package BACK

import chisel3._
import chisel3.util._

class SMUnitIO extends Bundle {
  val maxLen = Input(UInt(11.W))
  val enq = Flipped(Decoupled(UInt(8.W)))
  val deq = Decoupled(UInt(8.W))

}

abstract class SMUnitBase extends Module {
  val io: SMUnitIO = IO(new SMUnitIO)

  val enqCnt = Reg(UInt(11.W))
  val deqCnt = Reg(UInt(11.W))





  val dataBuf =
    for ( _ <- until 4 ) yield {
      Module( new Queue(UInt(8.W), 2048, useSyncReadMem = true) )        
    }

  val wPtr = RegInit(0.U((2+1).W))
  val rPtr = RegInit(0.U((2+1).W))

  val isFull =
    ( wPtr.extract(2) =/= rPtr.extract(2) ) & ( wPtr(1,0) === rPtr(1,0) )


  val isEmpty = ( wPtr === rPtr )

  when( io.enq.fire ){
    when( enqCnt === io.maxLen ){
      enqCnt := 0.U
    } .otherwise{
      enqCnt := enqCnt + 1.U
    }
  }

  when( io.deq.fire ){
    when( deqCnt === io.maxLen ){
      deqCnt := 0.U
    } .otherwise{
      deqCnt := deqCnt + 1.U
    }
  }


  when( io.enq.fire & enqCnt === io.maxLen ){
    wPtr := wPtr + 1.U
  }

  when( io.deq.fire & deqCnt === io.maxLen ){
    rPtr := rPtr + 1.U
  }


  when( wPtr === 0.U & ~isFull ){
    dataBuf(0).io.enq.valid := io.enq.valid
    dataBuf(0).io.enq.bits  := io.enq.bits
    io.enq.ready := dataBuf(0).io.enq.ready

    dataBuf(1).io.enq.valid := false.B
    dataBuf(1).io.enq.bits  := 0.U
    dataBuf(2).io.enq.valid := false.B
    dataBuf(2).io.enq.bits  := 0.U
    dataBuf(3).io.enq.valid := false.B
    dataBuf(3).io.enq.bits  := 0.U
  } .elsewhen( wPtr === 1.U & ~isFull ){
    dataBuf(1).io.enq.valid := io.enq.valid
    dataBuf(1).io.enq.bits  := io.enq.bits
    io.enq.ready := dataBuf(1).io.enq.ready

    dataBuf(0).io.enq.valid := false.B
    dataBuf(0).io.enq.bits  := 0.U
    dataBuf(2).io.enq.valid := false.B
    dataBuf(2).io.enq.bits  := 0.U
    dataBuf(3).io.enq.valid := false.B
    dataBuf(3).io.enq.bits  := 0.U
  } .elsewhen( wPtr === 2.U & ~isFull ){
    dataBuf(2).io.enq.valid := io.enq.valid
    dataBuf(2).io.enq.bits  := io.enq.bits
    io.enq.ready := dataBuf(2).io.enq.ready

    dataBuf(0).io.enq.valid := false.B
    dataBuf(0).io.enq.bits  := 0.U
    dataBuf(1).io.enq.valid := false.B
    dataBuf(1).io.enq.bits  := 0.U
    dataBuf(3).io.enq.valid := false.B
    dataBuf(3).io.enq.bits  := 0.U
  } .elsewhen( wPtr === 3.U & ~isFull ){
    dataBuf(3).io.enq.valid := io.enq.valid
    dataBuf(3).io.enq.bits  := io.enq.bits
    io.enq.ready := dataBuf(3).io.enq.ready

    dataBuf(0).io.enq.valid := false.B
    dataBuf(0).io.enq.bits  := 0.U
    dataBuf(1).io.enq.valid := false.B
    dataBuf(1).io.enq.bits  := 0.U
    dataBuf(2).io.enq.valid := false.B
    dataBuf(2).io.enq.bits  := 0.U

  } .otherwise{

    io.enq.ready := false.B

    dataBuf(0).io.enq.valid := false.B
    dataBuf(0).io.enq.bits  := 0.U
    dataBuf(1).io.enq.valid := false.B
    dataBuf(1).io.enq.bits  := 0.U
    dataBuf(2).io.enq.valid := false.B
    dataBuf(2).io.enq.bits  := 0.U
    dataBuf(3).io.enq.valid := false.B
    dataBuf(3).io.enq.bits  := 0.U
  }

  when( rPtr === 0.U & ~isEmpty){
    io.deq.valid := dataBuf(0).io.deq.valid
    io.deq.bits  := dataBuf(0).io.deq.bits

    dataBuf(0).io.deq.ready := io.deq.ready
    dataBuf(1).io.deq.ready := false.B
    dataBuf(2).io.deq.ready := false.B
    dataBuf(3).io.deq.ready := false.B
  } .elsewhen( rPtr === 1.U & ~isEmpty){
    io.deq.valid := dataBuf(1).io.deq.valid
    io.deq.bits  := dataBuf(1).io.deq.bits

    dataBuf(0).io.deq.ready := false.B
    dataBuf(1).io.deq.ready := io.deq.ready
    dataBuf(2).io.deq.ready := false.B
    dataBuf(3).io.deq.ready := false.B
  } .elsewhen( rPtr === 2.U & ~isEmpty){
    io.deq.valid := dataBuf(2).io.deq.valid
    io.deq.bits  := dataBuf(2).io.deq.bits
    
    dataBuf(0).io.deq.ready := false.B
    dataBuf(1).io.deq.ready := false.B
    dataBuf(2).io.deq.ready := io.deq.ready
    dataBuf(3).io.deq.ready := false.B
  } .elsewhen( rPtr === 3.U & ~isEmpty){
    io.deq.valid := dataBuf(3).io.deq.valid
    io.deq.bits  := dataBuf(3).io.deq.bits
    
    dataBuf(0).io.deq.ready := false.B
    dataBuf(1).io.deq.ready := false.B
    dataBuf(2).io.deq.ready := false.B
    dataBuf(3).io.deq.ready := io.deq.ready
  } .otherwise{
    io.deq.valid := false.B
    io.deq.bits  := 0.U
    
    dataBuf(0).io.deq.ready := false.B
    dataBuf(1).io.deq.ready := false.B
    dataBuf(2).io.deq.ready := false.B
    dataBuf(3).io.deq.ready := io.deq.ready
  }





}

class SMUnit extends SMUnitBase {


}