CommonTests: Add tests for BitUtils

src/common-tests/CMakeLists.txt

@@ -1,4 +1,5 @@
 add_executable(common-tests
+  bitutils_tests.cpp
   event_tests.cpp
   rectangle_tests.cpp
 )

src/common-tests/bitutils_tests.cpp

@@ -0,0 +1,68 @@
+#include "common/bitutils.h"
+#include "gtest/gtest.h"
+#include <type_traits>
+
+template<typename T>
+static inline constexpr unsigned ManualCountLeadingZeros(T value)
+{
+  constexpr unsigned BITS = sizeof(T) * 8u;
+  constexpr T MASK = T(1) << (BITS - 1);
+
+  unsigned count = 0;
+  for (unsigned i = 0; i < BITS && (value & MASK) == 0; i++)
+  {
+    count++;
+    value <<= 1;
+  }
+
+  return count;
+}
+
+template<typename T>
+static inline constexpr unsigned ManualCountTrailingZeros(T value)
+{
+  constexpr unsigned BITS = sizeof(T) * 8u;
+  constexpr auto MASK = static_cast<std::make_unsigned_t<T>>(1);
+
+  auto u_value = static_cast<std::make_unsigned_t<T>>(value);
+
+  unsigned count = 0;
+  for (unsigned i = 0; i < BITS && (u_value & MASK) != MASK; i++)
+  {
+    count++;
+    u_value >>= 1;
+  }
+
+  return count;
+}
+
+TEST(BitUtils, Test8Bit)
+{
+  ASSERT_EQ(CountLeadingZeros(u8(1)), ManualCountLeadingZeros(u8(1)));
+  ASSERT_EQ(CountLeadingZeros(u8(2)), ManualCountLeadingZeros(u8(2)));
+  ASSERT_EQ(CountLeadingZeros(u8(4)), ManualCountLeadingZeros(u8(4)));
+  ASSERT_EQ(CountLeadingZeros(u8(8)), ManualCountLeadingZeros(u8(8)));
+  ASSERT_EQ(CountLeadingZeros(u8(16)), ManualCountLeadingZeros(u8(16)));
+  ASSERT_EQ(CountLeadingZeros(u8(32)), ManualCountLeadingZeros(u8(32)));
+  ASSERT_EQ(CountLeadingZeros(u8(64)), ManualCountLeadingZeros(u8(64)));
+  ASSERT_EQ(CountLeadingZeros(u8(128)), ManualCountLeadingZeros(u8(128)));
+
+  ASSERT_EQ(CountTrailingZeros(u8(1)), ManualCountTrailingZeros(u8(1)));
+  ASSERT_EQ(CountTrailingZeros(u8(2)), ManualCountTrailingZeros(u8(2)));
+  ASSERT_EQ(CountTrailingZeros(u8(4)), ManualCountTrailingZeros(u8(4)));
+  ASSERT_EQ(CountTrailingZeros(u8(8)), ManualCountTrailingZeros(u8(8)));
+  ASSERT_EQ(CountTrailingZeros(u8(16)), ManualCountTrailingZeros(u8(16)));
+  ASSERT_EQ(CountTrailingZeros(u8(32)), ManualCountTrailingZeros(u8(32)));
+  ASSERT_EQ(CountTrailingZeros(u8(64)), ManualCountTrailingZeros(u8(64)));
+  ASSERT_EQ(CountTrailingZeros(u8(128)), ManualCountTrailingZeros(u8(128)));
+}
+
+TEST(BitUtils, Test16Bit)
+{
+  for (u32 i = 1; i < 0x10000; i++)
+  {
+    u16 value = Truncate16(i);
+    ASSERT_EQ(CountLeadingZeros(value), ManualCountLeadingZeros(value));
+    ASSERT_EQ(CountTrailingZeros(value), ManualCountTrailingZeros(value));
+  }
+}

src/common-tests/common-tests.vcxproj

@@ -44,6 +44,7 @@
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="..\..\dep\googletest\src\gtest_main.cc" />
+    <ClCompile Include="bitutils_tests.cpp" />
     <ClCompile Include="event_tests.cpp" />
     <ClCompile Include="rectangle_tests.cpp" />
   </ItemGroup>

src/common-tests/common-tests.vcxproj.filters

@@ -4,5 +4,6 @@
     <ClCompile Include="..\..\dep\googletest\src\gtest_main.cc" />
     <ClCompile Include="rectangle_tests.cpp" />
     <ClCompile Include="event_tests.cpp" />
+    <ClCompile Include="bitutils_tests.cpp" />
   </ItemGroup>
 </Project>