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 REGENTS SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
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package firrtl.passes

import firrtl._
import firrtl.ir._
import firrtl.Utils._
import firrtl.PrimOps._

object seqCat {
  def apply(args: Seq[Expression]): Expression = args.length match {
    case 0 => error("Empty Seq passed to seqcat")
    case 1 => args.head
    case 2 => DoPrim(PrimOps.Cat, args, Nil, UIntType(UnknownWidth))
    case _ =>
      val (high, low) = args splitAt (args.length / 2)
      DoPrim(PrimOps.Cat, Seq(seqCat(high), seqCat(low)), Nil, UIntType(UnknownWidth))
  }
}

object toBits {
  def apply(e: Expression): Expression = e match {
    case ex @ (_: WRef | _: WSubField | _: WSubIndex) => hiercat(ex, ex.tpe)
    case t => error("Invalid operand expression for toBits!")
  }
  private def hiercat(e: Expression, dt: Type): Expression = dt match {
    case t: VectorType => seqCat((0 until t.size) map (i =>
      hiercat(WSubIndex(e, i, t.tpe, UNKNOWNGENDER),t.tpe)))
    case t: BundleType => seqCat(t.fields map (f =>
      hiercat(WSubField(e, f.name, f.tpe, UNKNOWNGENDER), f.tpe)))
    case t: GroundType => e
    case t => error("Unknown type encountered in toBits!")
  }
}

// TODO: make easier to understand
object toBitMask {
  def apply(e: Expression, dataType: Type): Expression = e match {
    case ex @ (_: WRef | _: WSubField | _: WSubIndex) => hiermask(ex, ex.tpe, dataType)
    case t => error("Invalid operand expression for toBits!")
  }
  private def hiermask(e: Expression, maskType: Type, dataType: Type): Expression =
    (maskType, dataType) match {
      case (mt: VectorType, dt: VectorType) =>
        seqCat((0 until mt.size).reverse map { i =>
          hiermask(WSubIndex(e, i, mt.tpe, UNKNOWNGENDER), mt.tpe, dt.tpe)
        })
      case (mt: BundleType, dt: BundleType) =>
        seqCat((mt.fields zip dt.fields) map { case (mf, df) =>
          hiermask(WSubField(e, mf.name, mf.tpe, UNKNOWNGENDER), mf.tpe, df.tpe)
        })
      case (mt: UIntType, dt: GroundType) =>
        seqCat(List.fill(bitWidth(dt).intValue)(e))
      case (mt, dt) => error("Invalid type for mask component!")
    }
}

object getWidth {
  def apply(t: Type): Width = t match {
    case t: GroundType => t.width
    case _ => error("No width!")
  }
  def apply(e: Expression): Width = apply(e.tpe)
}

object bitWidth {
  def apply(dt: Type): BigInt = widthOf(dt)
  private def widthOf(dt: Type): BigInt = dt match {
    case t: VectorType => t.size * bitWidth(t.tpe)
    case t: BundleType => t.fields.map(f => bitWidth(f.tpe)).foldLeft(BigInt(0))(_+_)
    case GroundType(IntWidth(width)) => width
    case t => error("Unknown type encountered in bitWidth!")
  }
}

object fromBits {
  def apply(lhs: Expression, rhs: Expression): Statement = {
    val fbits = lhs match {
      case ex @ (_: WRef | _: WSubField | _: WSubIndex) => getPart(ex, ex.tpe, rhs, 0)
      case _ => error("Invalid LHS expression for fromBits!")
    }
    Block(fbits._2)
  }
  private def getPartGround(lhs: Expression,
                            lhst: Type,
                            rhs: Expression,
                            offset: BigInt): (BigInt, Seq[Statement]) = {
    val intWidth = bitWidth(lhst)
    val sel = DoPrim(PrimOps.Bits, Seq(rhs), Seq(offset + intWidth - 1, offset), UnknownType)
    (offset + intWidth, Seq(Connect(NoInfo, lhs, sel)))
  }
  private def getPart(lhs: Expression,
                      lhst: Type,
                      rhs: Expression,
                      offset: BigInt): (BigInt, Seq[Statement]) =
    lhst match {
      case t: VectorType => (0 until t.size foldRight (offset, Seq[Statement]())) {
        case (i, (curOffset, stmts)) =>
          val subidx = WSubIndex(lhs, i, t.tpe, UNKNOWNGENDER)
          val (tmpOffset, substmts) = getPart(subidx, t.tpe, rhs, curOffset)
          (tmpOffset, stmts ++ substmts)
      }
      case t: BundleType => (t.fields foldRight (offset, Seq[Statement]())) {
        case (f, (curOffset, stmts)) =>
          val subfield = WSubField(lhs, f.name, f.tpe, UNKNOWNGENDER)
          val (tmpOffset, substmts) = getPart(subfield, f.tpe, rhs, curOffset)
          (tmpOffset, stmts ++ substmts)
      }
      case t: GroundType => getPartGround(lhs, t, rhs, offset)
      case t => error("Unknown type encountered in fromBits!")
    }
}

object createMask {
  def apply(dt: Type): Type = dt match {
    case t: VectorType => VectorType(apply(t.tpe), t.size)
    case t: BundleType => BundleType(t.fields map (f => f copy (tpe=apply(f.tpe))))
    case t: GroundType => BoolType
  }
}

object createRef {
  def apply(n: String, t: Type = UnknownType, k: Kind = ExpKind) = WRef(n, t, k, UNKNOWNGENDER)
}

object createSubField {
  def apply(exp: Expression, n: String) = WSubField(exp, n, field_type(exp.tpe, n), UNKNOWNGENDER)
}

object connectFields {
  def apply(lref: Expression, lname: String, rref: Expression, rname: String) =
    Connect(NoInfo, createSubField(lref, lname), createSubField(rref, rname))
}

object flattenType {
  def apply(t: Type) = UIntType(IntWidth(bitWidth(t)))
}

object MemPortUtils {
  type MemPortMap = collection.mutable.HashMap[String, Expression]
  type Memories = collection.mutable.ArrayBuffer[DefMemory]
  type Modules = collection.mutable.ArrayBuffer[DefModule]

  def defaultPortSeq(mem: DefMemory) = Seq(
    Field("addr", Default, UIntType(IntWidth(ceilLog2(mem.depth) max 1))),
    Field("en", Default, BoolType),
    Field("clk", Default, ClockType)
  )

  // Todo: merge it with memToBundle
  def memType(mem: DefMemory) = {
    val rType = BundleType(defaultPortSeq(mem) :+
      Field("data", Flip, mem.dataType))
    val wType = BundleType(defaultPortSeq(mem) ++ Seq(
      Field("data", Default, mem.dataType),
      Field("mask", Default, createMask(mem.dataType))))
    val rwType = BundleType(defaultPortSeq(mem) ++ Seq(
      Field("rdata", Flip, mem.dataType),
      Field("wmode", Default, BoolType),
      Field("wdata", Default, mem.dataType),
      Field("wmask", Default, createMask(mem.dataType))))
    BundleType(
      (mem.readers map (Field(_, Flip, rType))) ++
      (mem.writers map (Field(_, Flip, wType))) ++
      (mem.readwriters map (Field(_, Flip, rwType))))
  }

  def memPortField(s: DefMemory, p: String, f: String) = {
    val mem = WRef(s.name, memType(s), MemKind, UNKNOWNGENDER)
    val t1 = field_type(mem.tpe, p)
    val t2 = field_type(t1, f)
    WSubField(WSubField(mem, p, t1, UNKNOWNGENDER), f, t2, UNKNOWNGENDER)
  }
}