Merge branch 'multi-coin'

1 files changed, 637 insertions, 0 deletions

diff --git a/consensus/ethash/consensus.go b/consensus/ethash/consensus.go
new file mode 100644
index 0000000..d9130ec
--- /dev/null
+++ b/consensus/ethash/consensus.go
@@ -0,0 +1,637 @@
+// Copyright 2017 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 ethash
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"math/big"
+	"runtime"
+	"time"
+
+	"github.com/ava-labs/coreth/consensus"
+	"github.com/ava-labs/coreth/consensus/misc"
+	"github.com/ava-labs/coreth/core/state"
+	"github.com/ava-labs/coreth/core/types"
+	"github.com/ava-labs/coreth/params"
+	"github.com/ava-labs/go-ethereum/common"
+	"github.com/ava-labs/go-ethereum/common/math"
+	"github.com/ava-labs/go-ethereum/rlp"
+	mapset "github.com/deckarep/golang-set"
+	"golang.org/x/crypto/sha3"
+)
+
+// Ethash proof-of-work protocol constants.
+var (
+	FrontierBlockReward       = big.NewInt(5e+18) // Block reward in wei for successfully mining a block
+	ByzantiumBlockReward      = big.NewInt(3e+18) // Block reward in wei for successfully mining a block upward from Byzantium
+	ConstantinopleBlockReward = big.NewInt(2e+18) // Block reward in wei for successfully mining a block upward from Constantinople
+	maxUncles                 = 2                 // Maximum number of uncles allowed in a single block
+	allowedFutureBlockTime    = 15 * time.Second  // Max time from current time allowed for blocks, before they're considered future blocks
+
+	// calcDifficultyConstantinople is the difficulty adjustment algorithm for Constantinople.
+	// It returns the difficulty that a new block should have when created at time given the
+	// parent block's time and difficulty. The calculation uses the Byzantium rules, but with
+	// bomb offset 5M.
+	// Specification EIP-1234: https://eips.ethereum.org/EIPS/eip-1234
+	calcDifficultyConstantinople = makeDifficultyCalculator(big.NewInt(5000000))
+
+	// calcDifficultyByzantium is the difficulty adjustment algorithm. It returns
+	// the difficulty that a new block should have when created at time given the
+	// parent block's time and difficulty. The calculation uses the Byzantium rules.
+	// Specification EIP-649: https://eips.ethereum.org/EIPS/eip-649
+	calcDifficultyByzantium = makeDifficultyCalculator(big.NewInt(3000000))
+)
+
+// Various error messages to mark blocks invalid. These should be private to
+// prevent engine specific errors from being referenced in the remainder of the
+// codebase, inherently breaking if the engine is swapped out. Please put common
+// error types into the consensus package.
+var (
+	errZeroBlockTime     = errors.New("timestamp equals parent's")
+	errTooManyUncles     = errors.New("too many uncles")
+	errDuplicateUncle    = errors.New("duplicate uncle")
+	errUncleIsAncestor   = errors.New("uncle is ancestor")
+	errDanglingUncle     = errors.New("uncle's parent is not ancestor")
+	errInvalidDifficulty = errors.New("non-positive difficulty")
+	errInvalidMixDigest  = errors.New("invalid mix digest")
+	errInvalidPoW        = errors.New("invalid proof-of-work")
+)
+
+// Author implements consensus.Engine, returning the header's coinbase as the
+// proof-of-work verified author of the block.
+func (ethash *Ethash) Author(header *types.Header) (common.Address, error) {
+	return header.Coinbase, nil
+}
+
+// VerifyHeader checks whether a header conforms to the consensus rules of the
+// stock Ethereum ethash engine.
+func (ethash *Ethash) VerifyHeader(chain consensus.ChainReader, header *types.Header, seal bool) error {
+	// If we're running a full engine faking, accept any input as valid
+	if ethash.config.PowMode == ModeFullFake {
+		return nil
+	}
+	// Short circuit if the header is known, or it's parent not
+	number := header.Number.Uint64()
+	if chain.GetHeader(header.Hash(), number) != nil {
+		return nil
+	}
+	parent := chain.GetHeader(header.ParentHash, number-1)
+	if parent == nil {
+		return consensus.ErrUnknownAncestor
+	}
+	// Sanity checks passed, do a proper verification
+	return ethash.verifyHeader(chain, header, parent, false, seal)
+}
+
+// VerifyHeaders is similar to VerifyHeader, but verifies a batch of headers
+// concurrently. The method returns a quit channel to abort the operations and
+// a results channel to retrieve the async verifications.
