package MAC

import chisel3._
import chisel3.util._

import freechips.rocketchip.tilelink._
import freechips.rocketchip.diplomacy._
import org.chipsalliance.cde.config._








abstract class MacTileLinkBase(edgeIn: TLEdgeIn, edgeOut: TLEdgeOut) extends Module{

  class MacTileLinkSlaveIO extends Bundle{
    val A = Flipped(Decoupled(new TLBundleA(edgeIn.bundle)))
    val D = Decoupled(new TLBundleD(edgeIn.bundle))
  }

  class MacTileLinkMasterIO extends Bundle{
    val A = Decoupled(new TLBundleA(edgeOut.bundle))
    val D = Flipped(Decoupled(new TLBundleD(edgeOut.bundle)))
  }

  class MacTileLinkIO extends Bundle{

    val tlSlv = new MacTileLinkSlaveIO
    val tlMst = new MacTileLinkMasterIO

    // Tx Status signals
    val RetryCntLatched  = Input(UInt(4.W))  // Latched Retry Counter
    val RetryLimit       = Input(Bool())     // Retry limit reached (Retry Max value +1 attempts were made)
    val LateCollLatched  = Input(Bool())     // Late collision occured
    val DeferLatched     = Input(Bool())     // Defer indication (Frame was defered before sucessfully sent)
    val CarrierSenseLost = Input(Bool())     // Carrier Sense was lost during the frame transmission

    // Tx
    val PerPacketCrcEn = Output(Bool())     // Per packet crc enable
    val PerPacketPad   = Output(Bool())     // Per packet pading

    //Register
    val r_TxEn    = Input(Bool())          // Transmit enable

    // Interrupts
    val TxB_IRQ  = Output(Bool())
    val TxE_IRQ  = Output(Bool())

    val BlockingTxStatusWrite = Output(Bool())

    val TxUsedData     = Input(Bool())      // Transmit packet used data    
   

    val TxValidBytesLatched = Output(UInt(2.W))
    


    val TxRetrySync  = Input(Bool())
    val TxAbortSync = Input(Bool())      // Transmit packet abort
    val TxDoneSync  = Input(Bool())      // Transmission ended





    val r_RxEn    = Input(Bool())         // Receive enable
    val RxDataLatched2_rxclk  = Input(UInt(32.W))
    val WriteRxDataToFifoSync = Input(Bool())
    val RxAbortSync           = Input(Bool())
    val LatchedRxLength_rxclk = Input(UInt(16.W))
    val RxStatusInLatched_rxclk = Input(UInt(9.W))
    val ShiftEndedSync = Input(Bool())
    val RxReady = Output(Bool())
    val rxDeq = new RevBuff_Enq_Bundle



    val TxStartFrm_wb = Output(Bool())
    val TxStartFrm_syncb = Input(Bool())
    val TxEndFrm_wb = Output(Bool())

    val TxData_wb = Output(UInt(32.W))
    val ReadTxDataFromFifo_sync = Input(Bool())

    val txEnq = Flipped(new TxBuff_Deq_Bundle)


  }


  
  val io = IO(new MacTileLinkIO)


  val ShiftEndedSyncPluse         = io.ShiftEndedSync          & ~RegNext(io.ShiftEndedSync, false.B)
  val RxAbortPluse                = io.RxAbortSync             & ~RegNext(io.RxAbortSync, false.B)
  val WriteRxDataToFifoSyncPluse  = io.WriteRxDataToFifoSync   & ~RegNext(io.WriteRxDataToFifoSync, false.B)

  val RxReady = RegInit(false.B); io.RxReady := RxReady


  val rxDeqCtrlValid = RegInit(false.B)
  io.rxDeq.ctrl.valid := rxDeqCtrlValid
  io.rxDeq.ctrl.bits.LatchedRxLength   := RegEnable(io.LatchedRxLength_rxclk,   ShiftEndedSyncPluse | RxAbortPluse)
  io.rxDeq.ctrl.bits.RxStatusInLatched := RegEnable(io.RxStatusInLatched_rxclk, ShiftEndedSyncPluse | RxAbortPluse)
  io.rxDeq.ctrl.bits.isRxAbort         := RegEnable(RxAbortPluse,      false.B, ShiftEndedSyncPluse | RxAbortPluse)

  when( io.rxDeq.ctrl.fire ){
    rxDeqCtrlValid := false.B
  } .elsewhen( ShiftEndedSyncPluse | RxAbortPluse ){
    rxDeqCtrlValid := true.B
  }



