Function _mm_maskz_getexp_round_sh

Convert the exponent of the lower half-precision (16-bit) floating-point element in b to a half-precision (16-bit) floating-point number representing the integer exponent, store the result in the lower element of dst using zeromask k (the element is zeroed out when mask bit 0 is not set), and copy the upper 7 packed elements from a to the upper elements of dst. This intrinsic essentially calculates floor(log2(x)) for the lower element. Exceptions can be suppressed by passing _MM_FROUND_NO_EXC in the sae parameter

Intel's documentation