| // Copyright 2020 The Pigweed 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 "pw_random/xor_shift.h" |
| |
| #include <cinttypes> |
| #include <cstddef> |
| #include <cstdint> |
| #include <cstdio> |
| |
| #include "gtest/gtest.h" |
| |
| namespace pw::random { |
| namespace { |
| |
| constexpr uint64_t seed1 = 5; |
| constexpr uint64_t result1[] = { |
| 0x423212e85fb37474u, |
| 0x96051f25a1aadc74u, |
| 0x8ac1f520f5595a79u, |
| 0x7587fe57095b7c11u, |
| }; |
| constexpr int result1_count = sizeof(result1) / sizeof(result1[0]); |
| |
| constexpr uint64_t seed2 = 0x21feabcd5fb37474u; |
| constexpr uint64_t result2[] = { |
| 0x568ea260a4f3e793u, |
| 0x5ea87d669ab04d36u, |
| 0x77a8675eec48ae8bu, |
| }; |
| constexpr int result2_count = sizeof(result2) / sizeof(result2[0]); |
| |
| TEST(XorShiftStarRng64, ValidateSeries1) { |
| XorShiftStarRng64 rng(seed1); |
| for (size_t i = 0; i < result1_count; ++i) { |
| uint64_t val = 0; |
| EXPECT_EQ(rng.GetInt(val).status(), OkStatus()); |
| EXPECT_EQ(val, result1[i]); |
| } |
| } |
| |
| TEST(XorShiftStarRng64, ValidateSeries2) { |
| XorShiftStarRng64 rng(seed2); |
| for (size_t i = 0; i < result2_count; ++i) { |
| uint64_t val = 0; |
| EXPECT_EQ(rng.GetInt(val).status(), OkStatus()); |
| EXPECT_EQ(val, result2[i]); |
| } |
| } |
| |
| TEST(XorShiftStarRng64, InjectEntropyBits) { |
| XorShiftStarRng64 rng(seed1); |
| uint64_t val = 0; |
| rng.InjectEntropyBits(0x1, 1); |
| EXPECT_EQ(rng.GetInt(val).status(), OkStatus()); |
| EXPECT_NE(val, result1[0]); |
| } |
| |
| // Ensure injecting the same entropy integer, but different bit counts causes |
| // the randomly generated number to differ. |
| TEST(XorShiftStarRng64, EntropyBitCount) { |
| XorShiftStarRng64 rng_1(seed1); |
| uint64_t first_val = 0; |
| rng_1.InjectEntropyBits(0x1, 1); |
| EXPECT_EQ(rng_1.GetInt(first_val).status(), OkStatus()); |
| |
| // Use the same starting seed. |
| XorShiftStarRng64 rng_2(seed1); |
| uint64_t second_val = 0; |
| // Use a different number of entropy bits. |
| rng_2.InjectEntropyBits(0x1, 2); |
| EXPECT_EQ(rng_2.GetInt(second_val).status(), OkStatus()); |
| |
| EXPECT_NE(first_val, second_val); |
| } |
| |
| // Ensure injecting the same integer bit-by-bit applies the same transformation |
| // as all in one call. This lets applications decide which is more convenient |
| // without worrying about algorithmic changes. |
| TEST(XorShiftStarRng64, IncrementalEntropy) { |
| XorShiftStarRng64 rng_1(seed1); |
| uint64_t first_val = 0; |
| rng_1.InjectEntropyBits(0x6, 3); |
| EXPECT_EQ(rng_1.GetInt(first_val).status(), OkStatus()); |
| |
| // Use the same starting seed. |
| XorShiftStarRng64 rng_2(seed1); |
| uint64_t second_val = 0; |
| // Use a different number of injection calls. 6 = 0b110 |
| rng_2.InjectEntropyBits(0x1, 1); |
| rng_2.InjectEntropyBits(0x1, 1); |
| rng_2.InjectEntropyBits(0x0, 1); |
| EXPECT_EQ(rng_2.GetInt(second_val).status(), OkStatus()); |
| |
| EXPECT_EQ(first_val, second_val); |
| } |
| |
| TEST(XorShiftStarRng64, InjectEntropy) { |
| XorShiftStarRng64 rng(seed1); |
| uint64_t val = 0; |
| constexpr std::array<const std::byte, 5> entropy{std::byte(0xaf), |
| std::byte(0x9b), |
| std::byte(0x33), |
| std::byte(0x17), |
| std::byte(0x02)}; |
| rng.InjectEntropy(entropy); |
| EXPECT_EQ(rng.GetInt(val).status(), OkStatus()); |
| EXPECT_NE(val, result1[0]); |
| } |
| |
| } // namespace |
| } // namespace pw::random |