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async_queue: Give names to all the registers which show up in the queue (#390)

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This is to aid debugging but even more so for backend constraint writers, who generally
need predictable names for registers to set false paths, etc.
This commit is contained in:
mwachs5
2016-10-08 17:50:50 -07:00
committed by GitHub
parent 4fd03ffdf1
commit a84a961a39
2 changed files with 31 additions and 28 deletions
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31
src/main/scala/util/AsyncQueue.scala
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@@ -4,17 +4,19 @@ package util
import Chisel._
object GrayCounter {
def apply(bits: Int, increment: Bool = Bool(true)): UInt = {
def apply(bits: Int, increment: Bool = Bool(true), name: String = "binary"): UInt = {
val incremented = Wire(UInt(width=bits))
val binary = AsyncResetReg(incremented, 0)
val binary = AsyncResetReg(incremented, name)
incremented := binary + increment.asUInt()
incremented ^ (incremented >> UInt(1))
}
}
object AsyncGrayCounter {
def apply(in: UInt, sync: Int): UInt = {
val syncv = List.fill(sync)(Module (new AsyncResetRegVec(w = in.getWidth, 0)))
def apply(in: UInt, sync: Int, name: String = "gray"): UInt = {
val syncv = List.tabulate(sync)(i =>
Module (new AsyncResetRegVec(w = in.getWidth, 0)).suggestName(s"${name}_sync_${i}")
)
syncv.last.io.d := in
syncv.last.io.en := Bool(true)
(syncv.init zip syncv.tail).foreach { case (sink, source) =>
@@ -37,16 +39,16 @@ class AsyncQueueSource[T <: Data](gen: T, depth: Int, sync: Int) extends Module
}
val mem = Reg(Vec(depth, gen)) //This does NOT need to be asynchronously reset.
val widx = GrayCounter(bits+1, io.enq.fire())
val ridx = AsyncGrayCounter(io.ridx, sync)
val widx = GrayCounter(bits+1, io.enq.fire(), "widx_bin")
val ridx = AsyncGrayCounter(io.ridx, sync, "ridx_gray")
val ready = widx =/= (ridx ^ UInt(depth | depth >> 1))
val index = if (depth == 1) UInt(0) else io.widx(bits-1, 0) ^ (io.widx(bits, bits) << (bits-1))
when (io.enq.fire() && !reset) { mem(index) := io.enq.bits }
val ready_reg = AsyncResetReg(ready, 0)
when (io.enq.fire()) { mem(index) := io.enq.bits }
val ready_reg = AsyncResetReg(ready, "ready")
io.enq.ready := ready_reg
val widx_reg = AsyncResetReg(widx, 0)
val widx_reg = AsyncResetReg(widx, "widx_gray")
io.widx := widx_reg
io.mem := mem
@@ -63,8 +65,8 @@ class AsyncQueueSink[T <: Data](gen: T, depth: Int, sync: Int) extends Module {
val mem = Vec(depth, gen).asInput
}
val ridx = GrayCounter(bits+1, io.deq.fire())
val widx = AsyncGrayCounter(io.widx, sync)
val ridx = GrayCounter(bits+1, io.deq.fire(), "ridx_bin")
val widx = AsyncGrayCounter(io.widx, sync, "widx_gray")
val valid = ridx =/= widx
// The mux is safe because timing analysis ensures ridx has reached the register
@@ -74,11 +76,12 @@ class AsyncQueueSink[T <: Data](gen: T, depth: Int, sync: Int) extends Module {
val index = if (depth == 1) UInt(0) else ridx(bits-1, 0) ^ (ridx(bits, bits) << (bits-1))
// This register does not NEED to be reset, as its contents will not
// be considered unless the asynchronously reset deq valid register is set.
io.deq.bits := RegEnable(io.mem(index), valid)
val data = RegEnable(io.mem(index), valid)
io.deq.bits := data
io.deq.valid := AsyncResetReg(valid, 0)
io.deq.valid := AsyncResetReg(valid, "valid_reg")
io.ridx := AsyncResetReg(ridx, 0)
io.ridx := AsyncResetReg(ridx, "ridx_gray")
}
class AsyncQueue[T <: Data](gen: T, depth: Int = 8, sync: Int = 3) extends Crossing[T] {