always @(x or currentState)
begin
case (currentState)
S0 : …
S1 : ...
S2 : ...
S3 :
case(x)
2'b00 : nextState<=S3;
2'b01 : nextState<=S1;
default : nextState<=S0;
endcase
default : ;
endcase
end
S0
S2
01/0
00/0
1x/0
00/1
01/0
00/0
01/1
00/1
1x/1
01/1
1x/1
1x/0
S1
S3