EFI_INPUT_READ_KEY_EX

The function reads the next keystroke from the input device. If there is no pending keystroke the function returns EFI_NOT_READY. If there is a pending keystroke, then KeyData.Key.ScanCode is the EFI scan code defined in Error! Reference source not found. The KeyData.Key.UnicodeChar is the actual printable character or is zero if the key does not represent a printable character (control key, function key, etc.). The KeyData.KeyState is shift state for the character reflected in KeyData.Key.UnicodeChar or KeyData.Key.ScanCode . When interpreting the data from this function, it should be noted that if a class of printable characters that are normally adjusted by shift modifiers (e.g. Shift Key + "f" key) would be presented solely as a KeyData.Key.UnicodeChar without the associated shift state. So in the previous example of a Shift Key + "f" key being pressed, the only pertinent data returned would be KeyData.Key.UnicodeChar with the value of "F". This of course would not typically be the case for non-printable characters such as the pressing of the Right Shift Key + F10 key since the corresponding returned data would be reflected both in the KeyData.KeyState.KeyShiftState and KeyData.Key.ScanCode values. UEFI drivers which implement the EFI_SIMPLE_TEXT_INPUT_EX protocol are required to return KeyData.Key and KeyData.KeyState values. These drivers must always return the most current state of KeyData.KeyState.KeyShiftState and KeyData.KeyState.KeyToggleState. It should also be noted that certain input devices may not be able to produce shift or toggle state information, and in those cases the high order bit in the respective Toggle and Shift state fields should not be active.