module count$8$Ones$($S$,$ X$)$;

input $[7$:$0]$ X;

output $[3$:$0]$ S;

wire $[5$:$0]$ Y;

integer row;

countOnes U$1($Y$[2$:$0],$ X$[3$:$0])$;

countOnes U$2($Y$[5$:$3],$ X$[7$:$4])$;

$8-$bit module for counting $1$s$,$ constructed using two of out $4-$bit, How many different input combinations are needed to thoroughly test the$$ count$8$Ones$()$ module