plugeth/trie/encoding.go

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package trie
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import (
"bytes"
"encoding/hex"
"strings"
)
func CompactEncode(hexSlice []byte) string {
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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)
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if oddlen != 0 {
hexSlice = append([]byte{flags}, hexSlice...)
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} else {
hexSlice = append([]byte{flags, 0}, hexSlice...)
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}
var buff bytes.Buffer
for i := 0; i < len(hexSlice); i += 2 {
buff.WriteByte(byte(16*hexSlice[i] + hexSlice[i+1]))
}
return buff.String()
}
func CompactDecode(str string) []byte {
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base := CompactHexDecode(str)
base = base[:len(base)-1]
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if base[0] >= 2 {
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base = append(base, 16)
}
if base[0]%2 == 1 {
base = base[1:]
} else {
base = base[2:]
}
return base
}
func CompactHexDecode(str string) []byte {
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base := "0123456789abcdef"
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var hexSlice []byte
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enc := hex.EncodeToString([]byte(str))
for _, v := range enc {
hexSlice = append(hexSlice, byte(strings.IndexByte(base, byte(v))))
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}
hexSlice = append(hexSlice, 16)
return hexSlice
}
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func DecodeCompact(key []byte) string {
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const base = "0123456789abcdef"
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var str string
for _, v := range key {
if v < 16 {
str += string(base[v])
}
}
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res, _ := hex.DecodeString(str)
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return string(res)
}