example.rs

fraction(1.1)
f32x4::splat(1.1).fract_first()

test.rs

#[inline(always)]
pub fn fraction(value: f32) -> f32 {
    unsafe {
        let packed = _mm_set1_ps(value);
        _mm_cvtss_f32(_mm_sub_ps(packed, _mm_cvtepi32_ps(_mm_cvttps_epi32(packed))))
    }
}

#[derive(Copy, Clone)]
#[repr(transparent)]
pub struct f32x4(__m128);

impl f32x4 {
    #[inline(always)]
    pub fn splat(value: f32) -> Self {
        f32x4(unsafe { _mm_set1_ps(value) })
    }

    #[inline(always)]
    pub fn fract_first(self) -> f32 {
        unsafe { _mm_cvtss_f32(_mm_sub_ps(self.0, _mm_cvtepi32_ps(_mm_cvttps_epi32(self.0)))) }
    }
}