| // 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. |
| |
| #include "absl/random/internal/fast_uniform_bits.h" |
| |
| #include <random> |
| |
| #include "gtest/gtest.h" |
| |
| namespace absl { |
| ABSL_NAMESPACE_BEGIN |
| namespace random_internal { |
| namespace { |
| |
| template <typename IntType> |
| class FastUniformBitsTypedTest : public ::testing::Test {}; |
| |
| using IntTypes = ::testing::Types<uint8_t, uint16_t, uint32_t, uint64_t>; |
| |
| TYPED_TEST_SUITE(FastUniformBitsTypedTest, IntTypes); |
| |
| TYPED_TEST(FastUniformBitsTypedTest, BasicTest) { |
| using Limits = std::numeric_limits<TypeParam>; |
| using FastBits = FastUniformBits<TypeParam>; |
| |
| EXPECT_EQ(0, FastBits::min()); |
| EXPECT_EQ(Limits::max(), FastBits::max()); |
| |
| constexpr int kIters = 10000; |
| std::random_device rd; |
| std::mt19937 gen(rd()); |
| FastBits fast; |
| for (int i = 0; i < kIters; i++) { |
| const auto v = fast(gen); |
| EXPECT_LE(v, FastBits::max()); |
| EXPECT_GE(v, FastBits::min()); |
| } |
| } |
| |
| template <typename UIntType, UIntType Lo, UIntType Hi, UIntType Val = Lo> |
| struct FakeUrbg { |
| using result_type = UIntType; |
| |
| static constexpr result_type(max)() { return Hi; } |
| static constexpr result_type(min)() { return Lo; } |
| result_type operator()() { return Val; } |
| }; |
| |
| using UrngOddbits = FakeUrbg<uint8_t, 1, 0xfe, 0x73>; |
| using Urng4bits = FakeUrbg<uint8_t, 1, 0x10, 2>; |
| using Urng31bits = FakeUrbg<uint32_t, 1, 0xfffffffe, 0x60070f03>; |
| using Urng32bits = FakeUrbg<uint32_t, 0, 0xffffffff, 0x74010f01>; |
| |
| TEST(FastUniformBitsTest, IsPowerOfTwoOrZero) { |
| EXPECT_TRUE(IsPowerOfTwoOrZero(uint8_t{0})); |
| EXPECT_TRUE(IsPowerOfTwoOrZero(uint8_t{1})); |
| EXPECT_TRUE(IsPowerOfTwoOrZero(uint8_t{2})); |
| EXPECT_FALSE(IsPowerOfTwoOrZero(uint8_t{3})); |
| EXPECT_TRUE(IsPowerOfTwoOrZero(uint8_t{16})); |
| EXPECT_FALSE(IsPowerOfTwoOrZero(uint8_t{17})); |
| EXPECT_FALSE(IsPowerOfTwoOrZero((std::numeric_limits<uint8_t>::max)())); |
| |
| EXPECT_TRUE(IsPowerOfTwoOrZero(uint16_t{0})); |
| EXPECT_TRUE(IsPowerOfTwoOrZero(uint16_t{1})); |
| EXPECT_TRUE(IsPowerOfTwoOrZero(uint16_t{2})); |
| EXPECT_FALSE(IsPowerOfTwoOrZero(uint16_t{3})); |
| EXPECT_TRUE(IsPowerOfTwoOrZero(uint16_t{16})); |
| EXPECT_FALSE(IsPowerOfTwoOrZero(uint16_t{17})); |
| EXPECT_FALSE(IsPowerOfTwoOrZero((std::numeric_limits<uint16_t>::max)())); |
| |
| EXPECT_TRUE(IsPowerOfTwoOrZero(uint32_t{0})); |
| EXPECT_TRUE(IsPowerOfTwoOrZero(uint32_t{1})); |
| EXPECT_TRUE(IsPowerOfTwoOrZero(uint32_t{2})); |
| EXPECT_FALSE(IsPowerOfTwoOrZero(uint32_t{3})); |
| EXPECT_TRUE(IsPowerOfTwoOrZero(uint32_t{32})); |
| EXPECT_FALSE(IsPowerOfTwoOrZero(uint32_t{17})); |
| EXPECT_FALSE(IsPowerOfTwoOrZero((std::numeric_limits<uint32_t>::max)())); |
| |
| EXPECT_TRUE(IsPowerOfTwoOrZero(uint64_t{0})); |
| EXPECT_TRUE(IsPowerOfTwoOrZero(uint64_t{1})); |
| EXPECT_TRUE(IsPowerOfTwoOrZero(uint64_t{2})); |
| EXPECT_FALSE(IsPowerOfTwoOrZero(uint64_t{3})); |
| EXPECT_TRUE(IsPowerOfTwoOrZero(uint64_t{64})); |
| EXPECT_FALSE(IsPowerOfTwoOrZero(uint64_t{17})); |
| EXPECT_FALSE(IsPowerOfTwoOrZero((std::numeric_limits<uint64_t>::max)())); |
| } |
| |
| TEST(FastUniformBitsTest, IntegerLog2) { |
| EXPECT_EQ(IntegerLog2(uint16_t{0}), 0); |
| EXPECT_EQ(IntegerLog2(uint16_t{1}), 0); |
| EXPECT_EQ(IntegerLog2(uint16_t{2}), 1); |
| EXPECT_EQ(IntegerLog2(uint16_t{3}), 1); |
| EXPECT_EQ(IntegerLog2(uint16_t{4}), 2); |
| EXPECT_EQ(IntegerLog2(uint16_t{5}), 2); |
| EXPECT_EQ(IntegerLog2(std::numeric_limits<uint64_t>::max()), 63); |
| } |
| |
| TEST(FastUniformBitsTest, RangeSize) { |
