Write assembly functions equivalent to the following C functions.

[5 pts] Add two 64-bit integers.

int64_t add64(int64_t a, int64_t b)

{

return a + b;

}

[5 pts] Subtract two 64-bit integers.

int64_t sub64(int64_t a, int64_t b)

{

return a - b;

}

[5 pts] Multiply two 32-bit signed integers, return an 64-bit result.

int64_t mult64(int32_t a, int32_t b)

{

return (int64_t) a * b;

}