GlueGen Struct [1]: Enhance com.jogamp.common.nio.* to serve a most native-free-code Struct-Code generation

Recfactored all NIO buffer utils to Buffers, i.e. buffer <-> address, memcpy, strnlen, etc

Buffers:
- Added copyNativeToDirectByteBuffer(..), allowing to copy a native memory slice into a direct buffer.
- Added typeNameToBufferClass(String) and sizeOfBufferElem(Class<? extends Buffer>)
- Completed slize2<Type>(..) buffer-mapping methods
- Exposure of safe getDirectByteBuffer(..) w/ null-check (package private)

Added NativeBuffer.storeDirectAddress(..), allowing to write the array address into a native buffer (struct, etc),
allowing to referencing the ElementBuffer (linear array of elements) and PointerBuffer (array of pointer).
Hint: This can be read via PointerBuffer.wrap(..).get(0)

Added ElementBuffer (a NativeBuffer) mapping an array of elements,
completing native abstraction next to PointerBuffer (array of pointer).

ElementBuffer can dereference an existing element-array by native address via ElementBuffer.derefPointer(..).
Views of its content can be directly accessed via ElementBuffer.slice(..).

+++

These utilities and buffer abstractions will allow to reuse code and simplify the GlueGen struct get/set implementations
and help to reduce native code injection.

1 files changed, 10 insertions, 4 deletions

diff --git a/src/java/com/jogamp/common/nio/StructAccessor.java b/src/java/com/jogamp/common/nio/StructAccessor.java
index 8ae0c29..79e8a36 100644
--- a/src/java/com/jogamp/common/nio/StructAccessor.java
+++ b/src/java/com/jogamp/common/nio/StructAccessor.java
@@ -1,6 +1,6 @@
 /*
+ * Copyright (c) 2010-2023 JogAmp Community. All rights reserved.
  * Copyright (c) 2003 Sun Microsystems, Inc. All Rights Reserved.
- * Copyright (c) 2010 JogAmp Community. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
@@ -42,22 +42,28 @@ package com.jogamp.common.nio;
 import java.nio.*;
 
 /**
- * @author Kenneth Russel, et al.
+ * @author Kenneth Russel, Sven Gothel, Michael Bien, et al.
  */
 public class StructAccessor {
 
     private final ByteBuffer bb;
 
+    /** Create a new instance. The {@link ByteBuffer} will be {@link ByteBuffer#rewind()} and native-order to be used with native code set. */
     public StructAccessor(final ByteBuffer bb) {
-        // Setting of byte order is concession to native code which needs
-        // to instantiate these
         this.bb = bb.order(ByteOrder.nativeOrder());
+        this.bb.rewind();
     }
 
+    /** Return the underlying native direct ByteBuffer */
     public final ByteBuffer getBuffer() {
         return bb;
     }
 
+    /** Returns the native address of the underlying native ByteBuffer. */
+    public final long getDirectBufferAddress() {
+        return Buffers.getDirectBufferAddressImpl(bb);
+    }
+
     /**
      * Returns a slice of the current ByteBuffer starting at the
      * specified byte offset and extending the specified number of