chisel/Buraq-mini/RV32i/src/main/scala/core/InstructionTypeDecode.scala

package core

import chisel3._

class InstructionTypeDecode extends Module {
    val io = IO(new Bundle {
     //   val enable_M_extension = Input(UInt(1.W))
        val func3 = Input(UInt(3.W))
        val func7  = Input(UInt(7.W))
        val opcode = Input(UInt(7.W))
        val r_type = Output(UInt(1.W))
        val load_type = Output(UInt(1.W))
        val s_type = Output(UInt(1.W))
        val sb_type = Output(UInt(1.W))
        val i_type = Output(UInt(1.W))
        val jalr_type = Output(UInt(1.W))
        val jal_type = Output(UInt(1.W))
        val lui_type = Output(UInt(1.W))
        val Auipc    = Output(UInt(1.W))
        val multiply = Output(UInt(1.W))
        val csr_imm_type = Output(UInt(1.W))
        val csr_type = Output(UInt(1.W))
        val csr_op = Output(UInt(2.W))
    })
        default_signals()

    when(io.opcode === "b0110011".U ) 
    {
        when(io.func7 === "b000001".U)
        {
          io.multiply := 1.U
          io.r_type   := 0.U
       }
        .otherwise
        {
          io.r_type := 1.U
        }
    } 
    .elsewhen(io.opcode === "b0000011".U) {
        io.load_type := 1.U
    } .elsewhen(io.opcode === "b0100011".U) {        
        io.s_type := 1.U        
    } .elsewhen(io.opcode === "b1100011".U) {        
        io.sb_type := 1.U        
    } .elsewhen(io.opcode === "b0010011".U) {        
        io.i_type := 1.U        
    } .elsewhen(io.opcode === "b1100111".U) {
        io.jalr_type := 1.U
    } .elsewhen(io.opcode === "b1101111".U) {
        io.jal_type := 1.U
    } .elsewhen(io.opcode === "b0110111".U) {
        io.lui_type := 1.U
    }
     .elsewhen(io.opcode === "b0010111".U) {
        io.Auipc := 1.U
    } .elsewhen(io.opcode === "b1110011".U && io.func3 === "b001".U) {
        io.csr_type := 1.U
        io.csr_op := "b01".U
    } .elsewhen(io.opcode === "b1110011".U && io.func3 === "b010".U) {
        io.csr_type := 1.U
        io.csr_op := "b10".U
    } .elsewhen(io.opcode === "b1110011".U && io.func3 === "b011".U) {
        io.csr_type := 1.U
        io.csr_op := "b11".U
    } .elsewhen(io.opcode === "b1110011".U && io.func3 === "b101".U) {
        io.csr_imm_type := 1.U
        io.csr_op := "b01".U
    } .elsewhen(io.opcode === "b1110011".U && io.func3 === "b110".U) {
        io.csr_imm_type := 1.U
        io.csr_op := "b10".U
    } .elsewhen(io.opcode === "b1110011".U && io.func3 === "b111".U) {
        io.csr_imm_type := 1.U
        io.csr_op := "b11".U
    }
     .otherwise 
     {
        default_signals()
    }

    def default_signals(): Unit = 
    {
        io.r_type := 0.U
        io.load_type := 0.U
        io.s_type := 0.U
        io.sb_type := 0.U
        io.i_type := 0.U
        io.jalr_type := 0.U
        io.jal_type := 0.U
        io.lui_type := 0.U
        io.Auipc    := 0.U
        io.multiply := 0.U
        io.csr_type := 0.U
        io.csr_imm_type := 0.U
        io.csr_op := 0.U
    }

}