Function core::arch::x86_64::_mm_floor_ss

pub unsafe fn _mm_floor_ss(a: __m128, b: __m128) -> __m128

This is supported on x86-64 and target feature sse4.1 only.

Round the lower single-precision (32-bit) floating-point element in b down to an integer value, store the result as a single-precision floating-point element in the lower element of the intrinsic result, and copy the upper 3 packed elements from a to the upper elements of the intrinsic result.

Intel's documentation