Restore old CO behaviour

diff --git a/passes/pmgen/ice40_dsp.cc b/passes/pmgen/ice40_dsp.cc
index 369cb211e0ab4c915cc2213ec70149c0ced09447..00794ca0df8670bcfd40e49db7d70b7273e9ce24 100644 (file)
--- a/passes/pmgen/ice40_dsp.cc
+++ b/passes/pmgen/ice40_dsp.cc
@@ -144,14 +144,15 @@ void create_ice40_dsp(ice40_dsp_pm &pm)
        // SB_MAC16 Output Interface
 
        SigSpec O = st.sigO;
-       if (GetSize(O) == 33) {
-               cell->setPort("\\CO", st.sigO[32]);
-               O.remove(32);
+       int O_width = GetSize(O);
+       if (O_width == 33) {
+               log_assert(st.addAB);
+               cell->setPort("\\CO", O[-1]);
+               O.remove(O_width-1);
        }
-       else {
-               log_assert(GetSize(O) <= 32);
+       else
                cell->setPort("\\CO", pm.module->addWire(NEW_ID));
-       }
+       log_assert(GetSize(O) <= 32);
        if (GetSize(O) < 32)
                O.append(pm.module->addWire(NEW_ID, 32-GetSize(O)));