virtual displays on 
        !one pasteboard. 
        ! 
        !The first virtual display contains instructions for the user, 
        !the second shows trapped unsolicited input, and the third 
        !lists trapped broadcast messages. The program sits in an 
        !infinite loop until the user types a Ctrl/Z. 
        ! 
        !When the program traps unsolicited input, both broadcast message 
        !and unsolicited input trapping are disabled, and a subprocess 
        !is spawned which executes the trapped user input. 
        ! 
        !When control returns to the main process, broadcast trapping and 
        !the trapping of unsolicited input are both reenabled. If the 
        !unsolicited input which is trapped is a Ctrl/Z, the program exits. 
        !- 
 
        OPTION TYPE = EXPLICIT 
 
        !+ 
        !Declaration of all routines called by the main program. 
        !- 
 
        %INCLUDE "LIB$ROUTINES" %FROM %LIBRARY "SYS$LIBRARY:BASIC$STARLET"  
        %INCLUDE "SMG$ROUTINES" %FROM %LIBRARY "SYS$LIBRARY:BASIC$STARLET"  
 
        !+ 
        !Declaration of the two AST routines: 
        !GET_MSG is called when a broadcast message is trapped 
        !GET_INPUT is called when there is unsolicited input 
        !GET_INPUT is the routine which spawns the subprocess 
        !- 
 
        EXTERNAL INTEGER GET_MSG 
        EXTERNAL INTEGER GET_INPUT 
 
        DECLARE LONG pb_id, ret_status, display_id, display2_id, display3_id, & 
                     key_id, key_tab_id, counter 
 
        !+ 
        !Create a MAP area for variables which must be shared between the 
        !main program and the AST routines. 
        !- 
 
        MAP (params) LONG disp_info(2), LONG keyboard_info(4), LONG done_flag 
 
        DECLARE STRING CONSTANT top_label = "User Input" 
        DECLARE STRING CONSTANT ins_label = "Instructions" 
        DECLARE STRING CONSTANT msg_label = "Messages" 
        DECLARE STRING CONSTANT instr_0 = "Type commands to fill INPUT display." 
        DECLARE STRING CONSTANT instr_1 = "Type Ctrl/T to fill MESSAGES display." 
        DECLARE STRING CONSTANT instr_2 = "Type Ctrl/Z to exit." 
        DECLARE LONG CONSTANT   advance = 1 
 
        %INCLUDE "$SMGDEF" %FROM %LIBRARY "SYS$LIBRARY:BASIC$STARLET"  
        %INCLUDE "$SMGMSG" %FROM %LIBRARY "SYS$LIBRARY:BASIC$STARLET"  
 
        !+ 
        !The done_flag variable is clear (0) unless the user input was 
        !a Ctrl/Z. In that case, the program exits. 
        !- 
        done_flag = 0 
 
        !+ 
        !Create the pasteboard and the virtual keyboard 
        !- 
 
        ret_status = SMG$CREATE_PASTEBOARD (pb_id) 
        IF (ret_status AND 1%) = 0% THEN 
           CALL LIB$STOP(ret_status BY VALUE) 
        END IF 
 
        !+ 
        !This is one of the values which must be stored in the MAP area. 
        !- 
 
        disp_info(0) = pb_id 
 
        ret_status = SMG$CREATE_VIRTUAL_KEYBOARD (key_id) 
        IF (ret_status AND 1%) = 0% THEN 
           CALL LIB$STOP(ret_status BY VALUE) 
        END IF 
 
        ret_status = SMG$CREATE_KEY_TABLE (key_tab_id) 
        IF (ret_status AND 1%) = 0% THEN 
           CALL LIB$STOP(ret_status BY VALUE) 
        END IF 
 
 
        !+ 
        !Create the three virtual displays 
        !- 
 
        ret_status = SMG$CREATE_VIRTUAL_DISPLAY(3 BY REF, 75 BY REF, & 
                display3_id, SMG$M_BORDER BY REF, SMG$M_REVERSE BY REF) 
        IF (ret_status AND 1%) = 0% THEN 
           CALL LIB$STOP(ret_status BY VALUE) 
        END IF 
 
        ret_status = SMG$CREATE_VIRTUAL_DISPLAY(6 BY REF, 75 BY REF, & 
                display_id, SMG$M_BORDER BY REF, SMG$M_REVERSE BY REF) 
        IF (ret_status AND 1%) = 0% THEN 
           CALL LIB$STOP(ret_status BY VALUE) 
        END IF 
 
        ret_status = SMG$CREATE_VIRTUAL_DISPLAY(6 BY REF, 75 BY REF, & 
                display2_id, SMG$M_BORDER BY REF, SMG$M_REVERSE BY REF) 
        IF (ret_status AND 1%) = 0% THEN 
           CALL LIB$STOP(ret_status BY VALUE) 
        END IF 
 
