Michael Rigby-Jones <PICLIST@mitvma.mit.edu> wrote:

> Shift a 16 bit value right two bits, allegedly the PIC takes 40
> cycles!
>
> clrc                    ;1
> rrf  val+1,f    ;1
> rrf  val,f              ;1
> clrc                    ;1
> rrf  val+1,f    ;1
> rrf  val,f              ;1
>
> I make that 6 cycles + a couple for initial bank setting if we are
> being fussy.

    No, that's not what they wanted... They're doing an ARITHMETIC
    right shift, so the MSB gets preserved rather than being cleared
    to 0.  Also, they explicitly say no bank switching was required.

    Still only takes 6 cycles, though:

        RLF HI,W
        RRF HI
        RRF LO

        RLF HI,W
        RRF HI
        RRF LO

    Interestingly, they've chosen to use "Bytes" as the unit of code
    space in all their comparisons.  If you do the natural thing and
    convert from bytes to 14-bit PIC instruction words, you'll
    "discover" (as though you could have had any doubt) that the PIC
    code is always shorter than the MAXQ code.

    Also interesting was the absence of any example that involved
    reading I/O pins.

    Not that any of this matters, of course, since the chips
    apparently haven't even taped out yet.

    -Andy

=== Andrew Warren -- aiw@cypress.com
=== Principal Design Engineer
=== Cypress Semiconductor Corporation
===
=== Opinions expressed above do not
=== necessarily represent those of
=== Cypress Semiconductor Corporation

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