fifo for isr

Peter Verkaik

Is there any specific reason why SX/B does not use the secret fifo
to temporarily save M and the 4 parameter bytes?
The attached source shows it saves 9 isr cycles and no need for parameterbyte copies.

regards peter

Peter Verkaik

Or make it optional?

regards peter

Bean

Peter,
You can use "INTERRUPT NOPRESERVE", then add the code yourself.
Bean.

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"SX-Video·Module" Now available from Parallax for only $28.95

http://www.parallax.com/detail.asp?product_id=30012

Product web site: www.sxvm.com

"One experiment is worth a thousand theories"
·

Peter Verkaik

Where would I place that in the SX/B template file?

Are there more options like that, and are these documented?

regards peter

Jon Williams

Peter,

There are options like that for INTERRUPT,· PROGRAM (see Directives), and BANK (see Directives).· If we need to clarify the documentation further, please let us know.

And, as everyone in this forum knows, I love SX/B because it lets me transfer a lot of my PBASIC skills to the SX.· What I mean to say is that I'm not as clever at ASM as most of you are.· That said, I took your FIFO code and incorporated it into an SX/B file.· The compiler (v1.40)·doesn't complain -- would you check to see if this works as you intended?· If it does, you could save this file (or derivative thereof) as your default template and start with it each time.

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Jon Williams
Applications Engineer, Parallax

Post Edited (Jon Williams (Parallax)) : 8/5/2005 3:12:55 PM GMT

Bean

Just a note, if you intend to use that code for the SX48/52 FSR needs to be set to $10 not cleared.

This always gets me into trouble when using asm in SX/B and moving from the SX28 to the SX48/52.

Bean.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
"SX-Video·Module" Now available from Parallax for only $28.95

http://www.parallax.com/detail.asp?product_id=30012

Product web site: www.sxvm.com

"One experiment is worth a thousand theories"
·

pjv

Hey Guys;

CAUTION HERE!!!!!

If you use the "secret FIFO" you WILL get screwed up if you alse expect to use the SX Key to DEBUG code in those places where you use that FIFO.

Once your code is properly running and the SX Key is no longer used, all seems to operate OK.

Where the problem comes in, is when your program breaks into the debugger, several of your global variables are stored in that FIFO, so if you mess with those contents then improper values may be restored yielding unpredictable results.

I have NOT tested this exhaustively, and my description is what my current understanding is; it could be flawed.

SO PLEASE, USER BE WARE

That said, have fun pushing the limits!

Peter (pjv)

Paul Baker

I think PeterM may be the only one to know the answer to this, but is there an environment variable availible in SASM that specifies whether the code once compiled will be in debug mode vs non-debug mode? It would be really nice to throw a compile error if the code will be run in debug mode when there are secret instructions used that would interfere with debugging.

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·1+1=10

PJMonty

Paul,

Sorry, but SASM doesn't have any such ability. SASM was written by Ubicom for public release as their reference assembler for the SX chips. I believe that due to it being a program "for public consumption", they probably had no intention of adding support, documented or not, for the hidden instructions. I have spent far more time than I ever imagined working on the SASM code and I can guarantee that functionality like that is not buried anywhere in the source files.

Thanks, PeterM

Paul Baker

Thanks Peter, it was just a thought, of course one could throw a warning instead of an error, but it would have been nice to completely prevent such an occurance.

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·1+1=10

Peter Verkaik

Jon,

I adapted your template to make the fifo use optional.

Bean,

I removed the clr fsr instruction, SX/B already sets it correct and the fifo code does not

touch the fsr.



regards peter