Extract the EIP1559 gas fee calculation in nim-eth, so it can be reused in nimbus-eth2

nimbus/constants.nim

@@ -28,8 +28,6 @@ const
   MAX_UNCLE_DEPTH* =                        6.u256
   MAX_UNCLES* =                             2
 
-  EMPTY_UNCLE_HASH* =                       "1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347".toDigest
-
   GENESIS_BLOCK_NUMBER* =                   0.toBlockNumber
   GENESIS_DIFFICULTY* =                     131_072.u256
   GENESIS_GAS_LIMIT* =                      3_141_592
@@ -42,7 +40,6 @@ const
   GAS_LIMIT_MAXIMUM* =                      high(GasInt)
   DEFAULT_GAS_LIMIT* =                      8_000_000
 
-  BLANK_ROOT_HASH* =                        "56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421".toDigest
   EMPTY_SHA3* =                             "c5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470".toDigest
 
   GAS_MOD_EXP_QUADRATIC_DENOMINATOR* =      20.u256

nimbus/p2p/gaslimit.nim

@@ -11,24 +11,14 @@
 import
   std/strformat,
   stew/results,
-  eth/common,
+  eth/[common, eip1559],
   ../db/db_chain,
   ../constants,
   ../chain_config,
   ../forks
 
-const
+export
-  EIP1559_BASE_FEE_CHANGE_DENOMINATOR* = ##\
+  eip1559
-    ## Bounds the amount the base fee can change between blocks.
-    8
-
-  EIP1559_ELASTICITY_MULTIPLIER* = ##\
-    ## Bounds the maximum gas limit an EIP-1559 block may have.
-    2
-
-  EIP1559_INITIAL_BASE_FEE* = ##\
-    ## Initial base fee for Eip1559 blocks.
-    1000000000.u256
  
 # ------------------------------------------------------------------------------
 # Pre Eip 1559 gas limit validation
@@ -75,40 +65,10 @@ proc calcEip1599BaseFee*(c: ChainConfig; parent: BlockHeader): UInt256 =
 
   # If the current block is the first EIP-1559 block, return the
   # initial base fee.
-  if not c.isLondonOrLater(parent.blockNumber):
+  if c.isLondonOrLater(parent.blockNumber):
-    return EIP1559_INITIAL_BASE_FEE
+    eip1559.calcEip1599BaseFee(parent.gasLimit, parent.gasUsed, parent.baseFee)
-
-  let parentGasTarget = parent.gasLimit div EIP1559_ELASTICITY_MULTIPLIER
-
-  # If the parent gasUsed is the same as the target, the baseFee remains
-  # unchanged.
-  if parent.gasUsed == parentGasTarget:
-    return parent.baseFee
-
-  let parentGasDenom = parentGasTarget.u256 *
-                         EIP1559_BASE_FEE_CHANGE_DENOMINATOR.u256
-
-  # baseFee is an Option[T]
-  let parentBaseFee  = parent.baseFee
-
-  if parentGasTarget < parent.gasUsed:
-    # If the parent block used more gas than its target, the baseFee should
-    # increase.
-    let
-      gasUsedDelta = (parent.gasUsed - parentGasTarget).u256
-      baseFeeDelta = (parentBaseFee * gasUsedDelta) div parentGasDenom
-
-    return parentBaseFee + max(baseFeeDelta, 1.u256)
-
   else:
-    # Otherwise if the parent block used less gas than its target, the
+    EIP1559_INITIAL_BASE_FEE
-    # baseFee should decrease.
-    let
-      gasUsedDelta = (parentGasTarget - parent.gasUsed).u256
-      baseFeeDelta = (parentBaseFee * gasUsedDelta) div parentGasDenom
-
-    return max(parentBaseFee - baseFeeDelta, 0.u256)
-
 
 # consensus/misc/eip1559.go(32): func VerifyEip1559Header(config [..]
 proc verifyEip1559Header(c: ChainConfig;

tests/replay/pp_light.nim

@@ -16,6 +16,7 @@
 import
   std/[sequtils, strformat, strutils, tables, times],
   nimcrypto/hash,
+  eth/common,
   ../../nimbus/constants
 
 export

vendor/nim-eth

@@ -1 +1 @@
-Subproject commit 2556b090ea78416410098172b1ad3cc4d21a6474
+Subproject commit 4c702938834d492a96593ea97ec2c813b4a80044