Recursively generate one-hot multiplexers for aggregates (#1557)

Test all cases in ParameterizedOneHotTesters

Co-authored-by: Jack Koenig <koenig@sifive.com>

1 files changed, 10 insertions, 3 deletions

diff --git a/core/src/main/scala/chisel3/SeqUtils.scala b/core/src/main/scala/chisel3/SeqUtils.scala
index 9f068898..97bdc505 100644
--- a/core/src/main/scala/chisel3/SeqUtils.scala
+++ b/core/src/main/scala/chisel3/SeqUtils.scala
@@ -113,10 +113,17 @@ private[chisel3] object SeqUtils {
             buildAndOrMultiplexor(sels.zip(inWidthMatched))
           }
 
-        case _: Aggregate =>
+        case agg: Aggregate =>
           val allDefineWidth = in.forall { case (_, element) => element.widthOption.isDefined }
-          if(allDefineWidth) {
-            buildAndOrMultiplexor(in)
+          if (allDefineWidth) {
+            val out = Wire(agg)
+            val (sel, inData) = in.unzip
+            val inElts = inData.map(_.asInstanceOf[Aggregate].getElements)
+            // We want to iterate on the columns of inElts, so we transpose
+            out.getElements.zip(inElts.transpose).foreach { case (outElt, elts) =>
+              outElt := oneHotMux(sel.zip(elts))
+            }
+            out.asInstanceOf[T]
           }
           else {
             throwException(s"Cannot Mux1H with aggregates with inferred widths")