[rtl] complete stdlib Queue and add "almost" ports

stdlib/src/Queue.scala

@@ -7,12 +7,14 @@ import org.chipsalliance.dwbb.interface.DW_fifo_s1_sf.{Interface => DwbbFifoInte
 import chisel3.ltl.AssertProperty
 import chisel3.util.{Decoupled, DecoupledIO, DeqIO, EnqIO, ReadyValidIO}
 
-class QueueIO[T <: Data](private val gen: T) extends Bundle {
+class QueueIO[T <: Data](private val gen: T, entries: Int) extends Bundle {
   val enq = Flipped(EnqIO(gen))
   val deq = Flipped(DeqIO(gen))
 
-  val empty = Output(Bool())
-  val full  = Output(Bool())
+  val empty       = Output(Bool())
+  val full        = Output(Bool())
+  val almostEmpty = if (entries >= 2) Some(Output(Bool())) else None
+  val almostFull  = if (entries >= 2) Some(Output(Bool())) else None
 }
 
 object Queue {
@@ -23,79 +25,108 @@ object Queue {
     flow:     Boolean = false,
     resetMem: Boolean = false
   ): DecoupledIO[T] = {
-
     val io = this.io(chiselTypeOf(enq.bits), entries, pipe, flow, resetMem)
     io.enq <> enq
 
     io.deq
   }
 
   def io[T <: Data](
-    gen:      T,
-    entries:  Int = 2,
-    pipe:     Boolean = false,
-    flow:     Boolean = false,
-    resetMem: Boolean = false
+    gen:              T,
+    entries:          Int = 2,
+    pipe:             Boolean = false,
+    flow:             Boolean = false,
+    resetMem:         Boolean = false,
+    almostEmptyLevel: Int = 1,
+    almostFullLevel:  Int = 1
   ): QueueIO[T] = {
-    require(gen.getWidth <= 2048, "Data width must be less than 2048")
-    require(entries <= 1024, "Entries must be less than 1024")
+    require(
+      Range.inclusive(1, 2048).contains(gen.getWidth),
+      "Data width must be between 1 and 2048"
+    )
+    require(
+      Range.inclusive(1, 1024).contains(entries),
+      "Entries must be between 1 and 1024"
+    )
 
-    val clock = Module.clock
-    val reset = Module.reset
+    val io = Wire(new QueueIO(gen, entries))
 
-    val io = Wire(new QueueIO(gen))
+    if (entries == 1) {
+      val data  = if (resetMem) RegInit(0.U.asTypeOf(gen)) else Reg(gen)
+      val empty = RegInit(true.B)
+      val full  = !empty
 
-    if (entries < 2) {
-      val queue = Module(new chisel3.util.Queue(gen, entries, pipe, flow))
-      queue.io.enq <> io.enq
-      queue.io.deq <> io.deq
-      io.empty := queue.io.count === 0.U
-      io.full  := queue.io.count === entries.U
+      val push = io.enq.fire && (if (flow) !(empty && io.deq.ready) else true.B)
+      io.enq.ready := empty || (if (pipe) io.deq.ready else false.B)
+      data         := Mux(push, io.enq.bits, data)
 
-      return io
-    }
+      val pop = io.deq.ready && full
+      io.deq.valid := full || (if (flow) io.enq.valid else false.B)
+      io.deq.bits  := (if (flow) Mux(empty, io.enq.bits, data) else data)
 
