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

--
http://www.piclist.com hint: To leave the PICList
mailto:piclist-unsubscribe-request@mitvma.mit.edu