Function safe_arch::average_u8_m128i

#[must_use]pub fn average_u8_m128i(a: m128i, b: m128i) -> m128i

This is supported with target feature sse2 only.

Lanewise average of the u8 values.

let a = m128i::from([
  u8::MAX, 0, 3, 4, 254, 2, 3, 4,
  3, 4, 1, 2, 1, 2, 128, 4,
]);
let b = m128i::from([
  u8::MAX, 0, 7, 8, 15, 26, 37, 48,
  7, 8, 15, 26, 15, 26, 37, 48,
]);
let c: [u8; 16] = average_u8_m128i(a, b).into();
assert_eq!(
  c,
  [
    u8::MAX, 0, 5, 6, 135, 14, 20, 26,
    5, 6, 8, 14, 8, 14, 83, 26
  ]
);