Function _ktestc_mask64_u8

#[target_feature(enable = "avx512bw")]
pub const fn _ktestc_mask64_u8(a: __mmask64, b: __mmask64) -> u8

Compute the bitwise NOT of 64-bit mask a and then AND with 8-bit mask b, if the result is all zeros, store 1 in dst, otherwise store 0 in dst.

Intel's Documentation