Write the Main Decoder truth table enhanced to support Jalr, according to below figures .

you can see below Example for Main Decoder truth table enhanced to support Jal

case 103: // jalr printf ("Main_Decoder_Pr osses jalr "); ImmSrc = 0; // for jalr i,e 12 bits MemWrite = 0; // mem write is not important here Reg_File_EW3 = 1; // register file write is important ALUOp = ; // this is don't care that's why ALUSrc = 0; // this is also don't care ResultSrc = 2; // To select for PC + 4 for register file Branch = 0; // branch is Jump = 1; // jump should be one JALR_sel = 1; // JALR_sel will be one to select for Pc or Src A I mi "11 i;il. LIIIIII Table 7.6 Main Decoder truth table enhanced to support jal Instruction RegWrite ImmSrc ALUSrc Mem Write ResultSrc Branch ALUOP Jump Opcode 0000011 1w 1 00 1 0 01 0 00 0 SW 0100011 0 01 1 1 XX 0 00 0 R-type 0110011 1 xx 0 0 00 0 10 0 be 1100011 0 10 0 0 XX 1 01 0 I-type ALU 0010011 1 00 1 0 00 0 10 0 jal 1101111 1 11 X 0 10 0 XX 1