Roman, you're right. I had forgotten about the "built-in macros" for Bn.
Sorry. (Too much pollen from yard work on Saturday affecting my brain!)

Douglas Wood
Software Engineer
dbwood@kc.rr.com

Home of the EPICIS Development System for the PIC and SX
http://epicis.piclist.com

----- Original Message -----
From: "Roman Black" <fastvid@EZY.NET.AU>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Sunday, June 10, 2001 3:05 AM
Subject: Re: [PIC]: instructions not in the instruction set !


> Douglas Wood wrote:
> >
> > Actually, Roman, they're not "standard mnemonics"; they're macros (or
> > #defines, if you like) that are built into MPASM. There is no entry in
any
> > instruction set descriptions from Microchip that list these
"instructions"
> > as real instructions. (See my PIC Microcontroller Instruction Set
Comparison
> > Matrix for a complete list of all PIC microcontroller instructions.
Note:
> > this chart DOES NOT include any of the new dsPIC instructions.)
>
>
> The "official" quick reference card I got from
> Microchip with MPASM users guide lists these as
> "PIC16C5X/PIC16CXX Special Instruction Mnemonics"
>
> And they are listed under the same name, all the
> same official mnemonics on page 135 of the MPASM
> users guide. Maybe they are not "real" instructions
> as such but if listed as part of MPASM that makes
> them official enough for me. And I never said they
> were official instructions, I said they were
> official mnemonics. :o)
>
>
> > Secondly, the Bn conditional branch instructions 1) only appear in the
> > enhanced 16-bit core products (i.e., 18Cxxxx/18Fxxxx) and 2) are all
encoded
> > in a single word (note, however, that they take two machine cycles, but
NOT
> > two program words). Skip instructions will work perfectly find with
them.
>
> Wrong again Douglas! :o)
> BZ, BNZ, BC etc are all included in the same list,
> and they assemble to 2 instructions as I said.
> See the "instruction set" pages in your MPASM
> guide, they are all listed.
>
> I also forgot a couple of the other official ones
> I use all the time; CLRC, SETC, CLRZ, SETZ.
>
> And one homemade one that is very useful to
> simplify close branching without having to resort
> to labels;
>
> #define   SKP2   goto $+1+2     ; skips the next 2 instructions
>
> Example:
>   DECFSZ register,f  ; dec register, and test zero
>   SKP2
>   (do blah)          ; if register==Z, do both these instructions
>   (do another blah)  ;
>                      ; if register==NZ, skipped them both
>
>
> I know some purists won't like that, but so
> often you need to do a conditonal test and then
> do (or not-do) 2 instructions. This saves having
> to add goto+label where there is really no need.
> I don't use this all the time, only some times
> when it gives simpler code.
> -Roman
>
>
>
> > ----- Original Message -----
>
> > > Patrick J wrote:
> > > >
> > > > U gurus seem to have some instructions to use that isnt in the
> > > > instruction set like "skpnc" and "skpc", "skpcnc". I have seen them
> > > > in examples and they compile so guess they are ok... weird.
> > > >
> > > > I have the PIC 16F87x pdf datasheet. Instruction set in page 138.
> > > > What does they mean, and are there more of  'em ?
> > >
> > >
> > > Hi Patrick, these are STANDARD Microchip mnemonics
> > > for their PIC instruction set. As such I don't see
> > > any problem in using them, in fact the opposite, I think
> > >
> > > SKPNZ (skip if not zero)
> > >
> > > is so much more sensible than
> > >
> > > BTFSC STATUS,Z
> > >
> > > Surely you agree? The MPASM handbook and associated
> > > .PDF format list these mnemonics.
> > >
> > > The only ones I don't like are the BZ, BNZ, etc which
> > > assemble to 2 instructions. That can cause problems
> > > with other "skip" situations and I don't use them.
> > >
> > > The standard mnemonics that assemble to ONE instruction
> > > are great, like SKPZ, SKPNZ, SKPC, SKPNC, and I use
> > > TSTF a lot, great for testing if a register is zero by:
> > >
> > > TSTF register
> > > SKPZ   (this code is very obvious what you tested)
> > > goto blah
> > >
> > > There are a few custom designed mnemonics that are not
> > > official Microchip ones, but which are really handy,
> > > I got these from Olin,
> > >
> > > SKPWGT   skip if w greater than
> > > SKPWLE   skip if w less or equal
> > > SKPWEQ   skip if w equal
> > > SKPWNE   skip if w not equal
> > >
> > > These are amazingly useful when using the sometimes
> > > confusing Microchip SUBLW and SUBWF instructions.
> > > That can save so much effort and debugging.
> > >
> > > You can make some custom instructions yourself just
> > > by using the define# command. A couple I like are INCW
> > > and DECW, very useful. As long as they assemble to
> > > one instruction I would recommend using these, they
> > > can help you write and debug code so much quicker.
> > >:o)
> > > -Roman
>
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