EVIOCGKEYCODE - can't deduce arguments.

[Brad H. <bh...@bi...>]

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I'm trying to finish off my documentation, and it's down to EVIOC[G,S]KEYCODE.

The problem is that I don't think I understand what the arguments are.

EVIOCGKEYCODE takes a int[2], and the first int looks like it should be passed 
in (ie I set int[0] to some value, then call ioctl(fd, EVIOCGKEYCODE, int), 
and then read back the other value in int[1]).

I guess that the first argument is a scancode, and the second is a keycode.

However when I pass in what I think is a reasonable value (as given by 
showkeys -s), I'm getting -EINVAL.

Example: showkey -s gives me 0x39 for a space bar held down. I assumed if I   

codes[0] = 0x39;
if(ioctl(fd, EVIOCGKEYCODE, codes))
    perror("evdev ioctl");
printf("[0]= %d, [1] = %d\n", codes[0], codes[1]);

Then I would get back codes[1] == KEY_SPACE.

However I get
evdev ioctl: Invalid argument
[0]= 57, [1] = 1073784704

Anyone familiar with this? Or can provide a hint?

I guess EVIOCSKEYCODE just assignes the int[1] keycode to the int[0] scancode. 
I can't make that work until I understand the scancodes business more, I 
think.

Brad
- -- 
http://linux.conf.au. 22-25Jan2003. Perth, Aust. I'm registered. Are you?
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