1 files changed, 142 insertions, 0 deletions
diff --git a/Firestore/core/test/firebase/firestore/util/bits_test.cc b/Firestore/core/test/firebase/firestore/util/bits_test.cc
new file mode 100644
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--- /dev/null
+++ b/Firestore/core/test/firebase/firestore/util/bits_test.cc
@@ -0,0 +1,142 @@
+/*
+ * Copyright 2017 Google
+ *
+ * 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
+ *
+ *      http://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 "Firestore/core/src/firebase/firestore/util/bits.h"
+
+#include <algorithm>
+#include <iostream>
+#include <limits>
+
+#include "Firestore/core/src/firebase/firestore/util/secure_random.h"
+#include "gtest/gtest.h"
+
+namespace firebase {
+namespace firestore {
+namespace util {
+
+const int kNumIterations = 10000;  // "Number of test iterations to run.
+
+class BitsTest : public testing::Test {
+ protected:
+  SecureRandom random_;
+};
+
+TEST_F(BitsTest, Log2EdgeCases) {
+  std::cout << "TestLog2EdgeCases" << std::endl;
+
+  EXPECT_EQ(-1, Bits::Log2Floor(0));
+  EXPECT_EQ(-1, Bits::Log2Floor64(0));
+
+  for (int i = 0; i < 32; i++) {
+    uint32_t n = 1U << i;
+    EXPECT_EQ(i, Bits::Log2Floor(n));
+    EXPECT_EQ(i, Bits::Log2FloorNonZero(n));
+    if (n > 2) {
+      EXPECT_EQ(i - 1, Bits::Log2Floor(n - 1));
+      EXPECT_EQ(i, Bits::Log2Floor(n + 1));
+      EXPECT_EQ(i - 1, Bits::Log2FloorNonZero(n - 1));
+      EXPECT_EQ(i, Bits::Log2FloorNonZero(n + 1));
+    }
+  }
+
+  for (int i = 0; i < 64; i++) {
+    uint64_t n = 1ULL << i;
+    EXPECT_EQ(i, Bits::Log2Floor64(n));
+    EXPECT_EQ(i, Bits::Log2FloorNonZero64(n));
+    if (n > 2) {
+      EXPECT_EQ(i - 1, Bits::Log2Floor64(n - 1));
+      EXPECT_EQ(i, Bits::Log2Floor64(n + 1));
+      EXPECT_EQ(i - 1, Bits::Log2FloorNonZero64(n - 1));
+      EXPECT_EQ(i, Bits::Log2FloorNonZero64(n + 1));
+    }
+  }
+}
+
+TEST_F(BitsTest, Log2Random) {
+  std::cout << "TestLog2Random" << std::endl;
+
+  for (int i = 0; i < kNumIterations; i++) {
+    int maxbit = -1;
+    uint32_t n = 0;
+    while (!random_.OneIn(32u)) {
+      int bit = static_cast<int>(random_.Uniform(32u));
+      n |= (1U << bit);
+      maxbit = std::max(bit, maxbit);
+    }
+    EXPECT_EQ(maxbit, Bits::Log2Floor(n));
+    if (n != 0) {
+      EXPECT_EQ(maxbit, Bits::Log2FloorNonZero(n));
+    }
+  }
+}
+
+TEST_F(BitsTest, Log2Random64) {
+  std::cout << "TestLog2Random64" << std::endl;
+
+  for (int i = 0; i < kNumIterations; i++) {
+    int maxbit = -1;
+    uint64_t n = 0;
+    while (!random_.OneIn(64u)) {
+      int bit = static_cast<int>(random_.Uniform(64u));
+      n |= (1ULL << bit);
+      maxbit = std::max(bit, maxbit);
+    }
+    EXPECT_EQ(maxbit, Bits::Log2Floor64(n));
+    if (n != 0) {
+      EXPECT_EQ(maxbit, Bits::Log2FloorNonZero64(n));
+    }
+  }
+}
+
+TEST(Bits, Port32) {
+  for (int shift = 0; shift < 32; shift++) {
+    for (uint32_t delta = 0; delta <= 2; delta++) {
+      const uint32_t v = (static_cast<uint32_t>(1) << shift) - 1 + delta;
+      EXPECT_EQ(Bits::Log2Floor_Portable(v), Bits::Log2Floor(v)) << v;
+      if (v != 0) {
+        EXPECT_EQ(Bits::Log2FloorNonZero_Portable(v), Bits::Log2FloorNonZero(v))
+            << v;
+      }
+    }
+  }
+  static const uint32_t M32 = std::numeric_limits<uint32_t>::max();
+  EXPECT_EQ(Bits::Log2Floor_Portable(M32), Bits::Log2Floor(M32)) << M32;
+  EXPECT_EQ(Bits::Log2FloorNonZero_Portable(M32), Bits::Log2FloorNonZero(M32))
+      << M32;
+}
+
+TEST(Bits, Port64) {
+  for (int shift = 0; shift < 64; shift++) {
+    for (uint64_t delta = 0; delta <= 2; delta++) {
+      const uint64_t v = (static_cast<uint64_t>(1) << shift) - 1 + delta;
+      EXPECT_EQ(Bits::Log2Floor64_Portable(v), Bits::Log2Floor64(v)) << v;
+      if (v != 0) {
+        EXPECT_EQ(Bits::Log2FloorNonZero64_Portable(v),
+                  Bits::Log2FloorNonZero64(v))
+            << v;
+      }
+    }
+  }
+  static const uint64_t M64 = std::numeric_limits<uint64_t>::max();
+  EXPECT_EQ(Bits::Log2Floor64_Portable(M64), Bits::Log2Floor64(M64)) << M64;
+  EXPECT_EQ(Bits::Log2FloorNonZero64_Portable(M64),
+            Bits::Log2FloorNonZero64(M64))
+      << M64;
+}
+
+}  // namespace util
+}  // namespace firestore
+}  // namespace firebase