Macro safe_arch::extract_m128d_from_m256d

macro_rules! extract_m128d_from_m256d {
    ($a:expr, $imm:expr) => { ... };
}

This is supported with target feature avx only.

Extracts an m128d from m256d

let a = m256d::from([13.0, 14.0, 15.0, 16.0]);
let b = m128d::from([15.0, 16.0]).to_array();
let c = extract_m128d_from_m256d!(a, 1).to_array();
assert_eq!(b, c);