Chisel language how to best use Queues?

问题

I'm new in chisel, if someone can explain the role of:

1- Queue 2- DecoupledIO 3- Decoupled 3- ValidIO 4- Valid

Is this piece of chisel code correct?

...

val a = Decoupled()
val b = Decoupled()
val c = Decoupled()

...

val Reg_a = Reg(UInt())
val Reg_b = Reg(UInt())

...

when(io.a.valid && io.a.ready && io.b.valid && io.b.ready && io.c.valid &&     io.c.ready)
{

  Reg_a := io.a.bits.data
  Reg_b := io.b.bits.data
}

io.c.bits := Reg_a & Reg_b

...

Module.io.a    <>    Queue(Module_1.io.a_1)
Module.io.b    <>    Queue(Module_1.io.b_1)
Module_1.io.c_1 <>   Queue(Module.io.c)

regards!

回答1:

Queue is a hardware module that implements a first in, first out queue with DecoupledIO inputs and outputs
DecoupledIO is a ready/valid interface type with members ready, valid, and bits
Decoupled is a helper to construct DecoupledIO from some other type
ValidIO is similar to DecoupledIO except that it only has valid and bits
Valid is similar to Decoupled for constructing ValidIOs

I can't tell what the code is trying to do, but here's an example of a Module that has 2 DecoupledIO inputs and 1 DecoupledIO output. It buffers the inputs with queues and then connects the output to the sum of the inputs:

import chisel3._
import chisel3.util._

class QueueModule extends Module {
  val io = IO(new Bundle {
    val a = Flipped(Decoupled(UInt(32.W))) // valid and bits are inputs
    val b = Flipped(Decoupled(UInt(32.W)))
    val z = Decoupled(UInt(32.W)) // valid and bits are outputs
  })
  // Note that a, b, and z are all of type DecoupledIO

  // Buffer the inputs with queues
  val qa = Queue(io.a) // io.a is the input to the FIFO
                       // qa is DecoupledIO output from FIFO
  val qb = Queue(io.b)

  // We only dequeue when io.z is ready
  qa.nodeq() // equivalent to qa.ready := false.B
  qb.nodeq()

  // When qa and qb have valid inputs and io.z is ready for an output
  when (qa.valid && qb.valid && io.z.ready) {
    io.z.enq(qa.deq() + qb.deq())
    /* The above is short for
      io.z.valid := true.B
      io.z.bits := qa.bits + qb.bits
      qa.ready := true.B
      qb.ready := true.B
    */
  }
}

Hope this helps!

来源：https://stackoverflow.com/questions/41122480/chisel-language-how-to-best-use-queues

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Chisel