rollup-fee for spec=feynman

src/l1block.rs

@@ -37,6 +37,8 @@ const L1_SCALAR_SLOT: U256 = U256::from_limbs([3u64, 0, 0, 0]);
 const L1_BLOB_BASE_FEE_SLOT: U256 = U256::from_limbs([5u64, 0, 0, 0]);
 
 /// The L1 commit scalar storage slot.
+///
+/// Post-FEYNMAN this represents the exec_scalar.
 const L1_COMMIT_SCALAR_SLOT: U256 = U256::from_limbs([6u64, 0, 0, 0]);
 
 /// The L1 blob scalar storage slot.
@@ -138,12 +140,69 @@ impl L1BlockInfo {
         self.calldata_gas.unwrap().saturating_add(blob_gas).wrapping_div(TX_L1_FEE_PRECISION)
     }
 
+    fn calculate_tx_l1_cost_feynman(&self, input: &[u8], spec_id: ScrollSpecId) -> U256 {
+        // rollup_fee(tx) = compression_factor(tx) * size(tx) * (component_exec + component_blob)
+        //
+        // - compression_factor(tx): compression_factor = 1 / compression_ratio, where
+        // compression_ratio is the estimated compressibility of the signed tx data. The tx is
+        // eventually a part of a L2 batch that should likely result in a better compression ratio,
+        // however a conservative estimate is the size of zstd-encoding of the signed tx.
+        //
+        // - size(tx): denotes the size of the signed tx.
+        //
+        // - component_exec: The component that accounts towards commiting this tx as part of a L2
+        // batch as well as gas costs for the eventual on-chain proof verification.
+        // => (compression_scalar + commit_scalar + verification_scalar) * l1_base_fee
+        // => (exec_scalar) * l1_base_fee
+        //
+        // - component_blob: The component that accounts the costs associated with data
+        // availability, i.e. the costs of posting this tx's data in the EIP-4844 blob.
+        // => (compression_scalar + blob_scalar) * l1_blob_base_fee
+        // => (new_blob_scalar) * l1_blob_base_fee
+        //
+        // Note that the same slots for L1_COMMIT_SCALAR_SLOT and L1_BLOB_SCALAR_SLOT are
+        // re-used/updated for the new values post-FEYNMAN.
+        let component_exec = {
+            let exec_scalar = self
+                .l1_commit_scalar
+                .unwrap_or_else(|| panic!("missing exec scalar in spec_id={:?}", spec_id));
+            exec_scalar.saturating_mul(self.l1_base_fee)
+        };
+        let component_blob = {
+            let blob_scalar = self
+                .l1_blob_scalar
+                .unwrap_or_else(|| panic!("missing l1 blob scalar in spec_id={:?}", spec_id));
+            let blob_base_fee = self
+                .l1_blob_base_fee
+                .unwrap_or_else(|| panic!("missing l1 blob base fee in spec_id={:?}", spec_id));
+            blob_scalar.saturating_mul(blob_base_fee)
+        };
+
+        // Assume compression_factor = 1 until we have specification for estimating compression
+        // ratio based on previous finalised batches.
+        //
+        // We use the `TX_L1_FEE_PRECISION` to allow fractions. We then divide the overall product
+        // by the precision value as well.
+        let compression_factor = |_input: &[u8]| -> U256 { TX_L1_FEE_PRECISION };
+
+        // size(tx) is just the length of the RLP-encoded signed tx data.
+        let tx_size = |input: &[u8]| -> U256 { U256::from(input.len()) };
+
+        compression_factor(input)
+            .saturating_mul(tx_size(input))
+            .saturating_mul(component_exec.saturating_add(component_blob))
+            .wrapping_div(TX_L1_FEE_PRECISION)
+            .wrapping_div(TX_L1_FEE_PRECISION)
+    }
+
     /// Calculate the gas cost of a transaction based on L1 block data posted on L2.
     pub fn calculate_tx_l1_cost(&self, input: &[u8], spec_id: ScrollSpecId) -> U256 {
         let l1_cost = if !spec_id.is_enabled_in(ScrollSpecId::CURIE) {
             self.calculate_tx_l1_cost_shanghai(input, spec_id)
-        } else {
+        } else if !spec_id.is_enabled_in(ScrollSpecId::FEYNMAN) {
             self.calculate_tx_l1_cost_curie(input, spec_id)
+        } else {
+            self.calculate_tx_l1_cost_feynman(input, spec_id)
         };
         l1_cost.min(U64_MAX)
     }