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Attempt to clarify interleave/deinterleave

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This commit is contained in:
Caleb Zulawski 2021-04-20 01:51:06 +00:00
parent 1999c54890
commit 7028a58294
1 changed files with 32 additions and 6 deletions
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38
crates/core_simd/src/permute.rs
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@ -31,11 +31,24 @@ macro_rules! impl_shuffle_lane {
/// Interleave two vectors.
///
/// The even lanes of the first result contain the lower half of `self`, and the odd
/// lanes contain the lower half of `other`.
/// Produces two vectors with lanes taken alternately from `self` and `other`.
///
/// The even lanes of the second result contain the upper half of `self`, and the odd
/// lanes contain the upper half of `other`.
/// The first result contains the first `LANES / 2` lanes from `self` and `other`,
/// alternating, starting with the first lane of `self`.
///
/// The second result contains the last `LANES / 2` lanes from `self` and `other`,
/// alternating, starting with the lane `LANES / 2` from the start of `self`.
///
/// This particular permutation is efficient on many architectures.
///
/// ```
/// # use core_simd::SimdU32;
/// let a = SimdU32::from_array([0, 1, 2, 3]);
/// let b = SimdU32::from_array([4, 5, 6, 7]);
/// let (x, y) = a.interleave(b);
/// assert_eq!(x.to_array(), [0, 4, 1, 5]);
/// assert_eq!(y.to_array(), [2, 6, 3, 7]);
/// ```
#[inline]
pub fn interleave(self, other: Self) -> (Self, Self) {
const fn lo() -> [u32; $n] {
@ -71,9 +84,22 @@ macro_rules! impl_shuffle_lane {
/// Deinterleave two vectors.
///
/// The first result contains the even lanes of `self` and then `other`, concatenated.
/// The first result takes every other lane of `self` and then `other`, starting with
/// the first lane.
///
/// The second result contains the odd lanes of `self` and then `other`, concatenated.
/// The second result takes every other lane of `self` and then `other`, starting with
/// the second lane.
///
/// This particular permutation is efficient on many architectures.
///
/// ```
/// # use core_simd::SimdU32;
/// let a = SimdU32::from_array([0, 4, 1, 5]);
/// let b = SimdU32::from_array([2, 6, 3, 7]);
/// let (x, y) = a.deinterleave(b);
/// assert_eq!(x.to_array(), [0, 1, 2, 3]);
/// assert_eq!(y.to_array(), [4, 5, 6, 7]);
/// ```
#[inline]
pub fn deinterleave(self, other: Self) -> (Self, Self) {
const fn even() -> [u32; $n] {