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// 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.
template <typename T, size_t N>
void Generate(T (&state)[N]) const {
static_assert(N * sizeof(T) == kStateBytes,
"Randen::Generate() requires kStateBytes of state");
#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.
template <typename S, size_t M, typename T, size_t N>
void Absorb(const S (&seed)[M], T (&state)[N]) const {
static_assert(M * sizeof(S) == RandenTraits::kSeedBytes,
"Randen::Absorb() requires kSeedBytes of seed");
static_assert(N * sizeof(T) == RandenTraits::kStateBytes,
"Randen::Absorb() requires kStateBytes of state");
#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_
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