package BACK

import chisel3._
import chisel3.util._

class QSPIInterfaceIO extends Bundle{
  val sck  = Input(Bool())
  val mosi = Input(UInt(4.W))
  val miso = Output(UInt(4.W))
  val isDirIn = Output(Bool())
  val csn  = Input(Bool())
}


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

class RegAccessInterfaceIO extends Bundle{
  val addrw = Output(UInt(16.W))
  val addrr = Output(UInt(16.W))
  val dataw   = Output( UInt(8.W) )
  val datar   = Input( UInt(8.W) )
  val isEnW   = Output(Bool())
  val isEnR   = Output(Bool())
}

abstract class SpiInterfaceBase extends Module with RequireAsyncReset{
  val io = IO(new RegAccessInterfaceIO)

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


  //数据信号相对SCK的稳定应该由外部主机保证，因此认为SCK采样时刻，数据都是稳定正确的
  val shiftSCK  = ShiftRegisters(sck, 3, false.B, true.B)
  val shiftCSn  = ShiftRegisters(csn, 3, true.B, true.B)



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

  val exRego = Reg(UInt(8.W))
  val exRegi = Reg(UInt(8.W))



  val addrw = RegInit(0.U(16.W))
  val addrr = RegInit(0.U(16.W))
  val spiCmd  = Reg(UInt(1.W))

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

  val bitSel  = Reg(UInt(3.W))
  val bitSelNext = RegNext(bitSel)
  val byteSel = Reg(UInt(12.W))
  val byteSelNext = RegNext(byteSel)


  io.isEnW := isSckPosedgeNext(0) & ~shiftCSn(1) & bitSelNext.andR & isSpiWrite & byteSelNext >= 3.U


  io.dataw := exRegi
  io.addrr := addrr
  io.addrw := addrw
  

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












}

class SSpiInterface extends SpiInterfaceBase{
  val spi = IO(new SSPIInterfaceIO)
  val shiftMOSI = ShiftRegisters(spi.mosi, 3)

  sck     := spi.sck
  csn     := spi.csn


  io.isEnR := 
             (isSckPosedgeNext(0) & ~shiftCSn(1) & bitSelNext === 0.U & shiftMOSI(1) === 1.U & byteSelNext === 2.U ) |
             (isSckPosedgeNext(0) & ~shiftCSn(1) & bitSelNext === 0.U & isSpiRead & byteSelNext >= 3.U)

  when( isSckPosedgeNext(0) & ~shiftCSn(1) & byteSelNext === 2.U & bitSelNext === 0.U ){ //CS为低，且SCK上跳的第0byte
    spiCmd := shiftMOSI(1)
  }


  spi.miso := exRego.extract(7)

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



  //输入看SCK上升沿
  when( isSckPosedge & ~shiftCSn(1) ){
    when( bitSel === 0.U ){
      exRegi := Cat( 0.U, shiftMOSI(1) )
    }.otherwise{
      exRegi := Cat( exRegi(6,0), shiftMOSI(1) )
    }
  }

  //输出在SCK下降沿准备数据
  when( shiftCSn(2) & ~shiftCSn(1) ){  //CS下跳
    exRego := 0.U //第一个byte 地址0
  } .elsewhen( isSckPosedge & ~shiftCSn(1) ){
    when( bitSel.andR ){
      when((byteSel === 0.U || byteSel === 1.U) ){
        exRego := 0.U //地址1，cmd
      } .elsewhen( isSpiRead ){
        exRego := io.datar
      }
    }.otherwise{
      exRego := exRego << 1
    }
  }


  when( shiftCSn(2) & ~shiftCSn(1) ){  //CS下跳
    addrr := 0.U
  } .elsewhen(isSckPosedge & ~shiftCSn(1) & bitSel.andR & byteSel === 0.U){ //CS为低，且SCK上跳的第0byte
    addrr := Cat( exRegi(6,0), shiftMOSI(1) )
  } .elsewhen(isSckPosedge & ~shiftCSn(1) & bitSel.andR & byteSel === 1.U) {//CS为低，且SCK上跳的第0byte
    addrr := Cat(addrr(7,0), exRegi(6,0), shiftMOSI(1))
  } .otherwise{ // byteSel > 1.U
    when( isSckPosedgeNext(0) & byteSelNext >= 2.U & bitSelNext === 0.U ){
      addrr := addrr + 1.U
    }
  }

