//******************************************************************************
// See LICENSE.Berkeley for license details.
//------------------------------------------------------------------------------
//------------------------------------------------------------------------------

package boom.v4.lsu

import chisel3._
import chisel3.util._

import org.chipsalliance.cde.config.Parameters
import freechips.rocketchip.diplomacy._
import freechips.rocketchip.tilelink._
import freechips.rocketchip.tile._
import freechips.rocketchip.util._
import freechips.rocketchip.rocket._

import boom.v4.common._
import boom.v4.exu.BrResolutionInfo
import boom.v4.util._



abstract class DataPrefetcher(implicit edge: TLEdgeOut, p: Parameters) extends BoomModule()(p)
{
  val io = IO(new Bundle {
    val mshr_avail = Input(Bool())
    val req_val    = Input(Bool())
    val req_addr   = Input(UInt(coreMaxAddrBits.W))
    val req_coh    = Input(new ClientMetadata)

    val prefetch   = Decoupled(new BoomDCacheReq)
  })
}

/**
  * Does not prefetch
  */
class NullPrefetcher(implicit edge: TLEdgeOut, p: Parameters) extends DataPrefetcher
{
  io.prefetch.valid := false.B
  io.prefetch.bits  := DontCare
}

/**
  * Next line prefetcher. Grabs the next line on a cache miss
  */
class NLPrefetcher(implicit edge: TLEdgeOut, p: Parameters) extends DataPrefetcher
{

  val req_valid = RegInit(false.B)
  val req_addr  = Reg(UInt(coreMaxAddrBits.W))
  val req_cmd   = Reg(UInt(M_SZ.W))

  val mshr_req_addr = io.req_addr + cacheBlockBytes.U
  val cacheable = edge.manager.supportsAcquireBSafe(mshr_req_addr, lgCacheBlockBytes.U)
  when (io.req_val && cacheable) {
    req_valid := true.B
    req_addr  := mshr_req_addr
    req_cmd   := Mux(ClientStates.hasWritePermission(io.req_coh.state), M_PFW, M_PFR)
  } .elsewhen (io.prefetch.fire) {
    req_valid := false.B
  }

  io.prefetch.valid            := req_valid && io.mshr_avail
  io.prefetch.bits.addr        := req_addr
  io.prefetch.bits.uop         := NullMicroOp
  io.prefetch.bits.uop.mem_cmd := req_cmd
  io.prefetch.bits.data        := DontCare
  io.prefetch.bits.is_hella    := false.B

}


