Write an LC-3 subroutine named ONES that counts the number of non-zero bits in the value in R0. Return the count in R1. Except for R1, no registers may be changed by the subroutine. Note that the value returned in R1 will be between 0 and 16. (Example: If R0 has the value 1010011011100011, then R1 will be 9 when the subroutine returns, because there are nine non-zero bits.)