PBP Wish List

[Darrel Taylor]

I agree, it would be nice to have functions built into PBP. But until that happens, here is a round about way of achieving the same thing, kinda, sorta.

First, you need to create a "macro" that copies the passed parameters into known locations. Then create your subroutine just like normal, keeping in mind that the input and output are always thru the known Temp variables.

After the macro copies the parameters to the Temp variables, it will call the code for the function. When the function is finished it will return to the macro which will copy the result to the third parameter. You can pass as many parameters as you want (as long as they fit on 1 line).

Temp1  var word
Temp2  var word
Temp3  var word

asm
Foo macro W1, W2, R1
   MOVE?WW   W1, _Temp1    ; Copy  first parameter to Temp Variable 1
   MOVE?WW   W2, _Temp2    ; Copy second parameter to Temp Variable 2
   L?CALL    _FooCode      ; call the Foo functions code
   MOVE?WW   _Temp3, R1    ; Copy Temp3 to result
   endm
endasm


FooCode:                  ' PBP code for the function
  Temp3 = Temp1 * Temp2
  ' and whatever else Foo does
  ' final result must be in Temp3
return

To use the new function

bar    var word
bleh   var word
belch  var word

@ Foo  _bar, _bleh, _belch

or

Dogs          var word
FleasPerDog   var word
TotalFleas    var word

@ Foo  _Dogs, _FleasPerDog, _TotalFleas

The example shown will only work with words, to use bytes: change the appropriate MOVE?WW to MOVE?BB

The biggest benefit of a function is the ability to embed it in a math formula or conditional test. Unfortunately, this Macro type function DOES NOT allow you to do that. So I'm still hoping for true functions in PBP also.