  // RxReady generation
  when(ShiftEndedSyncPluse | RxAbortPluse  ){
    RxReady := false.B
  } .elsewhen( io.r_RxEn & (io.rxDeq.data.ready) ){
    RxReady := true.B
  }


  io.rxDeq.data.bits := io.RxDataLatched2_rxclk
  io.rxDeq.data.valid := WriteRxDataToFifoSyncPluse 

  assert( (~io.rxDeq.data.valid & ~io.rxDeq.data.ready), "Assert Failed, rx overrun!" )





















  val TxStartFrm_wb = RegInit(false.B); io.TxStartFrm_wb := TxStartFrm_wb



  when( io.txEnq.ctrl.fire ){
    TxStartFrm_wb := true.B
  } .elsewhen(io.TxStartFrm_syncb){
    TxStartFrm_wb := false.B
  }


  when((TxLength === 0.U) & io.TxUsedData){
    TxEndFrm_wb := true.B
  } .elsewhen(TxRetryPulse | TxDonePulse | TxAbortPulse){
    TxEndFrm_wb := false.B
  }

  when( io.txEnq.ctrl.fire ){
    TxStatus := Cat(txBuffDesc.irq, txBuffDesc.wr, txBuffDesc.pad, txBuffDesc.crc) // Latching status from the tx buffer descriptor Data is avaliable one cycle after the access is started (at that time signal TxEn is not active)
    TxLength        := io.txEnq.ctrl.bits.txLength                                             //Latching length from the buffer descriptor;
    LatchedTxLength := io.txEnq.ctrl.bits.txLength
  } .elsewhen( io.txEnq.data.fire ){
    when( TxLength < 4.U ){
      TxLength := 0.U
    } .otherwise{
      TxLength := TxLength - 4.U    // Length is subtracted at the data request
    }
  }

  tx_fifo.io.data_in := io.tlMst.D.bits.data
  tx_fifo.io.write   := io.tlMst.D.fire & io.tlMst.D.bits.opcode === 1.U


  io.txEnq.data.ready    := ReadTxDataFromFifoSyncPluse & ~tx_fifo.io.empty
  assert( ~(io.txEnq.data.ready & ~io.txEnq.data.valid), "Assert Failed, Tx should never under run!" )

  io.TxData_wb       := io.txEnq.data.bits

  tx_fifo.io.clear   := TxAbortPacket | TxRetryPacket









  val TxRetryPacket = RegInit(false.B)
  val TxRetryPacket_NotCleared = RegInit(false.B)

  val TxDonePacket = RegInit(false.B)
  val TxDonePacket_NotCleared = RegInit(false.B)

  val TxAbortPacket = RegInit(false.B)
  val TxAbortPacket_NotCleared = RegInit(false.B)

  val TxBDReady = RegInit(false.B)
  val TxBDAddress = RegInit(0.U(7.W))   //[7:1]


  val ReadTxDataFromFifoSyncPluse = io.ReadTxDataFromFifo_sync & ~RegNext(io.ReadTxDataFromFifo_sync, false.B)

  val (_, _, isLastD, transDCnt) = edgeOut.count(io.tlMst.D)
  val tx_fifo = Module( new MacFifo(dw = 32, dp = 16) )
  val TxB_IRQ = RegInit(false.B); io.TxB_IRQ := TxB_IRQ
  val TxE_IRQ = RegInit(false.B); io.TxE_IRQ := TxE_IRQ
  val TxBDRead = RegInit(true.B)
  val TxStatusWrite = Wire(Bool())
  val TxLength = RegInit(0.U(16.W))
  val TxStatus = RegInit(0.U(4.W)) //[14:11]

