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

In plain C:

uint16_t sadd16(uint16_t a, uint16_t b) {
  return (a > 0xFFFF - b) ? 0xFFFF : a + b;
}
     
uint32_t sadd32(uint32_t a, uint32_t b) {
  return (a > 0xFFFFFFFF - b) ? 0xFFFFFFFF : a + b;
}

which is almost macro-ized and directly conveys the meaning.