pic microcontroller discussion list <> wrote on Wednesday, July 30, 2003
5:38 PM:

> Var=0b00000101;

That's an option too, but a switch statement is more flexible.

> This will blink 2 times wait time will be little longer
> By shifting right and reading bit 0 LSB whatever bit 0 is

You can probably even do it faster using the fact that the rightmost bit is
shifted into carry.  Not sure how to tell a compiler, in pic assembler it
would be something like
        rrf Pattern,f           ; Move the next bit onto Carry
        bcf LedShadow,LedPin    ; Start with the shadow pin off
        btfsc STATUS,C
        bsf LedShadow,LedPin    ; Turn it on if the bit was a 1

Actually, it's probably no faster than the way you are proposing.  However,
if all the other bits in LedShadow are irrelevant, you can do

        rrf Pattern,f   ; Move the next bit into Carry
        rlf LedShadow,f ; Move the bit onto LedShadow

And if you want to maintain the other bits in LedShadow, you can use

        rrf LedShadow,f ; Lose the previous bottom bit
        rrf Pattern,f   ; Move the next bit into Carry
        rlf LedShadow,f ; Move the bit onto LedShadow

> Then we can use 16 bit or 32 bit variable. I will show you Later.

True, and that would also be quite fast, only one more rotate needed per 8
bits.

> Thanks for code adjustment

No problem (and don't forget to add the ';' which I missed at the end of
the line!).  I thought about it again while walking my dog this morning,
and if code size is an issue, the following would probably compile
marginally smaller!

>>     case (4): timer1test=0x00; break;
>>     case (5): timer1test=0x00; break;
>>     case (6): timer1test=0x00; /* NO BREAK, FALL THROUGH TO DEFAULT !!!
*/
        default:led_count=0; break;
>>           }
>>     }

Nigel
--
Nigel Orr, Design Engineer                 nigel@axoninstruments.co.uk
Axon Instruments Ltd., Wardes Road,Inverurie,Aberdeenshire,UK,AB51 3TT
               Tel:+44 1467 622332 Fax:+44 1467 625235
                   http://www.axoninstruments.co.uk

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