        !+ 
        !The disp_info and keyboard_info arrays are required in the MAP. 
        !- 
        disp_info(1) = display2_id 
 
 
        keyboard_info(0) = key_id 
        keyboard_info(1) = key_tab_id 
        keyboard_info(2) = display_id 
        keyboard_info(4) = pb_id 
 
        !+ 
        !Put Label borders around the three virtual displays. 
        !- 
 
        ret_status = SMG$LABEL_BORDER (display3_id, ins_label,,, & 
                SMG$M_BOLD BY REF, SMG$M_REVERSE BY REF) 
        IF (ret_status AND 1%) = 0% THEN 
           CALL LIB$STOP(ret_status BY VALUE) 
        END IF 
 
        ret_status = SMG$LABEL_BORDER (display_id, top_label,,, & 
                SMG$M_BOLD BY REF,) 
        IF (ret_status AND 1%) = 0% THEN 
           CALL LIB$STOP(ret_status BY VALUE) 
        END IF 
 
        ret_status = SMG$LABEL_BORDER (display2_id, msg_label,,, & 
                SMG$M_BOLD BY REF,) 
        IF (ret_status AND 1%) = 0% THEN 
           CALL LIB$STOP(ret_status BY VALUE) 
        END IF 
 
 
        !+ 
        !Fill the INSTRUCTIONS virtual display with user instructions. 
        !- 
 
        ret_status = SMG$PUT_LINE(display3_id, instr_0, & 
    advance,,, smg$m_wrap_char) 
        IF (ret_status AND 1%) = 0% THEN 
           CALL LIB$STOP(ret_status BY VALUE) 
        END IF 
 
        ret_status = SMG$PUT_LINE(display3_id, instr_1, & 
    advance,,, smg$m_wrap_char) 
        IF (ret_status AND 1%) = 0% THEN 
           CALL LIB$STOP(ret_status BY VALUE) 
        END IF 
 
        ret_status = SMG$PUT_LINE(display3_id, instr_2, & 
    advance,,, smg$m_wrap_char) 
        IF (ret_status AND 1%) = 0% THEN 
           CALL LIB$STOP(ret_status BY VALUE) 
        END IF 
 
 
        !+ 
        !Paste the virtual displays to the screen. 
        !- 
 
        ret_status = SMG$PASTE_VIRTUAL_DISPLAY(display3_id, pb_id, & 
                2 BY REF, 4 BY REF) 
        IF (ret_status AND 1%) = 0% THEN 
           CALL LIB$STOP(ret_status BY VALUE) 
        END IF 
 
        ret_status = SMG$PASTE_VIRTUAL_DISPLAY(display_id, pb_id, & 
                8 BY REF, 4 BY REF) 
        IF (ret_status AND 1%) = 0% THEN 
           CALL LIB$STOP(ret_status BY VALUE) 
        END IF 
 
        ret_status = SMG$PASTE_VIRTUAL_DISPLAY(display2_id, pb_id, & 
                18 BY REF, 4 BY REF) 
        IF (ret_status AND 1%) = 0% THEN 
           CALL LIB$STOP(ret_status BY VALUE) 
        END IF 
 
 
        !+ 
        !Enable the trapping of unsolicited input. GET_INPUT is the 
        !AST procedure that is called when unsolicited input is 
        !received. This AST has one parameter, passed as null. 
        !- 
 
        ret_status = SMG$ENABLE_UNSOLICITED_INPUT(pb_id, LOC(GET_INPUT)) 
        IF (ret_status AND 1%) = 0% THEN 
           CALL LIB$STOP(ret_status BY VALUE) 
        END IF 
 
