mads Question about MADS macro syntax

[markmiller]

I've tried looking around for documentation on a bit of syntax in some MADS code I'm reading, and I am stumped. Could someone interpret it?

 

I'm talking specifically about the expression: ":>:num  iny" in the following macro (5th line).

 

.macro @ADD_BIT num
            bcc skip
            adc #<:num
  .if :num < $4FF
    :>:num  iny
    .if :num > $4F
            bcc skip
            iny
    .endif
  .else
  ...
  .endif
skip
.endm

 

Looking through the MADS manual, the closest I could get talks about :repeat, except it says that typically, a colon followed by a number refers to a parameter in a macro, if it's in decimal. Though, the inputs for @ADD_BIT are in hex.

 

Is that line getting the high-byte of the parameter (:num) and then using that as a counter for how many times to repeat "iny"?

[TGB1718]

What it's doing is using the high byte of the WORD num to produce the

number of repeats for the instruction "iny"

 

So for example if num=$400 then it will produce 4 iny instructions

 

Hope that makes sense