VGA_Text.Out($08) not working??

MacTuxLin · 2011-02-15 00:14

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 · 2011-02-15 00:22

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 · 2011-02-15 00:38

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 · 2011-02-15 01:04

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 · 2011-02-15 02:08

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 · 2011-02-15 05:19

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 · 2011-02-15 10:57

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 · 2011-02-15 18:06

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 · 2011-02-15 18:17

This is great!!! Thank you very much!

VGA_Text.Out($08) not working??

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