In SX Microcontrollers, SX/B Compiler and SX-Key Tool, JonnyMac wrote:

After spending some time with David's code I was able to get the text scrolling algorithm straight (in my own head) and add it to my version of the program.  This version supports characters from $20 (space) to $FF (arrow; non-ASCII), and will scroll text left or right.  The character maps for $20 to $7F are store in contiguous DATA statements which makes access of this data quite straightforward.  The program uses current SX/B standards encapsulating features into subroutines so they can be used very easy.

The text scrolling routines, SCROLL_LF and SCROLL_RT, can use inline strings or strings stored in a DATA statement.  If the DATA statement is used then you can embed a bell character (#7) into the string and the beeper will beep at that point while retrieving the next character.  You can also embed a CLS (#12) character into the string.  Scrolling speed is controlled with a variable so you can adjust this parameter before putting text on the screen.

This version of the program takes advantage of a subtle feature in SX/B: you can pass five parameters to a subroutine (or function) -- yes, five.  To do this, however, you must pass exactly five (and the SUB or FUNC has to be defined that way).  When this is the case the register that usually holds the parameter count (__PARAMCNT) is used as the fifth parameter (it is also aliased as __PARAM5).  Here's how I use it in this program to play a set of animation frames:

[code]' Use: PLAY_FRAMES Label, FrameCount, FrameTiming, Loops
' -- displays animation frames at "Label"
' -- "FrameCount" is number of 15-column frames in animation
' -- "FrameTiming" is display time for frame in milliseconds
' -- "Loops" is number of times to play frames sequence

SUB PLAY_FRAMES
  tmpW2 = __WPARAM12                            ' address of first frame
  tmpB1 = __PARAM3                              ' number of frames
  tmpB2 = __PARAM4                              ' delay between frames
  tmpB3 = __PARAM5                              ' animation loops

  DO WHILE tmpB3 > 0                            ' any loops left?
    tmpW3 = tmpW2                               ' point to first frame
    tmpB4 = tmpB1                               ' copy frame count
    DO WHILE tmpB4 > 0
      FOR tmpB5 = 0 TO 14                       ' grab a frame
        READINC tmpW3, dispBuf(tmpB5)           ' move frame to display
      NEXT
      DELAY_MS tmpB2                            ' hold
      DEC tmpB4                                 ' move to next frame
    LOOP
    DEC tmpB3                                   ' update loop count
  LOOP

  ENDSUB[/code]

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