[Coco] Which version of C?

K. Pruitt pruittk at roadrunner.com
Wed Jan 14 19:24:07 EST 2015


> On Monday, January 12, 2015 05:08:39 AM K. Pruitt did opine
> And Gene did reply:
 <SNIP>
>> >>
>> >> But the best optimizer is the human brain. By interrupting the
>> >> compiler and inspecting the assembly code as it would be sent to
>> >> c.asm (or rma today) and spend some time looking for bit shift
>> >> loops that shift by 8 one way or the other, nuke that code and sub
>> >> a tfr, clear statement pair in its place. That is one of the
>> >> tricks that took rzsz from just barely keeping up with a 2400 baud
>> >> modem, aka 240 bytes a second to nearly 720 bytes a second running
>> >> on a 6309. That, and changing to a table lookup crc which is much
>> >> faster than calculating it.
>> >>
>> >> Cheers, Gene Heskett
>> >
>> > Wow, Gene, I almost understood about 80% of that.  I normally only
>> > understand about half of what you're saying.  But I always flag your
>> > messages as important because even understanding only half of what
>> > you're talking about is like walking through a gold mine with
>> > nuggets strewn about just waiting to be picked up.  Eventually I'll
>> > understand even more of the gems you share here.  Thanks for doing
>> > so.  I wrote an Xmodem CRC utility for OS-9 years ago and the math
>> > was so extensive and honestly way above my head (polynomials?) and
>> > that actually helped me understand your code optimization comments.
>> > I'm still very fond of using tables instead of cycle-eating math
>> > when I can.
>> >
>> > By the way, my thanks also goes out to Robert Gault and a quite a
>> > few others here for all the great help you guys share here.
>>
>> Ah!  I had to consult Leventhal's book, but I now get what you're
>> saying.  I don't think I've ever used the TFR instruction before. You
>> can bet I'll be playing with it now.
>
> The somewhat funny part of that was that before I started building rzsz
> for coco's, a fellow named Paul Jerkatis was trying to do it, and
> failing.
>

Well, I was able to do it (xmodem) because I waited for the high speed T2 
drivers to show up.

I had no idea you wrote rzsz.  I literally used those daily for years for 
all my uploading and downloading. So thanks!



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