IntToFloat.scala

//package xiangshan.backend.fu.fpu
//
//import chisel3._
//import chisel3.util._
//import xiangshan.FuType
//import xiangshan.backend.fu.{CertainLatency, FuConfig}
//import xiangshan.backend.fu.fpu.util.ORTree
//
//class IntToFloat extends FPUPipelineModule(
//  FuConfig(FuType.i2f, 1, 0, writeIntRf = false, writeFpRf = true, hasRedirect = false, CertainLatency(2))
//) {
//  /** Stage 1: Count leading zeros and shift
//    */
//
//  val a = io.in.bits.src(0)
//  val aNeg = (~a).asUInt()
//  val aComp = aNeg + 1.U
//  val aSign = Mux(op(0), false.B, Mux(op(1), a(63), a(31)))
//
//  val leadingZerosComp = PriorityEncoder(Mux(op(1), aComp, aComp(31, 0)).asBools().reverse)
//  val leadingZerosNeg = PriorityEncoder(Mux(op(1), aNeg, aNeg(31, 0)).asBools().reverse)
//  val leadingZerosPos = PriorityEncoder(Mux(op(1), a, a(31,0)).asBools().reverse)
//
//  val aVal = Mux(aSign, Mux(op(1), aComp, aComp(31, 0)), Mux(op(1), a, a(31, 0)))
//  val leadingZeros = Mux(aSign, leadingZerosNeg, leadingZerosPos)
//
//  // exp = xlen - 1 - leadingZeros + bias
//  val expUnrounded = S1Reg(
//    Mux(isDouble,
//      (64 - 1 + Float64.expBiasInt).U - leadingZeros,
//      (64 - 1 + Float32.expBiasInt).U - leadingZeros
//    )
//  )
//  val leadingZeroHasError = S1Reg(aSign && (leadingZerosComp=/=leadingZerosNeg))
//  val rmReg = S1Reg(rm)
//  val opReg = S1Reg(op)
//  val isDoubleReg = S1Reg(isDouble)
//  val aIsZeroReg = S1Reg(a===0.U)
//  val aSignReg = S1Reg(aSign)
//  val aShifted = S1Reg((aVal << leadingZeros)(63, 0))
//
//  /** Stage 2: Rounding
//    */
//  val aShiftedFix = Mux(leadingZeroHasError, aShifted(63, 1), aShifted(62, 0))
//  val mantD = aShiftedFix(62, 62-51)
//  val mantS = aShiftedFix(62, 62-22)
//
//  val g = Mux(isDoubleReg, aShiftedFix(62-52), aShiftedFix(62-23))
//  val r = Mux(isDoubleReg, aShiftedFix(62-53), aShiftedFix(62-24))
//  val s = Mux(isDoubleReg, ORTree(aShiftedFix(62-54, 0)), ORTree(aShiftedFix(62-25, 0)))
//
//  val roudingUnit = Module(new RoundingUnit(Float64.mantWidth))
//  roudingUnit.io.in.rm := rmReg
//  roudingUnit.io.in.mant := Mux(isDoubleReg, mantD, mantS)
//  roudingUnit.io.in.sign := aSignReg
//  roudingUnit.io.in.guard := g
//  roudingUnit.io.in.round := r
//  roudingUnit.io.in.sticky := s
//
//  val mantRounded = roudingUnit.io.out.mantRounded
//  val expRounded = Mux(isDoubleReg,
//    expUnrounded + roudingUnit.io.out.mantCout,
//    expUnrounded + mantRounded(Float32.mantWidth)
//  ) + leadingZeroHasError
//
//  val resS = Cat(
//    aSignReg,
//    expRounded(Float32.expWidth-1, 0),
//    mantRounded(Float32.mantWidth-1, 0)
//  )
//  val resD = Cat(aSignReg, expRounded, mantRounded)
//
//  io.out.bits.data := S2Reg(Mux(aIsZeroReg, 0.U, Mux(isDoubleReg, resD, resS)))
//  fflags.inexact := S2Reg(roudingUnit.io.out.inexact)
//  fflags.underflow := false.B
//  fflags.overflow := false.B
//  fflags.infinite := false.B
//  fflags.invalid := false.B
//}