Rename chisel3 package.

1 files changed, 119 insertions, 0 deletions

diff --git a/src/main/scala/chisel3/util/Arbiter.scala b/src/main/scala/chisel3/util/Arbiter.scala
new file mode 100644
index 00000000..3723f2a9
--- /dev/null
+++ b/src/main/scala/chisel3/util/Arbiter.scala
@@ -0,0 +1,119 @@
+// See LICENSE for license details.
+
+/** Arbiters in all shapes and sizes.
+  */
+
+package chisel.util
+
+import chisel._
+
+/** An I/O bundle for the Arbiter */
+class ArbiterIO[T <: Data](gen: T, n: Int) extends Bundle {
+  val in  = Vec(n, Decoupled(gen)).flip
+  val out = Decoupled(gen)
+  val chosen = UInt(OUTPUT, log2Up(n))
+}
+
+/** Arbiter Control determining which producer has access */
+private object ArbiterCtrl
+{
+  def apply(request: Seq[Bool]): Seq[Bool] = request.length match {
+    case 0 => Seq()
+    case 1 => Seq(Bool(true))
+    case _ => Bool(true) +: request.tail.init.scanLeft(request.head)(_ || _).map(!_)
+  }
+}
+
+abstract class LockingArbiterLike[T <: Data](gen: T, n: Int, count: Int, needsLock: Option[T => Bool]) extends Module {
+  def grant: Seq[Bool]
+  def choice: UInt
+  val io = new ArbiterIO(gen, n)
+
+  io.chosen := choice
+  io.out.valid := io.in(io.chosen).valid
+  io.out.bits := io.in(io.chosen).bits
+
+  if (count > 1) {
+    val lockCount = Counter(count)
+    val lockIdx = Reg(UInt())
+    val locked = lockCount.value =/= UInt(0)
+    val wantsLock = needsLock.map(_(io.out.bits)).getOrElse(Bool(true))
+
+    when (io.out.fire() && wantsLock) {
+      lockIdx := io.chosen
+      lockCount.inc()
+    }
+
+    when (locked) { io.chosen := lockIdx }
+    for ((in, (g, i)) <- io.in zip grant.zipWithIndex)
+      in.ready := Mux(locked, lockIdx === UInt(i), g) && io.out.ready
+  } else {
+    for ((in, g) <- io.in zip grant)
+      in.ready := g && io.out.ready
+  }
+}
+
+class LockingRRArbiter[T <: Data](gen: T, n: Int, count: Int, needsLock: Option[T => Bool] = None)
+    extends LockingArbiterLike[T](gen, n, count, needsLock) {
+  lazy val lastGrant = RegEnable(io.chosen, io.out.fire())
+  lazy val grantMask = (0 until n).map(UInt(_) > lastGrant)
+  lazy val validMask = io.in zip grantMask map { case (in, g) => in.valid && g }
+
+  override def grant: Seq[Bool] = {
+    val ctrl = ArbiterCtrl((0 until n).map(i => validMask(i)) ++ io.in.map(_.valid))
+    (0 until n).map(i => ctrl(i) && grantMask(i) || ctrl(i + n))
+  }
+
+  override lazy val choice = Wire(init=UInt(n-1))
+  for (i <- n-2 to 0 by -1)
+    when (io.in(i).valid) { choice := UInt(i) }
+  for (i <- n-1 to 1 by -1)
+    when (validMask(i)) { choice := UInt(i) }
+}
+
+class LockingArbiter[T <: Data](gen: T, n: Int, count: Int, needsLock: Option[T => Bool] = None)
+    extends LockingArbiterLike[T](gen, n, count, needsLock) {
+  def grant: Seq[Bool] = ArbiterCtrl(io.in.map(_.valid))
+
+  override lazy val choice = Wire(init=UInt(n-1))
+  for (i <- n-2 to 0 by -1)
+    when (io.in(i).valid) { choice := UInt(i) }
+}
+
+/** Hardware module that is used to sequence n producers into 1 consumer.
+  Producers are chosen in round robin order.
+
+  Example usage:
+    val arb = new RRArbiter(2, UInt())
+    arb.io.in(0) <> producer0.io.out
+    arb.io.in(1) <> producer1.io.out
+    consumer.io.in <> arb.io.out
+  */
+class RRArbiter[T <: Data](gen:T, n: Int) extends LockingRRArbiter[T](gen, n, 1)
+
+/** Hardware module that is used to sequence n producers into 1 consumer.
+ Priority is given to lower producer
+
+ Example usage:
+   val arb = Module(new Arbiter(2, UInt()))
+   arb.io.in(0) <> producer0.io.out
+   arb.io.in(1) <> producer1.io.out
+   consumer.io.in <> arb.io.out
+ */
+class Arbiter[T <: Data](gen: T, n: Int) extends Module {
+  val io = new ArbiterIO(gen, n)
+
+  io.chosen := UInt(n-1)
+  io.out.bits := io.in(n-1).bits
+  for (i <- n-2 to 0 by -1) {
+    when (io.in(i).valid) {
+      io.chosen := UInt(i)
+      io.out.bits := io.in(i).bits
+    }
+  }
+
+  val grant = ArbiterCtrl(io.in.map(_.valid))
+  for ((in, g) <- io.in zip grant)
+    in.ready := g && io.out.ready
+  io.out.valid := !grant.last || io.in.last.valid
+}