Disable data value output on NOP

diff --git a/src/soc/experiment/alu_hier.py b/src/soc/experiment/alu_hier.py
index c01cc26ee2d5eb94811cfdd82a47f2f03c04c2a0..39e9cb92851652f3e39063285e60b67eac2344ae 100644 (file)
--- a/src/soc/experiment/alu_hier.py
+++ b/src/soc/experiment/alu_hier.py
@@ -317,11 +317,13 @@ class ALU(Elaboratable):
 
         # choose between zero-delay output, or registered
         with m.If(go_now):
-            m.d.comb += self.o.data.eq(sub.o)
+            with m.If(self.o.ok):
+                m.d.comb += self.o.data.eq(sub.o)
             m.d.comb += self.cr.ok.eq(self.op.rc.rc)
         # only present the result at the last computation cycle
         with m.Elif(alu_done):
-            m.d.comb += self.o.data.eq(alu_r)
+            with m.If(self.o.ok):
+                m.d.comb += self.o.data.eq(alu_r)
             m.d.comb += self.cr.ok.eq(cr_ok_r)
 
         # determine condition register bits based on the data output value