Mips assembly MARS
main. Test it on the source strings: “loop2:” and “Elephant!” In other words, code in your main program calls the procedure twice, once for each source string. You
should print a memory screen shot after the program runs, showing that both strings were converted – check the ASCII box.
You should add code to check if each byte is in fact a lowercase letter, and only convert if it is; otherwise it should just copy it.
In the program you could use $tn registers but in this program you should follow the conventions for using $sn and $tn registers.
Also, use the directive .space for the upper case strings, reserving at least 10 bytes for each of the 2 upper strings.
Table 2: Rubric for problem 2
Code and screen shot
Memory screen shots for 2 inputs
Correct procedure usage
Code checks a-z range
Correct use of $tn and $sn
Main code calls procedure twice
Code comments, formatting
1. Single-step through your program through the first subroutine call and back, then answer the following questions. Copy a-g below and paste your answers/screen
a. What is the value of PC before you execute the jal?
b. What is the value of $ra before you execute the jal?
c. Set a breakpoint to the jr instruction and run until then. What is the value of PC before the jr?
d. Single step back to the main program. What address is in the next instruction?
e. What value is in the PC?
f. Write a 2-3 sentence summary describing how the PC and $ra registers change when a subroutine is called and when we return from a subroutine.
Table 3: Rubric for problem 3