function [codeword,sita]=encoding(symbol_per_frame, x1, x2, table)
   S0=[0,0; 1;];
   S1=[1, 0;];
current_state=0;
            for i=1:symbol_per_frame,
                switch current_state,
                    case 0,
                        switch x2(i),
                                case 0,
                                    codeword(i,1)=x1(i);
                                    codeword(i,2)=S0(x1(i)+1);
                                    sita(i)=0;
                                    current_state=0;
                                case 1,
                                    codeword(i,1)=x1(i);
                                    codeword(i,2)=S1(x1(i)+1);
                                    sita(i)=pi;
                                    current_state=1;
                                otherwise,
                                    display('encoding input is error');
                        end;
                    case 1,
                        switch x2(i),
                            case 0,
                                    codeword(i,1)=x1(i);
                                    codeword(i,2)=S1(x1(i)+1);
                                    sita(i)=0;
                                    current_state=0;
                            case 1,
                                    codeword(i,1)=x1(i);
                                    codeword(i,2)=S0(x1(i)+1);
                                    sita(i)=pi;
                                    current_state=1;
                            otherwise,
                                display('encoding input is error');
                        end;
                    otherwise,
                        display('encoding input is error');
                end; %end for switch current states
            end;      %end for i