From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Sat, 3 Aug 2019 22:39:12 +0000 (+0100)
Subject: only pass on the uncancelled mask bits
X-Git-Tag: ls180-24jan2020~551
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=ecc0461e2bbe497a282274d1fddd9304f389f5d6;p=ieee754fpu.git

only pass on the uncancelled mask bits
---

diff --git a/src/nmutil/singlepipe.py b/src/nmutil/singlepipe.py
index 17df104c..7f146585 100644
--- a/src/nmutil/singlepipe.py
+++ b/src/nmutil/singlepipe.py
@@ -432,12 +432,15 @@ class MaskCancellable(ControlBase):
         # is NOT "normal" for the Stage API.
         p_valid_i = Signal(reset_less=True)
         #print ("self.p.data_i", self.p.data_i)
-        m.d.comb += p_valid_i.eq(((self.p.mask_i & ~self.p.stop_i).bool()))
+        maskedout = Signal(len(self.p.mask_i), reset_less=True)
+        m.d.comb += maskedout.eq(self.p.mask_i & ~self.p.stop_i)
+        m.d.comb += p_valid_i.eq(maskedout.bool())
 
         # if idmask nonzero, mask gets passed on (and register set).
         # register is left as-is if idmask is zero, but out-mask is set to zero
+        # note however: only the *uncancelled* mask bits get passed on
         m.d.sync += self.n.valid_o.eq(p_valid_i)
-        m.d.sync += self.n.mask_o.eq(Mux(p_valid_i, self.p.mask_i, 0))
+        m.d.sync += self.n.mask_o.eq(Mux(p_valid_i, maskedout, 0))
         with m.If(p_valid_i):
             data_o = self._postprocess(result) # XXX TBD, does nothing right now
             m.d.sync += nmoperator.eq(self.n.data_o, data_o) # update output