From aa844899c937bde5d2b24f276b59997e5b668bde Mon Sep 17 00:00:00 2001 From: Abseil Team Date: Thu, 8 Aug 2019 10:56:58 -0700 Subject: Creation of LTS branch "lts_2019_08_08" - 9ee91d3e430fb33a4590486573792eb0fa146c2d Export of internal Abseil changes by Abseil Team - 8efba58a3b656e9b41fb0471ae6453425a61c520 Export of internal Abseil changes by Abseil Team - b49b8d16b67ec6912899684b732e6367f258cfdb Export of internal Abseil changes by Abseil Team - 67222ffc4c83d918ce8395aa61769eeb77df4c4d Export of internal Abseil changes by Abseil Team - c5c4db4f5191fe5e76cbf68dcc71fb28702f7d2b Export of internal Abseil changes by Abseil Team - 14550beb3b7b97195e483fb74b5efb906395c31e Export of internal Abseil changes. by Abseil Team - 52e88ee56b72cf32bc66534d942c7398ce481331 Export of internal Abseil changes. by Abseil Team - 36d37ab992038f52276ca66b9da80c1cf0f57dc2 Export of internal Abseil changes. by Abseil Team - ad1485c8986246b2ae9105e512738d0e97aec887 Export of internal Abseil changes. by Abseil Team - f3840bc5e33ce4932e35986cf3718450c6f02af2 Export of internal Abseil changes. by Abseil Team - 278b26058c036833a4f7f3047d3f4d9296527f87 Export of internal Abseil changes. by Abseil Team - c6c3c1b498e4ee939b24be59cae29d59c3863be8 Export of internal Abseil changes. by Abseil Team - 44efe96dfca674a17b45ca53fc77fb69f1e29bf4 Export of internal Abseil changes. by Abseil Team - 3c98fcc0461bd2a4b9c149d4748a7373a225cf4b Merge pull request #340 from jtsylve/macos_cxx17_fix by Matt Calabrese <38107210+mattcalabrese-google@users.noreply.github.com> - 74d91756c11bc22f9b0108b94da9326f7f9e376f Export of internal Abseil changes. by Abseil Team - e6b050212c859fbaf67abac76105da10ec348274 Export of internal Abseil changes. by Abseil Team - c964fcffac27bd4a9ff67fe393410dd1146ef8b8 Export of internal Abseil changes. by Abseil Team - 72e09a54d993b192db32be14c65adf7e9bd08c31 Export of internal Abseil changes. by Abseil Team - d65e19dfcd8697076f68598c0131c6930cdcd74d Export of internal Abseil changes. by Abseil Team - 5162fc83d2f3b79a9753ed59594c43966afdd37a Merge pull request #336 from shields/patch-2 by Shaindel Schwartz <31392632+shaindelschwartz@users.noreply.github.com> - 0389f7bf58fa41f35b3ad60be61d32f31e4f8ed6 Merge pull request #335 from shields/patch-1 by Shaindel Schwartz <31392632+shaindelschwartz@users.noreply.github.com> - e9324d926a9189e222741fce6e676f0944661a72 Export of internal Abseil changes. by Abseil Team - 43ef2148c0936ebf7cb4be6b19927a9d9d145b8f Export of internal Abseil changes. by Abseil Team - a13d3df2b3ba68aeead92e2d078fba0510d55024 Merge pull request #323 from gosnik/master by Gennadiy Rozental - 310a11865c97c5cdcc42a4ee2c2e3578423afe69 Merge pull request #324 from RasPat1/patch-1 by Gennadiy Rozental - 8f11724067248acc330b4d1f12f0c76d03f2cfb1 Export of internal Abseil changes. by Abseil Team - b1dd425423380126f6441ce4fbb6f8f6c75b793a Export of internal Abseil changes. by Abseil Team - 361cb8a9db2f2130442389fd80593255be26d681 Export of internal Abseil changes. by Abseil Team - 0238ab0a831f179518c1a814f9584e99da2d75a3 Merge pull request #321 from christoph-cullmann/c4245_fix... by Xiaoyi Zhang - 61c9bf3e3e1c28a4aa6d7f1be4b37fd473bb5529 Export of internal Abseil changes. by Abseil Team - bc9101f9982391019521161a36179b52555ed212 Merge pull request #320 from christoph-cullmann/master by Xiaoyi Zhang - 2f76a9bf50046e396138cc8eeb3cdc17b7a5ac24 Export of internal Abseil changes. by Abseil Team - 