TYPE state IS (s0,s1,s2,s3); --正交编码器的状态
SIGNAL status1,status2,status3:state;         --状态变量

case status1 is
    when s0 =>if((inaclear='1')and (inbclear='0')) then
              status1<=s1;
              --direct1<='0';
              --inpout1last<=inpout1;
              inpout0<='1';
              ct6<=0;
              elsif((inaclear='0')and (inbclear='1')) then
              status1<=s3;
              --direct1<='1';
              --inpout1last<=inpout1;
              inpout1<='1';
              ct6<=0;
              else if(int2mask(5)='0' and not((inaclear='0')and (inbclear='0'))) then
                    codebit<='1';
                    vecint2(5)<='1';
                   end if;
              end if;
    when s1 =>if((inaclear='1')and (inbclear='1')) then
              status1<=s2;
              --direct1<='0';
              --inpout1last<=inpout1;
              inpout0<='1';
              ct6<=0;
              elsif((inaclear='0') and (inbclear='0')) then
              status1<=s0;
              --direct1<='1';
              --inpout1last<=inpout1;
              inpout1<='1';
              ct6<=0;
              else if(int2mask(5)='0' and not((inaclear='1')and (inbclear='0'))) then
                    codebit<='1';
                    vecint2(5)<='1';
                   end if;
              end if;
   when s2 =>if((inaclear='0')and (inbclear='1')) then
              status1<=s3;
              --direct1<='0';
              --inpout1last<=inpout1;
              inpout0<='1';
              ct6<=0;
              elsif((inaclear='1') and (inbclear='0')) then
              status1<=s1;
              --direct1<='1';
              --inpout1last<=inpout1;
              inpout1<='1';
              ct6<=0;
              else if(int2mask(5)='0' and not((inaclear='1')and (inbclear='1'))) then
                    codebit<='1';
                    vecint2(5)<='1';
                   end if;
              end if;
   when s3 =>if((inaclear='0')and (inbclear='0')) then
              status1<=s0;
              --direct1<='0';
              --inpout1last<=inpout1;
              inpout0<='1';
              ct6<=0;
              elsif((inaclear='1') and (inbclear='1')) then
              status1<=s2;
              --direct1<='1';
              --inpout1last<=inpout1;
              inpout1<='1';
              ct6<=0;
              else if(int2mask(5)='0' and not((inaclear='0')and (inbclear='1'))) then
                    codebit<='1';
                    vecint2(5)<='1';
                   end if;
              end if;
   when OTHERS =>null;
   end case;