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Make ntt.rs shorter #7

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merged 2 commits into from
Sep 21, 2023
Merged

Make ntt.rs shorter #7

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8ecb65d
Make ntt.rs shorter
byeongkeunahn Sep 21, 2023
3f8c2c5
Make ntt.rs shorter
byeongkeunahn Sep 21, 2023
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24 changes: 9 additions & 15 deletions src/biguint/ntt.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -237,12 +237,7 @@ impl<const P: u64, const INV: bool> NttKernelImpl<P, INV> {
const U4: u64 = Arith::<P>::mpowmod(Self::ROOTR, Arith::<P>::MAX_NTT_LEN/4);
const U5: u64 = Arith::<P>::mpowmod(Self::ROOTR, Arith::<P>::MAX_NTT_LEN/5);
const U6: u64 = Arith::<P>::mpowmod(Self::ROOTR, Arith::<P>::MAX_NTT_LEN/6);
const C51: u64 = Self::c5().0;
const C52: u64 = Self::c5().1;
const C53: u64 = Self::c5().2;
const C54: u64 = Self::c5().3;
const C55: u64 = Self::c5().4;
const fn c5() -> (u64, u64, u64, u64, u64) {
const C5: (u64, u64, u64, u64, u64, u64) = {
let w = Self::U5;
let w2 = Arith::<P>::mpowmod(w, 2);
let w4 = Arith::<P>::mpowmod(w, 4);
Expand All @@ -253,8 +248,8 @@ impl<const P: u64, const INV: bool> NttKernelImpl<P, INV> {
let c53 = Arith::<P>::mmulmod(inv2, Arith::<P>::submod(w, w4)); // 2^-1 * (w - w^4) mod P
let c54 = Arith::<P>::addmod(Arith::<P>::addmod(w, w2), inv2); // 2^-1 * (2*w + 2*w^2 + 1) mod P
let c55 = Arith::<P>::addmod(Arith::<P>::addmod(w2, w4), inv2); // 2^-1 * (2*w^2 + 2*w^4 + 1) mod P
(c51, c52, c53, c54, c55)
}
(0, c51, c52, c53, c54, c55)
};
}
const fn ntt2_kernel<const P: u64, const INV: bool, const TWIDDLE: bool>(
w1: u64,
Expand Down Expand Up @@ -348,11 +343,11 @@ const fn ntt5_kernel<const P: u64, const INV: bool, const TWIDDLE: bool>(
let t6 = Arith::<P>::submod(t1, t2);
let t7 = Arith::<P>::addmod64(t3, t4);
let m1 = Arith::<P>::addmod(a, t5);
let m2 = Arith::<P>::mmulsubmod(NttKernelImpl::<P, INV>::C51, t5, m1);
let m3 = Arith::<P>::mmulmod(NttKernelImpl::<P, INV>::C52, t6);
let m4 = Arith::<P>::mmulmod(NttKernelImpl::<P, INV>::C53, t7);
let m5 = Arith::<P>::mmulsubmod(NttKernelImpl::<P, INV>::C54, t4, m4);
let m6 = Arith::<P>::mmulsubmod(P.wrapping_sub(NttKernelImpl::<P, INV>::C55), t3, m4);
let m2 = Arith::<P>::mmulsubmod(NttKernelImpl::<P, INV>::C5.1, t5, m1);
let m3 = Arith::<P>::mmulmod(NttKernelImpl::<P, INV>::C5.2, t6);
let m4 = Arith::<P>::mmulmod(NttKernelImpl::<P, INV>::C5.3, t7);
let m5 = Arith::<P>::mmulsubmod(NttKernelImpl::<P, INV>::C5.4, t4, m4);
let m6 = Arith::<P>::mmulsubmod(P.wrapping_sub(NttKernelImpl::<P, INV>::C5.5), t3, m4);
let s1 = Arith::<P>::submod(m3, m2);
let s2 = Arith::<P>::addmod(m2, m3);
let out0 = m1;
Expand Down Expand Up @@ -547,7 +542,6 @@ const P1: u64 = 14_259_017_916_245_606_401; // Max NTT length = 2^22 * 3^21 * 5^
const P2: u64 = 17_984_575_660_032_000_001; // Max NTT length = 2^19 * 3^17 * 5^6 = 1_057_916_215_296_000_000
const P3: u64 = 17_995_154_822_184_960_001; // Max NTT length = 2^17 * 3^22 * 5^4 = 2_570_736_403_169_280_000

const P2P3: u128 = P2 as u128 * P3 as u128;
const P1INV_R_MOD_P2: u64 = Arith::<P2>::mmulmod(Arith::<P2>::R2, arith::invmod(P1, P2));
const P1P2INV_R_MOD_P3: u64 = Arith::<P3>::mmulmod(Arith::<P3>::R2, arith::invmod((P1 as u128 * P2 as u128 % P3 as u128) as u64, P3));
const P1_R_MOD_P3: u64 = Arith::<P3>::mmulmod(Arith::<P3>::R2, P1);
Expand Down Expand Up @@ -618,7 +612,7 @@ fn mac3_two_primes(acc: &mut [u64], b: &[u64], c: &[u64], bits: u64) {
/* extract the convolution result */
let (a, b) = (x[i], y[i]);
let (mut v, overflow) = (a as u128 * P3 as u128 + carry).overflowing_sub(b as u128 * P2 as u128);
if overflow { v = v.wrapping_add(P2P3); }
if overflow { v = v.wrapping_add(P2 as u128 * P3 as u128); }
carry = v >> bits;

/* write to s */
Expand Down