  val TxRetryPulse                = io.TxRetrySync             & ~RegNext(io.TxRetrySync, false.B)
  val TxDonePulse                 = io.TxDoneSync              & ~RegNext(io.TxDoneSync,  false.B)
  val TxAbortPulse                = io.TxAbortSync             & ~RegNext(io.TxAbortSync, false.B)
  val LatchedTxLength = RegInit(0.U(16.W))


  val BlockingTxStatusWrite = RegInit(false.B); io.BlockingTxStatusWrite := BlockingTxStatusWrite
  val BlockingTxBDRead = RegInit(false.B)




  val BDWrite = RegInit(0.U(4.W))     // BD Write Enable for access from WISHBONE side
  val BDRead  = RegInit(false.B)      // BD Read access from WISHBONE side


  val TxEndFrm_wb = RegInit(false.B); io.TxEndFrm_wb := TxEndFrm_wb

  // Delayed stage signals
  val r_TxEn_q = RegNext(io.r_TxEn, false.B) 

  def StateIdle = 0.U(3.W)
  def StateWB   = 1.U(3.W)
  def StateTX   = 2.U(3.W)

  val stateNxt = RegInit( StateWB )
  val stateCur = RegNext( stateNxt, StateIdle )

  
  val ram_addr = RegInit(0.U(8.W))
  val ram_di = RegInit(0.U(32.W))




  val TxPointerRead = RegInit(false.B)
  val TxEn_needed = RegInit(false.B)






  val BlockReadTxDataFromMemory = RegInit(false.B)


  val ReadTxDataFromMemory = RegInit(false.B)

  val MasterWbTX = RegInit(false.B)

  val TxPointerMSB = RegInit(0.U(30.W)) //[31:2]





  // Generic synchronous single-port RAM interface
  val bd_ram = Module(new MacSRAM)
  val txBuffDesc = bd_ram.io.dato.asTypeOf(new TxBuffDesc)

  bd_ram.io.we :=
    Mux1H(Seq(
      (stateNxt === StateWB & stateCur === StateWB) -> BDWrite,
      (TxStatusWrite )               -> "b1111".U
    )).asBools

  bd_ram.io.oe :=
    Mux1H(Seq(
      (( stateNxt === StateWB ) & ( stateCur === StateWB )) -> BDRead,
      (( stateNxt === StateTX ) & ( stateCur === StateTX )) -> (TxBDRead | TxPointerRead),
    ))


  bd_ram.io.addr := ram_addr
  bd_ram.io.di := ram_di




  when(~TxBDReady & io.r_TxEn & stateNxt === StateWB & stateCur =/= StateWB){
    TxEn_needed := true.B
  } .elsewhen(TxPointerRead & stateNxt === StateTX & stateCur === StateTX){
    TxEn_needed := false.B
  }

  // Enabling access to the RAM for three devices.
  // Switching between three stages depends on enable signals
  switch( stateCur ){
    is(StateIdle){
      when( TxEn_needed === false.B ){
        stateNxt := StateWB // Idle state. We go to WbEn access stage.
        
        ram_addr := io.tlSlv.A.bits.address(9,2) // [11:2 ] -> [9:2]
        ram_di   := io.tlSlv.A.bits.data
        BDWrite  := io.tlSlv.A.bits.mask & Fill(4, io.tlSlv.A.valid & io.tlSlv.A.bits.address(10) & ((io.tlSlv.A.bits.opcode === 0.U) || (io.tlSlv.A.bits.opcode === 1.U)) )
        BDRead   := io.tlSlv.A.bits.mask.orR     & io.tlSlv.A.valid & io.tlSlv.A.bits.address(10) &  (io.tlSlv.A.bits.opcode === 4.U) // 0x400 - 0x7FF
      }

