write a SPIM procedure to add 4 numbers; this procedure adds these 4 numbers by repeatedly calling another procedure that adds 2 numbers and returns their sum. Make sure you preserve all saved registers using the stack. Note, given 4 numbers a, b, c, and d, you need to call the second procedure 3 times to add a and b (save the returned value somewhere, say in s1), c and d (save the returned value somewhere, say in s2), and s1 and s2.

plz give me the correct and complete SPIM code for digital electronics.