        !+ 
        !Enable the trapping of broadcast messages. GET_MSG is the 
        !AST which is called when broadcast messages are received. 
        !This AST outputs the trapped message into the MESSAGES display. 
        !- 
 
        ret_status = SMG$SET_BROADCAST_TRAPPING(pb_id, LOC(GET_MSG)) 
        IF (ret_status AND 1%) = 0% THEN 
           CALL LIB$STOP(ret_status BY VALUE) 
        END IF 
 
        !+ 
        !This loop continually executes until done_flag is set to 1. 
        !Done_flag is set to 1 when the user input is a Ctrl/Z. 
        !If done_flag is 1, delete the pasteboard and exit the program. 
        !- 
 
      Infinite_loop: 
        IF done_flag = 0 THEN 
           GOTO infinite_loop 
        ELSE 
           ret_status = SMG$DELETE_PASTEBOARD (pb_id) 
           GOTO all_done 
        END IF 
 
     All_done: 
        END 
 
20      !+ 
        !Start of AST routine GET_INPUT. This AST is called whenever there 
        !is unsolicited input. The unsolicited input is displayed in the 
        !INPUT virtual display, and if this input is not Ctrl/Z, a subprocess 
        !is spawned and the input command is executed. While this spawned 
        !subprocess is executing, broadcast and unsolicited input trapping 
        !are disabled. 
        !- 
 
        SUB GET_INPUT (paste_id, param, nl_1, nl_2, nl_3, nl_4) 
 
        MAP (params) LONG disp_info(2), LONG keyboard_info(4), LONG done_flag 
 
        DECLARE LONG z_status, status2, keybd_id, keybd_tab_id, disp_id, & 
                     pastebd, new_display, spawn_status 
        DECLARE WORD msg2_len 
        DECLARE STRING msg2 
        DECLARE LONG CONSTANT next_line = 1 
 
        %INCLUDE "SMG$ROUTINES" %FROM %LIBRARY "SYS$LIBRARY:BASIC$STARLET"  
        %INCLUDE "LIB$ROUTINES" %FROM %LIBRARY "SYS$LIBRARY:BASIC$STARLET"  
        %INCLUDE "$SMGMSG" %FROM %LIBRARY "SYS$LIBRARY:BASIC$STARLET"  
 
        EXTERNAL INTEGER GET_MSG 
        EXTERNAL INTEGER GET_INPUT 
        
        !+ 
        !Assign to the local variables the values that were stored from 
        !the main program using the MAP area. 
        !- 
 
        keybd_id = keyboard_info(0) 
        keybd_tab_id = keyboard_info(1) 
        disp_id = keyboard_info(2) 
        pastebd = keyboard_info(3) 
 
        !+ 
        !SMG$ENABLE_UNSOLICITED_INPUT does not read the input, it simply 
        !signals the specified AST when there is unsolicited input present. 
        !You must use SMG$READ_COMPOSED_LINE to actually read the input. 
        ! 
        !At this time, we check to see if the unsolicited input was a Ctrl/Z. 
        !If so, we skip over the program lines that spawn the subprocess and 
        !get ready to exit the program. 
        !- 
 
        status2 = SMG$READ_COMPOSED_LINE (keybd_id, keybd_tab_id, msg2,, & 
                   msg2_len, disp_id) 
        IF (status2 = SMG$_EOF) THEN 
           GOTO Control_Z 
        END IF 
 
        IF (status2 AND 1%) = 0% THEN 
           CALL LIB$STOP (status2 BY VALUE) 
        END IF 
 
        !+ 
        !In order to spawn a subprocess, we must first disable 
        !unsolicited input trapping and broadcast trapping. 
        !- 
 
        status2 = SMG$DISABLE_UNSOLICITED_INPUT (pastebd) 
        IF (status2 AND 1%) = 0% THEN 
           CALL LIB$STOP (status2 BY VALUE) 
        END IF 
 
        status2 = SMG$DISABLE_BROADCAST_TRAPPING (pastebd) 
        IF (status2 AND 1%) = 0% THEN 
           CALL LIB$STOP (status2 BY VALUE) 
        END IF 
 
 
        !+ 
        !Save the current screen so that it will not be destroyed when 
        !the subprocess is executing. 
        !- 
 
        status2 = SMG$SAVE_PHYSICAL_SCREEN (pastebd, new_display) 
        IF (status2 AND 1%) = 0% THEN 
           CALL LIB$STOP (status2 BY VALUE) 
        END IF 
 
