plugeth/consensus/ethash/algorithm_go1.7.go
Péter Szilágyi 09777952ee core, consensus: pluggable consensus engines (#3817)
This commit adds pluggable consensus engines to go-ethereum. In short, it
introduces a generic consensus interface, and refactors the entire codebase to
use this interface.
2017-04-05 00:16:29 +02:00

48 lines
2.0 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
// 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]
}
// We don't have a way to verify primes fast before Go 1.8
panic("fast prime testing unsupported in Go < 1.8")
}
// 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]
}
// We don't have a way to verify primes fast before Go 1.8
panic("fast prime testing unsupported in Go < 1.8")
}