Re: evdev types

[Vojtech P. <vo...@su...>]

On Mon, Apr 15, 2002 at 08:41:33PM +1000, Brad Hards wrote:
> On Mon, 15 Apr 2002 17:40, Vojtech Pavlik wrote:
> > Yes, if this is cleaner. I have much bigger worries about the size of
> > 'long' in EVIOCGBIT and /proc/bus/input/devices output on archs that
> > support mixed 32/64-bit binaries (SPARC, PPC, x86-64).
> Oh. Ugly.

Yeah. setbit() et al work on longs, and longs are OK in an API which
isn't on a mixed 32/64-bit arch. But since the 32/64 bit stuff happens,
it gets pretty ugly.

> I thought that those definitions were purely internal - I hadn't got that far 
> into the detail of the API.

Unfortunately they are not - they can't be - apps need to know what
valuators, keys, whatever the device has.

> I'll continue along with the documentation/tutorial, and raise questions / 
> patches as appropriate.
> 
> BTW: The documentation is for USB HID, to try to answer questions for 
> developers of products and userspace apps.
> It covers hiddev, evdev, joystick (including force feedback), mouse and 
> keyboard.

God bless you for that. It is really needed. And I never can get me to
write docs. :(

> I am doing hiddev and evdev in detail, since I think these are basically 
> undocumented. I've just done a couple of ioctl examples for each so far.
> I am doing joystick by direct reference to the kernel docs - I may copy the 
> kernel files into the documentation (and docbook them) at a later stage and 
> add some examples, but the initial work work will be on evdev and hiddev, and 
> there is plenty there.

That's exactly what's needed - actually joydev (and its api) is
obsoleted by evdev.

> What is missing is keyboard and mouse. I'd be willing to leave out keyboard 
> (because the stdin/scanf/getc semantic is probably enough.

There isn't any keyboard API other than evdev and the console.

> What I don't have 
> is mouse coverage. Does anyone have a good pointer to programming with the 
> PS2 variations? I was thinking about just pointing to libgpm, but that 
> doesn't really explain what comes out of /dev/input/mouse[0..30] when you 
> read. 

 /dev/input/mouse[0..30] simulates (quite exactly, both directions) the
protocol of Microsoft IntelliMouse Explorer. But no new applications
should use it, evdev is more powerful and easier to write for.

I hope both mousedev and joydev will not be needed by 2.6 (2.8) or so.

-- 
Vojtech Pavlik
SuSE Labs