102 lines
2.5 KiB
Go
102 lines
2.5 KiB
Go
// Copyright 2014 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 rle implements the run-length encoding used for Ethereum data.
|
|
package rle
|
|
|
|
import (
|
|
"bytes"
|
|
"errors"
|
|
|
|
"github.com/ethereum/go-ethereum/crypto"
|
|
)
|
|
|
|
const (
|
|
token byte = 0xfe
|
|
emptyShaToken = 0xfd
|
|
emptyListShaToken = 0xfe
|
|
tokenToken = 0xff
|
|
)
|
|
|
|
var empty = crypto.Keccak256([]byte(""))
|
|
var emptyList = crypto.Keccak256([]byte{0x80})
|
|
|
|
func Decompress(dat []byte) ([]byte, error) {
|
|
buf := new(bytes.Buffer)
|
|
|
|
for i := 0; i < len(dat); i++ {
|
|
if dat[i] == token {
|
|
if i+1 < len(dat) {
|
|
switch dat[i+1] {
|
|
case emptyShaToken:
|
|
buf.Write(empty)
|
|
case emptyListShaToken:
|
|
buf.Write(emptyList)
|
|
case tokenToken:
|
|
buf.WriteByte(token)
|
|
default:
|
|
buf.Write(make([]byte, int(dat[i+1]-2)))
|
|
}
|
|
i++
|
|
} else {
|
|
return nil, errors.New("error reading bytes. token encountered without proceeding bytes")
|
|
}
|
|
} else {
|
|
buf.WriteByte(dat[i])
|
|
}
|
|
}
|
|
|
|
return buf.Bytes(), nil
|
|
}
|
|
|
|
func compressChunk(dat []byte) (ret []byte, n int) {
|
|
switch {
|
|
case dat[0] == token:
|
|
return []byte{token, tokenToken}, 1
|
|
case len(dat) > 1 && dat[0] == 0x0 && dat[1] == 0x0:
|
|
j := 0
|
|
for j <= 254 && j < len(dat) {
|
|
if dat[j] != 0 {
|
|
break
|
|
}
|
|
j++
|
|
}
|
|
return []byte{token, byte(j + 2)}, j
|
|
case len(dat) >= 32:
|
|
if dat[0] == empty[0] && bytes.Equal(dat[:32], empty) {
|
|
return []byte{token, emptyShaToken}, 32
|
|
} else if dat[0] == emptyList[0] && bytes.Equal(dat[:32], emptyList) {
|
|
return []byte{token, emptyListShaToken}, 32
|
|
}
|
|
fallthrough
|
|
default:
|
|
return dat[:1], 1
|
|
}
|
|
}
|
|
|
|
func Compress(dat []byte) []byte {
|
|
buf := new(bytes.Buffer)
|
|
|
|
i := 0
|
|
for i < len(dat) {
|
|
b, n := compressChunk(dat[i:])
|
|
buf.Write(b)
|
|
i += n
|
|
}
|
|
|
|
return buf.Bytes()
|
|
}
|