Help converting CASE SELECT to IF THEN ELSE statements (BS2 to SX/B)

T&E Engineer

I am trying to convert this routine from a BS2 to SX/B:

Main:
DO
· GOSUB getkey
· 'DEBUG TAB,HEX3 scancode
· IF scancode<$FF THEN
··· SELECT scancode
····· CASE $12,$59
······· shiftbit=~F0bit
······· F0bit=0
······· ascii=0
····· CASE $E0·· 'extended key
········· ascii=0
····· CASE $F0· 'erase key release
······· F0bit=1
······· ascii=0
····· CASE >143
······· ascii=0
····· CASE ELSE
······· IF F0bit=0 THEN READ (144 * shiftbit + scancode),ascii
······· F0bit=0
··· ENDSELECT
··· IF ascii > 0 THEN DEBUG ascii
· ENDIF
LOOP

The SELECT and CASE Statements are getting a bit hairy on the IF THEN conversion.

Any help would be appreciated. I understand that the GOSUB keyword statement needs to be removed and that DEBUG needs to be removed too.

Thanks.

Clock Loop

Use lookup and lookdown.

I have found that those work better as a replaement for select case, over if then statements.

Look at the sx/b help file for examples on lookup and lookdown.

If you still don't see how those can be used, post here again what you came up with, and I can help you.

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Meh. Nothing here, move along.

JonnyMac

PBASIC 2.5 SELECT-CASE structures generate a lot of internal (unseen by you) code -- so it's likely your IF-THENs will be a little "hairy" doing a manual conversion. Using LOOKDOWN is an option, just set your comparisons in ascending order.

Update: It turns out not to be that bad -- I left plenty of whitespace to make it easy to read:

Main:
  scanCode = GET_KEY
  IF scanCode = $FF THEN Main

  temp = scanCode
  LOOKDOWN scanCode, $12, $59, $E0, $F0, temp

  IF temp < 2 THEN                ' $12 or $59
    shiftBit = ~F0bit
    F0bit = 0
    ascii = 0
    GOTO Main_2
  ENDIF

  IF temp = 2 THEN                ' $E0
    ascii = 0
    GOTO Main_2
  ENDIF

  IF temp = 3 THEN                ' $F0
    F0bit = 1
    ascii = 0
    GOTO Main_2
  ENDIF

  IF temp > 143 THEN
    ascii = 0
  ELSE
    IF F0bit = 0 THEN
      addr = 144 * shiftBit
      addr = addr + scanCode
      READ addr, ascii
    ENDIF
  ENDIF
  
Main_2:
  ' next step

Post Edited (JonnyMac) : 2/7/2007 1:55:30 AM GMT

T&amp;E Engineer

Thanks for all the help. However, I beleive I have figured the IF THEN part out - now it has errors with START: when trying to compile.

I have the program attached and I followed the SX Template.

Any Help. Also if my IF THEN portion looks wrong then I will attemp a LOOKDOWN approach. I like this approach too - but I don't want to change it if I get no compile errors on this section.

Very weird. See attached.

JonnyMac

Start is in the template as the beginning point of the program -- and you're trying to use that as a variable name (change the var, that fixes the error).

Other notes:
-- Using OUTPUT with the PIN directive takes care of the TRIS register for you (so you don't need the TRIS = %00000000 line)
-- You're using INPUT with a variable; are you trying to float a pin pointed to by that variable?
-- With the TRIS register set you don't need to use HIGH and LOW; just do ThePin = 1 or ThePin = 0 (saves a bit of code space)
-- On your SUB definition, set the parameters count to 0; this will save a bit of code
-- You need to identify your tables with labels as data storage does not start a address 0 as does the BASIC Stamp
-- READ needs the starting addess of table, plus and offset. Use one of the labels from above and add the calculated offset.

Post Edited (JonnyMac) : 2/7/2007 6:10:23 PM GMT

T&amp;E Engineer

JonnyMac,

Great analysis! All is·compiling except for the SHIFTIN statement - once I incorporated your comments. Thank you so much!!

SHIFTIN datain, clock, MSBPRE, [noparse][[/noparse]scancode]

ERROR is: BYTE VARIABLE EXPECTED "[noparse][[/noparse]scancode]"

Any ideas?

Thanks again.

Bean

SX/B doesn't use brackets. Just use:

SHIFTIN datain, clock MSBPRE, scancode

Bean.

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T&amp;E Engineer

Thanks Bean.

I am out on business travel in Indianapolis for the next couple of days but I will try this code when I get back over the weekend. It looks like it wasn't too hard to convert it from BS2 to SX/B with everyone's great help!

Thanks again to all!

Tim