VGA_Text.Out($08) not working??

MacTuxLin

Hello All,

I need to do up a mini station using PPB with VGA & PS2 KB/Mouse real quick but seems to hit a problem & its 2nd day now :frown: My code is:

CON
  _clkmode = xtal1 + pll16x
  _xinfreq = 5_000_000                                          ' use 5MHz crystal

  _ConClkFreq = ((_clkmode - xtal1) >> 6) * _xinfreq
  _Ms_001   = _ConClkFreq / 1_000
  _Us_001   = _ConClkFreq / 1_000_000

OBJ
  KB  : "Keyboard"
  VGA : "VGA_Text"


PUB Main
  '--- --- --- --- --- --- --- --- ---
  '--- --- VGA Cog --- ---
  '--- --- --- --- --- --- --- --- ---
  ifnot(VGA.Start(16))
    reboot

  '--- --- --- --- --- --- --- --- ---
  '--- --- Keyboard Cog --- ---
  '--- --- --- --- --- --- --- --- ---
  ifnot(KB.start(26, 27))
    reboot


  VGA.Out($00)
  VGA.Str(String($C,6))
  repeat

    result := VGA.Out(KB.GetKey)
    if result == $C8
      VGA.Out($08)
    
    VGA.Str(13)

Instead of getting a backspace, I got a "E" with a comma on top? (picture). Am I overlooking something?

Thanks a lot!!

kuroneko

Well, result := VGA.Out(KB.GetKey) outputs whatever is returned from the keyboard. That includes $C8 which is your special E character. As the out method doesn't return anything (zero in fact) you never even send a back space to the device. Your filter logic needs more thought.

MacTuxLin

kuroneko wrote: »

Well, result := VGA.Out(KB.GetKey) outputs whatever is returned from the keyboard. That includes $C8 which is your special E character. As the out method doesn't return anything (zero in fact) you never even send a back space to the device. Your filter logic needs more thought.

(Slapping my forehead) >< Thanks Kuroneko. Thought could do this mini-guy within a few days ... OK, let me do a sanity-check.

MacTuxLin

OK, I think I'm exhausted but could anyone please help me so I could call it a day to see what I've boo-boo again as I could only erase (backspace) 1 character on screen but the actual value (backspaced) is correct.

  repeat
    result := KB.GetKey
    if result == $C8
      result := $08
      Str.putCharacter(result)
      VGA.Out(result)
      VGA.Str(String($C,8))
      VGA.Out($20)
    else
      if result <> $D 
        VGA.Str(String($C,6))
        VGA.Out(result)
        Str.putCharacter(result)
      else  
        VGA.Str(String($C,8))
        VGA.Str(Str.trimString(Str.getCharacters(true)))
        quit

Thanks a lot!!

Added: I should not have added the space

VGA.Out($20)

. But hmm... how do I change the colour for those on the right of the "invisible" cursor??

MacTuxLin

OK, I've found a way to do it but is this the best way ???

  xPtr := 0
  repeat
    result := KB.GetKey
    if result == $C8
      result := $08
      Str.putCharacter(result)
      VGA.Out(result)
      if xPtr
        xPtr--      
        VGA.Out($A)
        VGA.Out(xPtr)
        VGA.Out($B)
        VGA.Out($0)        
        VGA.Str(String($C,8))
        repeat i from 0 to 31-xPtr
          VGA.Out($20)
        VGA.Out($A)
        VGA.Out(xPtr)
        VGA.Out($B)
        VGA.Out($0)        
    else
      if result <> $D 
        VGA.Str(String($C,6))
        VGA.Out(result)
        Str.putCharacter(result)
        xPtr++
      else  
        VGA.Str(String($C,8))
        VGA.Str(Str.trimString(Str.getCharacters(true)))
        quit

kuroneko

Could you post the complete code? I'm not entirely sure as to why you need the Str object (which is what???). What are you trying to achieve?

MacTuxLin

Thanks. Yes, attached. Basically, I needed the Backspace to look like a real backspace on the VGA screen (when user press the Backspace key once, the last digit entered should be deleted on screen). I used the Str to lineup the strings entered.

I mean, the Backspacing portion doesn't seems to look efficient so may I know is there a better way to do this instead?

Thanks a lot!

kuroneko

One issue here is that the backspace code for the standard VGA driver only seems to work for the current line, i.e. multi-line edits are out of the question. Doing so will get your screen display out-of-sync with the string buffer. As for the visual back space effect, what about:

if result == $C8
      Str.putCharacter([COLOR="blue"]8[/COLOR])
      VGA.str(string([COLOR="blue"]8[/COLOR],[COLOR="red"]12,8[/COLOR],[COLOR="blue"]32[/COLOR],[COLOR="red"]12,6[/COLOR],[COLOR="blue"]8[/COLOR]))
    else
      if result <> $D

What this does is issue a backspace (8), print a space (32) in color 8 (12,8), change colour back to 6 (12,6) and finally issue another backspace to counter the effect of the space.

Edit: Just re-checked, backspace only affects the current column, i.e. it is confined to the current row.

MacTuxLin

This is great!!! Thank you very much!