2015-10-02 23:19:51 +02:00
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/// See LICENSE for license details.
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package junctions
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import Chisel._
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2015-10-22 03:15:46 +02:00
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import cde.Parameters
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2015-10-02 23:19:51 +02:00
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object bigIntPow2 {
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def apply(in: BigInt): Boolean = in > 0 && ((in & (in-1)) == 0)
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}
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2015-10-03 00:37:41 +02:00
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2015-10-06 05:33:55 +02:00
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class ParameterizedBundle(implicit p: Parameters) extends Bundle {
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2015-10-03 00:37:41 +02:00
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override def cloneType = this.getClass.getConstructors.head.newInstance(p).asInstanceOf[this.type]
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}
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class HellaFlowQueue[T <: Data](val entries: Int)(data: => T) extends Module {
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val io = new QueueIO(data, entries)
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require(entries > 1)
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val do_flow = Wire(Bool())
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val do_enq = io.enq.fire() && !do_flow
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val do_deq = io.deq.fire() && !do_flow
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val maybe_full = Reg(init=Bool(false))
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val enq_ptr = Counter(do_enq, entries)._1
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val (deq_ptr, deq_done) = Counter(do_deq, entries)
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when (do_enq != do_deq) { maybe_full := do_enq }
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val ptr_match = enq_ptr === deq_ptr
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val empty = ptr_match && !maybe_full
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val full = ptr_match && maybe_full
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val atLeastTwo = full || enq_ptr - deq_ptr >= UInt(2)
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do_flow := empty && io.deq.ready
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val ram = SeqMem(data, entries)
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when (do_enq) { ram.write(enq_ptr, io.enq.bits) }
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val ren = io.deq.ready && (atLeastTwo || !io.deq.valid && !empty)
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val raddr = Mux(io.deq.valid, Mux(deq_done, UInt(0), deq_ptr + UInt(1)), deq_ptr)
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val ram_out_valid = Reg(next = ren)
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io.deq.valid := Mux(empty, io.enq.valid, ram_out_valid)
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io.enq.ready := !full
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io.deq.bits := Mux(empty, io.enq.bits, ram.read(raddr, ren))
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}
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class HellaQueue[T <: Data](val entries: Int)(data: => T) extends Module {
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val io = new QueueIO(data, entries)
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val fq = Module(new HellaFlowQueue(entries)(data))
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fq.io.enq <> io.enq
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io.deq <> Queue(fq.io.deq, 1, pipe = true)
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}
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object HellaQueue {
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def apply[T <: Data](enq: DecoupledIO[T], entries: Int) = {
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val q = Module((new HellaQueue(entries)) { enq.bits })
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q.io.enq.valid := enq.valid // not using <> so that override is allowed
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q.io.enq.bits := enq.bits
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enq.ready := q.io.enq.ready
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q.io.deq
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}
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}
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2015-10-21 03:36:19 +02:00
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/** A generalized locking RR arbiter that addresses the limitations of the
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* version in the Chisel standard library */
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abstract class JunctionsAbstractLockingArbiter[T <: Data](typ: T, arbN: Int)
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extends Module {
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val io = new Bundle {
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val in = Vec(Decoupled(typ.cloneType), arbN).flip
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val out = Decoupled(typ.cloneType)
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}
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def rotateLeft[T <: Data](norm: Vec[T], rot: UInt): Vec[T] = {
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val n = norm.size
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Vec.tabulate(n) { i =>
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Mux(rot < UInt(n - i), norm(UInt(i) + rot), norm(rot - UInt(n - i)))
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}
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}
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val lockIdx = Reg(init = UInt(0, log2Up(arbN)))
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val locked = Reg(init = Bool(false))
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val choice = PriorityMux(
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rotateLeft(Vec(io.in.map(_.valid)), lockIdx + UInt(1)),
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rotateLeft(Vec((0 until arbN).map(UInt(_))), lockIdx + UInt(1)))
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val chosen = Mux(locked, lockIdx, choice)
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for (i <- 0 until arbN) {
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io.in(i).ready := io.out.ready && chosen === UInt(i)
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}
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io.out.valid := io.in(chosen).valid
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io.out.bits := io.in(chosen).bits
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}
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/** This locking arbiter determines when it is safe to unlock
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* by peeking at the data */
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class JunctionsPeekingArbiter[T <: Data](
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typ: T, arbN: Int,
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canUnlock: T => Bool,
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needsLock: Option[T => Bool] = None)
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extends JunctionsAbstractLockingArbiter(typ, arbN) {
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def realNeedsLock(data: T): Bool =
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needsLock.map(_(data)).getOrElse(Bool(true))
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when (io.out.fire()) {
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when (!locked && realNeedsLock(io.out.bits)) {
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lockIdx := choice
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locked := Bool(true)
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}
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// the unlock statement takes precedent
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when (canUnlock(io.out.bits)) {
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locked := Bool(false)
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}
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}
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}
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/** This arbiter determines when it is safe to unlock by counting transactions */
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class JunctionsCountingArbiter[T <: Data](
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typ: T, arbN: Int, count: Int,
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val needsLock: Option[T => Bool] = None)
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extends JunctionsAbstractLockingArbiter(typ, arbN) {
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def realNeedsLock(data: T): Bool =
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needsLock.map(_(data)).getOrElse(Bool(true))
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// if count is 1, you should use a non-locking arbiter
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require(count > 1, "CountingArbiter cannot have count <= 1")
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val lock_ctr = Counter(count)
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when (io.out.fire()) {
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when (!locked && realNeedsLock(io.out.bits)) {
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lockIdx := choice
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locked := Bool(true)
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lock_ctr.inc()
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}
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when (locked) {
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when (lock_ctr.inc()) { locked := Bool(false) }
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}
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}
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}
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