dense polynomial can be defined over base field

Author: kunxian-xia

spartan_parallel/src/dense_mlpoly.rs

@@ -1,5 +1,7 @@
 #![allow(clippy::too_many_arguments)]
 use crate::scalar::SpartanExtensionField;
+use crate::dense_mlpoly::MLE::Base;
+use crate::dense_mlpoly::MLE::Ext;
 
 use super::errors::ProofVerifyError;
 use super::math::Math;
@@ -10,15 +12,31 @@ use core::ops::Index;
 use merlin::Transcript;
 use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
+use ff::Field;
 
 #[cfg(feature = "multicore")]
 use rayon::prelude::*;
 
+#[derive(Debug, Clone)]
+pub enum MLE<S: SpartanExtensionField> {
+  Base(Vec<S::BaseField>),
+  Ext(Vec<S>),
+}
+
+impl<S: SpartanExtensionField> MLE<S> {
+  pub(crate) fn len(&self) -> usize {
+    match self {
+      Base(v) => v.len(),
+      Ext(v) => v.len(),
+    }
+  }
+}
+
 #[derive(Debug, Clone)]
 pub struct DensePolynomial<S: SpartanExtensionField> {
   num_vars: usize, // the number of variables in the multilinear polynomial
   len: usize,
-  Z: Vec<S>, // evaluations of the polynomial in all the 2^num_vars Boolean inputs
+  Z: MLE<S>, // evaluations of the polynomial in all the 2^num_vars Boolean inputs
 }
 
 pub struct PolyCommitmentBlinds<S: SpartanExtensionField> {
@@ -127,7 +145,18 @@ impl<S: SpartanExtensionField> DensePolynomial<S> {
     DensePolynomial {
       num_vars: Z.len().log_2(),
       len: Z.len(),
-      Z,
+      Z: MLE::Ext(Z),
+    }
+  }
+
+  pub fn new_from_base(mut Z: Vec<S::BaseField>) -> Self {
+    // If length of Z is not a power of 2, append Z with 0
+    let zero = S::BaseField::ZERO;
+    Z.extend(vec![zero; Z.len().next_power_of_two() - Z.len()]);
+    DensePolynomial {
+      num_vars: Z.len().log_2(),
+      len: Z.len(),
+      Z: MLE::Base(Z),
     }
   }
 
@@ -139,10 +168,6 @@ impl<S: SpartanExtensionField> DensePolynomial<S> {
     self.len
   }
 
-  pub fn clone(&self) -> DensePolynomial<S> {
-    DensePolynomial::new(self.Z[0..self.len].to_vec())
-  }
-
   pub fn split(&self, idx: usize) -> (DensePolynomial<S>, DensePolynomial<S>) {
     assert!(idx < self.len());
     (

spartan_parallel/src/scalar/mod.rs

@@ -49,7 +49,7 @@ pub trait SpartanExtensionField:
   type InnerType: ExtensionField + Field;
 
   /// Basefield for conserving computational resources
-  type BaseField: SmallField + for<'a> Deserialize<'a>;
+  type BaseField: SmallField + Field + for<'a> Deserialize<'a>;
 
   /// Return inner Goldilocks field element
   fn inner(&self) -> &Self::InnerType;