+func (ethash *Ethash) VerifyHeaders(chain consensus.ChainReader, headers []*types.Header, seals []bool) (chan<- struct{}, <-chan error) {
+	// If we're running a full engine faking, accept any input as valid
+	if ethash.config.PowMode == ModeFullFake || len(headers) == 0 {
+		abort, results := make(chan struct{}), make(chan error, len(headers))
+		for i := 0; i < len(headers); i++ {
+			results <- nil
+		}
+		return abort, results
+	}
+
+	// Spawn as many workers as allowed threads
+	workers := runtime.GOMAXPROCS(0)
+	if len(headers) < workers {
+		workers = len(headers)
+	}
+
+	// Create a task channel and spawn the verifiers
+	var (
+		inputs = make(chan int)
+		done   = make(chan int, workers)
+		errors = make([]error, len(headers))
+		abort  = make(chan struct{})
+	)
+	for i := 0; i < workers; i++ {
+		go func() {
+			for index := range inputs {
+				errors[index] = ethash.verifyHeaderWorker(chain, headers, seals, index)
+				done <- index
+			}
+		}()
+	}
+
+	errorsOut := make(chan error, len(headers))
+	go func() {
+		defer close(inputs)
+		var (
+			in, out = 0, 0
+			checked = make([]bool, len(headers))
+			inputs  = inputs
+		)
+		for {
+			select {
+			case inputs <- in:
+				if in++; in == len(headers) {
+					// Reached end of headers. Stop sending to workers.
+					inputs = nil
+				}
+			case index := <-done:
+				for checked[index] = true; checked[out]; out++ {
+					errorsOut <- errors[out]
+					if out == len(headers)-1 {
+						return
+					}
+				}
+			case <-abort:
+				return
+			}
+		}
+	}()
+	return abort, errorsOut
+}
+
+func (ethash *Ethash) verifyHeaderWorker(chain consensus.ChainReader, headers []*types.Header, seals []bool, index int) error {
+	var parent *types.Header
+	if index == 0 {
+		parent = chain.GetHeader(headers[0].ParentHash, headers[0].Number.Uint64()-1)
+	} else if headers[index-1].Hash() == headers[index].ParentHash {
+		parent = headers[index-1]
+	}
+	if parent == nil {
+		return consensus.ErrUnknownAncestor
+	}
+	if chain.GetHeader(headers[index].Hash(), headers[index].Number.Uint64()) != nil {
+		return nil // known block
+	}
+	return ethash.verifyHeader(chain, headers[index], parent, false, seals[index])
+}
+
+// VerifyUncles verifies that the given block's uncles conform to the consensus
+// rules of the stock Ethereum ethash engine.
+func (ethash *Ethash) VerifyUncles(chain consensus.ChainReader, block *types.Block) error {
+	// If we're running a full engine faking, accept any input as valid
+	if ethash.config.PowMode == ModeFullFake {
+		return nil
+	}
+	// Verify that there are at most 2 uncles included in this block
+	if len(block.Uncles()) > maxUncles {
+		return errTooManyUncles
+	}
+	if len(block.Uncles()) == 0 {
+		return nil
+	}
+	// Gather the set of past uncles and ancestors
+	uncles, ancestors := mapset.NewSet(), make(map[common.Hash]*types.Header)
+
+	number, parent := block.NumberU64()-1, block.ParentHash()
+	for i := 0; i < 7; i++ {
+		ancestor := chain.GetBlock(parent, number)
+		if ancestor == nil {
+			break
+		}
+		ancestors[ancestor.Hash()] = ancestor.Header()
+		for _, uncle := range ancestor.Uncles() {
+			uncles.Add(uncle.Hash())
+		}
+		parent, number = ancestor.ParentHash(), number-1
+	}
+	ancestors[block.Hash()] = block.Header()
+	uncles.Add(block.Hash())
+
+	// Verify each of the uncles that it's recent, but not an ancestor
+	for _, uncle := range block.Uncles() {
+		// Make sure every uncle is rewarded only once
+		hash := uncle.Hash()
+		if uncles.Contains(hash) {
+			return errDuplicateUncle
+		}
+		uncles.Add(hash)
+
+		// Make sure the uncle has a valid ancestry
+		if ancestors[hash] != nil {
+			return errUncleIsAncestor
+		}
+		if ancestors[uncle.ParentHash] == nil || uncle.ParentHash == block.ParentHash() {
+			return errDanglingUncle
+		}
+		if err := ethash.verifyHeader(chain, uncle, ancestors[uncle.ParentHash], true, true); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// verifyHeader checks whether a header conforms to the consensus rules of the
+// stock Ethereum ethash engine.
