1use ark_ff::{
  2    biginteger::{BigInt, BigInteger256 as BigInteger},
  3    fields::*,
  4};
  5
  6pub type Fr = Fp256<FrParameters>;
  7
  8pub struct FrParameters;
  9
 10impl Fp256Parameters for FrParameters {}
 11impl FftParameters for FrParameters {
 12    type BigInt = BigInteger;
 13
 14    const TWO_ADICITY: u32 = 28;
 15
 16    #[rustfmt::skip]
 17    const TWO_ADIC_ROOT_OF_UNITY: BigInteger = BigInt::new([
 18        7164790868263648668u64,
 19        11685701338293206998u64,
 20        6216421865291908056u64,
 21        1756667274303109607u64,
 22    ]);
 23}
 24impl FpParameters for FrParameters {
 25    /// MODULUS = 21888242871839275222246405745257275088548364400416034343698204186575808495617
 26    #[rustfmt::skip]
 27    const MODULUS: BigInteger = BigInt::new([
 28        4891460686036598785u64,
 29        2896914383306846353u64,
 30        13281191951274694749u64,
 31        3486998266802970665u64,
 32    ]);
 33
 34    const MODULUS_BITS: u32 = 254;
 35
 36    const CAPACITY: u32 = Self::MODULUS_BITS - 1;
 37
 38    const REPR_SHAVE_BITS: u32 = 2;
 39
 40    /// R = pow(2, 256) % MODULUS
 41    ///   = 6350874878119819312338956282401532410528162663560392320966563075034087161851
 42    #[rustfmt::skip]
 43    const R: BigInteger = BigInt::new([
 44        12436184717236109307u64,
 45        3962172157175319849u64,
 46        7381016538464732718u64,
 47        1011752739694698287u64,
 48    ]);
 49
 50    /// R2 = R * R % MODULUS
 51    ///    = 944936681149208446651664254269745548490766851729442924617792859073125903783
 52    #[rustfmt::skip]
 53    const R2: BigInteger = BigInt::new([
 54        1997599621687373223u64,
 55        6052339484930628067u64,
 56        10108755138030829701u64,
 57        150537098327114917u64,
 58    ]);
 59
 60    /// INV = (-MODULUS) ^ {-1} % pow(2, 64) = 14042775128853446655
 61    const INV: u64 = 14042775128853446655u64;
 62
 63    /// GENERATOR = 5
 64    #[rustfmt::skip]
 65    const GENERATOR: BigInteger = BigInt::new([
 66        1949230679015292902u64,
 67        16913946402569752895u64,
 68        5177146667339417225u64,
 69        1571765431670520771u64,
 70    ]);
 71
 72    /// (MODULUS - 1)/2 =
 73    /// 10944121435919637611123202872628637544274182200208017171849102093287904247808
 74    #[rustfmt::skip]
 75    const MODULUS_MINUS_ONE_DIV_TWO: BigInteger = BigInt::new([
 76        0xa1f0fac9f8000000,
 77        0x9419f4243cdcb848,
 78        0xdc2822db40c0ac2e,
 79        0x183227397098d014,
 80    ]);
 81
 82    // T and T_MINUS_ONE_DIV_TWO, where r - 1 = 2^s * t
 83
 84    /// T = (MODULUS - 1) / 2^s =
 85    /// 81540058820840996586704275553141814055101440848469862132140264610111
 86    #[rustfmt::skip]
 87    const T: BigInteger = BigInt::new([
 88        0x9b9709143e1f593f,
 89        0x181585d2833e8487,
 90        0x131a029b85045b68,
 91        0x30644e72e,
 92    ]);
 93
 94    /// (T - 1) / 2 =
 95    /// 40770029410420498293352137776570907027550720424234931066070132305055
 96    #[rustfmt::skip]
 97    const T_MINUS_ONE_DIV_TWO: BigInteger = BigInt::new([
 98        0xcdcb848a1f0fac9f,
 99        0x0c0ac2e9419f4243,
100        0x098d014dc2822db4,
101        0x183227397,
102    ]);
103}