如何从展平的Bundle中推断宽度？

Question

我正在尝试将BlackBox连接到任意的Bundle，但是宽度推断似乎不适用于fromBits函数。下面的代码可以正常编译：

class testBundle extends Bundle {
  val io1 = Bool(INPUT)
  val io2 = UInt(INPUT,10)
}

class testBox extends BlackBox {
  val io = new Bundle {
    val in = Bits(INPUT) # Width inference works fine here
    val out = Bits(OUTPUT,(new testBundle).getWidth) # But it doesn't work here!
  }
}

class test extends Module {
  val io = new Bundle {
    val in = new testBundle
    val out = (new testBundle).flip()
  }
  val testbox = Module(new testBox)
  testbox.io.in := io.in.toBits
  io.out := io.out.fromBits(testbox.io.out)
}

但是如果我去掉(new testBundle).getWidth参数，Chisel就不能推断输出端口的宽度，就会出错。如何让testBox连接到任意捆绑包？

Answer 1

现在，我通过将捆绑包作为参数传递给BlackBox来解决这个问题：

class testBox(b:Bundle) extends BlackBox {
  val w = b.getWidth
  val io = new Bundle {
    val in = Bits(INPUT,w)
    val out = Bits(OUTPUT,w)
  }
}

class test extends Module {
  val io = new Bundle {
    val in = new testBundle
    val out = (new testBundle).flip()
  }
  val testbox = Module(new testBox(io.in))
  testbox.io.in := io.in.toBits
  io.out := io.out.fromBits(testbox.io.out)
}

不过，我会欢迎一种更干净的解决方案。