encoding.gno

 1package mpt
 2
 3// keybytesToHex mirrors keybytesToHex.
 4// Reference:
 5// https://github.com/ethereum/go-ethereum/blob/v1.10.26/trie/encoding.go#L96-L104
 6func keybytesToHex(str []byte) []byte {
 7	l := len(str)*2 + 1
 8	nibbles := make([]byte, l)
 9
10	for i, b := range str {
11		nibbles[i*2] = b / 16
12		nibbles[i*2+1] = b % 16
13	}
14
15	nibbles[l-1] = 16
16
17	return nibbles
18}
19
20// compactToHex mirrors compactToHex exactly, reusing keybytesToHex the same
21// way: base[0] is compact's flag nibble, <2 means extension (drop the
22// terminator keybytesToHex appended), and the low bit of the flag says
23// whether to chop 1 or 2 leading nibbles (odd vs even length).
24// Reference:
25// https://github.com/ethereum/go-ethereum/blob/v1.10.26/trie/encoding.go#L82-L92
26func compactToHex(compact []byte) []byte {
27	if len(compact) == 0 {
28		return compact
29	}
30
31	base := keybytesToHex(compact)
32	if base[0] < 2 {
33		base = base[:len(base)-1]
34	}
35
36	chop := 2 - base[0]&1
37
38	return base[chop:]
39}
40
41// hasTerm reports whether a hex key has the terminator flag.
42// Reference:
43// https://github.com/ethereum/go-ethereum/blob/v1.10.26/trie/encoding.go#L143-L145
44func hasTerm(s []byte) bool {
45	return len(s) > 0 && s[len(s)-1] == 16
46}