forked from TrueCloudLab/neoneo-go
78 lines
1.7 KiB
Go
Executable file
78 lines
1.7 KiB
Go
Executable file
package base58
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import (
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"fmt"
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"math/big"
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)
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const prefix rune = '1'
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var decodeMap = map[rune]int64{
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'1': 0, '2': 1, '3': 2, '4': 3, '5': 4,
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'6': 5, '7': 6, '8': 7, '9': 8, 'A': 9,
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'B': 10, 'C': 11, 'D': 12, 'E': 13, 'F': 14,
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'G': 15, 'H': 16, 'J': 17, 'K': 18, 'L': 19,
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'M': 20, 'N': 21, 'P': 22, 'Q': 23, 'R': 24,
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'S': 25, 'T': 26, 'U': 27, 'V': 28, 'W': 29,
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'X': 30, 'Y': 31, 'Z': 32, 'a': 33, 'b': 34,
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'c': 35, 'd': 36, 'e': 37, 'f': 38, 'g': 39,
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'h': 40, 'i': 41, 'j': 42, 'k': 43, 'm': 44,
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'n': 45, 'o': 46, 'p': 47, 'q': 48, 'r': 49,
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's': 50, 't': 51, 'u': 52, 'v': 53, 'w': 54,
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'x': 55, 'y': 56, 'z': 57,
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}
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// Decode decodes the base58 encoded string.
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func Decode(s string) ([]byte, error) {
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var (
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startIndex = 0
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zero = 0
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)
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for i, c := range s {
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if c == prefix {
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zero++
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} else {
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startIndex = i
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break
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}
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}
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var (
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n = big.NewInt(0)
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div = big.NewInt(58)
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)
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for _, c := range s[startIndex:] {
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charIndex, ok := decodeMap[c]
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if !ok {
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return nil, fmt.Errorf(
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"invalid character '%c' when decoding this base58 string: '%s'", c, s,
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)
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}
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n.Add(n.Mul(n, div), big.NewInt(charIndex))
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}
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out := n.Bytes()
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buf := make([]byte, (zero + len(out)))
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copy(buf[zero:], out[:])
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return buf, nil
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}
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// Encode encodes a byte slice to be a base58 encoded string.
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func Encode(bytes []byte) string {
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var (
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lookupTable = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"
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x = new(big.Int).SetBytes(bytes)
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r = new(big.Int)
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m = big.NewInt(58)
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zero = big.NewInt(0)
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encoded string
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)
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for x.Cmp(zero) > 0 {
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x.QuoRem(x, m, r)
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encoded = string(lookupTable[r.Int64()]) + encoded
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}
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return encoded
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}
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