bits.h

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/*
 *    Copyright 2023 The ChampSim Contributors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 
#ifndef MSL_BITS_H
#define MSL_BITS_H
 
#include <cstdint>
#include <limits>
 
namespace champsim::msl
{
constexpr unsigned lg2(uint64_t n) { return n < 2 ? 0 : 1 + lg2(n / 2); }
 
constexpr uint64_t bitmask(std::size_t begin, std::size_t end = 0)
{
  return (begin - end < 64) ? ((1ull << (begin - end)) - 1) << end : std::numeric_limits<uint64_t>::max();
}
 
constexpr uint64_t splice_bits(uint64_t upper, uint64_t lower, std::size_t bits) { return (upper & ~bitmask(bits)) | (lower & bitmask(bits)); }
} // namespace champsim::msl
 
#endif