add TODO comment

diff --git a/src/add/nmigen_add_experiment.py b/src/add/nmigen_add_experiment.py
index 8f075cf18075be165c22c506bb0e33bc5bdb3e72..a751ea2e2505a0e4766d28b991126349450f9903 100644 (file)
--- a/src/add/nmigen_add_experiment.py
+++ b/src/add/nmigen_add_experiment.py
@@ -115,6 +115,9 @@ class FPADD(FPBase):
                     # This one however (single-cycle) will do the shift
                     # in one go.
 
+                    # XXX TODO: the shifter used here is quite expensive
+                    # having only one would be better
+
                     ediff = Signal((len(a.e), True))
                     ediffr = Signal((len(a.e), True))
                     m.d.comb += ediff.eq(a.e - b.e)