chip::mul_fixed: Move running_sum_config into mul_fixed::Config.

src/circuit/gadget/ecc/chip.rs

@@ -1,8 +1,7 @@
 use super::EccInstructions;
 use crate::{
     circuit::gadget::utilities::{
-        copy, decompose_running_sum::RunningSumConfig, lookup_range_check::LookupRangeCheckConfig,
+        copy, lookup_range_check::LookupRangeCheckConfig, CellValue, UtilitiesInstructions, Var,
-        CellValue, UtilitiesInstructions, Var,
     },
     constants::{self, NullifierK, OrchardFixedBasesFull, ValueCommitV},
     primitives::sinsemilla,
@@ -151,17 +150,12 @@ pub struct EccConfig {
     pub q_mul_fixed_short: Selector,
     /// Canonicity checks on base field element used as scalar in fixed-base mul
     pub q_mul_fixed_base_field: Selector,
-    /// Running sum decomposition of a scalar used in fixed-base mul. This is used
-    /// when the scalar is a signed short exponent or a base-field element.
-    pub q_mul_fixed_running_sum: Selector,
 
     /// Witness point
     witness_point: witness_point::Config,
 
     /// Lookup range check using 10-bit lookup table
     pub lookup_config: LookupRangeCheckConfig<pallas::Base, { sinsemilla::K }>,
-    /// Running sum decomposition.
-    pub running_sum_config: RunningSumConfig<pallas::Base, { constants::FIXED_BASE_WINDOW_SIZE }>,
 }
 
 /// A chip implementing EccInstructions
@@ -213,10 +207,6 @@ impl EccChip {
             meta.enable_equality((*column).into());
         }
 
-        let q_mul_fixed_running_sum = meta.selector();
-        let running_sum_config =
-            RunningSumConfig::configure(meta, q_mul_fixed_running_sum, advices[4]);
-
         // Create witness point gate
         let witness_point = witness_point::Config::configure(meta, advices[0], advices[1]);
         // Create incomplete point addition gate
@@ -236,7 +226,6 @@ impl EccChip {
         // fixed-base scalar mul.
         let mul_fixed = mul_fixed::Config::configure(
             meta,
-            q_mul_fixed_running_sum,
             lagrange_coeffs,
             advices[4],
             advices[0],
@@ -255,10 +244,8 @@ impl EccChip {
             q_mul_fixed_full: meta.selector(),
             q_mul_fixed_short: meta.selector(),
             q_mul_fixed_base_field: meta.selector(),
-            q_mul_fixed_running_sum,
             witness_point,
             lookup_config: range_check,
-            running_sum_config,
         };
 
         // Create gate that is only used in full-width fixed-base scalar mul.

src/circuit/gadget/ecc/chip/mul_fixed.rs

@@ -2,6 +2,7 @@ use super::{
     add, add_incomplete, CellValue, EccBaseFieldElemFixed, EccScalarFixed, EccScalarFixedShort,
     NonIdentityEccPoint, Var,
 };
+use crate::circuit::gadget::utilities::decompose_running_sum::RunningSumConfig;
 use crate::constants::{
     self,
     load::{NullifierK, OrchardFixedBase, OrchardFixedBasesFull, ValueCommitV, WindowUs},
@@ -77,7 +78,7 @@ impl OrchardFixedBases {
 
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 pub struct Config {
-    q_mul_fixed_running_sum: Selector,
+    running_sum_config: RunningSumConfig<pallas::Base, { constants::FIXED_BASE_WINDOW_SIZE }>,
     // The fixed Lagrange interpolation coefficients for `x_p`.
     lagrange_coeffs: [Column<Fixed>; constants::H],
     // The fixed `z` for each window such that `y + z = u^2`.
@@ -101,7 +102,6 @@ impl Config {
     #[allow(clippy::too_many_arguments)]
     pub(super) fn configure(
         meta: &mut ConstraintSystem<pallas::Base>,
-        q_mul_fixed_running_sum: Selector,
         lagrange_coeffs: [Column<Fixed>; constants::H],
         window: Column<Advice>,
         x_p: Column<Advice>,
@@ -113,8 +113,11 @@ impl Config {
         meta.enable_equality(window.into());
         meta.enable_equality(u.into());
 
+        let q_running_sum = meta.selector();
+        let running_sum_config = RunningSumConfig::configure(meta, q_running_sum, window);
+
         let config = Self {
-            q_mul_fixed_running_sum,
+            running_sum_config,
             lagrange_coeffs,
             fixed_z: meta.fixed_column(),
             window,
@@ -171,7 +174,8 @@ impl Config {
     /// via a running sum.
     fn running_sum_coords_gate(&self, meta: &mut ConstraintSystem<pallas::Base>) {
         meta.create_gate("Running sum coordinates check", |meta| {
-            let q_mul_fixed_running_sum = meta.query_selector(self.q_mul_fixed_running_sum);
+            let q_mul_fixed_running_sum =
+                meta.query_selector(self.running_sum_config.q_range_check);
 
             let z_cur = meta.query_advice(self.window, Rotation::cur());
             let z_next = meta.query_advice(self.window, Rotation::next());

src/circuit/gadget/ecc/chip/mul_fixed/base_field_elem.rs

@@ -3,8 +3,8 @@ use super::H_BASE;
 
 use crate::{
     circuit::gadget::utilities::{
-        bitrange_subset, copy, decompose_running_sum::RunningSumConfig,
+        bitrange_subset, copy, lookup_range_check::LookupRangeCheckConfig, range_check, CellValue,
-        lookup_range_check::LookupRangeCheckConfig, range_check, CellValue, Var,
+        Var,
     },
     constants::{self, T_P},
     primitives::sinsemilla,
@@ -19,22 +19,18 @@ use pasta_curves::{arithmetic::FieldExt, pallas};
 use std::convert::TryInto;
 
