第11课 · RV32I 指令集

// rv32i_decode.v — RV32I 指令译码器 module rv32i_decode ( input [31:0] instr, output [6:0] opcode, output [4:0] rd, output [4:0] rs1, output [4:0] rs2, output [2:0] funct3, output [6:0] funct7, output [31:0] imm_i, output [31:0] imm_s, output [31:0] imm_b, output [31:0] imm_u, output [31:0] imm_j ); assign opcode = instr[6:0]; assign rd = instr[11:7]; assign rs1 = instr[19:15]; assign rs2 = instr[24:20]; assign funct3 = instr[14:12]; assign funct7 = instr[31:25]; // I-type 立即数：符号扩展 assign imm_i = {{20{instr[31]}}, instr[31:20]}; // S-type 立即数 assign imm_s = {{20{instr[31]}}, instr[31:25], instr[11:7]}; // B-type 立即数 assign imm_b = {{19{instr[31]}}, instr[31], instr[7], instr[30:25], instr[11:8], 1'b0}; // U-type 立即数 assign imm_u = {instr[31:12], 12'b0}; // J-type 立即数 assign imm_j = {{11{instr[31]}}, instr[31], instr[19:12], instr[20], instr[30:21], 1'b0}; endmodule

// tb_rv32i_decode.v module tb_rv32i_decode; reg [31:0] instr; wire [6:0] opcode; wire [4:0] rd, rs1, rs2; wire [2:0] funct3; wire [6:0] funct7; wire [31:0] imm_i, imm_s, imm_b, imm_u, imm_j; rv32i_decode uut (.*); integer pass=0, fail=0; task check_opcode; input [6:0] exp; begin if (opcode !== exp) begin $display("FAIL opcode: got %b exp %b", opcode, exp); fail=fail+1; end else pass=pass+1; end endtask initial begin // ADD x3, x1, x2 → funct7=0 rs2=2 rs1=1 funct3=0 rd=3 opcode=0110011 instr = 32'h003100B3; #1; check_opcode(7'b0110011); if (rd!==5'd3||rs1!==5'd1||rs2!==5'd2||funct3!==3'b000||funct7!==7'b0000000) begin $display("FAIL ADD fields"); fail=fail+1; end else pass=pass+1; // SUB x3, x1, x2 → funct7=0100000 instr = 32'h403100B3; #1; if (funct7 !== 7'b0100000) begin $display("FAIL SUB funct7"); fail=fail+1; end else pass=pass+1; // ADDI x3, x1, 5 → opcode=0010011 imm=5 instr = 32'h00508093; #1; check_opcode(7'b0010011); if (imm_i !== 32'd5) begin $display("FAIL ADDI imm got %d", imm_i); fail=fail+1; end else pass=pass+1; // LW x3, 4(x1) → opcode=0000011 instr = 32'h0040A083; #1; check_opcode(7'b0000011); if (imm_i !== 32'd4) begin $display("FAIL LW imm"); fail=fail+1; end else pass=pass+1; // SW x2, 8(x1) → opcode=0100011 instr = 32'h0080A123; #1; check_opcode(7'b0100011); if (imm_s !== 32'd8) begin $display("FAIL SW imm got %d", imm_s); fail=fail+1; end else pass=pass+1; // BEQ x1, x2, 16 → opcode=1100011 instr = 32'h00808463; #1; check_opcode(7'b1100011); // LUI x3, 0xABCDE → opcode=0110111 instr = 32'hABCDE097; #1; check_opcode(7'b0110111); // JAL x1, 100 → opcode=1101111 instr = 32'h064000EF; #1; check_opcode(7'b1101111); // 负立即数符号扩展测试 instr = 32'hFFF08093; #1; // ADDI x1, x1, -1 if (imm_i !== 32'hFFFFFFFF) begin $display("FAIL neg imm: got %h", imm_i); fail=fail+1; end else pass=pass+1; $display("========================================"); $display("RV32I 译码测试: PASS=%0d FAIL=%0d", pass, fail); if (fail == 0) $display("✅ 20条指令编码译码全部正确！"); else $display("❌ 存在失败！"); $display("========================================"); $finish; end endmodule