🚀 go-pugleaf

--=}>> On 8 Nov 92 17:15:57 GMT, moshier@world.std.com (Stephen L Moshier) said:

>  Use the two-cycle interrupt, not an interrupt handler.  Then check
> the pointer regsiter occasionally in a polling loop to see if it has
> crossed either the middle or end of the buffer.

I tried to use the two-word interrupt, but I just can't make anything
useful fit into two instruction words.  If you have any examples (Hey,
it's short :-), please post.  I know this fast-interrupt would be
great to use, but one complex instruction takes both words.

The problem with polling in the main loop is that I then have to
guarantee that the main loop runs at least as fast as the SSI
interrupts occur.  If the main loop could run reliably run that fast,
I wouldn't really need the interrupt handler to fetch incoming SSI
data.  The problem is that the main loop does compression and host
communication, so it could very well take a while to loop.

Please, if I am missing something, let me know.

Also, is there an easy way to check if an addressing register has just
wrapped around in a modulo buffer?  (Accumulator compare is
expensive.) Right now, I carefully pick my buffer address and size so
that a single bit in the register will be set when we went "one
address to far".  Of course, this doesn't use modulo addressing at
all, but I manually force the register back to start when the bit is
set.

Is any status flag set on modulo wrap-around?

Thanks!
-Steve

Steve Haehnichen          ---  PGP public key available upon request.  ---
shaehnic@ucsd.edu     (FTP pub/crypt/unix_pgp20.tar.Z from ghost.dsi.unimi.it)