64-bit Adds: Write a MIPS assembly program in the MARS simulator that solves the following problem. Ask the user to enter 4 unsigned (positive) 32-bit integers. Read these 4 integers; let's call them A, B, C, D. At the end of your program, registers $t8 and $t9 should contain the 64-bit result of ((A*B) + (C*D)); $t8 should have the most significant 32 bits and $t9 should have the least significant 32 bits. We will not test your code with invalid inputs, so you don't need to clutter your code with checks for invalid inputs. Hint: The tricky part here of course is to perform addition on two 64-bit values. Since you can only do 32-bit additions in MARS, you'll somehow have to figure out how to propagate a carry from the 32nd bit to the 33rd bit. When you add two large 32-bit numbers (with addu $t1, $t2, $t3), the result may be a 33-bit number, but MIPS does not give you access to that 33rd bit. So you'll have to explicitly compute that 33rd bit. Note that the 33rd bit is a 1 if at least two of the following three bits are 1: (i) the 32nd bit of the first operand, (ii) the 32nd bit of the second operand, (iii) the carry generated by the sum of the 31 least significant bits.

Don't forget to point to the example procedure call in your program with correct saves/restores.