gaspersic/go-ethereum
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

pow: only support prime calculations on Go 1.8 and above

Browse Source
This commit is contained in:
Péter Szilágyi
2017-03-06 15:00:20 +02:00
committed by Felix Lange
parent 023670f6ba
commit df72e20cc5
6 changed files with 157 additions and 63 deletions
Download Patch File Download Diff File Expand all files Collapse all files

37
pow/ethash_algo.go
View File

@ -19,7 +19,6 @@ package pow
import (
"encoding/binary"
"io"
"math/big"
"runtime"
"sync"
"sync/atomic"
@ -45,42 +44,6 @@ const (
loopAccesses = 64 // Number of accesses in hashimoto loop
)
// 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 := uint64(cacheInitBytes + cacheGrowthBytes*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 := uint64(datasetInitBytes + datasetGrowthBytes*epoch - mixBytes)
for !new(big.Int).SetUint64(size / mixBytes).ProbablyPrime(1) { // Always accurate for n < 2^64
size -= 2 * mixBytes
}
return size
}
// seedHash is the seed to use for generating a verification cache and the mining
// dataset.
func seedHash(block uint64) []byte {