Question

我是Scala的新生，并打算研究火箭的源代码（由Scala / Chisel开发），并且我不理解下面的案例类源代码。我的问题是，当我们引用reg_cycle时，返回的值是什么（值？）？并且您可以做一些介绍为什么在Scala中发生这种情况吗？

//source code for how to use case calss
  val reg_instret = WideCounter(64, io.retire)
  val reg_cycle = if (enableCommitLog) reg_instret else WideCounter(64)

  if (xLen == 32) {
      read_mapping += CSRs.mcycleh -> (**reg_cycle** >> 32)
      read_mapping += CSRs.minstreth -> (reg_instret >> 32)
      if (usingUser) {
        read_mapping += CSRs.cycleh -> (reg_cycle >> 32)
        read_mapping += CSRs.instreth -> (reg_instret >> 32)
      }
    }

//source code for case calss
case class WideCounter(width: Int, inc: UInt = UInt(1), reset: Boolean = true)
{
  private val isWide = width > 2*inc.getWidth
  private val smallWidth = if (isWide) inc.getWidth max log2Up(width) else width
  private val small = if (reset) Reg(init=UInt(0, smallWidth)) else Reg(UInt(width = smallWidth))
  private val nextSmall = small +& inc
  small := nextSmall

  private val large = if (isWide) {
    val r = if (reset) Reg(init=UInt(0, width - smallWidth)) else Reg(UInt(width = width - smallWidth))
    when (nextSmall(smallWidth)) { r := r + UInt(1) }
    r
  } else null  

  val value = if (isWide) Cat(large, small) else small
  lazy val carryOut = {
    val lo = (small ^ nextSmall) >> 1
    if (!isWide) lo else {
      val hi = Mux(nextSmall(smallWidth), large ^ (large +& UInt(1)), UInt(0)) >> 1
      Cat(hi, lo)
    }
  }

  def := (x: UInt) = {
    small := x
    if (isWide) large := x >> smallWidth
  }
}

Answer 1

reg_cycle是WideCounter。根据记录的布尔值将其初始化为不同的特定实例。

WideCounter有几个字段，可以通过它们的名称，宽度，公司和重置来访问。

返回case cals的值，为什么会在scala中发生这种情况？

1 个答案: