Document null return for SIMD levels the CPU doesn't support

include/FastNoise/FastNoise.h

@@ -32,6 +32,7 @@ namespace FastNoise
      *  @param  maxFeatureSet  Maximum SIMD feature set to use. Defaults to auto-detecting
      *                         the best available on the current CPU.
      *  @return A SmartNode<T> owning the new node. null if the maxFeatureSet is below the min compiled SIMD feature set
+     *          or above what the CPU supports
      */
     template<typename T>
     SmartNode<T> New( FastSIMD::FeatureSet maxFeatureSet /*= FastSIMD::FeatureSet::Max*/ )
@@ -60,7 +61,7 @@ namespace FastNoise
      *
      *  @param  encodedNodeTreeString  Encoded node tree string.
      *  @param  maxFeatureSet          Maximum SIMD feature set to use. Defaults to auto-detect.
-     *  @return Root node of the deserialised tree, or nullptr if the string is invalid.
+     *  @return Root node of the deserialised tree, or nullptr if the string is invalid or the CPU doesn't support maxFeatureSet.
      */
     FASTNOISE_API SmartNode<> NewFromEncodedNodeTree( const char* encodedNodeTreeString, FastSIMD::FeatureSet maxFeatureSet = FastSIMD::FeatureSet::Max );
 }

include/FastNoise/FastNoise_C.h

@@ -22,7 +22,7 @@ extern "C" {
  *
  *  @param encodedString  Encoded node tree string (e.g. from the Node Editor).
  *  @param maxFeatureSet  Maximum auto-detected SIMD feature set. Pass ~0u (uint32_max) for no limit.
- *  @return Opaque node handle, or NULL on failure.
+ *  @return Opaque node handle, or NULL if the string is invalid or the CPU doesn't support maxFeatureSet.
  */
 FASTNOISE_API void* fnNewFromEncodedNodeTree( const char* encodedString, unsigned /*FastSIMD::FeatureSet*/ maxFeatureSet );
 
@@ -327,7 +327,7 @@ FASTNOISE_API const char* fnGetMetadataName( int id );
  *
  *  @param id         Metadata ID identifying the node type (0 to fnGetMetadataCount()-1).
  *  @param maxFeatureSet  Maximum auto-detected SIMD feature set. Pass ~0u (uint32_max) for no limit.
- *  @return Opaque node handle, or NULL if the ID is invalid. Must be freed with fnDeleteNodeRef().
+ *  @return Opaque node handle, or NULL if the ID is invalid or the CPU doesn't support maxFeatureSet. Must be freed with fnDeleteNodeRef().
  */
 FASTNOISE_API void* fnNewFromMetadata( int id, unsigned /*FastSIMD::FeatureSet*/ maxFeatureSet );
 

include/FastNoise/Metadata.h

@@ -267,7 +267,8 @@ namespace FastNoise
          *  @endcode
          *
          *  @param maxFeatureSet  Maximum SIMD feature set to use. Defaults to auto-detect.
-         *  @return A SmartNode owning the new generator, or null if maxFeatureSet is below the min compiled SIMD feature set.
+         *  @return A SmartNode owning the new generator, or null if maxFeatureSet is below the min compiled SIMD feature set
+         *          or above what the CPU supports.
          */
         virtual SmartNode<> CreateNode( FastSIMD::FeatureSet maxFeatureSet = FastSIMD::FeatureSet::Max ) const = 0;