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// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
//
// Copyright (c) DUSK NETWORK. All rights reserved.
use crate::constraint_system::{Constraint, TurboComposer, Witness};
use dusk_bls12_381::BlsScalar;
impl TurboComposer {
/// Evaluate and return `o` by appending a new constraint into the circuit.
///
/// The output of the constraint will be overwritten with
/// `o := q_l · a + q_r · b + q_4 · d + q_c + PI`
pub fn gate_add(&mut self, s: Constraint) -> Witness {
let s = Constraint::arithmetic(&s).output(-BlsScalar::one());
let o = self.append_output_witness(s);
let s = s.o(o);
self.append_gate(s);
o
}
/// Evaluate and return `o` by appending a new constraint into the circuit.
///
/// The output of the constraint will be overwritten with
/// `o := q_m · a · b + q_4 · d + q_c + PI`
pub fn gate_mul(&mut self, s: Constraint) -> Witness {
let s = Constraint::arithmetic(&s).output(-BlsScalar::one());
let o = self.append_output_witness(s);
let s = s.o(o);
self.append_gate(s);
o
}
}
#[cfg(feature = "std")]
#[cfg(test)]
mod tests {
use crate::constraint_system::{helper, Constraint};
use dusk_bls12_381::BlsScalar;
#[test]
fn test_public_inputs() {
helper::gadget_tester(
|composer| {
let one = composer.append_witness(BlsScalar::one());
composer.append_dummy_gates();
let constraint =
Constraint::new().left(1).right(1).public(1).a(one).b(one);
let should_be_three = composer.gate_add(constraint);
composer.assert_equal_constant(
should_be_three,
BlsScalar::from(3),
None,
);
let constraint =
Constraint::new().left(1).right(1).public(2).a(one).b(one);
let should_be_four = composer.gate_add(constraint);
composer.assert_equal_constant(
should_be_four,
BlsScalar::from(4),
None,
);
},
200,
)
.expect("Failed to test circuit public inputs");
}
#[test]
fn test_correct_add_mul_gate() {
let res = helper::gadget_tester(
|composer| {
// Verify that (4+5+5) * (6+7+7) = 280
let four = composer.append_witness(BlsScalar::from(4));
let five = composer.append_witness(BlsScalar::from(5));
let six = composer.append_witness(BlsScalar::from(6));
let seven = composer.append_witness(BlsScalar::from(7));
let constraint = Constraint::new()
.left(1)
.right(1)
.fourth(1)
.a(four)
.b(five)
.d(five);
let fourteen = composer.gate_add(constraint);
let constraint = Constraint::new()
.left(1)
.right(1)
.fourth(1)
.a(six)
.b(seven)
.d(seven);
let twenty = composer.gate_add(constraint);
// There are quite a few ways to check the equation is correct,
// depending on your circumstance If we already
// have the output wire, we can constrain the output of the
// mul_gate to be equal to it If we do not, we
// can compute it using the `mul` If the output
// is public, we can also constrain the output wire of the mul
// gate to it. This is what this test does
let constraint =
Constraint::new().mult(1).a(fourteen).b(twenty);
let output = composer.gate_mul(constraint);
composer.assert_equal_constant(
output,
BlsScalar::from(280),
None,
);
},
200,
);
assert!(res.is_ok());
}
#[test]
fn test_correct_add_gate() {
helper::gadget_tester(
|composer| {
let one = composer.append_witness(BlsScalar::one());
let constraint = Constraint::new().left(1).constant(2).a(one);
let c = composer.gate_add(constraint);
composer.assert_equal_constant(c, BlsScalar::from(3), None);
},
32,
)
.expect("Circuit consistency failed");
}
#[test]
fn test_correct_big_add_mul_gate() {
let res = helper::gadget_tester(
|composer| {
// Verify that (4+5+5) * (6+7+7) + (8*9) = 352
let four = composer.append_witness(BlsScalar::from(4));
let five = composer.append_witness(BlsScalar::from(5));
let six = composer.append_witness(BlsScalar::from(6));
let seven = composer.append_witness(BlsScalar::from(7));
let nine = composer.append_witness(BlsScalar::from(9));
let constraint = Constraint::new()
.left(1)
.right(1)
.fourth(1)
.a(four)
.b(five)
.d(five);
let fourteen = composer.gate_add(constraint);
let constraint = Constraint::new()
.left(1)
.right(1)
.fourth(1)
.a(six)
.b(seven)
.d(seven);
let twenty = composer.gate_add(constraint);
let constraint = Constraint::new()
.mult(1)
.fourth(8)
.a(fourteen)
.b(twenty)
.d(nine);
let output = composer.gate_mul(constraint);
composer.assert_equal_constant(
output,
BlsScalar::from(352),
None,
);
},
200,
);
assert!(res.is_ok());
}
#[test]
fn test_incorrect_add_mul_gate() {
let res = helper::gadget_tester(
|composer| {
// Verify that (5+5) * (6+7) != 117
let five = composer.append_witness(BlsScalar::from(5));
let six = composer.append_witness(BlsScalar::from(6));
let seven = composer.append_witness(BlsScalar::from(7));
let constraint =
Constraint::new().left(1).right(1).a(five).b(five);
let five_plus_five = composer.gate_add(constraint);
let constraint =
Constraint::new().left(1).right(1).a(six).b(seven);
let six_plus_seven = composer.gate_add(constraint);
let constraint = Constraint::new()
.mult(1)
.a(five_plus_five)
.b(six_plus_seven);
let output = composer.gate_mul(constraint);
composer.assert_equal_constant(
output,
BlsScalar::from(117),
None,
);
},
200,
);
assert!(res.is_err());
}
}