1 // ZigZag endoging used for efficient transfer of signed integers
2 // https://developers.google.com/protocol-buffers/docs/encoding#types
3
decode_zig_zag_32(n: u32) -> i324 pub fn decode_zig_zag_32(n: u32) -> i32 {
5 ((n >> 1) as i32) ^ (-((n & 1) as i32))
6 }
7
decode_zig_zag_64(n: u64) -> i648 pub fn decode_zig_zag_64(n: u64) -> i64 {
9 ((n >> 1) as i64) ^ (-((n & 1) as i64))
10 }
11
encode_zig_zag_32(n: i32) -> u3212 pub fn encode_zig_zag_32(n: i32) -> u32 {
13 ((n << 1) ^ (n >> 31)) as u32
14 }
15
encode_zig_zag_64(n: i64) -> u6416 pub fn encode_zig_zag_64(n: i64) -> u64 {
17 ((n << 1) ^ (n >> 63)) as u64
18 }
19
20 #[cfg(test)]
21 mod test {
22
23 use super::decode_zig_zag_32;
24 use super::decode_zig_zag_64;
25 use super::encode_zig_zag_32;
26 use super::encode_zig_zag_64;
27
28 #[test]
test_zig_zag()29 fn test_zig_zag() {
30 fn test_zig_zag_pair_64(decoded: i64, encoded: u64) {
31 assert_eq!(decoded, decode_zig_zag_64(encoded));
32 assert_eq!(encoded, encode_zig_zag_64(decoded));
33 }
34
35 fn test_zig_zag_pair(decoded: i32, encoded: u32) {
36 assert_eq!(decoded, decode_zig_zag_32(encoded));
37 assert_eq!(encoded, encode_zig_zag_32(decoded));
38 test_zig_zag_pair_64(decoded as i64, encoded as u64);
39 }
40
41 test_zig_zag_pair(0, 0);
42 test_zig_zag_pair(-1, 1);
43 test_zig_zag_pair(1, 2);
44 test_zig_zag_pair(-2, 3);
45 test_zig_zag_pair(2147483647, 4294967294);
46 test_zig_zag_pair(-2147483648, 4294967295);
47 test_zig_zag_pair_64(9223372036854775807, 18446744073709551614);
48 test_zig_zag_pair_64(-9223372036854775808, 18446744073709551615);
49 }
50 }
51