chromium/third_party/abseil-cpp/absl/random/internal/wide_multiply.h

// Copyright 2017 The Abseil Authors.
//
// 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
//
//      https://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 ABSL_RANDOM_INTERNAL_WIDE_MULTIPLY_H_
#define ABSL_RANDOM_INTERNAL_WIDE_MULTIPLY_H_

#include <cstdint>
#include <limits>
#include <type_traits>

#if (defined(_WIN32) || defined(_WIN64)) && defined(_M_IA64)
#include <intrin.h>  // NOLINT(build/include_order)
#pragma intrinsic(_umul128)
#define ABSL_INTERNAL_USE_UMUL128 …
#endif

#include "absl/base/config.h"
#include "absl/numeric/bits.h"
#include "absl/numeric/int128.h"
#include "absl/random/internal/traits.h"

namespace absl {
ABSL_NAMESPACE_BEGIN
namespace random_internal {

// wide_multiply<T> multiplies two N-bit values to a 2N-bit result.
template <typename UIntType>
struct wide_multiply { … };

// MultiplyU128ToU256 multiplies two 128-bit values to a 256-bit value.
inline U256 MultiplyU128ToU256(uint128 a, uint128 b) { … }


template <>
struct wide_multiply<uint128> { … };

}  // namespace random_internal
ABSL_NAMESPACE_END
}  // namespace absl

#endif  // ABSL_RANDOM_INTERNAL_WIDE_MULTIPLY_H_