Merge branch 'sdtwigg_rebase_renamechisel3' into sdtwigg_wrap_renamechisel3

1 files changed, 57 insertions, 0 deletions

diff --git a/src/main/scala/chisel3/util/Reg.scala b/src/main/scala/chisel3/util/Reg.scala
new file mode 100644
index 00000000..81de4754
--- /dev/null
+++ b/src/main/scala/chisel3/util/Reg.scala
@@ -0,0 +1,57 @@
+// See LICENSE for license details.
+
+/** Variations and helpers for registers.
+  */
+
+package chisel3.util
+
+import chisel3._
+
+object RegNext {
+
+  def apply[T <: Data](next: T): T = Reg[T](null.asInstanceOf[T], next, null.asInstanceOf[T])
+
+  def apply[T <: Data](next: T, init: T): T = Reg[T](null.asInstanceOf[T], next, init)
+
+}
+
+object RegInit {
+
+  def apply[T <: Data](init: T): T = Reg[T](null.asInstanceOf[T], null.asInstanceOf[T], init)
+
+}
+
+/** A register with an Enable signal */
+object RegEnable
+{
+  def apply[T <: Data](updateData: T, enable: Bool): T = {
+    val r = Reg(updateData)
+    when (enable) { r := updateData }
+    r
+  }
+  def apply[T <: Data](updateData: T, resetData: T, enable: Bool): T = {
+    val r = RegInit(resetData)
+    when (enable) { r := updateData }
+    r
+  }
+}
+
+/** Returns the n-cycle delayed version of the input signal.
+  */
+object ShiftRegister
+{
+  /** @param in input to delay
+    * @param n number of cycles to delay
+    * @param en enable the shift */
+  def apply[T <: Data](in: T, n: Int, en: Bool = Bool(true)): T =
+  {
+    // The order of tests reflects the expected use cases.
+    if (n == 1) {
+      RegEnable(in, en)
+    } else if (n != 0) {
+      RegNext(apply(in, n-1, en))
+    } else {
+      in
+    }
+  }
+}