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Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
// 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_FAST_UNIFORM_BITS_H_
#define ABSL_RANDOM_INTERNAL_FAST_UNIFORM_BITS_H_
#include <cstddef>
#include <cstdint>
#include <limits>
#include <type_traits>
#include "absl/base/config.h"
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
#include "absl/meta/type_traits.h"
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace random_internal {
// Returns true if the input value is zero or a power of two. Useful for
// determining if the range of output values in a URBG
template <typename UIntType>
constexpr bool IsPowerOfTwoOrZero(UIntType n) {
return (n == 0) || ((n & (n - 1)) == 0);
}
// Computes the length of the range of values producible by the URBG, or returns
// zero if that would encompass the entire range of representable values in
// URBG::result_type.
template <typename URBG>
constexpr typename URBG::result_type RangeSize() {
using result_type = typename URBG::result_type;
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
static_assert((URBG::max)() != (URBG::min)(), "URBG range cannot be 0.");
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
return ((URBG::max)() == (std::numeric_limits<result_type>::max)() &&
(URBG::min)() == std::numeric_limits<result_type>::lowest())
? result_type{0}
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
: ((URBG::max)() - (URBG::min)() + result_type{1});
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
}
// Computes the floor of the log. (i.e., std::floor(std::log2(N));
template <typename UIntType>
constexpr UIntType IntegerLog2(UIntType n) {
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
return (n <= 1) ? 0 : 1 + IntegerLog2(n >> 1);
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
}
// Returns the number of bits of randomness returned through
// `PowerOfTwoVariate(urbg)`.
template <typename URBG>
constexpr size_t NumBits() {
return RangeSize<URBG>() == 0
? std::numeric_limits<typename URBG::result_type>::digits
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
: IntegerLog2(RangeSize<URBG>());
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
}
// Given a shift value `n`, constructs a mask with exactly the low `n` bits set.
// If `n == 0`, all bits are set.
template <typename UIntType>
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
constexpr UIntType MaskFromShift(size_t n) {
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
return ((n % std::numeric_limits<UIntType>::digits) == 0)
? ~UIntType{0}
: (UIntType{1} << n) - UIntType{1};
}
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
// Tags used to dispatch FastUniformBits::generate to the simple or more complex
// entropy extraction algorithm.
struct SimplifiedLoopTag {};
struct RejectionLoopTag {};
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
// FastUniformBits implements a fast path to acquire uniform independent bits
// from a type which conforms to the [rand.req.urbg] concept.
// Parameterized by:
// `UIntType`: the result (output) type
//
// The std::independent_bits_engine [rand.adapt.ibits] adaptor can be
// instantiated from an existing generator through a copy or a move. It does
// not, however, facilitate the production of pseudorandom bits from an un-owned
// generator that will outlive the std::independent_bits_engine instance.
template <typename UIntType = uint64_t>
class FastUniformBits {
public:
using result_type = UIntType;
static constexpr result_type(min)() { return 0; }
static constexpr result_type(max)() {
return (std::numeric_limits<result_type>::max)();
}
template <typename URBG>
result_type operator()(URBG& g); // NOLINT(runtime/references)
private:
static_assert(std::is_unsigned<UIntType>::value,
"Class-template FastUniformBits<> must be parameterized using "
"an unsigned type.");
// Generate() generates a random value, dispatched on whether
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
// the underlying URBG must use rejection sampling to generate a value,
// or whether a simplified loop will suffice.
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
template <typename URBG>
result_type Generate(URBG& g, // NOLINT(runtime/references)
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
SimplifiedLoopTag);
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
template <typename URBG>
result_type Generate(URBG& g, // NOLINT(runtime/references)
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
RejectionLoopTag);
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
};
template <typename UIntType>
template <typename URBG>
typename FastUniformBits<UIntType>::result_type
FastUniformBits<UIntType>::operator()(URBG& g) { // NOLINT(runtime/references)
// kRangeMask is the mask used when sampling variates from the URBG when the
// width of the URBG range is not a power of 2.