4adaf5490921f13028b55018c9f550277de5aebb Export of internal Abseil changes. by Abseil Team - 27c30ec671cb7b5ba84c4e79feff7fd0b0ac6338 Avoid undefined behavior when nullptr is passed to memcpy... by Roman Gershman - ce65f5ac3cbf897bb5e3de1a51d80fd00866abaa Export of internal Abseil changes. by Abseil Team - a18fc7461e7409c2ad64e28537261db1e02e76fa Export of internal Abseil changes. by Abseil Team - 8a394b19c149cab50534b04c5e21d42bc2217a7d Export of internal Abseil changes. by Abseil Team - daf381e8535a1f1f1b8a75966a74e7cca63dee89 Export of internal Abseil changes. by Abseil Team - fa00c321073c7ea40a4fc3dfc8a06309eae3d025 Export of internal Abseil changes. by Abseil Team - 436ba6c4a0ea3a06eca6e055f9c8d296bf3bae12 Export of internal Abseil changes. by Abseil Team - 0cbdc774b97f7e80ab60dbe2ed4eaca3b2e33fc8 Export of internal Abseil changes. by Abseil Team - 27c2f6e2f3b5929fbd322b0f0ca392eb02efd9f8 Export of internal Abseil changes. by Abseil Team - aa468ad75539619b47979911297efbb629c52e44 Export of internal Abseil changes. by Abseil Team - cd86d0d20ab167c33b23d3875db68d1d4bad3a3b Export of internal Abseil changes. by Abseil Team - 33841c5c963aa9c3f096ef8e6c1e71624b941940 Export of internal Abseil changes. by Abseil Team - ca3f87560a0eef716195cadf66dc6b938a579ec6 Export of internal Abseil changes. by Abseil Team - d902eb869bcfacc1bad14933ed9af4bed006d481 Export of internal Abseil changes. by Abseil Team - a02f62f456f2c4a7ecf2be3104fe0c6e16fbad9a Export of internal Abseil changes. by Abseil Team - 0b545b460141b882b244a1efcef7621d59278160 Export of internal Abseil changes. by Abseil Team - dbae8764fbd429bf7d7745e24bcf73962177a7c0 Export of internal Abseil changes. by Abseil Team - 044da8a29c923506af0f0b46bc46f43c1e1300b5 Export of internal Abseil changes. by Abseil Team - 6cc6ac44e065b9e8975fadfd6ccb99cbcf89aac4 Export of internal Abseil changes. by Abseil Team - 666fc1266bccfd8e6eaaa084e7b42580bb8eb199 Export of internal Abseil changes. by Abseil Team - 93dfcf74cb5fccae3da07897d8613ae6cab958a0 Export of internal Abseil changes. by Abseil Team - 2c8421e1c6cef0da9e8a20b01c15256ec9ec116d Export of internal Abseil changes. by Abseil Team - 5b65c4af5107176555b23a638e5947686410ac1f Export of internal Abseil changes. by Abseil Team - eab2078b53c9e3d9d240135c09d27e3393acb50a Export of internal Abseil changes. by Abseil Team - 253eb7416421661873afbaa33828a850db978541 [CMake] Set correct flags for clang-cl (#278) by Loo Rong Jie - e75672f6afc7e8f23ee7b532e86d1b3b9be3984e Export of internal Abseil changes. by Abseil Team - bf29470384a101b307873b26d358433138c857fc Export of internal Abseil changes. by Abseil Team - 6fd827124facd8336981e73218997f9e73029b4f Merge pull request #280 from chiumichael/master by Derek Mauro <761129+derekmauro@users.noreply.github.com> - 7c7754fb3ed9ffb57d35fe8658f3ba4d73a31e72 Export of internal Abseil changes. by Abseil Team - 256be563447a315f2a7993ec669460ba475fa86a Export of internal Abseil changes. by Abseil Team - 88a152ae747c3c42dc9167d46c590929b048d436 Export of internal Abseil changes. by Abseil Team - c1cecb25a94c075725e9d2640f6b978a8f61957b Implement Span::first and Span::last from C++20 (#274) by Girts - 38b704384cd2f17590b3922b97744be0b43622c9 Changed HTTP URLs to HTTPS where possible (#270) by nik7273 - febc5ee6a92d0eb7dac1fceaa6c648cf6521b4dc Export of internal Abseil changes. by Abseil Team - 9fdf5e5b805412cb2a2e624d3e9a11588120465f Export of internal Abseil changes. by