[MiNT] vim slow

[Vincent Rivière <vincent.riviere@freesbee.fr>]

Hello.

I have noticed that vim was slow in input mode. Just type a character, and 
it takes a fraction of second to be displayed. Even worse, if you keep the 
key pressed for key repeat, the characters are only displayed when you 
release the keys. Because the processing of each character is too slow. This 
slowdown only occurs in input mode, on the opposite command mode "Esc :" is 
very fast.

This slowdown occurs identically on the FireBee and ARAnyM. It is very 
surprising because they are 2 fast machines. And ARAnyM has an extremely 
fast CPU, I can't believe that something could be slow on it. So I thought 
at some kernel issue.

By looking at the vim sources and running it with strace, it seems that vim 
examines multiple times the terminal to see if characters are available. 
With the current MiNTLib, it falls into Fpoll(). I see the source in the 
kernel: sys/dosfile.c, function sys_f_poll().

I don't fully understand that function, but it looks strange.
Around line 1264, there is:
	if (count == 0)
	{
		/* no data is ready yet */

Then there is wait stuff like addtimeout(), spl7(), etc.
That wait code is called even when the timeout value is 0, I can't 
understand why. I would expect it would just return immediately.
As an experiment, if I put a "goto cancel;" at that place, vim suddenly 
becomes very fast, as expected.

So I wonder if the current code of sys_f_poll() is correct or not.
If there is a bug there, the fix could speed up many things.

Any thoughts?

--
Vincent Rivière