package BACK

import chisel3._
import chisel3.util._

class SlaveParserIO extends Module{
  val downOut = Decoupled(new AXIS_Bundle(8))
  val downIn  = Flipped( Decoupled(new AXIS_Bundle(8)) )

  val upOut = Decoupled(new AXIS_Bundle(8))
  val upIn  = Flipped( Decoupled(new AXIS_Bundle(8)) )

  val sram
}

abstract class SlaveParserBase extends Module{
  val io: SlaveParserIO = IO(new SlaveParserIO)

  val FRAME_STYLE_COMMON = 0.U
  val FRAME_STYLE_PROBE  = 1.U


  val STATE_IDLE            = 0.U //空闲
  val STATE_HEADER          = 1.U //长度/ /保留2bits //包类型
  val STATE_PAYLOAD_INDEX_STYLE   = 4.U //子报文设备索引 //子报文类型
  val STATE_PAYLOAD_ADDR    = 6.U //子报文地址
  val STATE_PAYLOAD_OP_LENGTH   = 7.U //子报文命令类型 //子报文长度
  val STATE_PAYLOAD_WORKCNT = 9.U //子报文工作计数
  val STATE_PAYLOAD_DATA    = 10.U //子报文数据
  val STATE_CRC             = 11.U //CRC校验
  val STATE_ERROR           = 12.U //


  val downStateNext = Wire(UInt(4.W))
  val downStateCurr = RegNext(downStateNext, STATE_IDLE(4.W))

  val lengthCnt = Reg(UInt(11.W)) //动态计数器
  val subMsgCnt = Reg(UInt(7.W)) //子报文不超过64个？
  val subMsgLenAim = Reg(UInt(11.W)) //子报文长度
  val FrameLenAim  = Reg(UInt(11.W)) //帧长度目标
  val FrameLenCnt  = Reg(UInt(11.W)) //帧长度计数
  val isCrcPass: Bool
  val isTxEnd: Bool
  val isShortRx: Bool //接收长度小于预期

  downStateNext := 
    Mux1H(Seq(
                                                        //必须使用上升沿触发，以避免前一帧长度超过预期
      ( downStateCurr === STATE_IDLE                ) -> Mux( ~RegNext(io.downIn.axis.valid) & io.downIn.axis.valid, STATE_HEADER, STATE_IDLE ), 
      ( downStateCurr === STATE_HEADER              ) -> Mux( isShortRx, STATE_ERROR,
          MuxCase( STATE_ERROR, Array(
            ( io.downIn.axis.bits(1,0) === FRAME_STYLE_COMMON ) -> STATE_PAYLOAD_INDEX_STYLE,
            ( io.downIn.axis.bits(1,0) === FRAME_STYLE_PROBE  ) -> STATE_CRC,
          ))
        ),
      ( downStateCurr === STATE_PAYLOAD_INDEX_STYLE ) -> Mux( isShortRx, STATE_ERROR,
          STATE_PAYLOAD_ADDR
        ),
      ( downStateCurr === STATE_PAYLOAD_ADDR        ) -> Mux( isShortRx,
          STATE_PAYLOAD_OP_LENGTH
        ),
      ( downStateCurr === STATE_PAYLOAD_OP_LENGTH   ) -> Mux( isShortRx,
          STATE_PAYLOAD_WORKCNT
        ),
      ( downStateCurr === STATE_PAYLOAD_WORKCNT     ) -> Mux( isShortRx,
          Mux( lengthCnt === (2 - 1).U, STATE_PAYLOAD_DATA, STATE_PAYLOAD_WORKCNT )
        ),
      ( downStateCurr === STATE_PAYLOAD_DATA        ) -> Mux( isShortRx, 
          Mux( lengthCnt === (subMsgLen - 1.U), 
            Mux(FrameLenCnt === FrameLenAim, STATE_CRC, STATE_PAYLOAD_INDEX_STYLE
          ), STATE_PAYLOAD_DATA )
        ),
      ( downStateCurr === STATE_CRC                 ) -> Mux( isShortRx, 
          Mux( lengthCnt === (4 - 1).U, Mux( isCrcPass, STATE_IDLE, STATE_ERROR), STATE_CRC )
        ),
      ( downStateCurr === STATE_ERROR               ) -> Mux( isTxEnd, STATE_IDLE, STATE_ERROR ), 
    ))

  // assert( ~(downStateCurr === STATE_HEADER              & ~io.downIn.axis.fire), "Assert Failed!" )
  // assert( ~(downStateCurr === STATE_PAYLOAD_INDEX_STYLE & ~io.downIn.axis.fire), "Assert Failed!" )
  // assert( ~(downStateCurr === STATE_PAYLOAD_ADDR        & ~io.downIn.axis.fire), "Assert Failed!" )
}





class SlaveParser extends SlaveParserBase{

}