 pub struct Config {
-    q_mul_fixed_running_sum: Selector,
     q_mul_fixed_base_field: Selector,
     canon_advices: [Column<Advice>; 3],
     lookup_config: LookupRangeCheckConfig<pallas::Base, { sinsemilla::K }>,
-    running_sum_config: RunningSumConfig<pallas::Base, { constants::FIXED_BASE_WINDOW_SIZE }>,
     super_config: super::Config,
 }
 
 impl From<&EccConfig> for Config {
     fn from(config: &EccConfig) -> Self {
         let config = Self {
-            q_mul_fixed_running_sum: config.q_mul_fixed_running_sum,
             q_mul_fixed_base_field: config.q_mul_fixed_base_field,
             canon_advices: [config.advices[6], config.advices[7], config.advices[8]],
             lookup_config: config.lookup_config,
-            running_sum_config: config.running_sum_config.clone(),
             super_config: config.mul_fixed,
         };
 
@@ -46,8 +42,6 @@ impl From<&EccConfig> for Config {
             );
         }
 
-        assert_eq!(config.running_sum_config.z, config.super_config.window);
-
         config
     }
 }
@@ -166,7 +160,7 @@ impl Config {
 
                 // Decompose scalar
                 let scalar = {
-                    let running_sum = self.running_sum_config.copy_decompose(
+                    let running_sum = self.super_config.running_sum_config.copy_decompose(
                         &mut region,
                         offset,
                         scalar,
@@ -187,7 +181,7 @@ impl Config {
                         offset,
                         &(&scalar).into(),
                         base.into(),
-                        self.q_mul_fixed_running_sum,
+                        self.super_config.running_sum_config.q_range_check,
                     )?;
 
                 Ok((scalar, acc, mul_b))

src/circuit/gadget/ecc/chip/mul_fixed/full_width.rs

@@ -124,13 +124,15 @@ impl Config {
 
                 let scalar = self.witness(&mut region, offset, scalar)?;
 
-                let (acc, mul_b) = self.super_config.assign_region_inner::<NUM_WINDOWS>(
+                let (acc, mul_b) = self
-                    &mut region,
+                    .super_config
-                    offset,
+                    .assign_region_inner::<{ constants::NUM_WINDOWS }>(
-                    &(&scalar).into(),
+                        &mut region,
-                    base.into(),
+                        offset,
-                    self.q_mul_fixed_full,
+                        &(&scalar).into(),
-                )?;
+                        base.into(),
+                        self.q_mul_fixed_full,
+                    )?;
 
                 Ok((scalar, acc, mul_b))
             },

src/circuit/gadget/ecc/chip/mul_fixed/short.rs

@@ -2,10 +2,8 @@ use std::{array, convert::TryInto};
 
 use super::super::{EccConfig, EccPoint, EccScalarFixedShort};
 use crate::{
-    circuit::gadget::utilities::{
+    circuit::gadget::utilities::{bool_check, copy, CellValue, Var},
-        bool_check, copy, decompose_running_sum::RunningSumConfig, CellValue, Var,
+    constants::{ValueCommitV, L_VALUE, NUM_WINDOWS_SHORT},
-    },
-    constants::{ValueCommitV, FIXED_BASE_WINDOW_SIZE, L_VALUE, NUM_WINDOWS_SHORT},
 };
 
 use halo2::{
@@ -19,8 +17,6 @@ use pasta_curves::pallas;
 pub struct Config {
     // Selector used for fixed-base scalar mul with short signed exponent.
     q_mul_fixed_short: Selector,
-    q_mul_fixed_running_sum: Selector,
-    running_sum_config: RunningSumConfig<pallas::Base, { FIXED_BASE_WINDOW_SIZE }>,
     super_config: super::Config,
 }
 
@@ -28,8 +24,6 @@ impl From<&EccConfig> for Config {
     fn from(config: &EccConfig) -> Self {
         Self {
             q_mul_fixed_short: config.q_mul_fixed_short,
-            q_mul_fixed_running_sum: config.q_mul_fixed_running_sum,
-            running_sum_config: config.running_sum_config.clone(),
             super_config: config.mul_fixed,
         }
     }
@@ -80,7 +74,7 @@ impl Config {
         let (magnitude, sign) = magnitude_sign;
 
         // Decompose magnitude
-        let running_sum = self.running_sum_config.copy_decompose(
+        let running_sum = self.super_config.running_sum_config.copy_decompose(
             region,
             offset,
             magnitude,
@@ -115,7 +109,7 @@ impl Config {
                     offset,
                     &(&scalar).into(),
                     base.clone().into(),
-                    self.q_mul_fixed_running_sum,
+                    self.super_config.running_sum_config.q_range_check,
                 )?;
 
                 Ok((scalar, acc, mul_b))

src/circuit/gadget/utilities/decompose_running_sum.rs

@@ -44,9 +44,9 @@ impl<F: FieldExt + PrimeFieldBits> std::ops::Deref for RunningSum<F> {
     }
 }
 
-#[derive(Debug, Clone, Eq, PartialEq)]
+#[derive(Debug, Clone, Copy, Eq, PartialEq)]
 pub struct RunningSumConfig<F: FieldExt + PrimeFieldBits, const WINDOW_NUM_BITS: usize> {
-    q_range_check: Selector,
+    pub q_range_check: Selector,
     pub z: Column<Advice>,
     _marker: PhantomData<F>,
 }