    }
    is(StateWB){
      when( TxEn_needed ){
        stateNxt := StateTX // wb access stage, r_RxEn is disabled but r_TxEn is enabled

        ram_addr := Cat(TxBDAddress, TxPointerRead) //[7,1] + [0]
        ram_di   := Cat(LatchedTxLength, 0.U(1.W), TxStatus, 0.U(2.W), false.B, io.RetryCntLatched, io.RetryLimit, io.LateCollLatched, io.DeferLatched, io.CarrierSenseLost)
      } .otherwise{
        stateNxt := StateIdle // WbEn access stage and there is no need for other stages. WbEn needs to be switched off for a bit
      }
    }
    is(StateTX){
      when( true.B ){
        stateNxt := StateWB  // TxEn access stage (we always go to wb access stage)

        ram_addr := io.tlSlv.A.bits.address(9,2) //[11:2 ] ->[9:2]
        ram_di   := io.tlSlv.A.bits.data
        BDWrite  := io.tlSlv.A.bits.mask & Fill(4, io.tlSlv.A.valid & io.tlSlv.A.bits.address(10) & ((io.tlSlv.A.bits.opcode === 0.U) || (io.tlSlv.A.bits.opcode === 1.U)) )
        BDRead   := io.tlSlv.A.bits.mask.orR     & io.tlSlv.A.valid & io.tlSlv.A.bits.address(10) &  (io.tlSlv.A.bits.opcode === 4.U)
      }
    }
  }





  val ResetTxBDReady = TxDonePulse | TxAbortPulse | TxRetryPulse


  // Latching READY status of the Tx buffer descriptor
  when(stateNxt === StateTX & stateCur === StateTX & TxBDRead){ // TxBDReady is sampled only once at the beginning.
    TxBDReady := txBuffDesc.rd & (txBuffDesc.len > 4.U)
  } .elsewhen(ResetTxBDReady){ // Only packets larger then 4 bytes are transmitted.
    TxBDReady := false.B
  }


  val StartTxBDRead = (TxRetryPacket_NotCleared | TxStatusWrite) & ~BlockingTxBDRead & ~TxBDReady // Reading the Tx buffer descriptor

  when(StartTxBDRead){
    TxBDRead := true.B
  } .elsewhen(TxBDReady){
    TxBDRead := false.B
  }

  // Reading Tx BD Pointer
  when(TxBDRead & TxBDReady){
    TxPointerRead := true.B
  } .elsewhen(stateCur === StateTX){
    TxPointerRead := false.B
  }



  // Writing status back to the Tx buffer descriptor
  TxStatusWrite := (TxDonePacket_NotCleared | TxAbortPacket_NotCleared) & stateNxt === StateTX & stateCur === StateTX & ~BlockingTxStatusWrite


  // Status writing must occur only once. Meanwhile it is blocked.
  when(~io.TxDoneSync & ~io.TxAbortSync){
    BlockingTxStatusWrite := false.B
  } .elsewhen(TxStatusWrite){
    BlockingTxStatusWrite := true.B
  }






  // TxBDRead state is activated only once. 
  when(StartTxBDRead){
    BlockingTxBDRead := true.B
  } .elsewhen(~StartTxBDRead & ~TxBDReady){
    BlockingTxBDRead := false.B
  }



  





  








  when(stateNxt === StateTX & stateCur === StateTX & TxPointerRead){
    TxPointerMSB := bd_ram.io.dato(31,2)  // Latching Tx buffer pointer from buffer descriptor. Only 30 MSB bits are latched because TxPointerMSB is only used for word-aligned accesses.
    when( bd_ram.io.dato(1,0) =/= 0.U ){
      printf("Warning, force to align at tx ram")
    }
  } .elsewhen( io.tlMst.D.fire & io.tlMst.D.bits.opcode === 1.U ){
    TxPointerMSB := TxPointerMSB + 1.U // TxPointer is word-aligned
  }
    


  val isTlMstBusy = RegInit(false.B)


  when( (TxLength === 0.U) | TxAbortPulse | TxRetryPulse){
    ReadTxDataFromMemory := false.B
  } .elsewhen(stateNxt === StateTX & stateCur === StateTX & TxPointerRead){
    ReadTxDataFromMemory := true.B
  }

  val ReadTxDataFromMemory_2 = ReadTxDataFromMemory & ~BlockReadTxDataFromMemory;