-    // TODO: use sync reset for now and wait for t1 to migrate to FixedIOModule
-    // require(reset.typeName == "Bool" || reset.typeName == "AsyncReset")
-    val useAsyncReset = reset.typeName == "AsyncReset"
-
-    val fifo = Instantiate(
-      new DwbbFifo(
-        new DwbbFifoParameter(
-          width = gen.getWidth,
-          depth = entries,
-          errMode = "unlatched",
-          rstMode = (useAsyncReset, resetMem) match {
-            case (false, false) => "sync_wo_mem"
-            case (false, true)  => "sync_with_mem"
-            case (true, false)  => "async_wo_mem"
-            case (true, true)   => "async_with_mem"
-          }
+      empty := Mux(push =/= pop, pop, empty)
+
+      io.empty := empty
+      io.full  := full
+    } else {
+      require(
+        Range.inclusive(1, entries - 1).contains(almostEmptyLevel),
+        "almost empty level must be between 1 and entries-1"
+      )
+      require(
+        Range.inclusive(1, entries - 1).contains(almostFullLevel),
+        "almost full level must be between 1 and entries-1"
+      )
+
+      val clock = Module.clock
+      val reset = Module.reset
+
+      // TODO: use sync reset for now and wait for t1 to migrate to FixedIOModule
+      // require(reset.typeName == "Bool" || reset.typeName == "AsyncReset")
+      val useAsyncReset = reset.typeName == "AsyncReset"
+
+      val fifo = Instantiate(
+        new DwbbFifo(
+          new DwbbFifoParameter(
+            width = gen.getWidth,
+            depth = entries,
+            aeLevel = almostEmptyLevel,
+            afLevel = almostFullLevel,
+            errMode = "unlatched",
+            rstMode = (useAsyncReset, resetMem) match {
+              case (false, false) => "sync_wo_mem"
+              case (false, true)  => "sync_with_mem"
+              case (true, false)  => "async_wo_mem"
+              case (true, true)   => "async_with_mem"
+            }
+          )
         )
       )
-    )
 
-    val dataIn  = io.enq.bits.asUInt
-    val dataOut = fifo.io.data_out.asTypeOf(io.deq.bits)
+      val dataIn  = io.enq.bits.asUInt
+      val dataOut = fifo.io.data_out.asTypeOf(io.deq.bits)
 
-    fifo.io.clk   := clock
-    fifo.io.rst_n := ~(reset.asBool)
+      fifo.io.clk   := clock
+      fifo.io.rst_n := ~(reset.asBool)
 
-    fifo.io.diag_n := ~(false.B)
+      fifo.io.diag_n := ~(false.B)
 
-    io.enq.ready       := !fifo.io.full || (if (pipe) io.deq.ready else false.B)
-    fifo.io.push_req_n := ~(io.enq.fire && (if (flow) !(fifo.io.empty && io.deq.ready) else true.B))
-    fifo.io.data_in    := dataIn
+      io.enq.ready       := !fifo.io.full || (if (pipe) io.deq.ready else false.B)
+      fifo.io.push_req_n := ~(io.enq.fire && (if (flow) !(fifo.io.empty && io.deq.ready) else true.B))
+      fifo.io.data_in    := dataIn
 
-    io.deq.valid      := !fifo.io.empty || (if (flow) io.enq.valid else false.B)
-    fifo.io.pop_req_n := ~(io.deq.ready && !fifo.io.empty)
-    io.deq.bits       := (if (flow) Mux(fifo.io.empty, io.enq.bits, dataOut) else dataOut)
+      io.deq.valid      := !fifo.io.empty || (if (flow) io.enq.valid else false.B)
+      fifo.io.pop_req_n := ~(io.deq.ready && !fifo.io.empty)
+      io.deq.bits       := (if (flow) Mux(fifo.io.empty, io.enq.bits, dataOut) else dataOut)
 
-    io.empty := fifo.io.empty
-    io.full  := fifo.io.full
+      io.empty           := fifo.io.empty
+      io.full            := fifo.io.full
+      io.almostEmpty.get := fifo.io.almost_empty
+      io.almostFull.get  := fifo.io.almost_full
 
-    // There should be no error since we guarantee to push/pop items only when the fifo is neither empty nor full.
-    AssertProperty(!fifo.io.error)
+      // There should be no error since we guarantee to push/pop items only when the fifo is neither empty nor full.
+      AssertProperty(!fifo.io.error)
+    }
 
     io
   }