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Simplify and improve QoR of ShiftQueue

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Andrew Waterman 2017-06-01 02:22:18 -07:00 committed by Wesley W. Terpstra
parent 8229bdee03
commit 0ffb2c8baf
1 changed files with 9 additions and 20 deletions
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29
src/main/scala/util/ShiftQueue.scala
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@ -21,23 +21,16 @@ class ShiftQueue[T <: Data](gen: T,
private val valid = RegInit(UInt(0, entries))
private val elts = Reg(Vec(entries, gen))
private val do_enq = Wire(init=io.enq.fire())
private val do_deq = Wire(init=io.deq.fire())
private val do_enq = io.enq.fire()
private val do_deq = io.deq.fire()
when (do_deq) {
when (!do_enq) { valid := (valid >> 1) }
for (i <- 1 until entries)
when (valid(i)) { elts(i-1) := elts(i) }
}
when (do_enq && do_deq) {
for (i <- 0 until entries)
when (valid(i) && (if (i == entries-1) true.B else !valid(i+1))) { elts(i) := io.enq.bits }
}
when (do_enq && !do_deq) {
valid := (valid << 1) | UInt(1)
for (i <- 0 until entries)
when (!valid(i) && (if (i == 0) true.B else valid(i-1))) { elts(i) := io.enq.bits }
for (i <- 0 until entries) {
val wdata = if (i == entries-1) io.enq.bits else Mux(valid(i+1), elts(i+1), io.enq.bits)
val shiftDown = if (i == entries-1) false.B else io.deq.ready && valid(i+1)
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) }
io.enq.ready := !valid(entries-1)
io.deq.valid := valid(0)
@ -45,11 +38,7 @@ class ShiftQueue[T <: Data](gen: T,
if (flow) {
when (io.enq.valid) { io.deq.valid := true.B }
when (!valid(0)) {
io.deq.bits := io.enq.bits
do_deq := false.B
when (io.deq.ready) { do_enq := false.B }
}
when (!valid(0)) { io.deq.bits := io.enq.bits }
}
if (pipe) {