c6c3c1b498
-- ed3a3431eee9e48e6553b0320e0308d2dde6725c by Derek Mauro <dmauro@google.com>: Project import generated by Copybara. PiperOrigin-RevId: 258631680 GitOrigin-RevId: ed3a3431eee9e48e6553b0320e0308d2dde6725c Change-Id: I1d7ae86a79783842092d29504605ba039c369603
272 lines
11 KiB
C++
272 lines
11 KiB
C++
// Copyright 2017 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "absl/random/internal/fast_uniform_bits.h"
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#include <random>
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#include "gtest/gtest.h"
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namespace absl {
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namespace random_internal {
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namespace {
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template <typename IntType>
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class FastUniformBitsTypedTest : public ::testing::Test {};
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using IntTypes = ::testing::Types<uint8_t, uint16_t, uint32_t, uint64_t>;
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TYPED_TEST_SUITE(FastUniformBitsTypedTest, IntTypes);
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TYPED_TEST(FastUniformBitsTypedTest, BasicTest) {
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using Limits = std::numeric_limits<TypeParam>;
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using FastBits = FastUniformBits<TypeParam>;
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EXPECT_EQ(0, FastBits::min());
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EXPECT_EQ(Limits::max(), FastBits::max());
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constexpr int kIters = 10000;
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std::random_device rd;
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std::mt19937 gen(rd());
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FastBits fast;
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for (int i = 0; i < kIters; i++) {
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const auto v = fast(gen);
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EXPECT_LE(v, FastBits::max());
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EXPECT_GE(v, FastBits::min());
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}
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}
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template <typename UIntType, UIntType Lo, UIntType Hi, UIntType Val = Lo>
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struct FakeUrbg {
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using result_type = UIntType;
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static constexpr result_type(max)() { return Hi; }
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static constexpr result_type(min)() { return Lo; }
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result_type operator()() { return Val; }
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};
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using UrngOddbits = FakeUrbg<uint8_t, 1, 0xfe, 0x73>;
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using Urng4bits = FakeUrbg<uint8_t, 1, 0x10, 2>;
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using Urng31bits = FakeUrbg<uint32_t, 1, 0xfffffffe, 0x60070f03>;
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using Urng32bits = FakeUrbg<uint32_t, 0, 0xffffffff, 0x74010f01>;
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TEST(FastUniformBitsTest, IsPowerOfTwoOrZero) {
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EXPECT_TRUE(IsPowerOfTwoOrZero(uint8_t{0}));
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EXPECT_TRUE(IsPowerOfTwoOrZero(uint8_t{1}));
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EXPECT_TRUE(IsPowerOfTwoOrZero(uint8_t{2}));
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EXPECT_FALSE(IsPowerOfTwoOrZero(uint8_t{3}));
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EXPECT_TRUE(IsPowerOfTwoOrZero(uint8_t{16}));
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EXPECT_FALSE(IsPowerOfTwoOrZero(uint8_t{17}));
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EXPECT_FALSE(IsPowerOfTwoOrZero((std::numeric_limits<uint8_t>::max)()));
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EXPECT_TRUE(IsPowerOfTwoOrZero(uint16_t{0}));
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EXPECT_TRUE(IsPowerOfTwoOrZero(uint16_t{1}));
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EXPECT_TRUE(IsPowerOfTwoOrZero(uint16_t{2}));
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EXPECT_FALSE(IsPowerOfTwoOrZero(uint16_t{3}));
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EXPECT_TRUE(IsPowerOfTwoOrZero(uint16_t{16}));
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EXPECT_FALSE(IsPowerOfTwoOrZero(uint16_t{17}));
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EXPECT_FALSE(IsPowerOfTwoOrZero((std::numeric_limits<uint16_t>::max)()));
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EXPECT_TRUE(IsPowerOfTwoOrZero(uint32_t{0}));
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EXPECT_TRUE(IsPowerOfTwoOrZero(uint32_t{1}));
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EXPECT_TRUE(IsPowerOfTwoOrZero(uint32_t{2}));
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EXPECT_FALSE(IsPowerOfTwoOrZero(uint32_t{3}));
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EXPECT_TRUE(IsPowerOfTwoOrZero(uint32_t{32}));
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EXPECT_FALSE(IsPowerOfTwoOrZero(uint32_t{17}));
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EXPECT_FALSE(IsPowerOfTwoOrZero((std::numeric_limits<uint32_t>::max)()));
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EXPECT_TRUE(IsPowerOfTwoOrZero(uint64_t{0}));
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EXPECT_TRUE(IsPowerOfTwoOrZero(uint64_t{1}));
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EXPECT_TRUE(IsPowerOfTwoOrZero(uint64_t{2}));
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EXPECT_FALSE(IsPowerOfTwoOrZero(uint64_t{3}));
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EXPECT_TRUE(IsPowerOfTwoOrZero(uint64_t{64}));
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EXPECT_FALSE(IsPowerOfTwoOrZero(uint64_t{17}));
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EXPECT_FALSE(IsPowerOfTwoOrZero((std::numeric_limits<uint64_t>::max)()));
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}
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TEST(FastUniformBitsTest, IntegerLog2) {
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EXPECT_EQ(IntegerLog2(uint16_t{0}), 0);
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EXPECT_EQ(IntegerLog2(uint16_t{1}), 0);
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EXPECT_EQ(IntegerLog2(uint16_t{2}), 1);
