// See LICENSE.SiFive for license details.
// See LICENSE.Berkeley for license details.

package junctions

import Chisel._
import config._
import scala.collection.mutable.HashMap

case class MemAttr(prot: Int, cacheable: Boolean = false)

sealed abstract class MemRegion {
  def start: BigInt
  def size: BigInt
  def numSlaves: Int
  def attr: MemAttr

  def containsAddress(x: UInt) = UInt(start) <= x && x < UInt(start + size)
}

case class MemSize(size: BigInt, attr: MemAttr) extends MemRegion {
  def start = 0
  def numSlaves = 1
}

case class MemRange(start: BigInt, size: BigInt, attr: MemAttr) extends MemRegion {
  def numSlaves = 1
}

object AddrMapProt {
  val R = 0x1
  val W = 0x2
  val X = 0x4
  val RW = R | W
  val RX = R | X
  val RWX = R | W | X
  val SZ = 3
}

class AddrMapProt extends Bundle {
  val x = Bool()
  val w = Bool()
  val r = Bool()
}

case class AddrMapEntry(name: String, region: MemRegion)

object AddrMap {
  def apply(elems: AddrMapEntry*): AddrMap = new AddrMap(elems)
}

class AddrMap(
    entriesIn: Seq[AddrMapEntry],
    val start: BigInt = BigInt(0),
    val collapse: Boolean = false) extends MemRegion {
  private val slavePorts = HashMap[String, Int]()
  private val mapping = HashMap[String, MemRegion]()

  def isEmpty = entries.isEmpty
  def length = entries.size
  def numSlaves = slavePorts.size

  val (size: BigInt, entries: Seq[AddrMapEntry], attr: MemAttr) = {
    var ind = 0
    var base = start
    var rebasedEntries = collection.mutable.ArrayBuffer[AddrMapEntry]()
    var prot = 0
    var cacheable = true
    for (AddrMapEntry(name, r) <- entriesIn) {
      require (!mapping.contains(name))
      base = r.start

      r match {
        case r: AddrMap =>
          val subMap = new AddrMap(r.entries, base, r.collapse)
          rebasedEntries += AddrMapEntry(name, subMap)
          mapping += name -> subMap
          mapping ++= subMap.mapping.map { case (k, v) => s"$name:$k" -> v }
          if (r.collapse) {
            slavePorts += (name -> ind)
            ind += 1
          } else {
            slavePorts ++= subMap.slavePorts.map {
              case (k, v) => s"$name:$k" -> (ind + v)
            }
            ind += r.numSlaves
          }
        case _ =>
          val e = MemRange(base, r.size, r.attr)
          rebasedEntries += AddrMapEntry(name, e)
          mapping += name -> e
          slavePorts += name -> ind
          ind += r.numSlaves
      }

      base += r.size
      prot |= r.attr.prot
      cacheable &&= r.attr.cacheable
    }
    (base - start, rebasedEntries, MemAttr(prot, cacheable))
  }

  val flatten: Seq[AddrMapEntry] = {
    mapping.toSeq.map {
      case (name, range: MemRange) => Some(AddrMapEntry(name, range))
      case _ => None
    }.flatten.sortBy(_.region.start)
  }

  // checks to see whether any MemRange overlaps within this AddrMap
  flatten.combinations(2) foreach {
    case (Seq(AddrMapEntry(an, ar), AddrMapEntry(bn, br))) =>
      val arEnd = ar.start + ar.size
      val brEnd = br.start + br.size
      val abOverlaps = ar.start < brEnd && br.start < arEnd
      require(!abOverlaps,
        s"region $an@0x${ar.start.toString(16)} overlaps region $bn@0x${br.start.toString(16)}")
  }

  def toRange: MemRange = MemRange(start, size, attr)
  def apply(name: String): MemRegion = mapping(name)
  def contains(name: String): Boolean = mapping.contains(name)
  def port(name: String): Int = slavePorts(name)
  def subMap(name: String): AddrMap = mapping(name).asInstanceOf[AddrMap]
  def isInRegion(name: String, addr: UInt): Bool = mapping(name).containsAddress(addr)

  def isCacheable(addr: UInt): Bool = {
    flatten.filter(_.region.attr.cacheable).map(
      _.region.containsAddress(addr)
    ).foldLeft(Bool(false))(_ || _)
  }

  def isValid(addr: UInt): Bool = {
    flatten.map(_.region.containsAddress(addr)).foldLeft(Bool(false))(_ || _)
  }

  def getProt(addr: UInt): AddrMapProt = {
    val protForRegion = flatten.map { entry =>
      Mux(entry.region.containsAddress(addr),
        UInt(entry.region.attr.prot, AddrMapProt.SZ), UInt(0))
    }
    new AddrMapProt().fromBits(protForRegion.reduce(_|_))
  }

  override def containsAddress(x: UInt) = {
    flatten.map(_.region.containsAddress(x)).reduce(_||_)
  }
}
