ok gotcha - i'm writing my buffer now - thanks dennis

nish
----

Dennis Frost wrote:
>
> Hi Nishant
>
> There is a register called the FSR (I think that stands for File Select
> Register). You load the address of the start of the buffer into this
> register. Then you read register 0 (I think it is called INDF) this
> register will now hold the value of the register pointed to by the FSR.
>
> Thus you would do something like this:
>
> movlw   Buffer          ;this places the address of you 'Buffer' into w
> movwf   FSR             ;place the address into FSR
>
> Now you can work with the buffer:
>
> movfw   INDF            ;This will put the value at Buffer into w
>
> incf    FSR             ;Point to buffer+1
>
> clrf    INDF            ;clear the data at Buffer+1
>
> You can increment, decrement, add to & subtract from the FSR like with any
> other register
>
> I often use this method when I have a piece of code that performs a similar
> function of a lot of registers.
>
> Here is an example of how I define my variables:
>
>         CBLOCK  0ch
>         SaveW           ;01 holds W register durring interrupt
>         SaveS           ;02 holds Status register durring interrupt
>         SaveFSR         ;03 Holds copy of FSR durring interrupt
>         T1              ;04 Timer values
>         T2              ;05
>         T3              ;06
>         T4              ;07
>         ENDC
>
> I like using this method because if I want to add a variable say between
> SaveS and SaveFSR (it makes more visual sense for whatever reason) the I
> don't have to renumber all the variables. The compiler will renumber
> consecutively them from 0ch until it reaches ENDC.
>
> As for setting up the buffer, I have not had to do that so I couldn't tell
> you for sure but I think you are right.
>
> Cheers
>         Dennis
> ____________________________________________________
> FROST - Electronic Design, Manufacture & Consulting.
> Dennis Frost
> Tel:   +27 331 965125
> Cel:   +83 2275216
> Email: dennis.frost@pixie.co.za
> Pietermaritzburg, South Africa
> Products:       Medical Motivational equipment
>                 Timers for food processing
>                 Random number generator
>                 Temperature controllers
> ____________________________________________________
>
> PS Anyone looking for someone in the hardware/software development fields,
> I am available. I intend leaving South Africa for the West coast of the US
> early this year.
> ----------
>
> > From: Nishant Deshpande <nd4@DOC.IC.AC.UK>
> > To: PICLIST@MITVMA.MIT.EDU
> > Subject: programming question
> > Date: 02 March 1997 09:57
> >
> > hi all,
> >
> > i've just started programming the pic - i've got the led's lit up
> > etc etc now moving on to bigger & better things..
> >
> > a couple of questions regarding common practice :
> >
> > -       i started off assigning my own registers just using
> >         CTR     EQU     20h
> >         (for example)
> >         what i meant was i wanted to use address 20h
> >         now is it usual to use the 'DS' command to do this
> >         kind of thing? i.e.
> >                 ORG     20h
> >         CTR     DS      1
> >                 ORG     21h
> >         CTR2    DS      1
> >
> >         i'm kinda unsure about the direct/indirect addressing..
> >
> > -       say i want a small buffer (i.e. maybe 12/16 bits) - i do this
> >                 ORG     30h
> >         BUFFER  DS      16
> >
> >         now how do i get at this buffer? i know i can do BUFFER+<offset>
> >         but i want to use 'a variable' for the offset, increment it,
> >         etc etc as i would in a high level language...
> >
> >         i thought of having another memory location holding a 'pointer'
> >         to my buffer and then incrementing/decrementing this - but
> >         trying to implement this seems kinda unnecessarily complex..
> >
> > any tips? i guess i'm still thinking high level language...
> >
> > thanks
> >
> > nishant
> > ISE III BEng
> > Incremental Sanity Erosion at Imperial College