Abseil Team - 419f3184f8ebcdb23105295eadd2a569f3351eb9 Export of internal Abseil changes. by Abseil Team - b312c3cb53a0aad75a85ac2bf57c4a614fbd48d4 Export of internal Abseil changes. by Abseil Team - 308ce31528a7edfa39f5f6d36142278a0ae1bf45 Export of internal Abseil changes. by Abseil Team - 93d155bc4414f6c121bb1f19dba9fdb27c8943bc Export of internal Abseil changes. by Abseil Team - 426eaa4aa44e4580418bee46c1bd13911151bfb1 Export of internal Abseil changes. by Abseil Team - 2901ec32a919311384d6ad4194e2d927c06831f7 Export of internal Abseil changes. by Abseil Team - d78310fe5a82f2e0e6e16509ef8079c8d7e4674e Export of internal Abseil changes. by Abseil Team - a4cb1c8ba61531a63f9d309eea01ac1d43d8371d Export of internal Abseil changes. by Abseil Team - 540e2537b92cd4abfae6ceddfe24304345461f32 Export of internal Abseil changes. by Abseil Team - 89ea0c5ff34aaa5855cfc7aa41f323b8a0ef0ede Merge pull request #255 from uilianries/hotfix/conan by ahedberg - 5e0dcf72c64fae912184d2e0de87195fe8f0a425 Export of internal Abseil changes. by Abseil Team - 0dffca4e36791c7beeda04da10460b534283948a Export of internal Abseil changes. by Abseil Team - 6b4201f9ef650637510a21b8d6cbcc3bee4a606f Fix GCC8 warnings by Boris Staletic - 0b1e6d417b414aad9282e32e8c49c719edeb63c1 Export of internal Abseil changes. by Abseil Team - efccc502606bed768e50a6cd5806d8eb13e4e935 Export of internal Abseil changes. by Abseil Team - 5e6a78131f7bd5940218462c07d88cdefdd75dbe Export of internal Abseil changes. by Abseil Team - 5eea0f713c14ac17788b83e496f11903f8e2bbb0 Export of internal Abseil changes. by Abseil Team - 66f9becbb98ecc083f4db349b4b1e0ca9de93b15 Export of internal Abseil changes. by Abseil Team - 018b4db1d73ec8238e6dc4b17fd9e1fd7468d0ed Export of internal Abseil changes. by Abseil Team - 9449ae94397f2fd683851348e25ed8c93f75b3b9 Merge pull request #243 from ThomsonTan/FixIntrinsic by Alex Strelnikov - b16aeb6756bdab08cdf12d40baab5b51f7d15b16 Export of internal Abseil changes. by Abseil Team - 7ffbe09f3d85504bd018783bbe1e2c12992fe47c Export of internal Abseil changes. by Abseil Team - 01b471d9f3ebef27f5aaca14b66509099fa8cd6c Export of internal Abseil changes. by Abseil Team - 7bd8f36c741c7cbe311611d7981bf38ba04c6fef Export of internal Abseil changes. by Abseil Team - 968a34ffdaadd7db062a9621dfbdf8b2d16e05af Export of internal Abseil changes. by Abseil Team - 3e2e9b5557e76d098de4b8a2a659125b98ca519b Merge pull request #231 from uilianries/feature/conan by Mark Barolak - 111ca7060a6ff50115ca85b59f6b5d8c8c5e9105 Export of internal Abseil changes. by Abseil Team - 389ec3f906f018661a5308458d623d01f96d7b23 Export of internal Abseil changes. by Abseil Team - 8fbcdb90952c57828c4a9c2f6d79fcd7cae9088f Export of internal Abseil changes. by Abseil Team - 455dc17ba1af9635f0b60155bc565bc572a1e722 Export of internal Abseil changes. by Abseil Team - f197d7c72a54064cfde5a2058f1513a4a0ee36fb Export of internal Abseil changes. by Abseil Team - 284378a71b32dfb3af4e3661f585e671d1b603a3 Export of internal Abseil changes. by Abseil Team GitOrigin-RevId: 9ee91d3e430fb33a4590486573792eb0fa146c2d Change-Id: Ia06e548bc106cc9d136f6c65714be6645317aced --- absl/random/internal/randen_engine.h | 230 +++++++++++++++++++++++++++++++++++ 1 file changed, 230 insertions(+) create mode 100644 absl/random/internal/randen_engine.h (limited to 'absl/random/internal/randen_engine.h') diff --git a/absl/random/internal/randen_engine.h b/absl/random/internal/randen_engine.h