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// 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 trie
func CompactEncode(hexSlice []byte) []byte {
terminator := 0
if hexSlice[len(hexSlice)-1] == 16 {
terminator = 1
}
if terminator == 1 {
hexSlice = hexSlice[:len(hexSlice)-1]
}
oddlen := len(hexSlice) % 2
flags := byte(2*terminator + oddlen)
if oddlen != 0 {
hexSlice = append([]byte{flags}, hexSlice...)
} else {
hexSlice = append([]byte{flags, 0}, hexSlice...)
}
l := len(hexSlice) / 2
var buf = make([]byte, l)
for i := 0; i < l; i++ {
buf[i] = 16*hexSlice[2*i] + hexSlice[2*i+1]
}
return buf
}
func CompactDecode(str []byte) []byte {
base := CompactHexDecode(str)
base = base[:len(base)-1]
if base[0] >= 2 {
base = append(base, 16)
}
if base[0]%2 == 1 {
base = base[1:]
} else {
base = base[2:]
}
return base
}
func CompactHexDecode(str []byte) []byte {
l := len(str)*2 + 1
var nibbles = make([]byte, l)
for i, b := range str {
nibbles[i*2] = b / 16
nibbles[i*2+1] = b % 16
}
nibbles[l-1] = 16
return nibbles
}
func DecodeCompact(key []byte) []byte {
l := len(key) / 2
var res = make([]byte, l)
for i := 0; i < l; i++ {
v1, v0 := key[2*i], key[2*i+1]
res[i] = v1*16 + v0
}
return res
}
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