d1cc45f223
__builtin_clz() can be implemented with two x86 instructions, so we don't want to hide it behind a function call. * spot/misc/clz.cc: Delete the implementation. * spot/misc/Makefile.am: Delete clz.cc. * spot/misc/clz.hh: Make the implementation public.
60 lines
1.5 KiB
C++
60 lines
1.5 KiB
C++
// -*- coding: utf-8 -*-
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// Copyright (C) 2018, 2021 Laboratoire de Recherche et Développement
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// de l'Epita (LRDE).
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//
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// This file is part of Spot, a model checking library.
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//
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// Spot is free software; you can redistribute it and/or modify it
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// under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 3 of the License, or
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// (at your option) any later version.
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//
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// Spot is distributed in the hope that it will be useful, but WITHOUT
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// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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// or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
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// License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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#pragma once
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#include <spot/misc/common.hh>
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#include <cstddef>
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#include <climits>
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namespace spot
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{
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template<typename Type,
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typename = std::enable_if_t<std::is_unsigned<Type>::value>>
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inline constexpr unsigned clz(Type n) noexcept
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{
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unsigned res = CHAR_BIT * sizeof(Type);
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while (n)
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{
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--res;
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n >>= 1;
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}
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return res;
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}
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#if __GNUC__
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template<>
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inline constexpr unsigned clz(unsigned n) noexcept
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{
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return __builtin_clz(n);
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}
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template<>
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inline constexpr unsigned clz(unsigned long n) noexcept
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{
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return __builtin_clzl(n);
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}
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template<>
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inline constexpr unsigned clz(unsigned long long n) noexcept
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{
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return __builtin_clzll(n);
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}
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#endif
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}
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