Adding code. Closes #0.

test/bit_utils_test.cc

@@ -0,0 +1,53 @@
+// Copyright 2017 Google Inc.
+//
+// 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 "internal/bit_utils.h"
+
+#include "gtest/gtest.h"
+
+namespace cpu_features {
+namespace {
+
+TEST(UtilsTest, IsBitSet) {
+  for (size_t bit_set = 0; bit_set < 32; ++bit_set) {
+    const uint32_t value = 1UL << bit_set;
+    for (size_t i = 0; i < 32; ++i) {
+      EXPECT_EQ(IsBitSet(value, i), i == bit_set);
+    }
+  }
+
+  // testing 0, all bits should be 0.
+  for (size_t i = 0; i < 32; ++i) {
+    EXPECT_FALSE(IsBitSet(0, i));
+  }
+
+  // testing ~0, all bits should be 1.
+  for (size_t i = 0; i < 32; ++i) {
+    EXPECT_TRUE(IsBitSet(-1, i));
+  }
+}
+
+TEST(UtilsTest, ExtractBitRange) {
+  // Extracting all bits gives the same number.
+  EXPECT_EQ(ExtractBitRange(123, 31, 0), 123);
+  // Extracting 1 bit gives parity.
+  EXPECT_EQ(ExtractBitRange(123, 0, 0), 1);
+  EXPECT_EQ(ExtractBitRange(122, 0, 0), 0);
+
+  EXPECT_EQ(ExtractBitRange(0xF0, 7, 4), 0xF);
+  EXPECT_EQ(ExtractBitRange(0x42 << 2, 10, 2), 0x42);
+}
+
+}  // namespace
+}  // namespace cpu_features