xref: /XiangShan/src/main/scala/xiangshan/backend/decode/isa/predecode/predecode.scala (revision b8b991d636e3eae0d6cc2e36846166652699f0c2)

/***************************************************************************************
* Copyright (c) 2020-2021 Institute of Computing Technology, Chinese Academy of Sciences
* Copyright (c) 2020-2021 Peng Cheng Laboratory
*
* XiangShan is licensed under Mulan PSL v2.
* You can use this software according to the terms and conditions of the Mulan PSL v2.
* You may obtain a copy of Mulan PSL v2 at:
*          http://license.coscl.org.cn/MulanPSL2
*
* THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
* EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
* MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
*
* See the Mulan PSL v2 for more details.
***************************************************************************************/

package xiangshan.backend.decode.isa.predecode

import chisel3.util._
import xiangshan.frontend.BrType

object PreDecodeInst {
  // def C_JAL     = BitPat("b????????????????_?01_?_??_???_??_???_01") // RV32C
  def C_J       = BitPat("b????????????????_101_?_??_???_??_???_01")
  def C_EBREAK  = BitPat("b????????????????_100_?_00_000_00_000_10")
  def C_JALR    = BitPat("b????????????????_100_?_??_???_00_000_10")  // c.jalr & c.jr
  def C_BRANCH  = BitPat("b????????????????_11?_?_??_???_??_???_01")
  def JAL       = BitPat("b????????????????_???_?????_1101111")
  def JALR      = BitPat("b????????????????_000_?????_1100111")
  def BRANCH    = BitPat("b????????????????_???_?????_1100011")
  def NOP       = BitPat("b???????????????0_100_01010_0000001")   //li	a0,0


  val brTable = Array(
    // C_JAL     -> List(BrType.jal),
    C_EBREAK  -> List(BrType.notCFI), // c.ebreak should not be decoded as jalr, higher priority than c.jalr
    C_J       -> List(BrType.jal),
    C_JALR    -> List(BrType.jalr),
    C_BRANCH  -> List(BrType.branch),
    JAL       -> List(BrType.jal),
    JALR      -> List(BrType.jalr),
    BRANCH    -> List(BrType.branch)
  )
}