_mm512_mask_lzcnt_epi64
Classification
AVX-512, Bit Manipulation, CPUID Test: AVX512CD
Header File
immintrin.h
Instruction
VPLZCNTQ zmm {k}, zmm
Synopsis
 _mm512_mask_lzcnt_epi64(__m512i src, __mmask8 k, __m512i a);
Description
Counts the number of leading zero bits in each packed 64-bit integer in "a", and store the results in "dst" using writemask "k" (elements are copied from "src" when the corresponding mask bit is not set).
Operation
FOR j := 0 to 7
	i := j*64
	IF k[j]
		tmp := 63
		dst[i+63:i] := 0
		DO WHILE (tmp >= 0 AND a[i+tmp] == 0)
			tmp := tmp - 1
			dst[i+63:i] := dst[i+63:i] + 1
		OD
	ELSE
		dst[i+63:i] := src[i+63:i]
	FI
ENDFOR
dst[MAX:512] := 0