+// See YP section 4.3.4. "Block Header Validity"
+func (ethash *Ethash) verifyHeader(chain consensus.ChainReader, header, parent *types.Header, uncle bool, seal bool) error {
+	// Ensure that the header's extra-data section is of a reasonable size
+	if uint64(len(header.Extra)) > params.MaximumExtraDataSize {
+		return fmt.Errorf("extra-data too long: %d > %d", len(header.Extra), params.MaximumExtraDataSize)
+	}
+	// Verify the header's timestamp
+	if !uncle {
+		if header.Time > uint64(time.Now().Add(allowedFutureBlockTime).Unix()) {
+			return consensus.ErrFutureBlock
+		}
+	}
+	if header.Time <= parent.Time {
+		return errZeroBlockTime
+	}
+	// Verify the block's difficulty based in it's timestamp and parent's difficulty
+	expected := ethash.CalcDifficulty(chain, header.Time, parent)
+
+	if expected.Cmp(header.Difficulty) != 0 {
+		return fmt.Errorf("invalid difficulty: have %v, want %v", header.Difficulty, expected)
+	}
+	// Verify that the gas limit is <= 2^63-1
+	cap := uint64(0x7fffffffffffffff)
+	if header.GasLimit > cap {
+		return fmt.Errorf("invalid gasLimit: have %v, max %v", header.GasLimit, cap)
+	}
+	// Verify that the gasUsed is <= gasLimit
+	if header.GasUsed > header.GasLimit {
+		return fmt.Errorf("invalid gasUsed: have %d, gasLimit %d", header.GasUsed, header.GasLimit)
+	}
+
+	// Verify that the gas limit remains within allowed bounds
+	diff := int64(parent.GasLimit) - int64(header.GasLimit)
+	if diff < 0 {
+		diff *= -1
+	}
+	limit := parent.GasLimit / params.GasLimitBoundDivisor
+
+	if uint64(diff) >= limit || header.GasLimit < params.MinGasLimit {
+		return fmt.Errorf("invalid gas limit: have %d, want %d += %d", header.GasLimit, parent.GasLimit, limit)
+	}
+	// Verify that the block number is parent's +1
+	if diff := new(big.Int).Sub(header.Number, parent.Number); diff.Cmp(big.NewInt(1)) != 0 {
+		return consensus.ErrInvalidNumber
+	}
+	// Verify the engine specific seal securing the block
+	if seal {
+		if err := ethash.VerifySeal(chain, header); err != nil {
+			return err
+		}
+	}
+	// If all checks passed, validate any special fields for hard forks
+	if err := misc.VerifyDAOHeaderExtraData(chain.Config(), header); err != nil {
+		return err
+	}
+	if err := misc.VerifyForkHashes(chain.Config(), header, uncle); err != nil {
+		return err
+	}
+	return nil
+}
+
+// CalcDifficulty is the difficulty adjustment algorithm. It returns
+// the difficulty that a new block should have when created at time
+// given the parent block's time and difficulty.
+func (ethash *Ethash) CalcDifficulty(chain consensus.ChainReader, time uint64, parent *types.Header) *big.Int {
+	return CalcDifficulty(chain.Config(), time, parent)
+}
+
+// CalcDifficulty is the difficulty adjustment algorithm. It returns
+// the difficulty that a new block should have when created at time
+// given the parent block's time and difficulty.
+func CalcDifficulty(config *params.ChainConfig, time uint64, parent *types.Header) *big.Int {
+	next := new(big.Int).Add(parent.Number, big1)
+	switch {
+	case config.IsConstantinople(next):
+		return calcDifficultyConstantinople(time, parent)
+	case config.IsByzantium(next):
+		return calcDifficultyByzantium(time, parent)
+	case config.IsHomestead(next):
+		return calcDifficultyHomestead(time, parent)
+	default:
+		return calcDifficultyFrontier(time, parent)
+	}
+}
+
+// Some weird constants to avoid constant memory allocs for them.
+var (
+	expDiffPeriod = big.NewInt(100000)
+	big1          = big.NewInt(1)
+	big2          = big.NewInt(2)
+	big9          = big.NewInt(9)
+	big10         = big.NewInt(10)
+	bigMinus99    = big.NewInt(-99)
+)
+
+// makeDifficultyCalculator creates a difficultyCalculator with the given bomb-delay.
