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66 lines
1.3 KiB
66 lines
1.3 KiB
package modhex
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import (
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"errors"
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"fmt"
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)
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const hexChars = "0123456789abcdef"
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const modhexChars = "cbdefghijklnrtuv"
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var modhex2HexMap map[byte]byte
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var hex2ModhexMap map[byte]byte
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func init() {
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hex2ModhexMap = make(map[byte]byte)
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for i, h := range []byte(hexChars) {
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hex2ModhexMap[h] = modhexChars[i]
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}
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modhex2HexMap = make(map[byte]byte)
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for i, m := range []byte(modhexChars) {
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modhex2HexMap[m] = hexChars[i]
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}
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}
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// EncodeHex encodes a hex string into a modhex string
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func EncodeHex(hex string) (string, error) {
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size := len([]byte(hex))
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if size%2 == 1 {
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return "", errors.New("size of input hex input not even")
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}
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var modhex = make([]byte, size)
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for i, h := range []byte(hex) {
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if m, ok := hex2ModhexMap[h]; ok {
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modhex[i] = m
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} else {
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return "", fmt.Errorf("input not hex encoded; position %d", i)
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}
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}
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return string(modhex), nil
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}
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// DecodeHex decodes a modhex string into a hex string
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func DecodeHex(modhex string) (string, error) {
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size := len([]byte(modhex))
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if size%2 == 1 {
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return "", errors.New("size of modhex input not even")
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}
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var hex = make([]byte, size)
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for i, m := range []byte(modhex) {
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if h, ok := modhex2HexMap[m]; ok {
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hex[i] = h
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} else {
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return "", fmt.Errorf("input not modhex encoded; position %d", i)
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}
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}
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return string(hex), nil
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}
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