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authorDeterminant <[email protected]>2019-10-21 14:47:51 -0400
committerDeterminant <[email protected]>2019-10-21 14:47:51 -0400
commit79b1169a9ff0b54ddf3b520a70a79c78ba5c988d (patch)
tree13fc62be3ebf344544547eeb9979450a3c6ecd40 /core/evm.go
parent913e9439a7c7883881895ee597a0cc464fb92353 (diff)
customize Blockchain code
Diffstat (limited to 'core/evm.go')
-rw-r--r--core/evm.go97
1 files changed, 97 insertions, 0 deletions
diff --git a/core/evm.go b/core/evm.go
new file mode 100644
index 0000000..5c9d178
--- /dev/null
+++ b/core/evm.go
@@ -0,0 +1,97 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package core
+
+import (
+ "math/big"
+
+ "github.com/ava-labs/go-ethereum/common"
+ "github.com/ava-labs/go-ethereum/consensus"
+ "github.com/ava-labs/go-ethereum/core/types"
+ "github.com/ava-labs/go-ethereum/core/vm"
+)
+
+// ChainContext supports retrieving headers and consensus parameters from the
+// current blockchain to be used during transaction processing.
+type ChainContext interface {
+ // Engine retrieves the chain's consensus engine.
+ Engine() consensus.Engine
+
+ // GetHeader returns the hash corresponding to their hash.
+ GetHeader(common.Hash, uint64) *types.Header
+}
+
+// NewEVMContext creates a new context for use in the EVM.
+func NewEVMContext(msg Message, header *types.Header, chain ChainContext, author *common.Address) vm.Context {
+ // If we don't have an explicit author (i.e. not mining), extract from the header
+ var beneficiary common.Address
+ if author == nil {
+ beneficiary, _ = chain.Engine().Author(header) // Ignore error, we're past header validation
+ } else {
+ beneficiary = *author
+ }
+ return vm.Context{
+ CanTransfer: CanTransfer,
+ Transfer: Transfer,
+ GetHash: GetHashFn(header, chain),
+ Origin: msg.From(),
+ Coinbase: beneficiary,
+ BlockNumber: new(big.Int).Set(header.Number),
+ Time: new(big.Int).SetUint64(header.Time),
+ Difficulty: new(big.Int).Set(header.Difficulty),
+ GasLimit: header.GasLimit,
+ GasPrice: new(big.Int).Set(msg.GasPrice()),
+ }
+}
+
+// GetHashFn returns a GetHashFunc which retrieves header hashes by number
+func GetHashFn(ref *types.Header, chain ChainContext) func(n uint64) common.Hash {
+ var cache map[uint64]common.Hash
+
+ return func(n uint64) common.Hash {
+ // If there's no hash cache yet, make one
+ if cache == nil {
+ cache = map[uint64]common.Hash{
+ ref.Number.Uint64() - 1: ref.ParentHash,
+ }
+ }
+ // Try to fulfill the request from the cache
+ if hash, ok := cache[n]; ok {
+ return hash
+ }
+ // Not cached, iterate the blocks and cache the hashes
+ for header := chain.GetHeader(ref.ParentHash, ref.Number.Uint64()-1); header != nil; header = chain.GetHeader(header.ParentHash, header.Number.Uint64()-1) {
+ cache[header.Number.Uint64()-1] = header.ParentHash
+ if n == header.Number.Uint64()-1 {
+ return header.ParentHash
+ }
+ }
+ return common.Hash{}
+ }
+}
+
+// CanTransfer checks whether there are enough funds in the address' account to make a transfer.
+// This does not take the necessary gas in to account to make the transfer valid.
+func CanTransfer(db vm.StateDB, addr common.Address, amount *big.Int) bool {
+ return db.GetBalance(addr).Cmp(amount) >= 0
+}
+
+// Transfer subtracts amount from sender and adds amount to recipient using the given Db
+func Transfer(db vm.StateDB, sender, recipient common.Address, amount *big.Int) {
+ db.SubBalance(sender, amount)
+ db.AddBalance(recipient, amount)
+}