Asynchronous Terminals and Printer Processes Programming Manual

TERMINAL PROGRAMMING CONSIDERATIONS
Using Break (Single Process per Terminal)
INT BREAK^RECEIVED := 0,
.RECV^BUF[ 0:66 ];
Enable BREAK by calling SETMODE 11 and passing the file number
of the terminal and the CPU and process ID number ( pin ) of the
owner. For example:
| CALL SETMODE (TERM^NUM, SET^BREAK^OWNER, ME, NORMAL^MODE);
|
|
| ME is the value returned by the MYPID procedure. MYPID is a
| process-control procedure that returns the CPU and process ID of
| the caller. Following this call to SETMODE, the file system
monitors TERM^NUM for a break signal. If BREAK is pressed, a
system break message is sent to this process.
Issue a READ to the $RECEIVE file (open as a nowait file):
CALL READ ( RECV^FNUM, RECV^BUF, 132 );
Then periodically check $RECEIVE:
ERROR := 0;
CALL AWAITIO ( RECV^FNUM,, NUM^READ,, 0D );
IF = THEN ... ! user msg received
ELSE
IF > THEN ! system msg received
BEGIN
IF RECV^BUF = -20 THEN ! BREAK message
BREAK^RECEIVED := 1;
This procedure sets a flag that indicates that BREAK was pressed.
The break is processed in another part of the program:
ELSE
IF RECV^BUF = ... THEN ! another system message
END
ELSE ! error
CALL FILEINFO ( RECV^FNUM, ERROR );
! if read on $RECEIVE completed, issue another
IF ERROR <> 40 ! timeout
THEN
CALL READ ( RECV^FNUM, RECV^BUF, 132 );
4-16 November 1987