Raw access to keycodes/scancodes from userspace?
 

Is there an interface whereby a userspace program can retrieve the raw keycodes/scancodes from a keyboard? I'm trying to make something in the way of a piano keyboard, and I need to know when keys are pressed (possibly simultaneously), and when they are released.

Have a look here:
http://www.linuxquestions.org/questi...1/#post3956458
and here too:
http://www.faqs.org/docs/Linux-HOWTO...-HOWTO.html#s1

The first link just appears to be getting raw character codes from the keyboard. I need the keycodes instead because I need to know when a key is released as well as when it is pressed. The second link mentions scancode and keycode modes, but doesn't mention how to switch modes. :( I looked at termios, but I can't find anything there either. Is there something I missed?

Can you explain this in more detail ?

Well, The article in the second link mentions that when an application is in "keycode mode", keycodes are delivered to it instead of character codes. It does not mention how you would put your application in "keycode mode." Is there some ioctl or something you can call on stdin to do this?

How about this ?
http://linux.die.net/man/1/kbd_mode



Check out the following links too (but after the first one):
http://gunnarwrobel.de/wiki/Linux-an...oard.html#sec5
and
http://gunnarwrobel.de/wiki/Linux-an...oard.html#sec5

you could
keyboard()
{
fd=open(/dev/null);
read(fd)
}

That looks like what I'm trying to do, except that:
* It is an external program (I would like a library function or system call I can call from within a program), and
* As far as I can tell, Its action would be global (if I suspend my program, I'd like to be able to type correctly).
Is there a library function or system call that replaces this functionality?

Would that DO anything?

You can use system() function to call "kbd_mode" !

Note:
You should try searching Google before asking questions and then tell exactly what you found and how that was not helpful !

I know I could call kbd_mode. My main concern was that kbd_mode appears to affect all keyboard input. Is this correct?
I stay in console mode, switching back and forth between virtual terminals, and I don't want ALL my keyboard input to be in keycode mode.

Also, I just checked, and I don't have kbd_mode. :( If there's no library function to replace that functionality, is there somewhere I can get kbd_mode?

When you say you don't have kbd_mode does it mean when you run it from terminal nothing happens ??

Name your distribution !

sorry I take a mistake,it should be open("/dev/input/event")

I mean that to open a device file of keyboard with the system call "open"
and read data from the file,when a key is pressed or released the event have been save into the struct input_event
this is defined in /usr/include/linux/input.h. else some key code and input event defined in it
the define is following
struct input_event
{
struct timeval time;
_u16 type;
_u16 code;
_u32 value;
};
a simple example:
struct input_event ie;
memset(&ie,0,sizeof(struct input_event));
int fd=open("/dev/input/event0",O_RDONLY);
read(fd,&ie,sizeof(struct input_event))
switch(ie.code)
{
case KEY_ESC:
exit(0);
break;
case KEY_F1:
.....//your code
break;
........
default:
printf("No key pressed\n");
}
the above code may be take mistake too
:-)

I mean, when I say "which kbd_mode", it returns command not found. My distro is Puppy Linux 4.00, and is listed on the sidebar of my posts.

I tried :
on OpenSuse 11.2.

Check which package/RPM/DEB/tar etc is needed for Puppy Linux for keyboard programming !