Em 14/7/2011 15:13, Bob Ammerman escreveu:
> BTW, it is possible to properly use the RETLW as a lookup table in=20
> PIC24/dsPIC assembly code.
>
>             mov    <index value>,W0
>             bra     W0
>             retlw   valuefor0
>             retlw   valuefor1
>             retlw   valuefor2
>             .etc.
>
> This is significantly slower than using PSV, but is very simple to use.
>
> -- Bob Ammerman
> RAm Systems


It is 3 times slower than PSV (1 CALL + 1 BRA + 1 RETLW =3D 6 cycles
total, against 1 MOVE + 1 Stall =3D 2 cycles total) and uses twice as many
FLASH words.

Besides you are forced to use two different access methods, one for
constant data in FLASH and another for data in RAM.


Isaac

--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.