algorithm_go1.8.go

// This file is part of the go-sberex library. The go-sberex 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-sberex 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 <http://www.gnu.org/licenses/> for more details.

// +build go1.8

package ethash

import "math/big"

// cacheSize returns the size of the ethash verification cache that belongs to a certain
// block number.
func cacheSize(block uint64) uint64 {
	epoch := int(block / epochLength)
	if epoch < maxEpoch {
	return cacheSizes[epoch]
	}
	return calcCacheSize(epoch)
}

// calcCacheSize calculates the cache size for epoch. 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 calcCacheSize(epoch int) uint64 {
	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 returns the size of the ethash mining dataset that belongs to a certain
// block number.
func datasetSize(block uint64) uint64 {
	epoch := int(block / epochLength)
	if epoch < maxEpoch {
		return datasetSizes[epoch]
	}
	return calcDatasetSize(epoch)
}

// calcDatasetSize calculates the dataset size for epoch. 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 calcDatasetSize(epoch int) uint64 {
	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
}