/********************************************************************
/********************************************************************
/ ASYNCHRONOUS DISPLAY OUTPUT SUPPORT

/ THE DISPLAY OPERATES IN AN INTERRUPT DRIVEN MANNER IN ITS OWN
/ THREAD. IF THERE IS NO DISPLAY OPERATION PENDING, IT FALLS
/ ASLEEP.

DINIT,	0		/ CALLED BY MAIN THREAD
	TCF		/ CLEAR TELEPRINTER FLAG
	DCA	DTMP	/ SAVE AC FOR A LITTLE MOMENT
	TAD	PDPROC	/ GET POINTER TO DISPLAY PROCESS ENTRY
	DCA	TTOUT	/ GENERATE RETURN ADDRESS
	DCA	TTAC
	DCA	TTL
	DCA	DFLAGS	/ CLEAR DISPLAY COMMAND FLAGS
	TAD	DTMP	/ RESTORE CALLER'S AC
	JMP I	DINIT	/ RETURN TO CALLING THREAD
	
DSUB,	0		/ SUBMIT A FLAG TO SET
	CMA	
	DCA	TMP	/ SAVE INVERSE OF FLAG
	CLL		/ CLEAR LINK
	TAD	DFLAGS
	SNA	
	CML		/ LINK INDICATES RESTART NOW
	CMA
	AND	TMP
	CMA
	DCA	DFLAGS	/ NEW DFLAGS HAVE BEEN INSTALLED.
	SZL		/ SKIP IF NO LINK
	SPF		/ SET TTO FLAG -> DISPLAY RESUME
	ION
	JMP I	DSUB
	
/*************************************************
DPROC,		/ ENTRY POINT TO THE DISPLAY PROCESS.
	/....

	/ TEST, SLEEP, RESTART
	CLA CLL
	TAD	DFLAGS
	SZA	
	JMP	DPROC	/ WORK TO DO
	TFC		/ CLEAR FLAG, NO WORK TO DO.
	JMS	TTOUT	/ DUMMY TYPING WITHOUT TLS
	JMP	DPROC	/ AND JUMP BACK TO START OF THREAD
		



PDPROC,	DPROC	/ POINTER TO DISPLAY PROCESS
TTAC,	0
TTL,	0
DTMP,	0

/********************************************************************
/ TELETYPE OUTPUT HANDLER AND MANAGEMENT


TTOUT,	0		/ SEND CHARACTER - CALLED FROM DISPLAY THREAD!
	TSF		/ IF NO FLAG - GO SLEEPING ONLY
	SKP
	TLS		/ GET IT OUT!
	DCA	TTAC	/ SAVE AC, JUST POLITE
	RAR
	DCA	TTL	/ SAVE LINK, STILL POLITE
	JMP	IEND	/ END OF INTERRUPT HANDLING
TTOHAN,	TAD	TTL
	RAL
	TAD	TTAC
	JMP I	TTOUT	/ RESUME DISPLAY THREAD