+// the difficulty is calculated with Byzantium rules, which differs from Homestead in
+// how uncles affect the calculation
+func makeDifficultyCalculator(bombDelay *big.Int) func(time uint64, parent *types.Header) *big.Int {
+	// Note, the calculations below looks at the parent number, which is 1 below
+	// the block number. Thus we remove one from the delay given
+	bombDelayFromParent := new(big.Int).Sub(bombDelay, big1)
+	return func(time uint64, parent *types.Header) *big.Int {
+		// https://github.com/ethereum/EIPs/issues/100.
+		// algorithm:
+		// diff = (parent_diff +
+		//         (parent_diff / 2048 * max((2 if len(parent.uncles) else 1) - ((timestamp - parent.timestamp) // 9), -99))
+		//        ) + 2^(periodCount - 2)
+
+		bigTime := new(big.Int).SetUint64(time)
+		bigParentTime := new(big.Int).SetUint64(parent.Time)
+
+		// holds intermediate values to make the algo easier to read & audit
+		x := new(big.Int)
+		y := new(big.Int)
+
+		// (2 if len(parent_uncles) else 1) - (block_timestamp - parent_timestamp) // 9
+		x.Sub(bigTime, bigParentTime)
+		x.Div(x, big9)
+		if parent.UncleHash == types.EmptyUncleHash {
+			x.Sub(big1, x)
+		} else {
+			x.Sub(big2, x)
+		}
+		// max((2 if len(parent_uncles) else 1) - (block_timestamp - parent_timestamp) // 9, -99)
+		if x.Cmp(bigMinus99) < 0 {
+			x.Set(bigMinus99)
+		}
+		// parent_diff + (parent_diff / 2048 * max((2 if len(parent.uncles) else 1) - ((timestamp - parent.timestamp) // 9), -99))
+		y.Div(parent.Difficulty, params.DifficultyBoundDivisor)
+		x.Mul(y, x)
+		x.Add(parent.Difficulty, x)
+
+		// minimum difficulty can ever be (before exponential factor)
+		if x.Cmp(params.MinimumDifficulty) < 0 {
+			x.Set(params.MinimumDifficulty)
+		}
+		// calculate a fake block number for the ice-age delay
+		// Specification: https://eips.ethereum.org/EIPS/eip-1234
+		fakeBlockNumber := new(big.Int)
+		if parent.Number.Cmp(bombDelayFromParent) >= 0 {
+			fakeBlockNumber = fakeBlockNumber.Sub(parent.Number, bombDelayFromParent)
+		}
+		// for the exponential factor
+		periodCount := fakeBlockNumber
+		periodCount.Div(periodCount, expDiffPeriod)
+
+		// the exponential factor, commonly referred to as "the bomb"
+		// diff = diff + 2^(periodCount - 2)
+		if periodCount.Cmp(big1) > 0 {
+			y.Sub(periodCount, big2)
+			y.Exp(big2, y, nil)
+			x.Add(x, y)
+		}
+		return x
+	}
+}
+
+// calcDifficultyHomestead is the difficulty adjustment algorithm. It returns
+// the difficulty that a new block should have when created at time given the
+// parent block's time and difficulty. The calculation uses the Homestead rules.
+func calcDifficultyHomestead(time uint64, parent *types.Header) *big.Int {
+	// https://github.com/ethereum/EIPs/blob/master/EIPS/eip-2.md
+	// algorithm:
+	// diff = (parent_diff +
+	//         (parent_diff / 2048 * max(1 - (block_timestamp - parent_timestamp) // 10, -99))
+	//        ) + 2^(periodCount - 2)
+
+	bigTime := new(big.Int).SetUint64(time)
+	bigParentTime := new(big.Int).SetUint64(parent.Time)
+
+	// holds intermediate values to make the algo easier to read & audit
+	x := new(big.Int)
+	y := new(big.Int)
+
+	// 1 - (block_timestamp - parent_timestamp) // 10
+	x.Sub(bigTime, bigParentTime)
+	x.Div(x, big10)
+	x.Sub(big1, x)
+
+	// max(1 - (block_timestamp - parent_timestamp) // 10, -99)
+	if x.Cmp(bigMinus99) < 0 {
+		x.Set(bigMinus99)
+	}
+	// (parent_diff + parent_diff // 2048 * max(1 - (block_timestamp - parent_timestamp) // 10, -99))
+	y.Div(parent.Difficulty, params.DifficultyBoundDivisor)
+	x.Mul(y, x)
+	x.Add(parent.Difficulty, x)
+
+	// minimum difficulty can ever be (before exponential factor)
+	if x.Cmp(params.MinimumDifficulty) < 0 {
+		x.Set(params.MinimumDifficulty)
+	}
+	// for the exponential factor
+	periodCount := new(big.Int).Add(parent.Number, big1)
+	periodCount.Div(periodCount, expDiffPeriod)
+
+	// the exponential factor, commonly referred to as "the bomb"
+	// diff = diff + 2^(periodCount - 2)
+	if periodCount.Cmp(big1) > 0 {
+		y.Sub(periodCount, big2)
+		y.Exp(big2, y, nil)
+		x.Add(x, y)
+	}
+	return x
+}
+
+// calcDifficultyFrontier is the difficulty adjustment algorithm. It returns the
+// difficulty that a new block should have when created at time given the parent
+// block's time and difficulty. The calculation uses the Frontier rules.
