Simplify music sequence parameters

src/dhgr.tk/demos/darthgr/darthgr.pla

@@ -1,6 +1,4 @@
 include "inc/cmdsys.plh"
-include "inc/lines.plh"
-include "inc/args.plh"
 include "inc/fileio.plh"
 include "dhgr.tk/inc/dhgrlib.plh"
 include "dhgr.tk/inc/dhgrutils.plh"
@@ -9,27 +7,13 @@ include "inc/sndseq.plh"
 sysflags resxtxt1|reshgr1|resxhgr1
 
 var strWidth, strHeight
-byte ref
-var seq, len
 char darthstr = "DartH GRaphics"
-
-def backgroundProc#0
-    return
-end
-
 dcgrFont(fontRead("trade54.fon"))
 strWidth, strHeight = dcgrStrExtents(@darthstr)
 dhgrMode(DHGR_COLOR_MODE)
 screenRead("darth.dhgr")
-ref = fileio:open("imperial.seq")
-if ref
-    seq = heapalloc(heapavail - 256)
-    len = fileio:read(ref, seq, heapmark - seq)
-    fileio:close(ref)
-    heaprelease(seq + len)
-    musicPlay(seq, FALSE)
-    musicGetKey(16, @backgroundProc) // Yield every 16/16 second
-fin
+musicPlay(musicRead("imperial.seq"), FALSE)
+musicGetKey(16, NULL) // Yield every 16/16 second
 dcgrColor(CLR_WHITE)
 dcgrStr((140 - strWidth) / 2, (strHeight * 7) / 8, @darthstr)
 getc

src/inc/sndseq.plh

@@ -2,5 +2,6 @@ import sndseq
     word musicSequence // musicSequence(yield, backgroundProc)#0
     word spkrTone      // spkrTone(pitch, duration)#0
     word spkrPWM       // spkrPWM(sample, speed, len)#0
-    predef musicPlay(track, rept)#0, musicStop#0, musicGetKey(yield, backgroundProc)#1
+    predef musicPlay(track, rept)#0, musicStop#0
+    predef musicGetKey(yield, backgroundProc)#1,  musicRead(filename)#1
 end

src/libsrc/apple/sndseq.pla

@@ -366,6 +366,8 @@ asm a2keypressed
         DEY
 +       STY     ESTKL,X
         STY     ESTKH,X
+end
+asm nopBackground#0
         RTS
 end
 def a3keypressed
@@ -833,15 +835,35 @@ export def musicGetKey(yield, backgroundProc)#1
     char key
 
     key = 0
-    repeat
-        musicSequence(yield, backgroundProc)#0 // Call background proc every half second
-        if keypressed()
-            key       = getc
-            seqRepeat = FALSE
-        fin
-    until not seqRepeat
+    if backgroundProc == NULL; backgroundProc = @nopBackground; fin
+    if seqTrack
+        repeat
+            musicSequence(yield, backgroundProc)#0 // Call background proc every half second
+            if keypressed()
+                key       = getc
+                seqRepeat = FALSE
+            fin
+        until not seqRepeat
+    fin
     return key
 end
+//
+// Read sequence onto heap
+//
+export def musicRead(filename)#1
+    byte ref
+    word seq, len
+
+    seq = NULL
+    ref = fileio:open(filename)
+    if ref
+        seq = heapalloc(heapavail - 256)
+        len = fileio:read(ref, seq, heapmark - seq)
+        fileio:close(ref)
+        heaprelease(seq + len)
+    fin
+    return seq
+end
 
 when MACHID & MACHID_MODEL
     is MACHID_III