Chapter 3, Problem 3.61HW

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 conditional move instruction but argued that it was not valid, since it could attempt 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.