or download this
"longdblkind"
From d_longdbl.U:
...
big endian, 7 = 128-bit mixed-endian double-double (64-bit LEs in
"BE"), 8 = 128-bit mixed-endian double-double (64-bit BEs in "LE"),
9 = 128-bit "PDP"-style mixed-endian long doubles, -1 = unknown format
+.