+/* --- @mpx_uaddnlsl@ --- *
+ *
+ * Arguments: @mpw *dv, *dvl@ = destination and first argument vector
+ * @mpw a@ = second argument
+ * @unsigned o@ = offset in bits
+ *
+ * Returns: ---
+ *
+ * Use: Computes %$d + 2^o a$%. If the result overflows then
+ * high-order bits are discarded, as usual. We must have
+ * @0 < o < MPW_BITS@.
+ */
+
+void mpx_usubnlsl(mpw *dv, mpw *dvl, mpw a, unsigned o)
+{
+ mpw b = a >> (MPW_BITS - o);
+ a <<= o;
+
+ if (dv < dvl) {
+ mpd x = (mpd)*dv - (mpd)a;
+ *dv++ = MPW(x);
+ if (x >> MPW_BITS)
+ b++;
+ MPX_USUBN(dv, dvl, b);
+ }
+}
+