| EXPECT_EQ((RangeSize<FakeUrbg<uint8_t, 0, 3>>()), 4); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint8_t, 2, 2>>()), 1); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint8_t, 2, 5>>()), 4); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint8_t, 2, 6>>()), 5); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint8_t, 2, 10>>()), 9); |
| EXPECT_EQ( |
| (RangeSize<FakeUrbg<uint8_t, 0, std::numeric_limits<uint8_t>::max()>>()), |
| 0); |
| |
| EXPECT_EQ((RangeSize<FakeUrbg<uint16_t, 0, 3>>()), 4); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint16_t, 2, 2>>()), 1); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint16_t, 2, 5>>()), 4); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint16_t, 2, 6>>()), 5); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint16_t, 1000, 1017>>()), 18); |
| EXPECT_EQ((RangeSize< |
| FakeUrbg<uint16_t, 0, std::numeric_limits<uint16_t>::max()>>()), |
| 0); |
| |
| EXPECT_EQ((RangeSize<FakeUrbg<uint32_t, 0, 3>>()), 4); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint32_t, 2, 2>>()), 1); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint32_t, 2, 5>>()), 4); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint32_t, 2, 6>>()), 5); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint32_t, 1000, 1017>>()), 18); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint32_t, 0, 0xffffffff>>()), 0); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint32_t, 1, 0xffffffff>>()), 0xffffffff); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint32_t, 1, 0xfffffffe>>()), 0xfffffffe); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint32_t, 2, 0xfffffffe>>()), 0xfffffffd); |
| EXPECT_EQ((RangeSize< |
| FakeUrbg<uint32_t, 0, std::numeric_limits<uint32_t>::max()>>()), |
| 0); |
| |
| EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 0, 3>>()), 4); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 2, 2>>()), 1); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 2, 5>>()), 4); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 2, 6>>()), 5); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 1000, 1017>>()), 18); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 0, 0xffffffff>>()), 0x100000000ull); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 1, 0xffffffff>>()), 0xffffffffull); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 1, 0xfffffffe>>()), 0xfffffffeull); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 2, 0xfffffffe>>()), 0xfffffffdull); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 0, 0xffffffffffffffffull>>()), 0ull); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 1, 0xffffffffffffffffull>>()), |
| 0xffffffffffffffffull); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 1, 0xfffffffffffffffeull>>()), |
| 0xfffffffffffffffeull); |
| EXPECT_EQ((RangeSize<FakeUrbg<uint64_t, 2, 0xfffffffffffffffeull>>()), |
| 0xfffffffffffffffdull); |
| EXPECT_EQ((RangeSize< |
| FakeUrbg<uint64_t, 0, std::numeric_limits<uint64_t>::max()>>()), |
| 0); |
| } |
| |
| TEST(FastUniformBitsTest, PowerOfTwoSubRangeSize) { |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint8_t, 0, 3>>()), 4); |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint8_t, 2, 2>>()), 1); |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint8_t, 2, 5>>()), 4); |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint8_t, 2, 6>>()), 4); |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint8_t, 2, 10>>()), 8); |
| EXPECT_EQ((PowerOfTwoSubRangeSize< |
| FakeUrbg<uint8_t, 0, std::numeric_limits<uint8_t>::max()>>()), |
| 0); |
| |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint16_t, 0, 3>>()), 4); |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint16_t, 2, 2>>()), 1); |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint16_t, 2, 5>>()), 4); |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint16_t, 2, 6>>()), 4); |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint16_t, 1000, 1017>>()), 16); |
