Re: Sv: [cc65] Back on Track

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From: Spiro Trikaliotis (Spiro.Trikaliotis_at_gmx.de)
Date: 2000-01-22 17:04:00


Hi again Groepaz,

>With 'slow' seeks i was referring to the speed one could be expecting from eg
>a pc hd. on a 1541 ofcoz, you can hardly do any faster ;=P

Ok, now I got it.

>this way no more data than necessary has to travel the serial bus ;=) (which is
>the bottleneck in the cbm setup ;=)

Yes, that's what I meant.


>well, what you are thinking of is async-operations and YES it will be ofcoz
>possible to improve the disc-driver to use it.... however, due to the nature
>of the 'generalized' kernal and kernal-disc drivers its out of the question at
>this time.... but something to remember for the 1541-specific driver ;=)

Well, yes, that's something thas has to be adopted to the used floppy,
but it will be worth if, I believe.


>well...for a 664 blox file it would require 664*2 bytes for buffering the
>whole link-list.... maybe its too much you are right ... mmmhhhh, i have to
>think about some mechanism that retrieves the list when needed ;=P

Well, I did not think about the memory needed (which is quite a lot with
664 blocks, you're right) but the time needed!

If such a file were opened, you had to read the whole disc at startup
only to get the complete list, w/o possibility to read anything before
that!


I think of a solution in the following way:
With every read using a new sector, you transfer the link contents of
the sector to the host machine, so seeks up to the point you're
currently at could be handled this way.

When seeking, you do the same: Reading only the links up to the point
you actually need them.

A good option would be to program the floppy to collect this infor-
mation in its idle time.


>> Well, now I'm not sure, but I believe you should only close() _one_
>> pre-defined file handle at a time and re-open it immediately.

>this will also work. it will also be 'safer' than the way i mentioned above i
>think
>since it'll also work if stdin/out/err are NOT fd=0,1,2

Yes, this 'safety' is IHMO the reason why only one pre-defined handle
should be handled at once.


Gru,
   Spiro.


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