How to do unsigned saturating addition in C?

Question

What is the best (cleanest, most efficient) way to write saturating addition in C?

The function or macro should add two unsigned inputs (need both 16- and 32-bit ver

Answer 1

An alternative to the branch free x86 asm solution is (AT&T syntax, a and b in eax and ebx, result in eax):

add %eax,%ebx
sbb $0,%ebx