message-utils: use BigNumber

packages/sdk/src/utils/message-utils.ts

@@ -6,13 +6,13 @@ import { LowLevelMessage } from '../interfaces'
 const { hexDataLength } = utils
 
 // Constants used by `CrossDomainMessenger.baseGas`
-const RELAY_CONSTANT_OVERHEAD = 200_000
-const RELAY_PER_BYTE_DATA_COST = 16
-const MIN_GAS_DYNAMIC_OVERHEAD_NUMERATOR = 64
-const MIN_GAS_DYNAMIC_OVERHEAD_DENOMINATOR = 63
-const RELAY_CALL_OVERHEAD = 40_000
-const RELAY_RESERVED_GAS = 40_000
-const RELAY_GAS_CHECK_BUFFER = 5_000
+const RELAY_CONSTANT_OVERHEAD = BigNumber.from(200_000)
+const RELAY_PER_BYTE_DATA_COST = BigNumber.from(16)
+const MIN_GAS_DYNAMIC_OVERHEAD_NUMERATOR = BigNumber.from(64)
+const MIN_GAS_DYNAMIC_OVERHEAD_DENOMINATOR = BigNumber.from(63)
+const RELAY_CALL_OVERHEAD = BigNumber.from(40_000)
+const RELAY_RESERVED_GAS = BigNumber.from(40_000)
+const RELAY_GAS_CHECK_BUFFER = BigNumber.from(5_000)
 
 /**
  * Utility for hashing a LowLevelMessage object.
@@ -62,22 +62,21 @@ export const migratedWithdrawalGasLimit = (
   if (chainID === 420) {
     overhead = BigNumber.from(200_000)
   } else {
-    // Constant overhead
-    overhead = BigNumber.from(
-      RELAY_CONSTANT_OVERHEAD +
     // Dynamic overhead (EIP-150)
-        (MIN_GAS_DYNAMIC_OVERHEAD_NUMERATOR * 1_000_000) /
-          MIN_GAS_DYNAMIC_OVERHEAD_DENOMINATOR +
+    const dynamicOverhead = MIN_GAS_DYNAMIC_OVERHEAD_NUMERATOR.mul(1_000_000).div(MIN_GAS_DYNAMIC_OVERHEAD_DENOMINATOR)
+
+    // Constant overhead
+    overhead = RELAY_CONSTANT_OVERHEAD
+      .add(dynamicOverhead)
+      .add(RELAY_CALL_OVERHEAD)
       // Gas reserved for the worst-case cost of 3/5 of the `CALL` opcode's dynamic gas
       // factors. (Conservative)
-        RELAY_CALL_OVERHEAD +
       // Relay reserved gas (to ensure execution of `relayMessage` completes after the
       // subcontext finishes executing) (Conservative)
-        RELAY_RESERVED_GAS +
+      .add(RELAY_RESERVED_GAS)
       // Gas reserved for the execution between the `hasMinGas` check and the `CALL`
       // opcode. (Conservative)
-        RELAY_GAS_CHECK_BUFFER
-    )
+      .add(RELAY_GAS_CHECK_BUFFER)
   }
 
   let minGasLimit = dataCost.add(overhead)