In Section 3.6.6, we examined the following code as a candidate for the use of conditional data transfer: long cread(long *xp) { return (xp? *xp : 0) } We showed a trial implementation using a congitional move instruction but argued that it was not.valid, since it could attemnt to read from a null address. Write a C function cread_alt that has the same behavior as cread, except that it can be compiled to use conditional data transfer. When compiled, the generated code should use a conditional move instruction rather than one of the jump instructions.