]>
Commit | Line | Data |
---|---|---|
11fdf7f2 TL |
1 | /* |
2 | * This file is open source software, licensed to you under the terms | |
3 | * of the Apache License, Version 2.0 (the "License"). See the NOTICE file | |
4 | * distributed with this work for additional information regarding copyright | |
5 | * ownership. You may not use this file except in compliance with the License. | |
6 | * | |
7 | * You may obtain a copy of the License at | |
8 | * | |
9 | * http://www.apache.org/licenses/LICENSE-2.0 | |
10 | * | |
11 | * Unless required by applicable law or agreed to in writing, | |
12 | * software distributed under the License is distributed on an | |
13 | * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY | |
14 | * KIND, either express or implied. See the License for the | |
15 | * specific language governing permissions and limitations | |
16 | * under the License. | |
17 | */ | |
18 | /* | |
19 | * Copyright (C) 2014 Cloudius Systems, Ltd. | |
20 | */ | |
21 | ||
22 | #pragma once | |
23 | ||
24 | #include <limits> | |
1e59de90 TL |
25 | #include <type_traits> |
26 | #include <seastar/util/concepts.hh> | |
11fdf7f2 TL |
27 | |
28 | namespace seastar { | |
29 | ||
30 | inline | |
31 | constexpr unsigned count_leading_zeros(unsigned x) { | |
32 | return __builtin_clz(x); | |
33 | } | |
34 | ||
35 | inline | |
36 | constexpr unsigned count_leading_zeros(unsigned long x) { | |
37 | return __builtin_clzl(x); | |
38 | } | |
39 | ||
40 | inline | |
41 | constexpr unsigned count_leading_zeros(unsigned long long x) { | |
42 | return __builtin_clzll(x); | |
43 | } | |
44 | ||
45 | inline | |
46 | constexpr unsigned count_trailing_zeros(unsigned x) { | |
47 | return __builtin_ctz(x); | |
48 | } | |
49 | ||
50 | inline | |
51 | constexpr unsigned count_trailing_zeros(unsigned long x) { | |
52 | return __builtin_ctzl(x); | |
53 | } | |
54 | ||
55 | inline | |
56 | constexpr unsigned count_trailing_zeros(unsigned long long x) { | |
57 | return __builtin_ctzll(x); | |
58 | } | |
59 | ||
60 | template<typename T> | |
1e59de90 | 61 | SEASTAR_CONCEPT( requires std::is_integral_v<T> ) |
11fdf7f2 TL |
62 | inline constexpr unsigned log2ceil(T n) { |
63 | if (n == 1) { | |
64 | return 0; | |
65 | } | |
66 | return std::numeric_limits<T>::digits - count_leading_zeros(n - 1); | |
67 | } | |
68 | ||
69 | template<typename T> | |
1e59de90 | 70 | SEASTAR_CONCEPT( requires std::is_integral_v<T> ) |
11fdf7f2 TL |
71 | inline constexpr unsigned log2floor(T n) { |
72 | return std::numeric_limits<T>::digits - count_leading_zeros(n) - 1; | |
73 | } | |
74 | ||
75 | } |