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EXPECT_EQ(IntegerLog2(uint16_t{3}), 1);
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EXPECT_EQ(IntegerLog2(uint16_t{4}), 2);
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EXPECT_EQ(IntegerLog2(uint16_t{5}), 2);
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EXPECT_EQ(IntegerLog2(std::numeric_limits<uint64_t>::max()), 63);
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}
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TEST(FastUniformBitsTest, RangeSize) {
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EXPECT_EQ((RangeSize<FakeUrbg<uint8_t, 0, 3>>()), 4);
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EXPECT_EQ((RangeSize<FakeUrbg<uint8_t, 2, 2>>()), 1);
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EXPECT_EQ((RangeSize<FakeUrbg<uint8_t, 2, 5>>()), 4);
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EXPECT_EQ((RangeSize<FakeUrbg<uint8_t, 2, 6>>()), 5);
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EXPECT_EQ((RangeSize<FakeUrbg<uint8_t, 2, 10>>()), 9);
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EXPECT_EQ(
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(RangeSize<FakeUrbg<uint8_t, 0, std::numeric_limits<uint8_t>::max()>>()),
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0);
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EXPECT_EQ((RangeSize<FakeUrbg<uint16_t, 0, 3>>()), 4);
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EXPECT_EQ((RangeSize<FakeUrbg<uint16_t, 2, 2>>()), 1);
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EXPECT_EQ((RangeSize<FakeUrbg<uint16_t, 2, 5>>()), 4);
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EXPECT_EQ((RangeSize<FakeUrbg<uint16_t, 2, 6>>()), 5);
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EXPECT_EQ((RangeSize<FakeUrbg<uint16_t, 1000, 1017>>()), 18);
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EXPECT_EQ((RangeSize<
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FakeUrbg<uint16_t, 0, std::numeric_limits<uint16_t>::max()>>()),
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0);
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EXPECT_EQ((RangeSize<FakeUrbg<uint32_t, 0, 3>>()), 4);
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EXPECT_EQ((RangeSize<FakeUrbg<uint32_t, 2, 2>>()), 1);
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EXPECT_EQ((RangeSize<FakeUrbg<uint32_t, 2, 5>>()), 4);
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EXPECT_EQ((RangeSize<FakeUrbg<uint32_t, 2, 6>>()), 5);
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EXPECT_EQ((RangeSize<FakeUrbg<uint32_t, 1000, 1017>>()), 18);
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EXPECT_EQ((RangeSize<FakeUrbg<uint32_t, 0, 0xffffffff>>()), 0);
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EXPECT_EQ((RangeSize<FakeUrbg<uint32_t, 1, 0xffffffff>>()), 0xffffffff);
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EXPECT_EQ((RangeSize<FakeUrbg<uint32_t, 1, 0xfffffffe>>()), 0xfffffffe);
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EXPECT_EQ((RangeSize<FakeUrbg<uint32_t, 2, 0xfffffffe>>()), 0xfffffffd);
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EXPECT_EQ((RangeSize<
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FakeUrbg<uint32_t, 0, std::numeric_limits<uint32_t>::max()>>()),
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0);
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EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 0, 3>>()), 4);
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EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 2, 2>>()), 1);
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EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 2, 5>>()), 4);
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EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 2, 6>>()), 5);
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EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 1000, 1017>>()), 18);
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EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 0, 0xffffffff>>()), 0x100000000ull);
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EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 1, 0xffffffff>>()), 0xffffffffull);
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EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 1, 0xfffffffe>>()), 0xfffffffeull);
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EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 2, 0xfffffffe>>()), 0xfffffffdull);
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EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 0, 0xffffffffffffffffull>>()), 0ull);
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EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 1, 0xffffffffffffffffull>>()),
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0xffffffffffffffffull);
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EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 1, 0xfffffffffffffffeull>>()),
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0xfffffffffffffffeull);
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EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 2, 0xfffffffffffffffeull>>()),
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0xfffffffffffffffdull);
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EXPECT_EQ((RangeSize<
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FakeUrbg<uint64_t, 0, std::numeric_limits<uint64_t>::max()>>()),
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0);
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}
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TEST(FastUniformBitsTest, PowerOfTwoSubRangeSize) {
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint8_t, 0, 3>>()), 4);
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint8_t, 2, 2>>()), 1);
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint8_t, 2, 5>>()), 4);
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint8_t, 2, 6>>()), 4);
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint8_t, 2, 10>>()), 8);
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EXPECT_EQ((PowerOfTwoSubRangeSize<
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FakeUrbg<uint8_t, 0, std::numeric_limits<uint8_t>::max()>>()),
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0);
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint16_t, 0, 3>>()), 4);
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint16_t, 2, 2>>()), 1);
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint16_t, 2, 5>>()), 4);
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint16_t, 2, 6>>()), 4);
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint16_t, 1000, 1017>>()), 16);
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EXPECT_EQ((PowerOfTwoSubRangeSize<
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FakeUrbg<uint16_t, 0, std::numeric_limits<uint16_t>::max()>>()),
