package BACK

import chisel3._
import chisel3.util._


trait BackBoardSpiSlv{ this: BackBoardSlvLocal =>

  val sck = Wire(Bool())
  val mosi = Wire(Bool())
  val csn   = Wire(Bool())
  val clk100M = Wire(Bool())

  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 localUpdate = RegInit(0.U(16.W))

  val shiftSCK  = withClockAndReset( clk100M.asClock, reset ){ ShiftRegisters(sck, 3, false.B, true.B) }
  val shiftCSn  = withClockAndReset( clk100M.asClock, reset ){ ShiftRegisters(csn, 3, true.B, true.B) }
  val shiftMOSI = withClockAndReset( clk100M.asClock, reset ){ ShiftRegisters(mosi, 3) }


  val isSckPosedge     = ~shiftSCK(2) & shiftSCK(1)
  val isSckPosedgeNext = withClockAndReset( clk100M.asClock, reset ){ ShiftRegisters(isSckPosedge, 2, false.B, true.B) }


  val exReg_100M = withClockAndReset( clk100M.asClock, reset ){ Reg(UInt(8.W)) }
  val exMask_100M = withClockAndReset( clk100M.asClock, reset ){ Reg(UInt(16.W)) }
  val cmd_100M = withClockAndReset( clk100M.asClock, reset ){ Reg(UInt(8.W)) }
  val pageSel = cmd_100M(5,4)
  val spiCmd  = cmd_100M(3,0)

  val bitSel  = withClockAndReset( clk100M.asClock, reset ){ Reg(UInt(3.W)) }
  val byteSel = withClockAndReset( clk100M.asClock, reset ){ 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
     
  withClockAndReset( clk100M.asClock, reset ){//100M

    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
      bitSel   := 0.U
      byteSel  := 0.U
      cmd_100M := 0.U
    } .elsewhen( isSckPosedge & ~shiftCSn(1) & byteSel === 0.U ){ //CS为低，且SCK上跳的第0byte
      cmd_100M := Cat( cmd_100M(6,0), shiftMOSI(1) )
    }

    when( shiftCSn(2) & ~shiftCSn(1) ){  //CS下跳
      exReg_100M := upReg(0)
    } .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 ){
        exReg_100M := upReg(1)
      } .elsewhen( spiCmd === 2.U & byteSel === 2.U ){
        exReg_100M := localUpdate(7,0)
      } .elsewhen( spiCmd === 2.U & byteSel === 3.U ){
        exReg_100M := localUpdate(15,8)
      } .elsewhen( spiCmd === 0.U & (byteSel =/= 0.U | byteSel =/= 1.U) ){
        exReg_100M := spiRegDown.io.datar
      }
    } .elsewhen( isSckPosedge & ~shiftCSn(1) ){
      exReg_100M := Cat( exReg_100M(6 ,0), shiftMOSI(1) )
    }


    when(  isSckPosedgeNext(1) & ~shiftCSn(1) & byteSel === 3.U & bitSel === 0.U & spiCmd === 3.U ){
      exMask_100M := Cat( exReg_100M, exMask_100M(7,0) )
    } .elsewhen(  isSckPosedgeNext(1) & ~shiftCSn(1) & byteSel === 4.U & bitSel === 0.U & spiCmd === 3.U ){
      exMask_100M := Cat( exMask_100M(15,8), exReg_100M )
    }

  }
}


class SpiSlv extends BackBoardSlvLocal
with BackBoardSlvStatusPR
with BackBoardSpiSlv{

  val spi = IO(new Bundle{
    val sck  = Input(Bool())
    val mosi = Input(Bool())
    val miso = Output(Bool())
    val csn  = Input(Bool())
  })
  val clk100MIO = IO(Input(Bool()))
  val interrupt = IO(Output(Bool()))

  sck  := spi.sck
  mosi := spi.mosi
  csn  := spi.csn
  spi.miso := exReg_100M.extract(exReg_100M.getWidth-1)
  clk100M := clk100MIO

  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
  }


}