IMPLEMENTATION MODULE KTrace;

	(****************************************************************)
	(*								*)
	(*	Trace routines for Modula 2 program development.	*)
	(*								*)
	(*  This is the version which does NOT use windows.  It is	*)
	(*  intended for low-level tracing of the kernel, where a	*)
	(*  window-based tracing facility would be unsuitable because	*)
	(*  of critical section problems.  However, it is quite		*)
	(*  adequate for any application where we don't care too much	*)
	(*  about a pretty screen layout.				*)
	(*								*)
	(*  Note, however, that this module is missing the "Press any	*)
	(*  key to continue" option which my other trace modules have.	*)
	(*								*)
	(*  Programmer:		P. Moylan				*)
	(*  Last edited:	6 February 1989				*)
	(*  Status:		OK					*)
	(*								*)
	(****************************************************************)

FROM GlassTTY IMPORT
    (* proc *)	WriteString, WriteLn, WriteHexWord;

FROM MiscPMOS IMPORT
    (* proc *)	ProcessorStatus;

VAR TraceEnabled: BOOLEAN;
    nesting: CARDINAL;

(************************************************************************)

PROCEDURE NYI (name: ARRAY OF CHAR);

    (* Types a "not yet implemented" message.	*)

    BEGIN
	WriteString (name);  WriteString (" is not yet implemented.");
	WriteLn;
    END NYI;

(************************************************************************)

PROCEDURE InTrace (name: ARRAY OF CHAR);

    (* To be called when entering a procedure.	*)

    VAR j: CARDINAL;

    BEGIN
	IF TraceEnabled THEN
	    FOR j := 1 TO nesting DO
		WriteString ("   ");
	    END (*FOR*);
	    WriteString ("Entering ");  WriteString (name);
	    WriteString (" <");  WriteHexWord (ProcessorStatus());
	    WriteString (">");
	    WriteLn;
	END (*IF*);
	INC (nesting);
    END InTrace;

(************************************************************************)

PROCEDURE OutTrace (name: ARRAY OF CHAR);

    (* To be called when leaving a procedure.	*)

    VAR j: CARDINAL;

    BEGIN
	DEC (nesting);
	IF TraceEnabled THEN
	    FOR j := 1 TO nesting DO
		WriteString ("   ");
	    END (*FOR*);
	    WriteString ("Leaving ");  WriteString (name);
	    WriteString (" <");  WriteHexWord (ProcessorStatus());
	    WriteString (">");
	    WriteLn;
	END (*IF*);
    END OutTrace;

(************************************************************************)

PROCEDURE TraceOn;

    (* Turns tracing on.		*)

    BEGIN
	TraceEnabled := TRUE;
    END TraceOn;

(************************************************************************)

PROCEDURE TraceOff;

    (* Turns tracing off.		*)

    BEGIN
	TraceEnabled := FALSE;
    END TraceOff;

(************************************************************************)

PROCEDURE TraceStatus (): BOOLEAN;

    (* Says whether tracing is currently on.		*)

    BEGIN
	RETURN TraceEnabled;
    END TraceStatus;

(************************************************************************)
(*				INITIALISATION				*)
(************************************************************************)

BEGIN
    TraceEnabled := FALSE;  nesting := 0;
END KTrace.