Function core::arch::x86::_mm256_unpacklo_epi8

pub unsafe fn _mm256_unpacklo_epi8(a: __m256i, b: __m256i) -> __m256i

This is supported on x86 and target feature avx2 only.

Unpack and interleave 8-bit integers from the low half of each 128-bit lane of a and b.

#[cfg(target_arch = "x86")]
use std::arch::x86::*;
#[cfg(target_arch = "x86_64")]
use std::arch::x86_64::*;

let a = _mm256_setr_epi8(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31);
let b = _mm256_setr_epi8(0,-1,-2,-3,-4,-5,-6,-7,-8,-9,-10,-11,-12,-13,-14,-15,
-16,-17,-18,-19,-20,-21,-22,-23,-24,-25,-26,-27,-28,-29,-30,-31);

let c = _mm256_unpacklo_epi8(a, b);

let expected = _mm256_setr_epi8(0, 0, 1,-1, 2,-2, 3,-3, 4,-4, 5,-5, 6,-6, 7,-7,
16,-16, 17,-17, 18,-18, 19,-19, 20,-20, 21,-21, 22,-22, 23,-23);
assert_eq!(_mm256_movemask_epi8(_mm256_cmpeq_epi8(c, expected)), !0);

Intel's documentation