Isaac Marino Bavaresco wrote 2012-08-29 16:04:
> The instruction 'MOVF' has only room for 8 bits of the address. The
> other bits are obtained from the BSR register.
>
> So your "movf 0x240,w" will generate the exactly same binary encoding
> than a "movf 0x40,w". I think the assembler will give a warning saying
> that some bits of the address will be ignored (or at least it should).
>

I do not think it either does or should. :-)

When you are allocating memory using UDATA and RES, you
always gets symbols with full adresses. If not, the
BANKSEL would not work on any self-allocated variables,
BANKSEL would not be able to calculate the actual bank.

And you would get *a lot* of warnings also... :-)

Jan-Erik.


>
> Best regards,
>
> Isaac
>
>
>
>
> Em 29/8/2012 10:21, Nathan House escreveu:
>> I'm learning to program a PIC18 using assembly language and am curious
>> why there seems to be some redundancy with many instructions. Take the
>> MOVF instruction, for example:
>>
>> MOVLB 0x2          ;select bank 2
>> MOVF   0x240, W  ;move the value at 0x240 to W
>>
>> If my understanding is correct, then the "2" digit in the MOVF
>> instruction is ignored completely, making it redundant since the bank
>> is selected above. From what I've read, it seems that the assembler
>> automatically sets the access "a" bit based on the address when
>> translating to machine code, so what I'm wondering is why the
>> assembler doesn't automatically generate bank select instructions as
>> well?
>>
>> Thanks!
>>
>> Nathan
>>
>
--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.