spot 2.12.2
clz.hh
1// -*- coding: utf-8 -*-
2// Copyright (C) by the Spot authors, see the AUTHORS file for details.
3//
4// This file is part of Spot, a model checking library.
5//
6// Spot is free software; you can redistribute it and/or modify it
7// under the terms of the GNU General Public License as published by
8// the Free Software Foundation; either version 3 of the License, or
9// (at your option) any later version.
10//
11// Spot is distributed in the hope that it will be useful, but WITHOUT
12// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13// or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
14// License for more details.
15//
16// You should have received a copy of the GNU General Public License
17// along with this program. If not, see <http://www.gnu.org/licenses/>.
18
19#pragma once
20
21#include <spot/misc/common.hh>
22#include <cstddef>
23#include <climits>
24
25namespace spot
26{
27 template<typename Type,
28 typename = std::enable_if_t<std::is_unsigned<Type>::value>>
29 inline constexpr unsigned clz(Type n) noexcept
30 {
31 unsigned res = CHAR_BIT * sizeof(Type);
32 while (n)
33 {
34 --res;
35 n >>= 1;
36 }
37 return res;
38 }
39
40#if __GNUC__
41 template<>
42 inline constexpr unsigned clz(unsigned n) noexcept
43 {
44 return __builtin_clz(n);
45 }
46
47 template<>
48 inline constexpr unsigned clz(unsigned long n) noexcept
49 {
50 return __builtin_clzl(n);
51 }
52
53 template<>
54 inline constexpr unsigned clz(unsigned long long n) noexcept
55 {
56 return __builtin_clzll(n);
57 }
58#endif
59}
Definition: automata.hh:26

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