Use partial specialization

Author: Eichenherz

include/nbl/builtin/hlsl/glsl_compat/bit.hlsl

@@ -0,0 +1,46 @@
+// Copyright (C) 2023 - DevSH Graphics Programming Sp. z O.O.
+// This file is part of the "Nabla Engine".
+// For conditions of distribution and use, see copyright notice in nabla.h
+#ifndef _NBL_BUILTIN_HLSL_GLSL_BIT_INCLUDED_
+#define _NBL_BUILTIN_HLSL_GLSL_BIT_INCLUDED_
+
+#include "nbl/builtin/hlsl/cpp_compat.hlsl"
+#include "nbl/builtin/hlsl/spirv_intrinsics/core.hlsl"
+
+namespace nbl 
+{
+namespace hlsl
+{
+namespace glsl
+{
+namespace impl 
+{
+
+#ifdef __HLSL_VERSION
+
+template<typename T, bool isSigned, bool isIntegral>
+struct bitfieldExtract
+{
+    T operator()( T val, uint32_t offsetBits, uint32_t numBits )
+    {
+        if( isIntegral )
+        {
+            static_assert( false, "T must be an integral type" );
+        }
+        if( isSigned )
+        {
+            return spirv::bitFieldSExtract<T>( val, offsetBits, numBits );
+        }
+        return spirv::bitFieldUExtract<T>( val, offsetBits, numBits );
+    }
+};
+    
+}
+#endif
+
+}
+}
+}
+}
+
+#endif

include/nbl/builtin/hlsl/glsl_compat/core.hlsl

@@ -6,6 +6,7 @@
 
 #include "nbl/builtin/hlsl/cpp_compat.hlsl"
 #include "nbl/builtin/hlsl/spirv_intrinsics/core.hlsl"
+#include "nbl/builtin/hlsl/glsl_compat/bit.hlsl"
 
 namespace nbl 
 {
@@ -59,13 +60,7 @@ T atomicCompSwap(NBL_REF_ARG(T) ptr, T comparator, T value)
 template<typename T>
 T bitfieldExtract( T val, uint32_t offsetBits, uint32_t numBits )
 {
-    static_assert( is_integral<T>::value );
-    if( is_unsigned<T>::value )
-    {
-        return spirv::bitFieldUExtract<T>( val, offsetBits, numBits );
-    }
-    //if( is_signed<T>::value )
-        return spirv::bitFieldSExtract<T>( val, offsetBits, numBits );
+    return impl::bitfieldExtract<T, is_signed<T>::value, is_integral<T>::value>( val, offsetBits, numBits );
 }
 
 /**