make balance update readable

Author: ChihChengLiang

zkevm-circuits/src/evm_circuit/execution/end_tx.rs

@@ -75,10 +75,9 @@ impl<F: Field> ExecutionGadget<F> for EndTxGadget<F> {
             tx_gas_price.clone(),
             effective_refund.min() + cb.curr.state.gas_left.expr(),
         );
-        let gas_fee_refund = UpdateBalanceGadget::construct(
-            cb,
+        let gas_fee_refund = cb.increase_balance(
             tx_caller_address.to_word(),
-            vec![mul_gas_price_by_refund.product().clone()],
+            mul_gas_price_by_refund.product().clone(),
             None,
         );
 

zkevm-circuits/src/evm_circuit/util/common_gadget.rs

@@ -309,7 +309,7 @@ impl<F: Field, const N_ADDENDS: usize, const INCREASE: bool>
     pub(crate) fn construct(
         cb: &mut EVMConstraintBuilder<F>,
         address: WordLoHi<Expression<F>>,
-        updates: Vec<Word32Cell<F>>,
+        updates: &[Word32Cell<F>],
         reversion_info: Option<&mut ReversionInfo<F>>,
     ) -> Self {
         debug_assert!(updates.len() == N_ADDENDS - 1);
@@ -397,12 +397,7 @@ impl<F: Field> TransferToGadget<F> {
             );
         }
         let receiver = cb.condition(not::expr(value_is_zero.expr()), |cb| {
-            UpdateBalanceGadget::construct(
-                cb,
-                receiver_address,
-                vec![value.clone()],
-                reversion_info,
-            )
+            cb.increase_balance(receiver_address, value.clone(), reversion_info)
         });
 
         Self {
@@ -495,8 +490,7 @@ impl<F: Field> TransferWithGasFeeGadget<F> {
         gas_fee: Word32Cell<F>,
         reversion_info: &mut ReversionInfo<F>,
     ) -> Self {
-        let sender_sub_fee =
-            UpdateBalanceGadget::construct(cb, sender_address.to_word(), vec![gas_fee], None);
+        let sender_sub_fee = cb.decrease_balance(sender_address.to_word(), gas_fee, None);
         let value_is_zero = cb.is_zero_word(&value);
         // If receiver doesn't exist, create it
         TransferToGadget::create_account(
@@ -509,12 +503,7 @@ impl<F: Field> TransferWithGasFeeGadget<F> {
         );
         // Skip transfer if value == 0
         let sender_sub_value = cb.condition(not::expr(value_is_zero.expr()), |cb| {
-            UpdateBalanceGadget::construct(
-                cb,
-                sender_address,
-                vec![value.clone()],
-                Some(reversion_info),
-            )
+            cb.decrease_balance(sender_address, value.clone(), Some(reversion_info))
         });
         let receiver = TransferToGadget::construct(
             cb,
@@ -630,12 +619,7 @@ impl<F: Field> TransferGadget<F> {
         );
         // Skip transfer if value == 0
         let sender = cb.condition(not::expr(value_is_zero.expr()), |cb| {
-            UpdateBalanceGadget::construct(
-                cb,
-                sender_address,
-                vec![value.clone()],
-                Some(reversion_info),
-            )
+            cb.decrease_balance(sender_address, value.clone(), Some(reversion_info))
         });
         let receiver = TransferToGadget::construct(
             cb,

zkevm-circuits/src/evm_circuit/util/constraint_builder.rs

@@ -1,4 +1,5 @@
 use super::{
+    common_gadget::UpdateBalanceGadget,
     math_gadget::{
         ConstantDivisionGadget, IsEqualGadget, IsEqualWordGadget, IsZeroGadget, IsZeroWordGadget,
         LtGadget, LtWordGadget, MinMaxGadget,
@@ -639,6 +640,26 @@ impl<'a, F: Field> EVMConstraintBuilder<'a, F> {
         ConstantDivisionGadget::construct(self, numerator, denominator)
     }
 
+    // Common Gadget
+
+    pub(crate) fn increase_balance(
+        &mut self,
+        address: WordLoHi<Expression<F>>,
+        value: Word32Cell<F>,
+        reversion_info: Option<&mut ReversionInfo<F>>,
+    ) -> UpdateBalanceGadget<F, 2, true> {
+        UpdateBalanceGadget::construct(self, address, &[value], reversion_info)
+    }
+
+    pub(crate) fn decrease_balance(
+        &mut self,
+        address: WordLoHi<Expression<F>>,
+        value: Word32Cell<F>,
+        reversion_info: Option<&mut ReversionInfo<F>>,
+    ) -> UpdateBalanceGadget<F, 2, false> {
+        UpdateBalanceGadget::construct(self, address, &[value], reversion_info)
+    }
+
     // Fixed
 
     pub(crate) fn range_lookup(&mut self, value: Expression<F>, range: u64) {