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Add 32bit reduction code

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Henry de Valence 2017-11-13 23:47:38 -08:00 committed by Henry de Valence
parent e7ec5b3dd1
commit 7354b569bb
1 changed files with 50 additions and 12 deletions
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62
src/avx2/field.rs
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@ -218,20 +218,58 @@ impl FieldElement32x4 {
}
pub fn reduce32(&mut self) {
let mut b = [u64x4::splat(0); 10];
let (b0, b1) = unpack_pair(self.0[0]);
b[0] = b0.into(); b[1] = b1.into();
let (b2, b3) = unpack_pair(self.0[1]);
b[2] = b2.into(); b[3] = b3.into();
let (b4, b5) = unpack_pair(self.0[2]);
b[4] = b4.into(); b[5] = b5.into();
let (b6, b7) = unpack_pair(self.0[3]);
b[6] = b6.into(); b[7] = b7.into();
let (b8, b9) = unpack_pair(self.0[4]);
b[8] = b8.into(); b[9] = b9.into();
let shifts = i32x8::new(26,26,25,25,26,26,25,25);
let masks = u32x8::new((1<<26)-1, (1<<26)-1, (1<<25)-1, (1<<25)-1,
(1<<26)-1, (1<<26)-1, (1<<25)-1, (1<<25)-1);
*self = FieldElement32x4::reduce64(b);
let carry = |v: u32x8| -> u32x8 {
unsafe {
use stdsimd::vendor::_mm256_srlv_epi32;
_mm256_srlv_epi32(v.into(), shifts).into()
}
};
let swap_lanes = |v: u32x8| -> u32x8 {
unsafe {
use stdsimd::vendor::_mm256_shuffle_epi32;
_mm256_shuffle_epi32(v.into(), 0b01_00_11_10).into()
}
};
let combine = |v_lo: u32x8, v_hi: u32x8| -> u32x8 {
unsafe {
use stdsimd::vendor::_mm256_blend_epi32;
_mm256_blend_epi32(v_lo.into(), v_hi.into(), 0b11_00_11_00).into()
}
};
let v = &mut self.0;
let c10 = swap_lanes(carry(v[0]));
v[0] = (v[0] & masks) + combine(u32x8::splat(0), c10);
let c32 = swap_lanes(carry(v[1]));
v[1] = (v[1] & masks) + combine(c10, c32);
let c54 = swap_lanes(carry(v[2]));
v[2] = (v[2] & masks) + combine(c32, c54);
let c76 = swap_lanes(carry(v[3]));
v[3] = (v[3] & masks) + combine(c54, c76);
let c98 = swap_lanes(carry(v[4]));
v[4] = (v[4] & masks) + combine(c76, c98);
// Still need to account for c9
// c98 = (c9, c9, c8, c8, c9, c9, c8, c8)
//
let c9_19: u32x8;
unsafe {
use stdsimd::vendor::_mm256_mul_epu32;
use stdsimd::vendor::_mm256_shuffle_epi32;
let c9_spread: u32x8 = _mm256_shuffle_epi32(c98.into(), 0b11_01_10_00).into();
let c9_19_spread: u32x8 = _mm256_mul_epu32(c9_spread, u64x4::splat(19).into()).into();
c9_19 = _mm256_shuffle_epi32(c9_19_spread.into(), 0b11_01_10_00).into();
}
v[0] = v[0] + c9_19;
}
pub fn reduce64(mut z: [u64x4; 10]) -> FieldElement32x4 {