[sdiy] DSPIC computed branch and include help

[Vinicius Brazil]

HI Ritchie,
I just write in assembly and use much (in all my firmware) BRA Wx statement.
It works perfectly.
An example of code:

bra W0
bra LED_SawPositive
bra LED_SawNegative
bra LED_SQUARE
bra LED_Triangle
bra LED_SINE
bra LED_SquaredSine
bra LED_Pulse
bra LED_Noise
;---------------------------------
LED_SawPositive:
......
bra TSEnd
;---------------------------------
LED_SawNegative:
....
....
....

Usually I build everything in one file, but have written a program where
there was an include code.
I put the "include" just after the start, within the program area.

regards,
Vinicius



On Mon, Feb 22, 2016 at 2:16 PM, Richie Burnett <
rburnett at richieburnett.co.uk> wrote:

> Has anyone else here using Microchips DSPIC tried to implement a computed
> branch using the "BRA w0" instruction ?
>
> No matter what I do, I can't get it to work as explained in the
> programmers reference guide description of the BRA instruction.  It says
> that it should jump to the address (PC+2) + (2*w0)  (which makes sense
> because the program counter would already be ready to pre-fetch the next
> instruction, and instructions are aligned on 2-word boundaries,)  but
> instead it seems to jump to (PC+2) + w0  but ignores the LSB of w0,
> (otherwise it would produce a misaligned odd program counter address!)
> I've checked and checked this and I don't see what I'm doing wrong, and
> can't find an errata sheet that mentions this problem.  Chip being used is
> dsPIC33FJ128GP804.
>
> Also can someone tell me the correct way to include additional assembly
> source files *.s in MPLAB.  I just put
>
> .include "filters.s"
> .include "maths.s"
> .include "comms.s"
>
> etc... at the end of main.s but this seems to have completely broken MPLAB
> 8.92.  It assembles fine, programs fine and runs fine, but goes crazy when
> hitting a breakpoint or single-stepping inside any of the included source
> files.  I'm used to the included file just popping open and the program
> counter arrow switching between whichever source window it needs to be in
> as different routines are called.  I'm actually getting the program counter
> arrow moving to lines in the source file that just have comments on them
> before the actual code starts when it should switch to one of the included
> source contents.  Also FWIW the addresses in the "Disassembly Listing"
> window are all garbled too!  It only does this when I include additional
> source files, so I must be doing something wrong!?!?
>
> I'd like to divide the source code up into relevant sections in separate
> files to make a big project easier to follow, so really want to get this
> done right.
>
> Thanks in advance for any suggestions !
>
> -Richie,
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