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// Copyright (C) 2019-2021 Aleo Systems Inc. // This file is part of the snarkVM library. // The snarkVM library is free software: you can redistribute it and/or modify // it under the terms of the GNU General Public License as published by // the Free Software Foundation, either version 3 of the License, or // (at your option) any later version. // The snarkVM library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // You should have received a copy of the GNU General Public License // along with the snarkVM library. If not, see <https://www.gnu.org/licenses/>. use crate::{bits::Boolean, traits::bits::RippleCarryAdder}; use snarkvm_fields::Field; use snarkvm_r1cs::{errors::SynthesisError, ConstraintSystem}; /// Returns a negated representation of `self` in the constraint system. pub trait Neg<F: Field> where Self: std::marker::Sized, { type ErrorType; fn neg<CS: ConstraintSystem<F>>(&self, cs: CS) -> Result<Self, Self::ErrorType>; } impl<F: Field> Neg<F> for Vec<Boolean> { type ErrorType = SynthesisError; fn neg<CS: ConstraintSystem<F>>(&self, mut cs: CS) -> Result<Self, SynthesisError> { // flip all bits let flipped: Self = self.iter().map(|bit| bit.not()).collect(); // add one let mut one = vec![Boolean::constant(true)]; one.append(&mut vec![Boolean::Constant(false); self.len() - 1]); let mut bits = flipped.add_bits(cs.ns(|| "add one"), &one)?; let _carry = bits.pop(); // we already accounted for overflow above Ok(bits) } }