  when( shiftCSn(2) & ~shiftCSn(1) ){  //CS下跳
    addrw := 0.U
  } .elsewhen(isSckPosedge & ~shiftCSn(1) & bitSel.andR & byteSel === 0.U){ //CS为低，且SCK上跳的第0byte
    addrw := Cat( exRegi(6,0), shiftMOSI(1) )
  } .elsewhen(isSckPosedge & ~shiftCSn(1) & bitSel.andR & byteSel === 1.U) {//CS为低，且SCK上跳的第0byte
    addrw := Cat(addrw(7,0), exRegi(6,0), shiftMOSI(1) )
  } .otherwise{ // byteSel > 1.U
    when( isSckPosedgeNext(0) & byteSelNext >= 3.U & bitSelNext.andR ){
      addrw := addrw + 1.U
    }
  }

  io.isEnW := isSckPosedgeNext(0) & ~shiftCSn(1) & bitSelNext.andR & isSpiWrite & byteSelNext >= 3.U
}

class QSpiInterface extends SpiInterfaceBase{
  val qspi = IO(new QSPIInterfaceIO)
  val shiftMOSI = ShiftRegisters(qspi.mosi, 3)

  sck       := qspi.sck
  csn       := qspi.csn
  qspi.miso := exRego(7, 4)
  qspi.isDirIn := ~isSpiRead

  io.isEnR := 
             (isSckPosedgeNext(0) & ~shiftCSn(1) & bitSelNext === 0.U & shiftMOSI(2) === "b1000".U & byteSelNext === 2.U ) |
             (isSckPosedgeNext(0) & ~shiftCSn(1) & bitSelNext === 0.U & isSpiRead & byteSelNext >= 3.U)

  when( isSckPosedgeNext(0) & ~shiftCSn(1) & byteSelNext === 2.U & bitSelNext === 0.U ){ //CS为低，且SCK上跳的第0byte
    spiCmd := shiftMOSI(2).extract(3)
  }

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





  //输入看SCK上升沿
  when( isSckPosedge & ~shiftCSn(1) ){
    when( bitSel === 0.U ){
      exRegi := Cat( 0.U, shiftMOSI(1) )
    }.otherwise{
      exRegi := Cat( exRegi(3,0), shiftMOSI(1) )
    }
  }

  //输出在SCK下降沿准备数据
  when( shiftCSn(2) & ~shiftCSn(1) ){  //CS下跳
    exRego := 0.U //第一个byte 地址0
  } .elsewhen( isSckPosedge & ~shiftCSn(1) ){
    when( bitSel.andR ){
      when((byteSel === 0.U || byteSel === 1.U) ){
        exRego := 0.U //地址1，cmd
      } .elsewhen( isSpiRead ){
        exRego := io.datar
      }
    }.otherwise{
      exRego := exRego << 4
    }
  }

  when( shiftCSn(2) & ~shiftCSn(1) ){  //CS下跳
    addrr := 0.U
  } .elsewhen(isSckPosedge & ~shiftCSn(1) & bitSel.andR & byteSel === 0.U){ //CS为低，且SCK上跳的第0byte
    addrr := Cat( exRegi(3,0), shiftMOSI(1) )
  } .elsewhen(isSckPosedge & ~shiftCSn(1) & bitSel.andR & byteSel === 1.U) {//CS为低，且SCK上跳的第0byte
    addrr := Cat(addrr(7,0), exRegi(3,0), shiftMOSI(1))
  } .otherwise{ // byteSel > 1.U
    when( isSckPosedgeNext(0) & byteSelNext >= 2.U & bitSelNext === 0.U ){
      addrr := addrr + 1.U
    }
  }

  when( shiftCSn(2) & ~shiftCSn(1) ){  //CS下跳
    addrw := 0.U
  } .elsewhen(isSckPosedge & ~shiftCSn(1) & bitSel.andR & byteSel === 0.U){ //CS为低，且SCK上跳的第0byte
    addrw := Cat( exRegi(3,0), shiftMOSI(1) )
  } .elsewhen(isSckPosedge & ~shiftCSn(1) & bitSel.andR & byteSel === 1.U) {//CS为低，且SCK上跳的第0byte
    addrw := Cat(addrw(7,0), exRegi(3,0), shiftMOSI(1) )
  } .otherwise{ // byteSel > 1.U
    when( isSckPosedgeNext(0) & byteSelNext >= 3.U & bitSelNext.andR ){
      addrw := addrw + 1.U
    }
  }

}