Enhance views to [sometimes] support dynamic indexing and implement FlatIO (backport #2476) (#2479)

* Capture 1:1 mappings of Aggregates inside of views

This is implemented by including any corresponding Aggregates from the
DataView.mapping in the AggregateViewBinding.childMap (which is now of
type Map[Data, Data]).

This enables dynamically indexing Vecs that are themselves elements of
larger Aggregates in views when the corresponding element of the view is
a Vec of the same type. It also increases the number of cases where a
single Target can represent part of a view.

(cherry picked from commit 1f6b1ca14ccf86918065073c3f6f3626dd83a68e)

* Add FlatIO API for creating ports from Bundles without a prefix

(cherry picked from commit 772a3a1fe3b9372b7c2d7cd2d424b2adcd633cdb)

* [docs] Add FlatIO to the general cookbook

(cherry picked from commit b4159641350f238f0f899b69954142ce8ee11544)

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

1 files changed, 8 insertions, 3 deletions

diff --git a/core/src/main/scala/chisel3/internal/Binding.scala b/core/src/main/scala/chisel3/internal/Binding.scala
index 6431dd23..bab79bc1 100644
--- a/core/src/main/scala/chisel3/internal/Binding.scala
+++ b/core/src/main/scala/chisel3/internal/Binding.scala
@@ -141,11 +141,16 @@ case class DontCareBinding() extends UnconstrainedBinding
 private[chisel3] case class ViewBinding(target: Element) extends UnconstrainedBinding
 
 /** Binding for Aggregate Views
-  * @param childMap Mapping from children of this view to each child's target
+  * @param childMap Mapping from children of this view to their respective targets
   * @param target Optional Data this Aggregate views if the view is total and the target is a Data
+  * @note For any Elements in the childMap, both key and value must be Elements
+  * @note The types of key and value need not match for the top Data in a total view of type
+  *       Aggregate
   */
-private[chisel3] case class AggregateViewBinding(childMap: Map[Data, Element], target: Option[Data])
-    extends UnconstrainedBinding
+private[chisel3] case class AggregateViewBinding(childMap: Map[Data, Data]) extends UnconstrainedBinding {
+  // Helper lookup function since types of Elements always match
+  def lookup(key: Element): Option[Element] = childMap.get(key).map(_.asInstanceOf[Element])
+}
 
 /** Binding for Data's returned from accessing an Instance/Definition members, if not readable/writable port */
 private[chisel3] case object CrossModuleBinding extends TopBinding {