50.6 Integer exercises

50.6.1Integer overflow¶

The two overflowing statements must be replaced with an explicit call to the intrinsic wrapping multiplication. This has the effect to never overflow:

:clear

fn hash(key: u64) -> u32
{
  let mut h = key;
  h ^= h >> 33;
  h = h.wrapping_mul(0xff51afd7ed558ccd);
  h ^= h >> 33;
  h = h.wrapping_mul(0xc4ceb9fe1a85ec53);
  h ^= h >> 33;

  h as u32
}

Here are the results for three integers:

for i in [128u64, 367u64, 1056u64] {
  println!("hash({i}): {}", hash(i));
}

hash(128): 2342296294

hash(367): 715564590

hash(1056): 3728619970