$(40$ pts$)$ Write a complete subroutine in ARM assembly, ToLower, that is passed a pointer to a null$-$terminated character array $($string$).$ The subroutine should modify the string by converting upper$-$case letters to the corresponding lower$-$case letters. Lowercase letters, numbers, and other characters should not be modified. For example, when passed the string "HELLO$123",$ the subroutine should modify the string to read "hello$123".$ The subroutine does not return a value and must conform to the ARM procedure calling standard. The equivalent C$-$code declaration for the function is shown below. For reference, an ASCII table is included at the end of this document.

void ToLower$($char $*$str$)$;

a$.(5$ pts$)$ Draw a flowchart for the ToLower subroutine: