THUAI6/CAPI/cpp/grpc/include/absl/random/internal/randen.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_RANDEN_H_
#define ABSL_RANDOM_INTERNAL_RANDEN_H_

#include <cstddef>

#include "absl/random/internal/platform.h"
#include "absl/random/internal/randen_hwaes.h"
#include "absl/random/internal/randen_slow.h"
#include "absl/random/internal/randen_traits.h"

namespace absl
{
    ABSL_NAMESPACE_BEGIN
    namespace random_internal
    {

        // RANDen = RANDom generator or beetroots in Swiss High German.
        // 'Strong' (well-distributed, unpredictable, backtracking-resistant) random
        // generator, faster in some benchmarks than std::mt19937_64 and pcg64_c32.
        //
        // Randen implements the basic state manipulation methods.
        class Randen
        {
        public:
            static constexpr size_t kStateBytes = RandenTraits::kStateBytes;
            static constexpr size_t kCapacityBytes = RandenTraits::kCapacityBytes;
            static constexpr size_t kSeedBytes = RandenTraits::kSeedBytes;

            ~Randen() = default;

            Randen();

            // Generate updates the randen sponge. The outer portion of the sponge
            // (kCapacityBytes .. kStateBytes) may be consumed as PRNG state.
            // REQUIRES: state points to kStateBytes of state.
            inline void Generate(void* state) const
            {
#if ABSL_RANDOM_INTERNAL_AES_DISPATCH
                // HW AES Dispatch.
                if (has_crypto_)
                {
                    RandenHwAes::Generate(keys_, state);
                }
                else
                {
                    RandenSlow::Generate(keys_, state);
                }
#elif ABSL_HAVE_ACCELERATED_AES
                // HW AES is enabled.
                RandenHwAes::Generate(keys_, state);
#else
                // HW AES is disabled.
                RandenSlow::Generate(keys_, state);
#endif
            }

            // Absorb incorporates additional seed material into the randen sponge.  After
            // absorb returns, Generate must be called before the state may be consumed.
            // REQUIRES: seed points to kSeedBytes of seed.
            // REQUIRES: state points to kStateBytes of state.
            inline void Absorb(const void* seed, void* state) const
            {
#if ABSL_RANDOM_INTERNAL_AES_DISPATCH
                // HW AES Dispatch.
                if (has_crypto_)
                {
                    RandenHwAes::Absorb(seed, state);
                }
                else
                {
                    RandenSlow::Absorb(seed, state);
                }
#elif ABSL_HAVE_ACCELERATED_AES
                // HW AES is enabled.
                RandenHwAes::Absorb(seed, state);
#else
                // HW AES is disabled.
                RandenSlow::Absorb(seed, state);
#endif
            }

        private:
            const void* keys_;
#if ABSL_RANDOM_INTERNAL_AES_DISPATCH
            bool has_crypto_;
#endif
        };

    }  // namespace random_internal
    ABSL_NAMESPACE_END
}  // namespace absl

#endif  // ABSL_RANDOM_INTERNAL_RANDEN_H_