+ (logior (mask-field (byte 18 14) value)
+ (if (< value 0)
+ (1+ (ash (ldb (byte 13 0) value) 1))
+ (ash (ldb (byte 13 0) value) 1))))
+ (:load11u
+ (logior (if (< value 0)
+ (1+ (ash (ldb (byte 10 0) value) 1))
+ (ash (ldb (byte 11 0) value) 1))
+ (mask-field (byte 18 14) inst)))