Another thing about BRA vs. GOTO...

Consider these two examples :

Ex1

  DECFSZ   counter
  BRA      loop
  MOWLV    ...

Ex2

  DECFSZ   counter
  GOTO     loop
  MOWLV    ...

If the skip is *not* performed, both examples
execute in the same number of cycles. The BRA
and GOTO to label "loop" takes the same number
of cycles.

If the skip *is* performed, Ex1 skips directly
to the MOVLW instruction (since BRA is a one word
instruction), but Ex2 skips to the second word of
the GOTO, which is interpreted and executed as a NOP.

So after a "skip" instruction that "skips", BRA is faster.

Ex2 is as if Ex1 would have been written=20

  DECFSZ   counter
  BRA      loop
  NOP
  MOWLV    ...


Jan-Erik.



-----Original Message-----
From: Jan-erik S=F6derholm (QAC)=20
Sent: den 27 januari 2003 22:16
To: 'pic microcontroller discussion list'
Subject: RE: [pic]: pin high / low loop


BRA   : 1 program word, 2 program cycles
GOTO  : 2 program words, 2 program cycles

So BRA =3D half thet program size but the same "speed".

I you got a routine with a lot of "jumps", BRA could
save a quite a bit of program size.

Jan-Erik S=F6derholm.

>Well I still do not know the real purpose of BRA or Do I
>Even need to use BRA at all?
>
>Andre

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