  when(
    (tx_fifo.io.almost_full | TxLength <= 4.U) & MasterWbTX & isTlMstBusy & (~(TxAbortPacket_NotCleared | TxRetryPacket_NotCleared))){
    BlockReadTxDataFromMemory := true.B
  } .elsewhen(ReadTxDataFromFifoSyncPluse | TxDonePacket | TxAbortPacket | TxRetryPacket){
    BlockReadTxDataFromMemory := false.B
  }



  val TxError = io.RetryLimit | io.LateCollLatched | io.CarrierSenseLost

  // Tx Done Interrupt
  when(TxStatusWrite & TxIRQEn){
    TxB_IRQ := ~TxError
  } .otherwise{
    TxB_IRQ := false.B
  }

  // Tx Error Interrupt
  when(TxStatusWrite & TxIRQEn){
    TxE_IRQ := TxError
  } .otherwise{
    TxE_IRQ := false.B
  }









































































  // Marks which bytes are valid within the word.
  val TxValidBytesLatched = RegInit(0.U(2.W)); io.TxValidBytesLatched := TxValidBytesLatched


  val LatchValidBytes = ShiftRegisters((TxLength < 4.U) & TxBDReady, 2, false.B, true.B)
  val LatchValidBytesPluse = LatchValidBytes(0) & ~LatchValidBytes(1)

  // Latching valid bytes
  when(LatchValidBytesPluse){
    TxValidBytesLatched := Mux(TxLength < 4.U, TxLength(1,0), 0.U)
  } .elsewhen(TxRetryPulse | TxDonePulse | TxAbortPulse){
    TxValidBytesLatched := 0.U
  }


  val TxIRQEn         = TxStatus.extract(3) //[14:11]
  val WrapTxStatusBit = TxStatus.extract(2)
  io.PerPacketPad    := TxStatus.extract(1)
  io.PerPacketCrcEn  := TxStatus.extract(0)





  // Latching Tx buffer descriptor address
  when(io.r_TxEn & (~r_TxEn_q)){
    TxBDAddress := 0.U
  } .elsewhen(TxStatusWrite){
    when( TxStatusWrite & ~WrapTxStatusBit ){ //increase
      TxBDAddress := TxBDAddress + 1.U
    } .otherwise{ //wrap
      TxBDAddress := 0.U
    } 
  }








  val TxAbortPacketBlocked = RegInit(false.B)

  when(
    io.TxAbortSync & (~TxAbortPacketBlocked) &   MasterWbTX  & io.tlMst.D.fire & isLastD  |
    io.TxAbortSync & (~TxAbortPacketBlocked) & (~MasterWbTX) ){
    TxAbortPacket := true.B
  } .otherwise{
    TxAbortPacket := false.B
  }


  when(stateNxt === StateTX & stateCur === StateTX & TxAbortPacket_NotCleared){
    TxAbortPacket_NotCleared := false.B
  } .elsewhen(
    io.TxAbortSync & (~TxAbortPacketBlocked) &   MasterWbTX  & io.tlMst.D.fire & isLastD |
    io.TxAbortSync & (~TxAbortPacketBlocked) & (~MasterWbTX) ){
    TxAbortPacket_NotCleared := true.B
  }

  when(~io.TxAbortSync & RegNext(io.TxAbortSync, false.B)){
    TxAbortPacketBlocked := false.B
  } .elsewhen(TxAbortPacket){
    TxAbortPacketBlocked := true.B
  }



  val TxRetryPacketBlocked = RegInit(false.B)

  when(
    io.TxRetrySync & ~TxRetryPacketBlocked &  MasterWbTX & io.tlMst.D.fire & isLastD |
    io.TxRetrySync & ~TxRetryPacketBlocked & ~MasterWbTX ){
    TxRetryPacket := true.B
  } .otherwise{
    TxRetryPacket := false.B
  }





  when(StartTxBDRead){
    TxRetryPacket_NotCleared := false.B
  } .elsewhen(
    io.TxRetrySync & ~TxRetryPacketBlocked &  MasterWbTX & io.tlMst.D.fire & isLastD |
    io.TxRetrySync & ~TxRetryPacketBlocked & ~MasterWbTX ){
    TxRetryPacket_NotCleared := true.B
  }


