COMMENT * SIMULA specification;
OPTIONS(/E:QUICK,ttycheck);
BOOLEAN PROCEDURE ttycheck(timelimit); REAL timelimit;
COMMENT Returns TRUE if at least one character has been typed on the tty,
FALSE if the time limit (seconds) has elapsed without tty input.
If 0<timelimit<0.001, TTYCHECK does not wait. If timelimit <=0, it waits
indefinitely for a character.
;

!*;! MACRO-10 code !*;!

	TITLE	ttycheck
	ENTRY	ttycheck
	SUBTTL	SIMULA utility, Lars Enderin August 1977

;!*** Copyright 1977 by the Swedish Defence Research Institute. ***
;!*** Copying is allowed.					***


	sall
	search	simmac,simmcr,simrpa
	macinit

	;! Local definitions ;!

qw==(HB.RWJ+HB.RWT+HB.RWP+HB.RTC+HB.RTL+HB.RPT) ;! Wake bits for HIBER

ttycheck:PROC
	SKIPG	X1,(XTAC)
	SETZB	X1,(XTAC)
	IF	;! small positive limit
		JUMPLE	X1,FALSE
		CAML	[1.0E-3]
		GOTO	FALSE
	THEN	;! Do not wait, check for input directly
		GOTO	L7
	FI
	SETO
	WAKE
	MOVSI	X1,qw
	HIBER	X1,	;! Clear wake conditions
	 GOTO	L2	;! Error
	SKPINC
	 SKIPA
	  GOTO	L8	;! There was a character waiting
	L	(XTAC)
	FMPRI	(1.0E3)	;! Convert to millisecs
	FIXR	X1,
	HRLI	X1,qw
	HIBER	X1,
L2():!	TDZA	X1,X1	;! Error
L7():!	SKPINC
	TDZA	X1,X1	;! No input waiting
L8():!	SETO	X1,	;! Found a character
L9():!	ST	X1,(XTAC)
	RETURN
	EPROC
	LIT
	END;