anchor.diff:        (asif :zero
           (inc mptr-msb))
   
  +      ;; FIXME: Don't use these labels here.. that's cheating..
         (lda mptr-lsb)
         (cmp (imm (lsb (label :seq-end))))
         (asif :equal
           (lda mptr-msb)
           (cmp (imm (msb (label :seq-end))))
           (asif :equal
  -          (when break-at-end
  +          (when t ;;break-at-end
               (brk)
                (db #xF1)
                (rts))
  
positive.code:       (defun ,(intern "NSF-OUTPUT-FILE" package) (filename)
          (generate-nsf-preview ,name #',asm-fn-name :filename filename)))))
  
  (defun generate-nsf-preview (name continuation &key filename (break-at-end nil))
    (setf filename (or filename (format nil "/tmp/nsf-audition/~A.nsf" name)))
    (let* ((*context* (make-instance 'basic-context))
           ;; Music player vars
           (mfr-addr #x40)                ; Frame working pointer (temporary)
           (mfr-get (indi mfr-addr))
           (mptr #x42)                    ; Playback pointer
           (mptr-msb  (zp (1+ mptr)))
           (mptr-lsb  (zp mptr)))
  
      (emit-nsf-header 1 #x8000 'init 'play :song-name (format nil "~A" name))
  
      (setf *origin* #x8000)
  
      (procedure init
        (cld)
        (pokeword (label :seq-start) mptr)
        (rts))
  
      (procedure play
        (cld)
  
        ;; Transfer *MPTR to MFR and play this frame.
  
negative.code:         (lda mfr-get)
          (sta (abx #x4000))
          (dey))
        (rts))))
  
  (defun generate-nsf-preview (name continuation &key filename (break-at-end nil))
    (setf filename (or filename (format nil "/tmp/nsf-audition/~A.nsf" name)))
    (let ((*context* (make-instance 'basic-context)))
  
      (emit-nsf-header 1 #x8000 'init 'play-frame
                       :song-name (format nil "~A" name))
  
      (setf *origin* #x8000)
  
      (emit-fixed-cycle-player *context* #x80)
  
      (procedure init
        (cld)
        ;;(pokeword (label :seq-start) mptr)
        (pushword (label :seq-end))
        (pushword (label :seq-start))
        (jsr 'player-load)
        
        (rts))
  
      (write-song-data-for-reg-player (funcall continuation) :seq-start :seq-end)
  