[console] Include mappings for AltGr-Shift-<key>

The BIOS console's interpretation of LShift+RShift as equivalent to
AltGr requires the shifted ASCII characters to be present in the AltGr
mapping table, to allow AltGr-Shift-<key> to be interpreted in the
same way as AltGr-<key>.

For keyboard layouts that have different ASCII characters for
AltGr-<key> and AltGr-Shift-<key>, this will potentially leave the
character for AltGr-<key> inaccessible via the BIOS console if the
BIOS requires the use of the LShift+RShift workaround.  This
theoretically affects the numeric keys in the Lithuanian ("lt")
keyboard layout (where the numerals are accessed via AltGr-<key> and
punctuation characters via AltGr-Shift-<key>), but the simple
workaround for that keyboard layout is to avoid using AltGr and Shift
entirely since the unmodified numeric keys are not remapped anyway.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/util/genkeymap.py

@@ -365,9 +365,11 @@ class Keymap:
         """AltGr remapping table"""
         # Construct raw mapping from source ASCII to target ASCII
         raw = {
-            source:
-            self.target.get((key.modifiers | KeyModifiers.ALTGR),
-                            self.target[key.modifiers])[key.keycode].ascii
+            source: next((self.target[x][key.keycode].ascii
+                          for x in (key.modifiers | KeyModifiers.ALTGR,
+                                    KeyModifiers.ALTGR, key.modifiers)
+                          if x in self.target
+                          and self.target[x][key.keycode].ascii), None)
             for source, key in self.source.inverse.items()
         }
         # Identify printable keys that are unreachable via the basic map