From c0a3bb58e9789b098b1fa2d65cc8f008db481672 Mon Sep 17 00:00:00 2001 From: "Wesley W. Terpstra" Date: Tue, 18 Jul 2017 14:20:04 -0700 Subject: [PATCH] ShiftQueue: use Vec of Bool to support constant prop of enq.valid --- src/main/scala/util/ShiftQueue.scala | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/src/main/scala/util/ShiftQueue.scala b/src/main/scala/util/ShiftQueue.scala index e3a2511f..a64d3ee8 100644 --- a/src/main/scala/util/ShiftQueue.scala +++ b/src/main/scala/util/ShiftQueue.scala @@ -17,8 +17,7 @@ class ShiftQueue[T <: Data](gen: T, val mask = UInt(OUTPUT, entries) }) - private val ram = Mem(entries, gen) - private val valid = RegInit(UInt(0, entries)) + private val valid = RegInit(Vec.fill(entries) { Bool(false) }) private val elts = Reg(Vec(entries, gen)) private val do_enq = io.enq.fire() @@ -30,7 +29,12 @@ class ShiftQueue[T <: Data](gen: T, val enqNew = io.enq.fire() && Mux(io.deq.ready, valid(i), !valid(i) && (if (i == 0) true.B else valid(i-1))) when (shiftDown || enqNew) { elts(i) := wdata } } - when (do_enq =/= do_deq) { valid := Mux(do_enq, (valid << 1) | UInt(1), valid >> 1) } + + val padded = Seq(true.B) ++ valid ++ Seq(false.B) + for (i <- 0 until entries) { + when ( do_enq && !do_deq && padded(i+0)) { valid(i) := true.B } + when (!do_enq && do_deq && !padded(i+2)) { valid(i) := false.B } + } io.enq.ready := !valid(entries-1) io.deq.valid := valid(0) @@ -45,6 +49,6 @@ class ShiftQueue[T <: Data](gen: T, when (io.deq.ready) { io.enq.ready := true.B } } - io.count := PopCount(valid) - io.mask := valid + io.mask := valid.asUInt + io.count := PopCount(io.mask) }