[console] Add facility for rudimentary keyboard mapping

Allow for remapping of ASCII characters returned by the BIOS, using a
map consisting of (from,to) pairs.

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

src/include/ipxe/keymap.h

@@ -0,0 +1,30 @@
+#ifndef _IPXE_KEYMAP_H
+#define _IPXE_KEYMAP_H
+
+/**
+ * @file
+ *
+ * Keyboard mappings
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <stdint.h>
+#include <ipxe/tables.h>
+
+/** A keyboard mapping */
+struct key_mapping {
+	/** Character read from keyboard */
+	uint8_t from;
+	/** Character to be used instead */
+	uint8_t to;
+} __attribute__ (( packed ));
+
+/** Keyboard mapping table */
+#define KEYMAP __table ( struct key_mapping, "keymap" )
+
+/** Define a keyboard mapping */
+#define __keymap __table_entry ( KEYMAP, 01 )
+
+#endif /* _IPXE_KEYMAP_H */