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0);
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint32_t, 0, 3>>()), 4);
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint32_t, 2, 2>>()), 1);
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint32_t, 2, 5>>()), 4);
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint32_t, 2, 6>>()), 4);
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint32_t, 1000, 1017>>()), 16);
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint32_t, 0, 0xffffffff>>()), 0);
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint32_t, 1, 0xffffffff>>()),
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0x80000000);
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint32_t, 1, 0xfffffffe>>()),
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0x80000000);
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EXPECT_EQ((PowerOfTwoSubRangeSize<
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FakeUrbg<uint32_t, 0, std::numeric_limits<uint32_t>::max()>>()),
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0);
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint64_t, 0, 3>>()), 4);
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint64_t, 2, 2>>()), 1);
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint64_t, 2, 5>>()), 4);
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint64_t, 2, 6>>()), 4);
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint64_t, 1000, 1017>>()), 16);
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint64_t, 0, 0xffffffff>>()),
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0x100000000ull);
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint64_t, 1, 0xffffffff>>()),
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0x80000000ull);
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EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint64_t, 1, 0xfffffffe>>()),
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0x80000000ull);
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EXPECT_EQ(
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(PowerOfTwoSubRangeSize<FakeUrbg<uint64_t, 0, 0xffffffffffffffffull>>()),
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0);
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EXPECT_EQ(
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(PowerOfTwoSubRangeSize<FakeUrbg<uint64_t, 1, 0xffffffffffffffffull>>()),
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0x8000000000000000ull);
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EXPECT_EQ(
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(PowerOfTwoSubRangeSize<FakeUrbg<uint64_t, 1, 0xfffffffffffffffeull>>()),
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0x8000000000000000ull);
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EXPECT_EQ((PowerOfTwoSubRangeSize<
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FakeUrbg<uint64_t, 0, std::numeric_limits<uint64_t>::max()>>()),
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0);
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}
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TEST(FastUniformBitsTest, Urng4_VariousOutputs) {
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// Tests that how values are composed; the single-bit deltas should be spread
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// across each invocation.
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Urng4bits urng4;
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Urng31bits urng31;
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Urng32bits urng32;
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// 8-bit types
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{
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FastUniformBits<uint8_t> fast8;
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EXPECT_EQ(0x11, fast8(urng4));
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EXPECT_EQ(0x2, fast8(urng31));
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EXPECT_EQ(0x1, fast8(urng32));
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}
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// 16-bit types
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{
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FastUniformBits<uint16_t> fast16;
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EXPECT_EQ(0x1111, fast16(urng4));
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EXPECT_EQ(0xf02, fast16(urng31));
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EXPECT_EQ(0xf01, fast16(urng32));
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}
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// 32-bit types
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{
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FastUniformBits<uint32_t> fast32;
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EXPECT_EQ(0x11111111, fast32(urng4));
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EXPECT_EQ(0x0f020f02, fast32(urng31));
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EXPECT_EQ(0x74010f01, fast32(urng32));
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}
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// 64-bit types
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{
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FastUniformBits<uint64_t> fast64;
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EXPECT_EQ(0x1111111111111111, fast64(urng4));
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EXPECT_EQ(0x387811c3c0870f02, fast64(urng31));
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EXPECT_EQ(0x74010f0174010f01, fast64(urng32));
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}
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}
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TEST(FastUniformBitsTest, URBG32bitRegression) {
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// Validate with deterministic 32-bit std::minstd_rand
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// to ensure that operator() performs as expected.
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std::minstd_rand gen(1);
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FastUniformBits<uint64_t> fast64;
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EXPECT_EQ(0x05e47095f847c122ull, fast64(gen));
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EXPECT_EQ(0x8f82c1ba30b64d22ull, fast64(gen));
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EXPECT_EQ(0x3b971a3558155039ull, fast64(gen));
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}
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} // namespace
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} // namespace random_internal
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} // namespace absl
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