Question $6$

$[14$ points$]$

In a design document, outline the design and implementation strategy for an assembly pro$-$

cedure called strstr that searches for a string within a string. The procedure takes as its

two parameters the addresses of two $($null$-$terminated$)$ strings. If a sequence of characters in

the first string matches the entire second string, the procedure returns the starting index of

that sequence. If no sequence of characters in the first string matches the second string, the

procedure returns $-1.$ Your procedure should also handle empty strings correctly. If either

string is empty, the procedure should return $-1.$

Write, and test using QEMU, the RISC$-$V assembly procedure strstr$.$ Also, write a main

program to test your procedure. The program should prompt the user to input two strings

$($you can assume that the strings will be at most $40$ characters each, not including the zero

byte delimiter$),$ call the function, display the result of the function, and finally terminate.

Your code must use the "standard" conventions covered in class for passing

parameters, returning results, and using the stack.