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gadget::utilities: Adjustments to utilities gadgets and helpers.

This commit is contained in:
therealyingtong 2021-06-21 23:16:56 +08:00
parent 3840f280d7
commit c43c91b796
2 changed files with 27 additions and 15 deletions
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12
src/circuit/gadget/utilities.rs
View File

@ -4,19 +4,19 @@ use halo2::{
};
use pasta_curves::arithmetic::FieldExt;
mod cond_swap;
mod enable_flag;
mod lookup_range_check;
mod plonk;
pub(crate) mod cond_swap;
pub(crate) mod enable_flag;
pub(crate) mod lookup_range_check;
pub(crate) mod plonk;
/// A variable representing a number.
/// A variable representing a field element.
#[derive(Copy, Clone, Debug)]
pub struct CellValue<F: FieldExt> {
cell: Cell,
value: Option<F>,
}
pub trait Var<F: FieldExt> {
pub trait Var<F: FieldExt>: Copy + Clone + std::fmt::Debug {
fn new(cell: Cell, value: Option<F>) -> Self;
fn cell(&self) -> Cell;
fn value(&self) -> Option<F>;

30
src/circuit/gadget/utilities/cond_swap.rs
View File

@ -1,4 +1,4 @@
use super::{copy, CellValue, UtilitiesInstructions};
use super::{copy, CellValue, UtilitiesInstructions, Var};
use halo2::{
circuit::{Chip, Layouter},
plonk::{Advice, Column, ConstraintSystem, Error, Expression, Permutation, Selector},
@ -11,10 +11,14 @@ pub trait CondSwapInstructions<F: FieldExt>: UtilitiesInstructions<F> {
#[allow(clippy::type_complexity)]
/// Given an input pair (a,b) and a `swap` boolean flag, returns
/// (b,a) if `swap` is set, else (a,b) if `swap` is not set.
///
///
/// The second element of the pair is required to be a witnessed
/// value, not a variable that already exists in the circuit.
fn swap(
&self,
layouter: impl Layouter<F>,
pair: (Self::Var, Self::Var),
pair: (Self::Var, Option<F>),
swap: Option<bool>,
) -> Result<(Self::Var, Self::Var), Error>;
}
@ -59,7 +63,7 @@ impl<F: FieldExt> CondSwapInstructions<F> for CondSwapChip<F> {
fn swap(
&self,
mut layouter: impl Layouter<F>,
pair: (Self::Var, Self::Var),
pair: (Self::Var, Option<F>),
swap: Option<bool>,
) -> Result<(Self::Var, Self::Var), Error> {
let config = self.config();
@ -73,8 +77,16 @@ impl<F: FieldExt> CondSwapInstructions<F> for CondSwapChip<F> {
// Copy in `a` value
let a = copy(&mut region, || "copy a", config.a, 0, &pair.0, &config.perm)?;
// Copy in `b` value
let b = copy(&mut region, || "copy b", config.b, 0, &pair.1, &config.perm)?;
// Witness `b` value
let b = {
let cell = region.assign_advice(
|| "witness b",
config.b,
0,
|| pair.1.ok_or(Error::SynthesisError),
)?;
CellValue::new(cell, pair.1)
};
// Witness `swap` value
let swap_val = swap.map(|swap| F::from_u64(swap as u64));
@ -245,19 +257,19 @@ mod tests {
// Load the pair and the swap flag into the circuit.
let a = chip.load_private(layouter.namespace(|| "a"), config.a, self.a)?;
let b = chip.load_private(layouter.namespace(|| "b"), config.b, self.b)?;
// Return the swapped pair.
let swapped_pair = chip.swap(layouter.namespace(|| "swap"), (a, b), self.swap)?;
let swapped_pair =
chip.swap(layouter.namespace(|| "swap"), (a, self.b), self.swap)?;
if let Some(swap) = self.swap {
if swap {
// Check that `a` and `b` have been swapped
assert_eq!(swapped_pair.0.value.unwrap(), b.value.unwrap());
assert_eq!(swapped_pair.0.value.unwrap(), self.b.unwrap());
assert_eq!(swapped_pair.1.value.unwrap(), a.value.unwrap());
} else {
// Check that `a` and `b` have not been swapped
assert_eq!(swapped_pair.0.value.unwrap(), a.value.unwrap());
assert_eq!(swapped_pair.1.value.unwrap(), b.value.unwrap());
assert_eq!(swapped_pair.1.value.unwrap(), self.b.unwrap());
}
}