  when( ~io.TxRetrySync & RegNext(io.TxRetrySync, false.B) ){
    TxRetryPacketBlocked := false.B
  } .elsewhen(TxRetryPacket){
    TxRetryPacketBlocked := true.B
  }



  val TxDonePacketBlocked = RegInit(false.B)

  when(
    io.TxDoneSync & ~TxDonePacketBlocked &  MasterWbTX & io.tlMst.D.fire & isLastD |
    io.TxDoneSync & ~TxDonePacketBlocked & ~MasterWbTX  ){
    TxDonePacket := true.B
  }.otherwise{
    TxDonePacket := false.B
  }

  when(stateNxt === StateTX & stateCur === StateTX & TxDonePacket_NotCleared){
    TxDonePacket_NotCleared := false.B
  } .elsewhen(
    io.TxDoneSync & ~TxDonePacketBlocked &  MasterWbTX & io.tlMst.D.fire & isLastD |
    io.TxDoneSync & ~TxDonePacketBlocked & ~MasterWbTX ){
    TxDonePacket_NotCleared := true.B
  }


  when(~io.TxDoneSync & RegNext(io.TxDoneSync, false.B)){
    TxDonePacketBlocked := false.B
  } .elsewhen(TxDonePacket){
    TxDonePacketBlocked := true.B
  }
  













  
  val slvAInfo = RegEnable( io.tlSlv.A.bits, io.tlSlv.A.fire )
  val slvDValid = RegInit(false.B); io.tlSlv.D.valid := slvDValid
  val slvDDat = Reg(UInt(32.W))



  when( io.tlSlv.D.fire ){
    slvDValid := false.B
  } .elsewhen(io.tlSlv.A.fire){
    slvDValid := true.B
    slvDDat := bd_ram.io.dato
  }

  when(slvAInfo.opcode === 4.U) {
    io.tlSlv.D.bits := edgeIn.AccessAck(slvAInfo, slvDDat)
  } .otherwise {
    io.tlSlv.D.bits := edgeIn.AccessAck(slvAInfo)
  }

  io.tlSlv.A.ready := RegNext(stateNxt === StateWB & Mux( stateCur === StateWB , BDWrite.orR, BDRead ))
  
  assert( ~(io.tlSlv.A.ready & ~io.tlSlv.A.valid) )






  val mstAValid = RegInit(false.B)
  val mstABits  = Reg(new TLBundleA(edgeOut.bundle))


  when( io.tlMst.A.fire ){
    mstAValid := false.B
  } 
  .elsewhen( MasterWbTX & ~isTlMstBusy ){
    mstAValid := true.B
    mstABits :=
      edgeOut.Get(
        fromSource = 0.U,
        toAddress = TxPointerMSB << 2,
        lgSize = log2Ceil(32/8).U,
      )._2
  }

  when( io.tlMst.A.fire ){
    isTlMstBusy := true.B
  } .elsewhen( io.tlMst.D.fire ){
    isTlMstBusy := false.B
  }

  when( ~MasterWbTX ){
    when(ReadTxDataFromMemory_2) {
      MasterWbTX := true.B
    }
  } .elsewhen( MasterWbTX ){ //1 A + 1.4D memory to fifo
    when( io.tlMst.D.fire & isLastD & ~ReadTxDataFromMemory_2 ){
      MasterWbTX := false.B
    }
  }


  when(io.tlMst.D.fire & io.tlMst.D.bits.opcode === 1.U) { assert( MasterWbTX ) }

  val tlMstAValid_dbg = RegInit(true.B)
  io.tlMst.A.valid := mstAValid & tlMstAValid_dbg
  io.tlMst.A.bits  := mstABits


  val tlMstDReady = RegInit(true.B)

  io.tlMst.D.ready := tlMstDReady



}






class MacTileLink(edgeIn: TLEdgeIn, edgeOut: TLEdgeOut) extends MacTileLinkBase(edgeIn, edgeOut)