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-rw-r--r--bmt/bmt_r.go85
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diff --git a/bmt/bmt_r.go b/bmt/bmt_r.go
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--- a/bmt/bmt_r.go
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-// 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/>.
-
-// Package bmt is a 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
-}