| EXPECT_EQ((PowerOfTwoSubRangeSize< |
| FakeUrbg<uint16_t, 0, std::numeric_limits<uint16_t>::max()>>()), |
| 0); |
| |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint32_t, 0, 3>>()), 4); |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint32_t, 2, 2>>()), 1); |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint32_t, 2, 5>>()), 4); |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint32_t, 2, 6>>()), 4); |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint32_t, 1000, 1017>>()), 16); |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint32_t, 0, 0xffffffff>>()), 0); |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint32_t, 1, 0xffffffff>>()), |
| 0x80000000); |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint32_t, 1, 0xfffffffe>>()), |
| 0x80000000); |
| EXPECT_EQ((PowerOfTwoSubRangeSize< |
| FakeUrbg<uint32_t, 0, std::numeric_limits<uint32_t>::max()>>()), |
| 0); |
| |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint64_t, 0, 3>>()), 4); |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint64_t, 2, 2>>()), 1); |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint64_t, 2, 5>>()), 4); |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint64_t, 2, 6>>()), 4); |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint64_t, 1000, 1017>>()), 16); |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint64_t, 0, 0xffffffff>>()), |
| 0x100000000ull); |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint64_t, 1, 0xffffffff>>()), |
| 0x80000000ull); |
| EXPECT_EQ((PowerOfTwoSubRangeSize<FakeUrbg<uint64_t, 1, 0xfffffffe>>()), |
| 0x80000000ull); |
| EXPECT_EQ( |
| (PowerOfTwoSubRangeSize<FakeUrbg<uint64_t, 0, 0xffffffffffffffffull>>()), |
| 0); |
| EXPECT_EQ( |
| (PowerOfTwoSubRangeSize<FakeUrbg<uint64_t, 1, 0xffffffffffffffffull>>()), |
| 0x8000000000000000ull); |
| EXPECT_EQ( |
| (PowerOfTwoSubRangeSize<FakeUrbg<uint64_t, 1, 0xfffffffffffffffeull>>()), |
| 0x8000000000000000ull); |
| EXPECT_EQ((PowerOfTwoSubRangeSize< |
| FakeUrbg<uint64_t, 0, std::numeric_limits<uint64_t>::max()>>()), |
| 0); |
| } |
| |
| TEST(FastUniformBitsTest, Urng4_VariousOutputs) { |
| // Tests that how values are composed; the single-bit deltas should be spread |
| // across each invocation. |
| Urng4bits urng4; |
| Urng31bits urng31; |
| Urng32bits urng32; |
| |
| // 8-bit types |
| { |
| FastUniformBits<uint8_t> fast8; |
| EXPECT_EQ(0x11, fast8(urng4)); |
| EXPECT_EQ(0x2, fast8(urng31)); |
| EXPECT_EQ(0x1, fast8(urng32)); |
| } |
| |
| // 16-bit types |
| { |
| FastUniformBits<uint16_t> fast16; |
| EXPECT_EQ(0x1111, fast16(urng4)); |
| EXPECT_EQ(0xf02, fast16(urng31)); |
| EXPECT_EQ(0xf01, fast16(urng32)); |
| } |
| |
| // 32-bit types |
| { |
| FastUniformBits<uint32_t> fast32; |
| EXPECT_EQ(0x11111111, fast32(urng4)); |
| EXPECT_EQ(0x0f020f02, fast32(urng31)); |
| EXPECT_EQ(0x74010f01, fast32(urng32)); |
| } |
| |
| // 64-bit types |
| { |
| FastUniformBits<uint64_t> fast64; |
| EXPECT_EQ(0x1111111111111111, fast64(urng4)); |
| EXPECT_EQ(0x387811c3c0870f02, fast64(urng31)); |
| EXPECT_EQ(0x74010f0174010f01, fast64(urng32)); |
| } |
| } |
| |
| TEST(FastUniformBitsTest, URBG32bitRegression) { |
| // Validate with deterministic 32-bit std::minstd_rand |
| // to ensure that operator() performs as expected. |
| std::minstd_rand gen(1); |
| FastUniformBits<uint64_t> fast64; |
| |
| EXPECT_EQ(0x05e47095f847c122ull, fast64(gen)); |
| EXPECT_EQ(0x8f82c1ba30b64d22ull, fast64(gen)); |
| EXPECT_EQ(0x3b971a3558155039ull, fast64(gen)); |
| } |
| |
| } // namespace |
| } // namespace random_internal |
| ABSL_NAMESPACE_END |
| } // namespace absl |