75 lines
1.7 KiB
Go
75 lines
1.7 KiB
Go
package utils
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// HexToCompact converts a hex path to the compact encoded format
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func HexToCompact(hex []byte) []byte {
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return hexToCompact(hex)
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}
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func hexToCompact(hex []byte) []byte {
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terminator := byte(0)
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if hasTerm(hex) {
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terminator = 1
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hex = hex[:len(hex)-1]
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}
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buf := make([]byte, len(hex)/2+1)
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buf[0] = terminator << 5 // the flag byte
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if len(hex)&1 == 1 {
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buf[0] |= 1 << 4 // odd flag
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buf[0] |= hex[0] // first nibble is contained in the first byte
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hex = hex[1:]
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}
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decodeNibbles(hex, buf[1:])
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return buf
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}
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// CompactToHex converts a compact encoded path to hex format
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func CompactToHex(compact []byte) []byte {
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if len(compact) == 0 {
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return compact
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}
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base := KeybytesToHex(compact)
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// delete terminator flag
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if base[0] < 2 {
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base = base[:len(base)-1]
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}
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// apply odd flag
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chop := 2 - base[0]&1
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return base[chop:]
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}
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func KeybytesToHex(str []byte) []byte {
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l := len(str)*2 + 1
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var nibbles = make([]byte, l)
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for i, b := range str {
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nibbles[i*2] = b / 16
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nibbles[i*2+1] = b % 16
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}
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nibbles[l-1] = 16
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return nibbles
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}
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// HexToKeyBytes turns hex nibbles into key bytes.
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// This can only be used for keys of even length.
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func HexToKeyBytes(hex []byte) []byte {
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if hasTerm(hex) {
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hex = hex[:len(hex)-1]
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}
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if len(hex)&1 != 0 {
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panic("can't convert hex key of odd length")
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}
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key := make([]byte, len(hex)/2)
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decodeNibbles(hex, key)
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return key
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}
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func decodeNibbles(nibbles []byte, bytes []byte) {
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for bi, ni := 0, 0; ni < len(nibbles); bi, ni = bi+1, ni+2 {
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bytes[bi] = nibbles[ni]<<4 | nibbles[ni+1]
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}
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}
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// hasTerm returns whether a hex key has the terminator flag.
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func hasTerm(s []byte) bool {
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return len(s) > 0 && s[len(s)-1] == 16
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}
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