+func calcDifficultyFrontier(time uint64, parent *types.Header) *big.Int {
+	diff := new(big.Int)
+	adjust := new(big.Int).Div(parent.Difficulty, params.DifficultyBoundDivisor)
+	bigTime := new(big.Int)
+	bigParentTime := new(big.Int)
+
+	bigTime.SetUint64(time)
+	bigParentTime.SetUint64(parent.Time)
+
+	if bigTime.Sub(bigTime, bigParentTime).Cmp(params.DurationLimit) < 0 {
+		diff.Add(parent.Difficulty, adjust)
+	} else {
+		diff.Sub(parent.Difficulty, adjust)
+	}
+	if diff.Cmp(params.MinimumDifficulty) < 0 {
+		diff.Set(params.MinimumDifficulty)
+	}
+
+	periodCount := new(big.Int).Add(parent.Number, big1)
+	periodCount.Div(periodCount, expDiffPeriod)
+	if periodCount.Cmp(big1) > 0 {
+		// diff = diff + 2^(periodCount - 2)
+		expDiff := periodCount.Sub(periodCount, big2)
+		expDiff.Exp(big2, expDiff, nil)
+		diff.Add(diff, expDiff)
+		diff = math.BigMax(diff, params.MinimumDifficulty)
+	}
+	return diff
+}
+
+// VerifySeal implements consensus.Engine, checking whether the given block satisfies
+// the PoW difficulty requirements.
+func (ethash *Ethash) VerifySeal(chain consensus.ChainReader, header *types.Header) error {
+	return ethash.verifySeal(chain, header, false)
+}
+
+// verifySeal checks whether a block satisfies the PoW difficulty requirements,
+// either using the usual ethash cache for it, or alternatively using a full DAG
+// to make remote mining fast.
+func (ethash *Ethash) verifySeal(chain consensus.ChainReader, header *types.Header, fulldag bool) error {
+	// If we're running a fake PoW, accept any seal as valid
+	if ethash.config.PowMode == ModeFake || ethash.config.PowMode == ModeFullFake {
+		time.Sleep(ethash.fakeDelay)
+		if ethash.fakeFail == header.Number.Uint64() {
+			return errInvalidPoW
+		}
+		return nil
+	}
+	// If we're running a shared PoW, delegate verification to it
+	if ethash.shared != nil {
+		return ethash.shared.verifySeal(chain, header, fulldag)
+	}
+	// Ensure that we have a valid difficulty for the block
+	if header.Difficulty.Sign() <= 0 {
+		return errInvalidDifficulty
+	}
+	// Recompute the digest and PoW values
+	number := header.Number.Uint64()
+
+	var (
+		digest []byte
+		result []byte
+	)
+	// If fast-but-heavy PoW verification was requested, use an ethash dataset
+	if fulldag {
+		dataset := ethash.dataset(number, true)
+		if dataset.generated() {
+			digest, result = hashimotoFull(dataset.dataset, ethash.SealHash(header).Bytes(), header.Nonce.Uint64())
+
+			// Datasets are unmapped in a finalizer. Ensure that the dataset stays alive
+			// until after the call to hashimotoFull so it's not unmapped while being used.
+			runtime.KeepAlive(dataset)
+		} else {
+			// Dataset not yet generated, don't hang, use a cache instead
+			fulldag = false
+		}
+	}
+	// If slow-but-light PoW verification was requested (or DAG not yet ready), use an ethash cache
+	if !fulldag {
+		cache := ethash.cache(number)
+
+		size := datasetSize(number)
+		if ethash.config.PowMode == ModeTest {
+			size = 32 * 1024
+		}
+		digest, result = hashimotoLight(size, cache.cache, ethash.SealHash(header).Bytes(), header.Nonce.Uint64())
+
+		// Caches are unmapped in a finalizer. Ensure that the cache stays alive
+		// until after the call to hashimotoLight so it's not unmapped while being used.