        !+ 
        !Call LIB$SPAWN to create the subprocess, and pass the unsolicited 
        !input as the command line. 
        !- 
 
        spawn_status = LIB$SPAWN (msg2) 
 
        !+ 
        !Restore the saved screen image. 
        !- 
 
        status2 = SMG$RESTORE_PHYSICAL_SCREEN (pastebd, new_display) 
        IF (status2 AND 1%) = 0% THEN 
           CALL LIB$STOP (status2 BY VALUE) 
        END IF 
 
        !+ 
        !Reenable broadcast trapping and unsolicited input trapping. 
        !- 
 
        status2 = SMG$ENABLE_UNSOLICITED_INPUT (pastebd, LOC(GET_INPUT)) 
        IF (status2 AND 1%) = 0% THEN 
           CALL LIB$STOP (status2 BY VALUE) 
        END IF 
 
        status2 = SMG$SET_BROADCAST_TRAPPING (pastebd, LOC(GET_MSG)) 
        IF (status2 AND 1%) = 0% THEN 
           CALL LIB$STOP (status2 BY VALUE) 
        END IF 
 
        !+ 
        !Skip the steps which are performed if the unsolicited input 
        !was a Ctrl/Z. 
        !- 
 
        GOTO Out_of_sub 
 
      Control_Z: 
        !+ 
        !We should disable unsolicited input and broadcast trapping 
        !before we leave the program. 
        !- 
 
        status2 = SMG$DISABLE_UNSOLICITED_INPUT (pastebd) 
        IF (status2 AND 1%) = 0% THEN 
           CALL LIB$STOP (status2 BY VALUE) 
        END IF 
        status2 = SMG$DISABLE_BROADCAST_TRAPPING (pastebd) 
        IF (status2 AND 1%) = 0% THEN 
           CALL LIB$STOP (status2 BY VALUE) 
        END IF 
 
        !+ 
        !Set the done_flag to 1 so that the main program knows we have 
        !to exit. 
        !- 
 
        done_flag = 1 
 
      Out_of_sub: 
        END SUB 
 
30      !+ 
        !Start of AST routine GET_MSG. This AST is called whenever there 
        !is a broadcast message. This routine prints the message in the 
        !MESSAGES virtual display. 
        !- 
 
        SUB GET_MSG (paste_id, nl_1, nl_2, nl_3, nl_4) 
        DECLARE LONG status1, pasteboard, second_disp 
        DECLARE WORD msg_len 
        DECLARE STRING msg 
        DECLARE LONG CONSTANT forward = 1 
 
        MAP (params) LONG disp_info(2), LONG keyboard_info(4) 
 
        %INCLUDE "SMG$ROUTINES" %FROM %LIBRARY "SYS$LIBRARY:BASIC$STARLET"  
        %INCLUDE "LIB$ROUTINES" %FROM %LIBRARY "SYS$LIBRARY:BASIC$STARLET"  
        %INCLUDE "$SMGDEF" %FROM %LIBRARY "SYS$LIBRARY:BASIC$STARLET"  
        %INCLUDE "$SMGMSG" %FROM %LIBRARY "SYS$LIBRARY:BASIC$STARLET"  
 
        !+ 
        !Assign values to the local variables according to the values stored 
        !in the MAP area. 
        !- 
 
        pasteboard  = disp_info(0) 
        second_disp = disp_info(1) 
 
        !+ 
        !Print the trapped message in the MESSAGES display. If there are no 
        !more messages, go back to the infinite loop in the main program. 
        !- 
 
        WHILE 1 
              status1 = SMG$GET_BROADCAST_MESSAGE (pasteboard, msg, msg_len) 
              IF (status1 = SMG$_NO_MORMSG) THEN 
                 GOTO Exitloop 
              END IF 
              IF (status1 AND 1%) = 0% THEN 
                 CALL LIB$STOP (status1 BY VALUE) 
              END IF 
 
              status1 = SMG$PUT_LINE (second_disp, msg, & 
     forward,,, SMG$M_WRAP_CHAR) 
              IF (status1 AND 1%) = 0% THEN 
                 CALL LIB$STOP (status1 BY VALUE) 
              END IF 
        NEXT 
    Exitloop: 
        END SUB