简单的ALU

//definitions.sv

package definitions;
 
 parameter VERSION = "1.2";
 
 typedef enum bit [2:0] {ADD, SUB,  MULT, DIV, SL, SR} opcodes_t;
 
 typedef     logic    [31:0]    data_t;
    
 typedef struct packed {
    opcodes_t            opc;
    data_t                op_a;
    data_t                op_b;
 } instr_t;
 
endpackage 

//ALU.sv

 import definitions :: *;
 
 module ALU(
 input     logic      clock,
 input       instr_t     IW,
output     data_t      alu_out );
  
 always @(posedge clock) begin
    case  (IW.opc)
         ADD     :     alu_out = IW.op_a + IW.op_b;
         SUB     :     alu_out = IW.op_a -  IW.op_b;
         MULT     :     alu_out = IW.op_a *  IW.op_b;
         DIV    :     alu_out = IW.op_a /   IW.op_b;
         SL      :     alu_out = IW.op_a   <<  1;
         SR      :     alu_out = IW.op_a   >>  1;
    endcase
end
    
 endmodule 

//test.sv

 import definitions :: *;
  
 module test;
 
 timeunit 10ns;
 timeprecision 1ns;
 
 instr_t IW;
 logic [31:0] alu_out;
 logic  clock;
 
 ALU dut (.IW(IW), .alu_out(alu_out), .clock(clock));
 
 initial begin
    clock = 0;
    forever  #10 clock = ~ clock;
end
 
 initial begin
    @(negedge clock)
        IW = {ADD, 123, 456};
    @(negedge clock)
        IW = {SUB, 762, 456};
    @(negedge clock)
        IW = {DIV, 900, 12};
    @(negedge clock)
        IW = {MULT, 12, 46};
    @(negedge clock)
        IW = {SL, 123, 0};
    @(negedge clock)
        IW = {SR, 123, 0};
     #40
     $stop;
 end
 
 initial begin
    $monitor("%t\t%4d\t%4s\t%4d\t=%4d",  $realtime, IW.op_a, IW.opc, IW.op_b, alu_out);
 end
 endmodule 

#                    0    x  ADD    x =   x
#               200000  123  ADD  456 =   x
#               300000  123  ADD  456 = 579
#               400000  762  SUB  456 = 579
#               500000  762  SUB  456 = 306
#               600000  900  DIV   12 = 306
#               700000  900  DIV   12 =  75
#               800000   12 MULT   46 =  75
#               900000   12 MULT   46 = 552
#              1000000  123   SL    0 = 552
#              1100000  123   SL    0 = 246
#              1200000  123   SR    0 = 246
#              1300000  123   SR    0 =  61