DEFINITION MODULE Music3S;

	(********************************************************)
	(*							*)
	(*		Translates 3-part music from		*)
	(*		musical notation to the form		*)
	(*		expected by module Play3S.		*)
	(*							*)
	(*  Programmer:		P. Moylan			*)
	(*  Last edited:	21 March 1995			*)
	(*  Status:		OK				*)
	(*							*)
	(********************************************************)

TYPE
    VoiceNumber = [1..3];
    WaveformNumber = [0..7];

(************************************************************************)
(*									*)
(*  In the "notes" argument to each of the next three procedures,	*)
(*  the following options are accepted:					*)
(*	C D E F G A B	the usual notation for a note.			*)
(*	b #		flat or sharp, modifying the previously given	*)
(*			 note.  There is no legality checking; for	*)
(*			 example, B# is illegal but the software does	*)
(*			 check for this.				*)
(*	R		a rest.						*)
(*	*n   (n=0..9)	multiply the duration of the following notes	*)
(*			 by n.						*)
(*	*		a shorthand notation for *2.			*)
(*	/n   (n=0..9)	divide the duration of the following notes	*)
(*			 by n.						*)
(*	/		a shorthand notation for /2.			*)
(*	3		a shorthand notation for /3.			*)
(*			The *, /, and 3 options take effect for		*)
(*			 all following notes, until the duration is	*)
(*			 modified again by one of these options.	*)
(*	u		go up one octave.				*)
(*	d		go down one octave.  In many cases the u and d	*)
(*			 options are not needed because this module	*)
(*			 chooses the appropriate octave based on the	*)
(*			 assumption that successive notes will be	*)
(*			 close to each other; but u and d can override	*)
(*			 this assumption.				*)
(*									*)
(************************************************************************)

PROCEDURE EnableVoice (V: VoiceNumber;  enable: BOOLEAN);

    (* If enable is FALSE then the following data for voice V are	*)
    (* ignored.  (This is for testing, when you want to suppress a	*)
    (* voice in order to listen to the others more closely.)  The	*)
    (* default condition is that all voices are enabled.		*)

PROCEDURE SetWaveform (V: VoiceNumber;  N: WaveformNumber);

    (* Changes the waveform for voice V. *)

PROCEDURE SetEnvelope (V: VoiceNumber;  attack, decay, sustain: CARDINAL);

    (* Does nothing - this procedure is present for compatibility with	*)
    (* other versions, but the present version does not have the	*)
    (* capability of controlling the waveform envelope.			*)

PROCEDURE SetInstrument (N: WaveformNumber;
				attack, decay, sustain: CARDINAL);

    (* Changes the waveform for all voices.  The last four parameters	*)
    (* are ignored.							*)

PROCEDURE SetDuration (value: CARDINAL);

    (* Sets the duration for the following notes (all voices).  The	*)
    (* change takes place at the point immediately following all data	*)
    (* entered so far - i.e. at the "current time" for the voice for	*)
    (* which most data has been entered so far.				*)

PROCEDURE Voice1 (notes: ARRAY OF CHAR);
PROCEDURE Voice2 (notes: ARRAY OF CHAR);
PROCEDURE Voice3 (notes: ARRAY OF CHAR);

    (* Appends more notes to the music array kept internally by this	*)
    (* module.  Initially the array is empty.  The three voices can be	*)
    (* added in any order.						*)

PROCEDURE PlayTheMusic;

    (* Plays the music that has been stored so far. *)

END Music3S.