mirror of
https://gitlab.com/pulsechaincom/prysm-pulse.git
synced 2024-12-27 21:57:16 +00:00
da20785685
Former-commit-id: 23f542f43b4b493e38f5aa4c29788ed93a63b43b [formerly 71b23a6a28eb045fcfeab6329de69f1e5455486b] Former-commit-id: d12b3a6decc876f010a71f98e11df7387c1aaf2a
86 lines
2.2 KiB
Go
86 lines
2.2 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/>.
|
|
|
|
// simple nonconcurrent reference implementation for hashsize segment based
|
|
// Binary Merkle tree hash on arbitrary but fixed maximum chunksize
|
|
//
|
|
// This implementation does not take advantage of any paralellisms and uses
|
|
// far more memory than necessary, but it is easy to see that it is correct.
|
|
// It can be used for generating test cases for optimized implementations.
|
|
// see testBMTHasherCorrectness function in bmt_test.go
|
|
package bmt
|
|
|
|
import (
|
|
"hash"
|
|
)
|
|
|
|
// RefHasher is the non-optimized easy to read reference implementation of BMT
|
|
type RefHasher struct {
|
|
span int
|
|
section int
|
|
cap int
|
|
h hash.Hash
|
|
}
|
|
|
|
// NewRefHasher returns a new RefHasher
|
|
func NewRefHasher(hasher BaseHasher, count int) *RefHasher {
|
|
h := hasher()
|
|
hashsize := h.Size()
|
|
maxsize := hashsize * count
|
|
c := 2
|
|
for ; c < count; c *= 2 {
|
|
}
|
|
if c > 2 {
|
|
c /= 2
|
|
}
|
|
return &RefHasher{
|
|
section: 2 * hashsize,
|
|
span: c * hashsize,
|
|
cap: maxsize,
|
|
h: h,
|
|
}
|
|
}
|
|
|
|
// Hash returns the BMT hash of the byte slice
|
|
// implements the SwarmHash interface
|
|
func (rh *RefHasher) Hash(d []byte) []byte {
|
|
if len(d) > rh.cap {
|
|
d = d[:rh.cap]
|
|
}
|
|
|
|
return rh.hash(d, rh.span)
|
|
}
|
|
|
|
func (rh *RefHasher) hash(d []byte, s int) []byte {
|
|
l := len(d)
|
|
left := d
|
|
var right []byte
|
|
if l > rh.section {
|
|
for ; s >= l; s /= 2 {
|
|
}
|
|
left = rh.hash(d[:s], s)
|
|
right = d[s:]
|
|
if l-s > rh.section/2 {
|
|
right = rh.hash(right, s)
|
|
}
|
|
}
|
|
defer rh.h.Reset()
|
|
rh.h.Write(left)
|
|
rh.h.Write(right)
|
|
h := rh.h.Sum(nil)
|
|
return h
|
|
}
|