// Y = (2 ^ kRange) - 1
static_assert((URBG::max)() > (URBG::min)(),
"URBG::max and URBG::min may not be equal.");
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
using tag = absl::conditional_t<IsPowerOfTwoOrZero(RangeSize<URBG>()),
SimplifiedLoopTag, RejectionLoopTag>;
return Generate(g, tag{});
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
}
template <typename UIntType>
template <typename URBG>
typename FastUniformBits<UIntType>::result_type
FastUniformBits<UIntType>::Generate(URBG& g, // NOLINT(runtime/references)
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
SimplifiedLoopTag) {
// The simplified version of FastUniformBits works only on URBGs that have
// a range that is a power of 2. In this case we simply loop and shift without
// attempting to balance the bits across calls.
static_assert(IsPowerOfTwoOrZero(RangeSize<URBG>()),
"incorrect Generate tag for URBG instance");
static constexpr size_t kResultBits =
std::numeric_limits<result_type>::digits;
static constexpr size_t kUrbgBits = NumBits<URBG>();
static constexpr size_t kIters =
(kResultBits / kUrbgBits) + (kResultBits % kUrbgBits != 0);
static constexpr size_t kShift = (kIters == 1) ? 0 : kUrbgBits;
static constexpr auto kMin = (URBG::min)();
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
result_type r = static_cast<result_type>(g() - kMin);
for (size_t n = 1; n < kIters; ++n) {
r = (r << kShift) + static_cast<result_type>(g() - kMin);
}
return r;
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
}
template <typename UIntType>
template <typename URBG>
typename FastUniformBits<UIntType>::result_type
FastUniformBits<UIntType>::Generate(URBG& g, // NOLINT(runtime/references)
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
RejectionLoopTag) {
static_assert(!IsPowerOfTwoOrZero(RangeSize<URBG>()),
"incorrect Generate tag for URBG instance");
using urbg_result_type = typename URBG::result_type;
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
// See [rand.adapt.ibits] for more details on the constants calculated below.
//
// It is preferable to use roughly the same number of bits from each generator
// call, however this is only possible when the number of bits provided by the
// URBG is a divisor of the number of bits in `result_type`. In all other
// cases, the number of bits used cannot always be the same, but it can be
// guaranteed to be off by at most 1. Thus we run two loops, one with a
// smaller bit-width size (`kSmallWidth`) and one with a larger width size
// (satisfying `kLargeWidth == kSmallWidth + 1`). The loops are run
// `kSmallIters` and `kLargeIters` times respectively such
// that
//
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
// `kResultBits == kSmallIters * kSmallBits
// + kLargeIters * kLargeBits`
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
//
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
// where `kResultBits` is the total number of bits in `result_type`.
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
//
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
static constexpr size_t kResultBits =
std::numeric_limits<result_type>::digits; // w
static constexpr urbg_result_type kUrbgRange = RangeSize<URBG>(); // R
static constexpr size_t kUrbgBits = NumBits<URBG>(); // m
// compute the initial estimate of the bits used.
// [rand.adapt.ibits] 2 (c)
static constexpr size_t kA = // ceil(w/m)
(kResultBits / kUrbgBits) + ((kResultBits % kUrbgBits) != 0); // n'
static constexpr size_t kABits = kResultBits / kA; // w0'
static constexpr urbg_result_type kARejection =
((kUrbgRange >> kABits) << kABits); // y0'
// refine the selection to reduce the rejection frequency.
static constexpr size_t kTotalIters =
((kUrbgRange - kARejection) <= (kARejection / kA)) ? kA : (kA + 1); // n
// [rand.adapt.ibits] 2 (b)
static constexpr size_t kSmallIters =
kTotalIters - (kResultBits % kTotalIters); // n0
static constexpr size_t kSmallBits = kResultBits / kTotalIters; // w0
static constexpr urbg_result_type kSmallRejection =
((kUrbgRange >> kSmallBits) << kSmallBits); // y0
static constexpr size_t kLargeBits = kSmallBits + 1; // w0+1
static constexpr urbg_result_type kLargeRejection =
((kUrbgRange >> kLargeBits) << kLargeBits); // y1
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
//
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
// Because `kLargeBits == kSmallBits + 1`, it follows that
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
//
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
// `kResultBits == kSmallIters * kSmallBits + kLargeIters`
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
//
// and therefore
//
// `kLargeIters == kTotalWidth % kSmallWidth`
//
// Intuitively, each iteration with the large width accounts for one unit
// of the remainder when `kTotalWidth` is divided by `kSmallWidth`. As
// mentioned above, if the URBG width is a divisor of `kTotalWidth`, then
// there would be no need for any large iterations (i.e., one loop would
// suffice), and indeed, in this case, `kLargeIters` would be zero.
