Tom Messenger wrote:

> >Been seeing this notation in various bits of code, and can't quite
> ascertain what it really means.  Assumed it was related to pushing the
> program counter, or making jumps in code:

>
> The dollar sign - $ - means 'here'. So goto $ + 1 means to increment the pc
> by one. This is used in two ways, (at least). The usual idea is that when
> writing your program, you don't know where the assembler will stick your
> code.  If you need to reference a nearby location, you say $ which means
> where the current pc is. $ + 1 means to go to the next location.


I like these 3 home made mnemonics;
#define         skp1    goto $+1+1      ; skips one instruction
#define         skp2    goto $+1+2      ; skips 2 instructions
#define         skp3    goto $+1+3      ; skips 3 instructions
(never needed skp4)

These can really neaten-up code and avoid the use
of messy un-needed goto labels when all you want
to do is skip the next 3 instructions;

        btfss input,2           ; test input
        skp3                    ;
        movlw b'11001100'       ; input == hi, so do these 3
        movwf lastb             ;
        movwf PORTB             ;

I don't know if that makes the .asm purists cringe
but I see it as part of the natural evolution of
the .asm language that you develop new "instructions"
that make it easier to read, code, work with etc.
In many cases of .asm logic branching the goto
labels are not symbolic at all and just represent
"miss the next 3 instructions". I feel that these
particular labels can often be replaced by a neater
mnemonic, especially in complex logic trees. :o)
-Roman

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