it contains the top half of the previous multiply-with-subtract,
and the current product must be subtracted from it.
-The pseudocode for `maddx RT, RA, RB, RC` is:
+The pseudocode for `madded RT, RA, RB, RC` is:
prod[0:127] = (RA) * (RB)
sum[0:127] = EXTZ(RC) + prod
to it; the lower half of the result stored in RT and the upper half
in RS.
+The differences here to `maddhdu` are that `maddhdu` stores the upper
+half in RT, where `madded` stores the upper half in RS. There is no
+equivalent to `maddld` because `maddld` performs sign-extension on RC.
+
# Appendix
see [[appendix]]