-- IntMusic.mesa
-- edited by Woods,  November 13, 1980  1:54 PM  
-- edited by Brotz,  December 31, 1980  10:20 AM  
-- edited by Barth,  December 15, 1980  3:46 PM  
  
DIRECTORY
  inD: FROM "InteractorDefs",
  Inline,
  ProcessDefs,
  SegmentDefs,
  TimeDefs;
  
IntMusic: PROGRAM
  IMPORTS Inline, ProcessDefs, SegmentDefs, TimeDefs
  EXPORTS inD =

BEGIN

machineType: SegmentDefs.MachineType = SegmentDefs.memConfig.AltoType;


GetLongTime: PROCEDURE RETURNS [time: LONG CARDINAL] = INLINE
BEGIN
AltoITimeFormat: TYPE = MACHINE DEPENDENT RECORD
  [lowBits: [0 .. 1023], trailingZeros: [0 .. 63], highBits: CARDINAL];
AltoIITimeFormat: TYPE = MACHINE DEPENDENT RECORD
  [crud1: [0 .. 15], lowBits: [0 .. 1023], crud2: [0 .. 3], highBits: CARDINAL];
time _ TimeDefs.ReadClock[];
SELECT machineType FROM
  AltoI => NULL;
  AltoII, AltoIIXM =>
    LOOPHOLE[time, AltoITimeFormat].lowBits
      _ LOOPHOLE[time, AltoIITimeFormat].lowBits;
  ENDCASE => time _ 0;
LOOPHOLE[time, AltoITimeFormat].trailingZeros _ 0;
END;  -- of GetLongTime --
  
PlayNote: PROCEDURE [cps, ticks: CARDINAL] =
BEGIN -- play given note for given time
out: POINTER TO CARDINAL = LOOPHOLE[177016B];
nanosecs, startTime, rtinc: LONG CARDINAL;
time, outState: CARDINAL;
-- cannot read out^ directly, so keep private state of output port.

IF cps = 0 THEN
  BEGIN
  time _ inD.realTimeClock^;
  UNTIL inD.realTimeClock^ - time >= ticks DO out^ _ 0 ENDLOOP;
  END
ELSE BEGIN
  ProcessDefs.DisableInterrupts[];
  nanosecs _ (1000000000+LONG[cps/2])/LONG[cps];
  out^ _ outState _ 0;
  rtinc _ (nanosecs*LONG[32]) / LONG[38080];
  time _ 2*Inline.LowHalf[(LONG[ticks]*38993920)/nanosecs];
  startTime _ GetLongTime[];
  THROUGH [0..time) DO
    out^ _ outState _ IF outState=0 THEN 177777B ELSE 0;
    ProcessDefs.EnableInterrupts[];
    ProcessDefs.DisableInterrupts[];
    UNTIL GetLongTime[] - startTime >= rtinc DO ENDLOOP;
    startTime _ startTime + rtinc;
    ENDLOOP;
  ProcessDefs.EnableInterrupts[];
  END;
END;  -- of PlayNote --

-- PlayTune is the main procedure.  It interprets its string as follows:  A letter from "A"
-- through "G" specifies a note.  If the letter is followed by "#" then the corresponding
-- sharp-note is played (meaningful only for C, D, F, G, and A).  All notes are eighth-
-- notes (five ticks, to be precise), but upper-case letters cause tones that are "held" the
-- full time while lower-case notes last only three ticks followed by a brief rest.  C is the
-- bottom of the octave; B is higher than C.  When ">" is encountered, all subsequent notes
-- are an octave higher; a "<" lowers all subsequent notes by an octave.  Going up more
-- than 3 octaves is not permitted (the fourth ">" is ignored), and notes near the top of the
-- highest octave may not be struck accurately.  Finally, use "%" to get an eighth-rest.

PlayTune: PUBLIC PROCEDURE [s: STRING] =
-- Tweaks speaker output to play tune encoded in s.
BEGIN
secs: CARDINAL = 15;	-- maximum number of seconds of music we can handle
note: CARDINAL _ 0;	-- number of notes represented by s
cps, octaves, hold: ARRAY [1 .. 8*secs] OF CARDINAL;
scale: TYPE = CHARACTER ['A .. 'G];
twelfths: ARRAY scale OF CARDINAL = [12, 14, 3, 5, 7, 8, 10];
card: CARDINAL;
freq: LONG CARDINAL;
octave: CARDINAL _ 8;
root: LONG CARDINAL = 10595;		-- 12th root of 2, times 10000
freqA: LONG CARDINAL = 1760;		-- highest octave we'll bother with

SELECT machineType FROM
  AltoI, AltoII, AltoIIXM => NULL;
  ENDCASE => RETURN;

FOR card IN [0 .. s.length) DO
  SELECT s[card] FROM
    IN ['A..'G] => BEGIN
      cps[note _ MIN [note+1, 8*secs]] _ twelfths[s[card]];
      octaves[note] _ octave;
      hold[note] _ 5;
      END;
    IN ['a..'g] => BEGIN
      cps[note _ MIN [note+1, 8*secs]] _ twelfths[s[card]+('A-'a)];
      octaves[note] _ octave;
      hold[note] _ 3;
      END;
    '# => IF note>0 THEN cps[note] _ cps[note]+1;	-- sharps are one twelfth-octave higher
    '< => octave _ MIN [octave*2, 256];
    '> => octave _ MAX [octave/2, 1];
    '% => BEGIN
      cps[note _ MIN [note+1, 8*secs]] _ 0;
      hold[note] _ octaves[note] _ 5;
      END;
    ENDCASE;
  ENDLOOP;
FOR card IN [1..note] DO
  freq _ SELECT cps[card] FROM
    0 => LONG[0],
    <12 => freqA * LONG[100],
    ENDCASE => freqA * LONG[200];
  THROUGH [0..cps[card] MOD 12) DO freq _ freq*root/LONG[10000] ENDLOOP;
  cps[card] _ Inline.LowHalf[(freq/LONG[octaves[card]]+LONG[50])/LONG[100]];
  IF card>1 AND cps[card]=cps[card-1] AND (hold[card-1] MOD 5)=0 THEN
    BEGIN
    hold[card] _ hold[card]+hold[card-1];	-- combine notes for smoother play
    hold[card-1] _ 0;
    END;
  ENDLOOP;
FOR card IN [1..note] DO
  IF hold[card]#0 THEN PlayNote [cps[card], hold[card]];
  IF hold[card] MOD 5#0 THEN PlayNote [0, 5-(hold[card] MOD 5)];
  ENDLOOP;
END;  -- of PlayTune --


END.  -- of IntMusic --z19932(635)\f1