1 files changed, 61 insertions, 0 deletions
diff --git a/src/main/scala/chisel3/util/Valid.scala b/src/main/scala/chisel3/util/Valid.scala
new file mode 100644
index 00000000..56ac9abb
--- /dev/null
+++ b/src/main/scala/chisel3/util/Valid.scala
@@ -0,0 +1,61 @@
+// See LICENSE for license details.
+
+/** Wrappers for valid interfaces and associated circuit generators using them.
+  */
+
+package chisel.util
+
+import chisel._
+
+/** An I/O Bundle containing data and a signal determining if it is valid */
+class ValidIO[+T <: Data](gen2: T) extends Bundle
+{
+  val valid = Bool(OUTPUT)
+  val bits = gen2.cloneType.asOutput
+  def fire(dummy: Int = 0): Bool = valid
+  override def cloneType: this.type = new ValidIO(gen2).asInstanceOf[this.type]
+}
+
+/** Adds a valid protocol to any interface. The standard used is
+  that the consumer uses the flipped interface.
+*/
+object Valid {
+  def apply[T <: Data](gen: T): ValidIO[T] = new ValidIO(gen)
+}
+
+/** A hardware module that delays data coming down the pipeline
+  by the number of cycles set by the latency parameter. Functionality
+  is similar to ShiftRegister but this exposes a Pipe interface.
+
+  Example usage:
+    val pipe = new Pipe(UInt())
+    pipe.io.enq <> produce.io.out
+    consumer.io.in <> pipe.io.deq
+  */
+object Pipe
+{
+  def apply[T <: Data](enqValid: Bool, enqBits: T, latency: Int): ValidIO[T] = {
+    if (latency == 0) {
+      val out = Wire(Valid(enqBits))
+      out.valid <> enqValid
+      out.bits <> enqBits
+      out
+    } else {
+      val v = Reg(Bool(), next=enqValid, init=Bool(false))
+      val b = RegEnable(enqBits, enqValid)
+      apply(v, b, latency-1)
+    }
+  }
+  def apply[T <: Data](enqValid: Bool, enqBits: T): ValidIO[T] = apply(enqValid, enqBits, 1)
+  def apply[T <: Data](enq: ValidIO[T], latency: Int = 1): ValidIO[T] = apply(enq.valid, enq.bits, latency)
+}
+
+class Pipe[T <: Data](gen: T, latency: Int = 1) extends Module
+{
+  val io = new Bundle {
+    val enq = Valid(gen).flip
+    val deq = Valid(gen)
+  }
+
+  io.deq <> Pipe(io.enq, latency)
+}