Function core::arch::x86::_mm256_shuffle_epi8
1.27.0 · source · pub unsafe fn _mm256_shuffle_epi8(a: __m256i, b: __m256i) -> __m256i
Available on (x86 or x86-64) and target feature
avx2
and x86 only.Expand description
Shuffles bytes from a
according to the content of b
.
For each of the 128-bit low and high halves of the vectors, the last
4 bits of each byte of b
are used as addresses into the respective
low or high 16 bytes of a
. That is, the halves are shuffled separately.
In addition, if the highest significant bit of a byte of b
is set, the
respective destination byte is set to 0.
Picturing a
and b
as [u8; 32]
, _mm256_shuffle_epi8
is logically
equivalent to:
fn mm256_shuffle_epi8(a: [u8; 32], b: [u8; 32]) -> [u8; 32] {
let mut r = [0; 32];
for i in 0..16 {
// if the most significant bit of b is set,
// then the destination byte is set to 0.
if b[i] & 0x80 == 0u8 {
r[i] = a[(b[i] % 16) as usize];
}
if b[i + 16] & 0x80 == 0u8 {
r[i + 16] = a[(b[i + 16] % 16 + 16) as usize];
}
}
r
}
Run