New config program

[Donovan Rebbechi <elflord@pegasus.rutgers.edu>]

Hi. I realise that this message is a little out of place , can someone
forward it to the right list ? 

 I wrote a little perl program today that creates modelines. What it
 does is asks for  

hsync vsync dotclock resolution (selected from 640x480 , 800x600 ,
1024x768, 1280x1040 ) 

and then spits out a mode line. 

It essentially follows the way of thinking in the XFree86 Video
timings HOWTO. It was inspired by persistent failure of configuration
programs I've used. I've tested it on my monitor and the math is
correct (that is, if you choose a hsync , vsync and dot clock, you
really do get those settings) . Also, the modes it writes seem to work
(if you don't go outside your monitors specs). Of course some of them
look kind of funny (screen sometimes displaced or too narrow) but this
can usually be fixed with the buttons on the monitor and/or xvidtune.

I would be delighted if some people could test it, or take a look at
the code and work on it. Mail me if you're interested. I'd admit that
I'm not an expert programmer, but actually , this program is pretty
simple (it merely follows a slightly simplified version of the
procedure described in the HOWTO) 


It works on essentially the following logic: 

(a)	The horizontal sync pulse should ideally be 3.8 microseconds ,
3.5 microseconds is still OK , if 3.0 or more isn't possible, it gives
a pretty mean warning.

(b)	Simililarly for the vsync pulse. The numbers used are 100, 50
and 40 micro-seconds

(c) 	The "magic numbers" are defined at the top of the program which
is well commented

(d) 	THe horizontal  and vertical front and back porches are defined
by constants (I used 32 ,32 , 3 and 3 ) 

(e) 	The sync pulses are placed in the middle of the space between
the front and back porches

(f)	If the user specifies incompatible selections, (ie their
selection results in sync pulses that is too short) they are given
advice on how they could make a better choice. 

(g)	I want to eliminate asking the user to specify a dot clock , but
don't know how one should choose a dot clock. 

cheers

	-- DOnovan