This is very timely, as we've been approached by a PC keyboard
manufacturer that wants to enter the Mac market. Most of the
non-standard keys I can handle from a user land app (buttons for email,
music, pictures etc). However, the keys for Option and Command are
mapped backwards making the keyboard mostly unusable...
On Feb 3, 2005, at 1:39 PM, Rich Kubota wrote:
On the face of it, the task doesn't look too daunting. It should be a
simple matter of adapting the already available open source Apple
keyboard driver. Looking around on the Apple dev web site didn't turn
up (m)any clues about how usb keyboard input is handled, but
downloading the USBFamily.kext code made things a little clearer.
the IOUSBHIDDriver.cpp code does show that the process point for the
incoming report is with the
handleReport(_buffer) call line 1081.
At this point, the call takes you to the
IOHIDDevice::handleReport call in the IOHIDDevice.cpp file which is a
part of the IOHIDFamily source. The actual processing of the keystroke
is in the
IOHIDKeyboard::handleReport() call which is in the IOHIDKeyboard.cpp
code.
Here you can see how the report is processed.
This should help get you started. What you should be able to do is
implement a vendor specific driver for your keyboard modeled after the
standard HID class driver. When the incoming report is received, you
have a chance to inspect the bytes and twiddle them to make it appear
that a keys were pressed or released.
I've written a lot of Mac code, but never a kext before, so maybe you
can clarify this a bit. If it helps to pretend I'm dense, please do so.
:-)
What you are saying we should do is:
- Change the IOUSBHIDDriver project target to match against our
keyboard (plist change) and I presume change the name of the class to
something appropriate.
- In InterruptReadHandler, twiddle the raw data before handleReport is
called to make whatever modifications are desired.
Is that it?
Thanks,
Dave
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