new file mode 100644 index 00000000..e721559e --- /dev/null +++ b/absl/random/internal/randen_engine.h @@ -0,0 +1,230 @@ +// 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_ENGINE_H_ +#define ABSL_RANDOM_INTERNAL_RANDEN_ENGINE_H_ + +#include +#include +#include +#include +#include +#include +#include + +#include "absl/meta/type_traits.h" +#include "absl/random/internal/iostream_state_saver.h" +#include "absl/random/internal/randen.h" + +namespace absl { +inline namespace lts_2019_08_08 { +namespace random_internal { + +// Deterministic pseudorandom byte generator with backtracking resistance +// (leaking the state does not compromise prior outputs). Based on Reverie +// (see "A Robust and Sponge-Like PRNG with Improved Efficiency") instantiated +// with an improved Simpira-like permutation. +// Returns values of type "T" (must be a built-in unsigned integer type). +// +// 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. +template +class alignas(16) randen_engine { + public: + // C++11 URBG interface: + using result_type = T; + static_assert(std::is_unsigned::value, + "randen_engine template argument must be a built-in unsigned " + "integer type"); + + static constexpr result_type(min)() { + return (std::numeric_limits::min)(); + } + + static constexpr result_type(max)() { + return (std::numeric_limits::max)(); + } + + explicit randen_engine(result_type seed_value = 0) { seed(seed_value); } + + template ::value>> + explicit randen_engine(SeedSequence&& seq) { + seed(seq); + } + + randen_engine(const randen_engine&) = default; + + // Returns random bits from the buffer in units of result_type. + result_type operator()() { + // Refill the buffer if needed (unlikely). + if (next_ >= kStateSizeT) { + next_ = kCapacityT; + impl_.Generate(state_); + } + + return state_[next_++]; + } + + template + typename absl::enable_if_t< + !std::is_convertible::value> + seed(SeedSequence&& seq) { + // Zeroes the state. + seed(); + reseed(seq); + } + + void seed(result_type seed_value = 0) { + next_ = kStateSizeT; + // Zeroes the inner state and fills the outer state with seed_value to + // mimics behaviour of reseed + std::fill(std::begin(state_), std::begin(state_) + kCapacityT, 0); + std::fill(std::begin(state_) + kCapacityT, std::end(state_), seed_value); + } + + // Inserts entropy into (part of) the state. Calling this periodically with + // sufficient entropy ensures prediction resistance (attackers cannot predict + // future outputs even if state is compromised). + template + void reseed(SeedSequence& seq) { + using sequence_result_type = typename SeedSequence::result_type; + static_assert(sizeof(sequence_result_type) == 4, + "SeedSequence::result_type must be 32-bit"); + + constexpr size_t kBufferSize = + Randen::kSeedBytes / sizeof(sequence_result_type); + alignas(16) sequence_result_type buffer[kBufferSize]; + + // Randen::Absorb XORs the seed into state, which is then mixed by a call + // to Randen::Generate. Seeding with only the provided entropy is preferred + // to using an arbitrary generate() call, so use [rand.req.seed_seq] + // size as a proxy for the number of entropy units that can be generated + // without relying on seed sequence mixing... + const size_t entropy_size = seq.size(); + if (entropy_size < kBufferSize) { + // ... and only request that many values, or 256-bits, when unspecified. + const size_t requested_entropy = (entropy_size == 0) ? 