packages/engine/scram/src/ext/bits.h

Helper constexpr functions to make bit operations explicit.

Namespaces

Name
ext

Source code

/*
 * Copyright (C) 2014-2018 Olzhas Rakhimov
 * Copyright (C) 2023 OpenPRA ORG Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */


#pragma once

namespace ext {

constexpr bool test_bit(std::uint64_t bits, int index)  {
  return bits & (std::uint64_t(1) << index);
}

constexpr int count_trailing_zero_bits(std::uint64_t bits)  {
#if defined(__GNUC__)
  return __builtin_ctzl(bits);
#else
  int i = 0;
  while (!test_bit(bits, i))
    ++i;
  return i;
#endif
}

constexpr int one_bit_index(std::uint64_t bits)  {
  return count_trailing_zero_bits(bits);
}

}  // namespace ext

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Updated on 2026-01-09 at 21:59:12 +0000