Function core::arch::x86::_mm_round_ss

pub unsafe fn _mm_round_ss(a: __m128, b: __m128, rounding: i32) -> __m128

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

Round the lower single-precision (32-bit) floating-point element in b using the rounding parameter, 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 instrinsic result. Rounding is done according to the rounding parameter, which can be one of:

#![feature(stdsimd)]

#[cfg(target_arch = "x86")]
use std::arch::x86::*;
#[cfg(target_arch = "x86_64")]
use std::arch::x86_64::*;

// round to nearest, and suppress exceptions:
_MM_FROUND_TO_NEAREST_INT | _MM_FROUND_NO_EXC;
// round down, and suppress exceptions:
_MM_FROUND_TO_NEG_INF | _MM_FROUND_NO_EXC;
// round up, and suppress exceptions:
_MM_FROUND_TO_POS_INF | _MM_FROUND_NO_EXC;
// truncate, and suppress exceptions:
_MM_FROUND_TO_ZERO | _MM_FROUND_NO_EXC;
// use MXCSR.RC; see `_MM_SET_ROUNDING_MODE`:
_MM_FROUND_CUR_DIRECTION;

Intel's documentation