chromium/third_party/eigen3/src/unsupported/Eigen/CXX11/src/Tensor/TensorIntDiv.h

// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2014 Benoit Steiner <[email protected]>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.

#ifndef EIGEN_CXX11_TENSOR_TENSOR_INTDIV_H
#define EIGEN_CXX11_TENSOR_TENSOR_INTDIV_H

// IWYU pragma: private
#include "./InternalHeaderCheck.h"

namespace Eigen {

/** \internal
 *
 * \class TensorIntDiv
 * \ingroup CXX11_Tensor_Module
 *
 * \brief Fast integer division by a constant.
 *
 * See the paper from Granlund and Montgomery for explanation.
 *   (at https://doi.org/10.1145/773473.178249)
 *
 * \sa Tensor
 */

namespace internal {

// Note: result is undefined if val == 0
template <typename T>
EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE std::enable_if_t<sizeof(T) == 4, int> count_leading_zeros(const T val) { … }

template <typename T>
EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE std::enable_if_t<sizeof(T) == 8, int> count_leading_zeros(const T val) { … }

template <typename T>
struct UnsignedTraits { … };

template <typename T>
struct DividerTraits { … };

template <typename T>
EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE uint32_t muluh(const uint32_t a, const T b) { … }

template <typename T>
EIGEN_DEVICE_FUNC EIGEN_ALWAYS_INLINE uint64_t muluh(const uint64_t a, const T b) { … }

template <int N, typename T>
struct DividerHelper { … };

DividerHelper<64, T>;

template <typename T, bool div_gt_one = false>
struct TensorIntDivisor { … };

// Optimized version for signed 32 bit integers.
// Derived from Hacker's Delight.
// Only works for divisors strictly greater than one
template <>
class TensorIntDivisor<int32_t, true> { … };

template <typename T, bool div_gt_one>
EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE T operator/(const T& numerator, const TensorIntDivisor<T, div_gt_one>& divisor) { … }

}  // end namespace internal
}  // end namespace Eigen

#endif  // EIGEN_CXX11_TENSOR_TENSOR_INTDIV_H