Re: [cc65] "software" stack?

From: Oliver Schmidt <ol.sc1web.de>
Date: 2010-10-30 10:56:39
Hi Gábor,

> Ahaa, thanks a lot, it was useful for me! I was thought on replace RTS, JSR
> and other opcodes on the generated asm source by cc65 into my own solutions,
> which uses the "parameter stack" as well, so I would have a single stack,
> not the "return" (6502 hw) and the "parameter".  Then I would no need to
> save/restore the 6502 hw stack on context switching at all.  Thanks for the
> information!

My guess is that the current cc65 design point is already the sweet
spot. If the context switch frequency isn't *VERY* high then I believe
it'll be much cheaper to do the save/restore then to sacrifice
JSR/RTS. Especially as using page 1 only for JSR/RTS means that
typically only a small portion of page 1 is actually used - and with
TSX / TXS (you need on context switching the page 1 stack anyway) you
are already set to very effectively limit the loop for
saving/restoring page1 to the area actually used by the context
saved/restored.

Just my two cents,
Oliver
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Received on Sat Oct 30 11:01:17 2010

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