package BACK

import chisel3._
import chisel3.util._

class SPIInterfaceIO extends Bundle{
  val sck  = Input(Bool())
  val mosi = Input(Bool())
  val miso = Output(Bool())
  val csn  = Input(Bool())
}


class SpiInterface extends Module{
  val io = IO(new Bundle{
    val spi = new SPIInterfaceIO

    val addrSel = Output(UInt(16.W))
    val dataw   = Output( UInt(8.W) )
    val datar   = Input( UInt(8.W) )
    val isEnW   = Output(Bool())
    val isEnR   = Output(Bool())
  })


  val sck     = io.spi.sck
  val mosi    = io.spi.mosi
  val csn     = io.spi.csn


//   val spiRegDown = Module(new SpiSRAMDown)
//   val spiRegUp   = Module(new SpiSRAMUp)


//   spiRegDown.io.clockr := clk100M
//   spiRegDown.io.clockw := clock.asBool

//   spiRegUp.io.clockr := clock.asBool
//   spiRegUp.io.clockw := clk100M


  val shiftSCK  = ShiftRegisters(sck, 3, false.B, true.B)
  val shiftCSn  = ShiftRegisters(csn, 3, true.B, true.B)
  val shiftMOSI = ShiftRegisters(mosi, 3)


  val isSckPosedge     = ~shiftSCK(2) & shiftSCK(1)
  val isSckPosedgeNext = ShiftRegisters(isSckPosedge, 2, false.B, true.B)


  val exReg = Reg(UInt(8.W))

  io.spi.miso := exReg.extract(exReg.getWidth-1)

  val addrSel = Reg(UInt(16.W)); io.addrSel := addrSel
  val spiCmd  = Reg(UInt(8.W))

  val isSpiWrite = spiCmd === 0.U
  val isSpiRead  = spiCmd === 1.U

  val bitSel  = Reg(UInt(3.W))
  val byteSel = Reg(UInt(5.W))


//   spiRegDown.io.addrr := Cat(pageSel, byteSel)
//   spiRegDown.io.enr := spiCmd === 0.U & isSckPosedgeNext(0)

//   spiRegUp.io.addrw := Cat(pageSel, byteSel - 1.U)
//   spiRegUp.io.dataw := withClockAndReset( clk100M.asClock, reset ){ RegEnable(exReg_100M, bitSel === 0.U) }
     
//   spiRegUp.io.enw   := isSckPosedgeNext(1) & ~shiftCSn(1+1) & bitSel === 0.U & spiCmd === 1.U

    io.isEnR := isSckPosedgeNext(0) & isSpiRead
    io.isEnW := isSckPosedgeNext(1) & ~shiftCSn(1+1) & bitSel === 0.U & isSpiWrite
    io.dataw := exReg

  when( shiftCSn(2) & ~shiftCSn(1) ){
    bitSel   := 0.U
    byteSel  := 0.U
  } .elsewhen( isSckPosedge & ~shiftCSn(1)  ){
    bitSel := bitSel + 1.U
    when( bitSel === 7.U ){
      byteSel := byteSel + 1.U
    }
  }

  when( shiftCSn(2) & ~shiftCSn(1) ){  //CS下跳
    addrSel := 0.U
  } .elsewhen( isSckPosedge & ~shiftCSn(1) ){
    when( byteSel === 0.U || byteSel === 1.U) { //CS为低，且SCK上跳的第0byte
      addrSel := Cat( addrSel(14,0), shiftMOSI(1) )
    } .otherwise{ // byteSel > 1.U
      addrSel := addrSel + 1.U
    }
  }

  when( shiftCSn(2) & ~shiftCSn(1) ){  //CS下跳
    spiCmd  := "hFF".U
  } .elsewhen( isSckPosedge & ~shiftCSn(1) & byteSel === 2.U ){ //CS为低，且SCK上跳的第0byte
    spiCmd := Cat( spiCmd(6,0), shiftMOSI(1) )
  }

  when( shiftCSn(2) & ~shiftCSn(1) ){  //CS下跳 //第一个byte
    exReg := 0.U
  } .elsewhen( isSckPosedgeNext(1) & ~shiftCSn(1) & bitSel === 0.U ){ //CS为低，且SCK上跳补一拍 的第0bit
    when( byteSel === 1.U || byteSel === 2.U ){ //第1、2byte
      exReg := 0.U
    } .otherwise{
      when( isSpiWrite ){
        exReg := 0.U
      } .elsewhen( isSpiRead ){
        exReg := io.datar
      } .otherwise{
        printf("Warning, empty CMD!\n")
      }
    }
  } .elsewhen( isSckPosedge & ~shiftCSn(1) ){
    exReg := Cat( exReg(6 ,0), shiftMOSI(1) )
  }


}





  // val shiftCSn_10M = ShiftRegisters(csn, 3, true.B, true.B)


  // when( isCrcPass ){
  //   localUpdate := localUpdate & ~( 1.U << downRegTemp(0)(3,0) )
  // } .elsewhen( ~shiftCSn_10M(2) & shiftCSn_10M(1) ){
  //   localUpdate := localUpdate & ~exMask_100M
  // }
  

  

  // spiRegDown.io.enw := io.lvdsSlv.downstream_rx_data_valid & (downCnt =/= 0.U | downCnt =/= 1.U)
  // spiRegDown.io.dataw := io.lvdsSlv.downstream_rx_data_out
  // spiRegDown.io.addrw := Cat( downRegTemp(0)(3,0), downCnt(4,0))

  // spiRegUp.io.enr := io.lvdsSlv.upstream_tx_data_ready
  // spiRegUp.io.addrr := Cat( statusPage, upCnt(4,0)+1.U )


  // io.lvdsSlv.upstream_tx_data_in :=
  //   Mux(upCnt === 0.U | upCnt === 1.U | statusPage === 15.U, upReg(upCnt), spiRegUp.io.datar)

  // val int = RegInit(false.B); interrupt := int
  // when( int ){
  //   int := false.B
  // } .elsewhen( RegNext(io.lvdsSlv.upstream_tx_data_ready, false.B) & ~io.lvdsSlv.upstream_tx_data_ready ){
  //   int := true.B
  // }