Common: Add bitutils.h

src/common/CMakeLists.txt

@@ -5,6 +5,7 @@ add_library(common
   audio_stream.cpp
   audio_stream.h
   bitfield.h
+  bitutils.h
   byte_stream.cpp
   byte_stream.h
   cd_image.cpp

src/common/bitutils.h

@@ -0,0 +1,62 @@
+#pragma once
+#include "types.h"
+
+#ifdef _MSC_VER
+#include <intrin.h>
+#endif
+
+template<typename T>
+ALWAYS_INLINE unsigned CountLeadingZeros(T value)
+{
+#ifdef _MSC_VER
+  if constexpr (sizeof(value) >= sizeof(u64))
+  {
+    unsigned long index;
+    return _BitScanReverse64(&index, ZeroExtend64(value)) ? static_cast<unsigned>(index) : 0;
+  }
+  else
+  {
+    unsigned long index;
+    return _BitScanReverse(&index, ZeroExtend32(value)) ? static_cast<unsigned>(index) : 0;
+  }
+#else
+  if constexpr (sizeof(value) >= sizeof(u64))
+  {
+    const unsigned bits = static_cast<unsigned>(__builtin_clzl(ZeroExtend64(value)));
+    return (value != 0) ? static_cast<unsigned>(bits) : 0;
+  }
+  else
+  {
+    const unsigned bits = static_cast<unsigned>(__builtin_clz(ZeroExtend32(value)));
+    return (value != 0) ? static_cast<unsigned>(bits) : 0;
+  }
+#endif
+}
+
+template<typename T>
+ALWAYS_INLINE unsigned CountTrailingZeros(T value)
+{
+#ifdef _MSC_VER
+  if constexpr (sizeof(value) >= sizeof(u64))
+  {
+    unsigned long index;
+    return _BitScanForward64(&index, ZeroExtend64(value)) ? static_cast<unsigned>(index) : 0;
+  }
+  else
+  {
+    unsigned long index;
+    return _BitScanForward(&index, ZeroExtend32(value)) ? static_cast<unsigned>(index) : 0;
+  }
+#else
+  if constexpr (sizeof(value) >= sizeof(u64))
+  {
+    const unsigned bits = static_cast<unsigned>(__builtin_ctzl(ZeroExtend64(value)));
+    return (value != 0) ? static_cast<unsigned>(bits) : 0;
+  }
+  else
+  {
+    const unsigned bits = static_cast<unsigned>(__builtin_ctz(ZeroExtend32(value)));
+    return (value != 0) ? static_cast<unsigned>(bits) : 0;
+  }
+#endif
+}

src/common/common.vcxproj

@@ -39,6 +39,7 @@
     <ClInclude Include="assert.h" />
     <ClInclude Include="audio_stream.h" />
     <ClInclude Include="bitfield.h" />
+    <ClInclude Include="bitutils.h" />
     <ClInclude Include="byte_stream.h" />
     <ClInclude Include="cd_image.h" />
     <ClInclude Include="cpu_detect.h" />

src/common/common.vcxproj.filters

@@ -57,6 +57,7 @@
       <Filter>gl</Filter>
     </ClInclude>
     <ClInclude Include="event.h" />
+    <ClInclude Include="bitutils.h" />
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="jit_code_buffer.cpp" />