nautilus_model/defi/tick_map/
bit_math.rs

1// -------------------------------------------------------------------------------------------------
2//  Copyright (C) 2015-2026 Nautech Systems Pty Ltd. All rights reserved.
3//  https://nautechsystems.io
4//
5//  Licensed under the GNU Lesser General Public License Version 3.0 (the "License");
6//  You may not use this file except in compliance with the License.
7//  You may obtain a copy of the License at https://www.gnu.org/licenses/lgpl-3.0.en.html
8//
9//  Unless required by applicable law or agreed to in writing, software
10//  distributed under the License is distributed on an "AS IS" BASIS,
11//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12//  See the License for the specific language governing permissions and
13//  limitations under the License.
14// -------------------------------------------------------------------------------------------------
15
16use alloy_primitives::U256;
17
18/// Returns the position of the most significant bit (highest set bit) in a U256 number.
19#[must_use]
20pub fn most_significant_bit(x: U256) -> i32 {
21    if x.is_zero() {
22        return 0;
23    }
24
25    255 - x.leading_zeros() as i32
26}
27
28/// Returns the position of the least significant bit (lowest set bit) in a U256 number.
29#[must_use]
30pub fn least_significant_bit(x: U256) -> i32 {
31    if x.is_zero() {
32        return 0;
33    }
34    x.trailing_zeros() as i32
35}
36
37#[cfg(test)]
38mod tests {
39    use rstest::rstest;
40
41    use super::*;
42
43    #[rstest]
44    fn test_most_significant_bit() {
45        for i in 0..=255 {
46            let x = U256::ONE << i;
47            assert_eq!(most_significant_bit(x), i);
48        }
49
50        for i in 1..=255 {
51            let x = (U256::ONE << i) - U256::ONE;
52            assert_eq!(most_significant_bit(x), i - 1);
53        }
54        assert_eq!(most_significant_bit(U256::MAX), 255);
55    }
56
57    #[rstest]
58    fn test_least_significant_bit() {
59        for i in 0..=255 {
60            let x = U256::ONE << i;
61            assert_eq!(least_significant_bit(x), i);
62        }
63
64        for i in 1..=255 {
65            let x = (U256::ONE << i) - U256::ONE;
66            assert_eq!(least_significant_bit(x), 0);
67        }
68        assert_eq!(least_significant_bit(U256::MAX), 0);
69    }
70}
nautilus_model/defi/tick_map/bit_math.rs

nautilus_model/defi/tick_map/
bit_math.rs
