Function test_random_generator_equivalence

scripts/test_stringzilla.cpp:329–350

* @brief Tests Pseudo-Random Number Generators (PRNGs) ensuring that the same nonce * produces exactly the same output across different SIMD implementations. */

 *          produces exactly the same output across different SIMD implementations.
 */
void test_random_generator_equivalence(sz_fill_random_t generate_base, sz_fill_random_t generate_simd) {

    auto test_on_nonce = [&](std::size_t length, sz_u64_t nonce) {
        std::string text_base(length, '\0');
        std::string text_simd(length, '\0');
        generate_base(&text_base[0], static_cast<sz_size_t>(length), nonce);
        generate_simd(&text_simd[0], static_cast<sz_size_t>(length), nonce);
        assert(text_base == text_simd);
    };

    // Let's try different nonces:
    std::vector<sz_u64_t> nonces = {
        0u,
        42u,                                  //
        std::numeric_limits<sz_u32_t>::max(), //
        std::numeric_limits<sz_u64_t>::max(), //
    };
    std::vector<std::size_t> lengths = {1, 11, 23, 37, 40, 51, 64, 128, 1000};
    for (auto nonce : nonces)
        for (auto length : lengths) //
            test_on_nonce(length, nonce);
}

/**
 *  @brief  Tests SHA256 implementations, comparing serial and SIMD variants