+		runtime.KeepAlive(cache)
+	}
+	// Verify the calculated values against the ones provided in the header
+	if !bytes.Equal(header.MixDigest[:], digest) {
+		return errInvalidMixDigest
+	}
+	target := new(big.Int).Div(two256, header.Difficulty)
+	if new(big.Int).SetBytes(result).Cmp(target) > 0 {
+		return errInvalidPoW
+	}
+	return nil
+}
+
+// Prepare implements consensus.Engine, initializing the difficulty field of a
+// header to conform to the ethash protocol. The changes are done inline.
+func (ethash *Ethash) Prepare(chain consensus.ChainReader, header *types.Header) error {
+	parent := chain.GetHeader(header.ParentHash, header.Number.Uint64()-1)
+	if parent == nil {
+		return consensus.ErrUnknownAncestor
+	}
+	header.Difficulty = ethash.CalcDifficulty(chain, header.Time, parent)
+	return nil
+}
+
+// Finalize implements consensus.Engine, accumulating the block and uncle rewards,
+// setting the final state on the header
+func (ethash *Ethash) Finalize(chain consensus.ChainReader, header *types.Header, state *state.StateDB, txs []*types.Transaction, uncles []*types.Header) {
+	// Accumulate any block and uncle rewards and commit the final state root
+	accumulateRewards(chain.Config(), state, header, uncles)
+	header.Root = state.IntermediateRoot(chain.Config().IsEIP158(header.Number))
+}
+
+// FinalizeAndAssemble implements consensus.Engine, accumulating the block and
+// uncle rewards, setting the final state and assembling the block.
+func (ethash *Ethash) FinalizeAndAssemble(chain consensus.ChainReader, header *types.Header, state *state.StateDB, txs []*types.Transaction, uncles []*types.Header, receipts []*types.Receipt) (*types.Block, error) {
+	// Accumulate any block and uncle rewards and commit the final state root
+	accumulateRewards(chain.Config(), state, header, uncles)
+	header.Root = state.IntermediateRoot(chain.Config().IsEIP158(header.Number))
+
+	// Header seems complete, assemble into a block and return
+	return types.NewBlock(header, txs, uncles, receipts), nil
+}
+
+// SealHash returns the hash of a block prior to it being sealed.
+func (ethash *Ethash) SealHash(header *types.Header) (hash common.Hash) {
+	hasher := sha3.NewLegacyKeccak256()
+
+	rlp.Encode(hasher, []interface{}{
+		header.ParentHash,
+		header.UncleHash,
+		header.Coinbase,
+		header.Root,
+		header.TxHash,
+		header.ReceiptHash,
+		header.Bloom,
+		header.Difficulty,
+		header.Number,
+		header.GasLimit,
+		header.GasUsed,
+		header.Time,
+		header.Extra,
+	})
+	hasher.Sum(hash[:0])
+	return hash
+}
+
+// Some weird constants to avoid constant memory allocs for them.
+var (
+	big8  = big.NewInt(8)
+	big32 = big.NewInt(32)
+)
+
+// AccumulateRewards credits the coinbase of the given block with the mining
+// reward. The total reward consists of the static block reward and rewards for
+// included uncles. The coinbase of each uncle block is also rewarded.
+func accumulateRewards(config *params.ChainConfig, state *state.StateDB, header *types.Header, uncles []*types.Header) {
+	// Select the correct block reward based on chain progression
+	blockReward := FrontierBlockReward
+	if config.IsByzantium(header.Number) {
+		blockReward = ByzantiumBlockReward
+	}
+	if config.IsConstantinople(header.Number) {
+		blockReward = ConstantinopleBlockReward
+	}
+	// Accumulate the rewards for the miner and any included uncles
+	reward := new(big.Int).Set(blockReward)
+	r := new(big.Int)
+	for _, uncle := range uncles {
+		r.Add(uncle.Number, big8)
+		r.Sub(r, header.Number)
+		r.Mul(r, blockReward)
+		r.Div(r, big8)
+		state.AddBalance(uncle.Coinbase, r)
+
+		r.Div(blockReward, big32)
+		reward.Add(reward, r)
+	}
+	state.AddBalance(header.Coinbase, reward)
+}