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libraries/M5Utility/test/mmh3_test.cpp

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+/*
+ * SPDX-FileCopyrightText: 2024 M5Stack Technology CO LTD
+ *
+ * SPDX-License-Identifier: MIT
+ */
+/*
+  UnitTest for M5Utility
+*/
+#include <gtest/gtest.h>
+#include <random>
+#include <M5Utility.hpp>
+#include "MurmurHash3.h"  // from https://github.com/rurban/smhasher/tree/master (public domain)
+
+#if defined(ARDUINO)
+#include <WString.h>
+using string_t = String;
+#else
+#include <cstring>
+using string_t = std::string;
+#endif
+
+namespace {
+
+auto rng = std::default_random_engine{};
+
+string_t make_random_str()
+{
+    constexpr char dic[] =
+        "abcdefghijklmnopqrstuvwxyz"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+        "0123456789"
+        "!#$%&()=-~^|@[{]}:;+*,.<>/?_";
+
+    string_t s;
+    size_t len = 1 + (rng() & 31);
+    while (len--) {
+        s += dic[rng() % (sizeof(dic) / sizeof(dic[0]) - 1)];
+    }
+    return s;
+}
+
+using test_pair_t = std::pair<const char*, uint32_t>;
+
+test_pair_t test_pairs[] = {
+    {"", 0},
+    {"M5Stack", 0x8c97d1e0U},
+    {"M5Stack is a leading provider of IoT solutions.", 0x1a1eca6dU},
+};
+
+}  // namespace
+
+TEST(MurmurHash3, endianness)
+{
+    using namespace m5::utility::mmh3;
+
+    constexpr char tst[] = "M5ST";
+    auto big             = str2uint32<false>(tst);
+    auto little          = str2uint32<true>(tst);
+
+    EXPECT_EQ(big, 0x4d355354U);
+    EXPECT_EQ(little, 0x5453354dU);
+}
+
+// User-defined literals "_mmh3"
+TEST(MurmurHash3, user_defined_literals)
+{
+    using namespace m5::utility::mmh3;
+
+    constexpr auto h0 = ""_mmh3;
+    constexpr auto h1 = "M5Stack"_mmh3;
+    constexpr auto h2 = "M5Stack is a leading provider of IoT solutions."_mmh3;
+
+    EXPECT_EQ(h0, 0U);
+    EXPECT_EQ(h1, 0x8c97d1e0U);
+    EXPECT_EQ(h2, 0x1a1eca6dU);
+}
+
+// Verification of value correctness
+TEST(MurmurHash3, verify)
+{
+    for (auto&& e : test_pairs) {
+        auto& s = e.first;
+        auto h  = m5::utility::mmh3::calculate(s);
+        uint32_t h2{};
+        MurmurHash3_x86_32(s, strlen(s), 0, &h2);
+
+        EXPECT_EQ(e.second, h) << '[' << s << "] len:" << strlen(s);
+        EXPECT_EQ(h, h2) << '[' << s << "] len:" << strlen(s);
+    }
+
+    constexpr int count = 10000;
+    for (int i = 0; i < count; ++i) {
+        string_t s = make_random_str();
+        size_t len = strlen(s.c_str());
+        uint32_t h1{};
+        MurmurHash3_x86_32(s.c_str(), len, 0, &h1);
+        uint32_t h2 = m5::utility::mmh3::calculate(s.c_str());
+
+        EXPECT_EQ(h1, h2) << '[' << s.c_str() << "] len:" << strlen(s.c_str());
+    }
+}