The do$\_$add function takes as argument two integers in registers and does the following:

$1.$ Add the two integers without using the 'add$*\text{'}$ or 'sub$*\text{'}$ RISC$-$V instruction. This

restriction applies to any functions that do$\_$add calls. You may use addi to adjust

the stack pointer if necessary for making function calls. You will likely need to

use the $\text{'}$or$\text{'},$ 'and', 'xor', $\text{'}$sll$\text{'},$ and $\text{'}$srl$\text{'}$ instructions.

$2.$ Return the result in a register. If there is an arithmetic overflow, return an error

condition identifying that an overflow occurred in another register.