// Copyright 2014 The go-ethereum Authors
// This file is part of go-ethereum.
//
// go-ethereum 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.
//
// go-ethereum 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 go-ethereum. If not, see <http://www.gnu.org/licenses/>.
package ezp
import (
"encoding/binary"
"math/big"
"math/rand"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/crypto/sha3"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/pow"
)
var powlogger = logger.NewLogger("POW")
type EasyPow struct {
hash *big.Int
HashRate int64
turbo bool
}
func New() *EasyPow {
return &EasyPow{turbo: false}
}
func (pow *EasyPow) GetHashrate() int64 {
return pow.HashRate
}
func (pow *EasyPow) Turbo(on bool) {
pow.turbo = on
}
func (pow *EasyPow) Search(block pow.Block, stop <-chan struct{}) (uint64, []byte) {
r := rand.New(rand.NewSource(time.Now().UnixNano()))
hash := block.HashNoNonce()
diff := block.Difficulty()
//i := int64(0)
// TODO fix offset
i := rand.Int63()
starti := i
start := time.Now().UnixNano()
defer func() { pow.HashRate = 0 }()
// Make sure stop is empty
empty:
for {
select {
case <-stop:
default:
break empty
}
}
for {
select {
case <-stop:
return 0, nil
default:
i++
elapsed := time.Now().UnixNano() - start
hashes := ((float64(1e9) / float64(elapsed)) * float64(i-starti)) / 1000
pow.HashRate = int64(hashes)
sha := uint64(r.Int63())
if verify(hash, diff, sha) {
return sha, nil
}
}
if !pow.turbo {
time.Sleep(20 * time.Microsecond)
}
}
return 0, nil
}
func (pow *EasyPow) Verify(block pow.Block) bool {
return Verify(block)
}
func verify(hash common.Hash, diff *big.Int, nonce uint64) bool {
sha := sha3.NewKeccak256()
n := make([]byte, 8)
binary.PutUvarint(n, nonce)
sha.Write(n)
sha.Write(hash[:])
verification := new(big.Int).Div(common.BigPow(2, 256), diff)
res := common.BigD(sha.Sum(nil))
return res.Cmp(verification) <= 0
}
func Verify(block pow.Block) bool {
return verify(block.HashNoNonce(), block.Difficulty(), block.Nonce())
}