8u : entropy_size; + std::fill(std::begin(buffer) + requested_entropy, std::end(buffer), 0); + seq.generate(std::begin(buffer), std::begin(buffer) + requested_entropy); + // The Randen paper suggests preferentially initializing even-numbered + // 128-bit vectors of the randen state (there are 16 such vectors). + // The seed data is merged into the state offset by 128-bits, which + // implies prefering seed bytes [16..31, ..., 208..223]. Since the + // buffer is 32-bit values, we swap the corresponding buffer positions in + // 128-bit chunks. + size_t dst = kBufferSize; + while (dst > 7) { + // leave the odd bucket as-is. + dst -= 4; + size_t src = dst >> 1; + // swap 128-bits into the even bucket + std::swap(buffer[--dst], buffer[--src]); + std::swap(buffer[--dst], buffer[--src]); + std::swap(buffer[--dst], buffer[--src]); + std::swap(buffer[--dst], buffer[--src]); + } + } else { + seq.generate(std::begin(buffer), std::end(buffer)); + } + impl_.Absorb(buffer, state_); + + // Generate will be called when operator() is called + next_ = kStateSizeT; + } + + void discard(uint64_t count) { + uint64_t step = std::min(kStateSizeT - next_, count); + count -= step; + + constexpr uint64_t kRateT = kStateSizeT - kCapacityT; + while (count > 0) { + next_ = kCapacityT; + impl_.Generate(state_); + step = std::min(kRateT, count); + count -= step; + } + next_ += step; + } + + bool operator==(const randen_engine& other) const { + return next_ == other.next_ && + std::equal(std::begin(state_), std::end(state_), + std::begin(other.state_)); + } + + bool operator!=(const randen_engine& other) const { + return !(*this == other); + } + + template + friend std::basic_ostream& operator<<( + std::basic_ostream& os, // NOLINT(runtime/references) + const randen_engine& engine) { // NOLINT(runtime/references) + using numeric_type = + typename random_internal::stream_format_type::type; + auto saver = random_internal::make_ostream_state_saver(os); + for (const auto& elem : engine.state_) { + // In the case that `elem` is `uint8_t`, it must be cast to something + // larger so that it prints as an integer rather than a character. For + // simplicity, apply the cast all circumstances. + os << static_cast(elem) << os.fill(); + } + os << engine.next_; + return os; + } + + template + friend std::basic_istream& operator>>( + std::basic_istream& is, // NOLINT(runtime/references) + randen_engine& engine) { // NOLINT(runtime/references) + using numeric_type = + typename random_internal::stream_format_type::type; + result_type state[kStateSizeT]; + size_t next; + for (auto& elem : state) { + // It is not possible to read uint8_t from wide streams, so it is + // necessary to read a wider type and then cast it to uint8_t. + numeric_type value; + is >> value; + elem = static_cast(value); + } + is >> next; + if (is.fail()) { + return is; + } + std::memcpy(engine.state_, state, sizeof(engine.state_)); + engine.next_ = next; + return is; + } + + private: + static constexpr size_t kStateSizeT = + Randen::kStateBytes / sizeof(result_type); + static constexpr size_t kCapacityT = + Randen::kCapacityBytes / sizeof(result_type); + + // First kCapacityT are `inner', the others are accessible random bits. + alignas(16) result_type state_[kStateSizeT]; + size_t next_; // index within state_ + Randen impl_; +}; + +} // namespace random_internal +} // inline namespace lts_2019_08_08 +} // namespace absl + +#endif // ABSL_RANDOM_INTERNAL_RANDEN_ENGINE_H_ -- cgit v1.2.3