SetupDesignGuide.pdf - Firmware Encoding Index

Setup Design Guide
DRAFT
Modifier Key Value:
This defines the non-printable special function this key has assigned to it.
Under normal circumstances, a key that has any Unicode definitions generally has a Control key value
of SCAN_NULL. This means the key has no special function other than the printing of a character. If
any of the Unicode values have a value of 0xFFFF this is the exception to the rule. Though rarely used,
this is the one case which a key might have both a printable character and an active Control key value.
An example of this would be the numeric keypad’s insert key. The definition for this key on a standard
US keyboard is as follows:
Key Name = ZERO_KEY
Unicode Value = 0x0030 (basically a ‘0’)
Shifted Unicode Value = 0xFFFF (the exception to the rule)
Alt-GR Unicode Value = 0x0000
Shifted Alt-GR Unicode Value = 0x0000
Modifier Key Value = SCAN_INSERT
This is one of the few keys that under normal circumstances prints something out, but also has a special
function. These are generally limited to the numeric keypad, however this does not prevent someone
from having the flexibility to define these types of variations.
(Assuming for the implementation that the state of CapsLock and NumLock, etc will correctly handle
the shift states since they do it already……just wanted to mention it and it was thought about)
9.2 Modifier Key Definitions
Modifier keys are defined to allow for special functionality that is not necessarily accomplished by a
printable character. Many of these modifier keys are flags to toggle certain state bits on and off inside
of a keyboard driver. An example is CAPS_LOCK_MODIFIER. This state being active could alter
what the typing of a particular key produces. Other control keys affect the position of the cursor like
LEFT_ARROW_MODIFIER, END_MODIFIER, etc. One modifier key is likely unfamiliar to most
people who exclusively use US keyboards, and that key is the ALT_GR_MODIFIER key. This key’s
primary purpose is to activate a secondary type of shift modifier that exposes additional printable
characters on certain keys. In some keyboard layouts this key does not exist and is normally the
RIGHT_ALT_MODIFIER key. None of the other modifier key functions should be a mystery to
someone familiar with the usage of a standard computer keyboard.
An example of a few descriptor entries would be as follows:
Layout = {
EfiKeyLCtrl,0,0,0,0,LEFT_CONTROL_MODIFIER, //(Left control key)
EfiKeyA0,0,0,0,0,NULL_MODIFIER,
//(Not defined windows key)
EfiKeySpaceBar,0x0020,0x0020,0x0020,0x0020,NULL_MODIFIER //(Space Bar)
}
//
// Define the Control modifier value information
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