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
static_assert(kResultBits == kSmallIters * kSmallBits +
(kTotalIters - kSmallIters) * kLargeBits,
"Error in looping constant calculations.");
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
// The small shift is essentially small bits, but due to the potential
// of generating a smaller result_type from a larger urbg type, the actual
// shift might be 0.
static constexpr size_t kSmallShift = kSmallBits % kResultBits;
static constexpr auto kSmallMask =
MaskFromShift<urbg_result_type>(kSmallShift);
static constexpr size_t kLargeShift = kLargeBits % kResultBits;
static constexpr auto kLargeMask =
MaskFromShift<urbg_result_type>(kLargeShift);
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
static constexpr auto kMin = (URBG::min)();
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
result_type s = 0;
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
for (size_t n = 0; n < kSmallIters; ++n) {
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
urbg_result_type v;
do {
v = g() - kMin;
} while (v >= kSmallRejection);
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
s = (s << kSmallShift) + static_cast<result_type>(v & kSmallMask);
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
}
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
for (size_t n = kSmallIters; n < kTotalIters; ++n) {
urbg_result_type v;
do {
v = g() - kMin;
} while (v >= kLargeRejection);
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
Export of internal Abseil changes -- 4833151c207fac9f57a735efe6d5db4c83368415 by Gennadiy Rozental <rogeeff@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 320398694 -- a1becb36b223230f0a45f204a5fb33b83d2deffe by Gennadiy Rozental <rogeeff@google.com>: Update CMakeLists.txt Import of https://github.com/abseil/abseil-cpp/pull/737 PiperOrigin-RevId: 320391906 -- b529c45856fe7a3447f1f3259286d57e13b1f292 by Abseil Team <absl-team@google.com>: Improves a comment about use of absl::Condition. PiperOrigin-RevId: 320384329 -- c7b1dacda2739c10dc1ccbfb56b07ed7fe2464a4 by Laramie Leavitt <lar@google.com>: Improve FastUniformBits performance for std::minstd_rand. The rejection algorithm was too pessimistic before, and not in line with the [rand.adapt.ibits]. Specifically, when sampling from an URBG with a non power of 2 range, FastUniformBits constructed a rejection threshold with a power-of-2 range that was too restrictive. For example, minstd_rand has a range of [1, 2147483646], which has a range of 2145386495, or about 30.999 bits. Before FastUniformBits rejected values between 1<<30 and 2145386495, which includes approximately 50% of the generated values. However, since a minimum of 3 calls are required to generate a full 64-bit value from an entropy pool of 30.9 bits, the correct value for rejection sampling is the range value which masks 21 (0x7fe00000) or 22 bits and rejects values greater than that. This reduces the probability of rejecting a sample to about 0.1% NOTE: Abseil random does not guarantee sequence stability over time, and this is expected to change sequences in some cases. PiperOrigin-RevId: 320285836 -- 15800a39557a07dd52e0add66a0ab67aed00590b by Gennadiy Rozental <rogeeff@google.com>: Internal change. PiperOrigin-RevId: 320220913 -- ef39348360873f6d19669755fe0b5d09a945a501 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320181729 -- 4f9f6ef8034a24da1832e4c838c72f80fc2ea062 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176084 -- 6bfc8008462801657d231585bd5c37fc18bb25b6 by Gennadiy Rozental <rogeeff@google.com>: Internal change PiperOrigin-RevId: 320176070 -- b35b055ab1f41e6056031ff0641cabab23530027 by Abseil Team <absl-team@google.com>: Disabling using header module as well as building one for randen_hwaes_impl PiperOrigin-RevId: 320024299 GitOrigin-RevId: 4833151c207fac9f57a735efe6d5db4c83368415 Change-Id: I9cf102dbf46ed07752a508b7cda3ab3858857d0d
4 years ago
s = (s << kLargeShift) + static_cast<result_type>(v & kLargeMask);
}
Export of internal Abseil changes -- f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>: Slight restructuring of absl/random/internal randen implementation. Convert round-keys.inc into randen_round_keys.cc file. Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts. Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed. PiperOrigin-RevId: 312190313 -- dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>: Internal change. PiperOrigin-RevId: 312167304 -- f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>: Cleanup StrFormat extensions a little. PiperOrigin-RevId: 312166336 -- 9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 312105213 -- 9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>: Complete IGNORE_TYPE macro renaming. PiperOrigin-RevId: 311999699 -- 64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>: Switch to fixed bytes specific default value. This fixes the Abseil Flags for big endian platforms. PiperOrigin-RevId: 311844448 -- bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>: Change many distribution tests to use pcg_engine as a deterministic source of entropy. It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests. Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values. This changelist does the latter. PiperOrigin-RevId: 311840096 GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266 Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
5 years ago
return s;
}
} // namespace random_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif // ABSL_RANDOM_INTERNAL_FAST_UNIFORM_BITS_H_