message: Improve analysis of foriegn field subtractions on limbs
diff: @@ -14,6 +14,14 @@ pub const LIMB_BITS: usize = 88;
  /// Number of desired limbs for foreign field elements
  pub const LIMB_COUNT: usize = 3;
  +/// Max number of bits for $t$ modulus
  +pub const T_BITS: usize = LIMB_BITS + LIMB_COUNT;
  +
  +/// $t$ modulus = 2^{T_BITS}
  +pub fn t_modulus() -> BigUint {
  + BigUint::from(2u32).pow(T_BITS as u32)
  +}
  +
  /// The foreign field modulus of secp256k1 is the prime number (in big endian)
  /// FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFE FFFFFC2F
  /// given by the computation 2^256 - 2^32 - 2^9 - 2^8 - 2^7 - 2^6 - 2^4 - 1
  