From b51fad5fa74c6b1ed8fecac5493f636b6f45700b Mon Sep 17 00:00:00 2001
From: jangko <jangko128@gmail.com>
Date: Sun, 27 Jun 2021 20:19:22 +0700
Subject: [PATCH] EIP-3198: add baseFee op code in nim-evm2

---
 nimbus/vm2/computation.nim                          |  3 +++
 nimbus/vm2/interpreter/gas_costs.nim                |  1 +
 nimbus/vm2/interpreter/op_codes.nim                 |  3 ++-
 .../vm2/interpreter/op_handlers/oph_blockdata.nim   | 13 +++++++++++++
 nimbus/vm2/state.nim                                |  3 +++
 5 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/nimbus/vm2/computation.nim b/nimbus/vm2/computation.nim
index 2e39d55b1..db2192eb4 100644
--- a/nimbus/vm2/computation.nim
+++ b/nimbus/vm2/computation.nim
@@ -61,6 +61,9 @@ template getDifficulty*(c: Computation): DifficultyInt =
 template getGasLimit*(c: Computation): GasInt =
   c.vmState.gasLimit
 
+template getBaseFee*(c: Computation): Uint256 =
+  c.vmState.baseFee
+
 template getChainId*(c: Computation): uint =
   c.vmState.chaindb.config.chainId.uint
 
diff --git a/nimbus/vm2/interpreter/gas_costs.nim b/nimbus/vm2/interpreter/gas_costs.nim
index 70af68bda..0d7c4133c 100644
--- a/nimbus/vm2/interpreter/gas_costs.nim
+++ b/nimbus/vm2/interpreter/gas_costs.nim
@@ -507,6 +507,7 @@ template gasCosts(fork: Fork, prefix, ResultGasCostsName: untyped) =
           GasLimit:        fixed GasBase,
           ChainIdOp:       fixed GasBase,
           SelfBalance:     fixed GasLow,
+          BaseFee:         fixed GasBase,
 
           # 50s: Stack, Memory, Storage and Flow Operations
           Pop:            fixed GasBase,
diff --git a/nimbus/vm2/interpreter/op_codes.nim b/nimbus/vm2/interpreter/op_codes.nim
index d73e0a572..76184b26d 100644
--- a/nimbus/vm2/interpreter/op_codes.nim
+++ b/nimbus/vm2/interpreter/op_codes.nim
@@ -103,8 +103,9 @@ type
 
     ChainIdOp =      0x46, ## Get current chain’s EIP-155 unique identifier.
     SelfBalance =    0x47, ## Get current contract's balance.
+    BaseFee =        0x48, ## Get block’s base fee. EIP-3198
 
-    Nop0x48, Nop0x49, Nop0x4A, Nop0x4B, Nop0x4C, Nop0x4D,
+    Nop0x49, Nop0x4A, Nop0x4B, Nop0x4C, Nop0x4D,
     Nop0x4E, Nop0x4F, ## ..
 
     # 50s: Stack, Memory, Storage and Flow Operations
diff --git a/nimbus/vm2/interpreter/op_handlers/oph_blockdata.nim b/nimbus/vm2/interpreter/op_handlers/oph_blockdata.nim
index 60d1b1057..25779bcea 100644
--- a/nimbus/vm2/interpreter/op_handlers/oph_blockdata.nim
+++ b/nimbus/vm2/interpreter/op_handlers/oph_blockdata.nim
@@ -68,6 +68,11 @@ const
     k.cpt.stack.push:
       k.cpt.getBalance(k.cpt.msg.contractAddress)
 
+  baseFeeOp: Vm2OpFn = proc (k: var Vm2Ctx) =
+    ## 0x48, Get the block's base fee.
+    k.cpt.stack.push:
+      k.cpt.getBaseFee
+
 # ------------------------------------------------------------------------------
 # Public, op exec table entries
 # ------------------------------------------------------------------------------
@@ -137,6 +142,14 @@ const
      info: "Get current contract's balance",
      exec: (prep: vm2OpIgnore,
             run:  selfBalanceOp,
+            post: vm2OpIgnore)),
+
+    (opCode: BaseFee,     ## 0x48, EIP-1559 Block base fee.
+     forks: Vm2OpLondonAndLater,
+     name: "baseFee",
+     info: "Get current block's EIP-1559 base fee",
+     exec: (prep: vm2OpIgnore,
+            run:  baseFeeOp,
             post: vm2OpIgnore))]
 
 # ------------------------------------------------------------------------------
diff --git a/nimbus/vm2/state.nim b/nimbus/vm2/state.nim
index 2388ae272..8a9351161 100644
--- a/nimbus/vm2/state.nim
+++ b/nimbus/vm2/state.nim
@@ -129,6 +129,9 @@ method difficulty*(vmState: BaseVMState): UInt256 {.base, gcsafe.} =
 method gasLimit*(vmState: BaseVMState): GasInt {.base, gcsafe.} =
   vmState.blockHeader.gasLimit
 
+method baseFee*(vmState: BaseVMState): UInt256 {.base, gcsafe.} =
+  vmState.blockHeader.baseFee
+
 when defined(geth):
   import db/geth_db