58 lines
2.3 KiB
Go
58 lines
2.3 KiB
Go
// 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/>.
|
|
|
|
// +build go1.8
|
|
|
|
package ethash
|
|
|
|
import "math/big"
|
|
|
|
// cacheSize calculates and returns the size of the ethash verification cache that
|
|
// belongs to a certain block number. The cache size grows linearly, however, we
|
|
// always take the highest prime below the linearly growing threshold in order to
|
|
// reduce the risk of accidental regularities leading to cyclic behavior.
|
|
func cacheSize(block uint64) uint64 {
|
|
// If we have a pre-generated value, use that
|
|
epoch := int(block / epochLength)
|
|
if epoch < len(cacheSizes) {
|
|
return cacheSizes[epoch]
|
|
}
|
|
// No known cache size, calculate manually (sanity branch only)
|
|
size := cacheInitBytes + cacheGrowthBytes*uint64(epoch) - hashBytes
|
|
for !new(big.Int).SetUint64(size / hashBytes).ProbablyPrime(1) { // Always accurate for n < 2^64
|
|
size -= 2 * hashBytes
|
|
}
|
|
return size
|
|
}
|
|
|
|
// datasetSize calculates and returns the size of the ethash mining dataset that
|
|
// belongs to a certain block number. The dataset size grows linearly, however, we
|
|
// always take the highest prime below the linearly growing threshold in order to
|
|
// reduce the risk of accidental regularities leading to cyclic behavior.
|
|
func datasetSize(block uint64) uint64 {
|
|
// If we have a pre-generated value, use that
|
|
epoch := int(block / epochLength)
|
|
if epoch < len(datasetSizes) {
|
|
return datasetSizes[epoch]
|
|
}
|
|
// No known dataset size, calculate manually (sanity branch only)
|
|
size := datasetInitBytes + datasetGrowthBytes*uint64(epoch) - mixBytes
|
|
for !new(big.Int).SetUint64(size / mixBytes).ProbablyPrime(1) { // Always accurate for n < 2^64
|
|
size -= 2 * mixBytes
|
|
}
|
|
return size
|
|
}
|