Writing PBP Commands/macros

[Darrel Taylor]

Ditto what Bruce said.
But I would add ...

When working at the ASM level, everything is just Numbers.
The assembler doesn't know anything about Byte Word or Long variables.
And it has no way of knowing if you passed it a constant, variable or your birthday.

If you pass a constant, the number is the value of the constant.
Passing a variable, will give the starting address of that variable in RAM.
Passing a Label, will give the address to a piece of code in Flash.
They are all just numbers, and it's up to you to handle them properly.

If you look through PBP's .mac files, you'll see that there is a different macro for each possibility of inputs.

LCDOUT?C ; expects to be passed a constant.
LCDOUT?B ; will work with a byte variable
... the other vars each have their own LCDOUT macro ...

The ?CB suffix indicates the type of input, in PBP they are ...

A = W register (Accumulator)
C = Constant
B = Byte variable
W = Word variable
N = Long variable
T = Bit variable

Placing the suffix there, doesn't do anything by itself, it's just an easy way to recognize which macro you need to use, depending on the type of inputs you have.

With your PE_Write macro, there should be at least 4 versions.
And keeping with the PBP syntax, they might be called ...

;             :   Data,     Register
;-------------------------------------
PE_Write?CC   ; Constant,   Constant
PE_Write?CB   ; Constant,   Byte
PE_Write?BC   ; Byte,       Constant
PE_Write?BB   ; Byte,       Byte

Fortunately, PBP already has all the macros you need to move the different values around, so you don't really need to do MOVF, MOVWF, etc ... and those macro's will handle all the Banking issues that are difficult to manage with MOVF type instructions.
Those Macro's have the Name of MOVE?, and use the same suffixes shown above.

So the first macro using two constants would look like ...

ASM
PE_Write?CC   macro Data, Register
    MOVE?CB  Data, _DATA_BYTE
    MOVE?CB  Data, PORTB
    MOVE?CB  Register, _REGISTER_BYTE
    L?CALL   _SEND_PE_BYTE
  endm

The second macro with a constant Data, and Byte Register

PE_Write?CB   macro Data, Register
    MOVE?CB  Data, _DATA_BYTE
    MOVE?CB  Data, PORTB
    MOVE?BB  Register, _REGISTER_BYTE
    L?CALL   _SEND_PE_BYTE
  endm

Note that there is only one character different between the last two code sections (in blue).

The third macro ... Byte Data, Constant register ...

PE_Write?BC   macro Data, Register
    MOVE?BB  Data, _DATA_BYTE
    MOVE?BB  Data, PORTB
    MOVE?CB  Register, _REGISTER_BYTE
    L?CALL   _SEND_PE_BYTE
  endm

And the forth ... Byte Data, Byte register ...

PE_Write?BB   macro Data, Register
    MOVE?BB  Data, _DATA_BYTE
    MOVE?BB  Data, PORTB
    MOVE?BB  Register, _REGISTER_BYTE
    L?CALL   _SEND_PE_BYTE
  endm
ENDASM

You can probably see that if you consider ALL the possibilities, there's a lot of macros to write for a single function.

To use them, simply choose the macro that fits your inputs...

@  PE_Write?CC   55h, _GPIOA

Temp = $55
@  PE_Write?BC   _Temp, _GPIOA

Reg = GPIOA
@  PE_Write?BB   _Temp, _Reg

HTH,

[awmt102]

Bruce,

Thanks for the reply, looks like I have fallen foul of the curse of high level languages and forgotten all my assembler! I will have to go and brush up I think!:-D

Darrell,

Thanks also, I had seen the ?CB notation in your LCD Bargraphs but couldn't find any reference to it with google. I have now got my macros working nicely, thankyou.

I am guessing that since "everything is just numbers" there is no clever way to tidy it up and automatically detect what you have passed the macro?

Thanks

Andy