com.sun.glass.ui.monocle.C Maven / Gradle / Ivy
/*
* Copyright (c) 2013, 2014, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package com.sun.glass.ui.monocle;
import java.nio.ByteBuffer;
import java.security.Permission;
/**
* The C class provides ways to wrap pointers to native C structures in Java
* objects.
*
* C is a singleton. Its instance is obtained by calling C.getC(). This
* requires the RuntimePermission "loadLibrary.*".
*/
class C {
private static Permission permission = new RuntimePermission("loadLibrary.*");
private static C instance = new C();
/**
* Obtains the single instance of LinuxSystem. Calling this method requires
* the RuntimePermission "loadLibrary.*".
*/
static C getC() {
checkPermissions();
return instance;
}
private static void checkPermissions() {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkPermission(permission);
}
}
private C() {
}
/**
* Structure is used for wrapping C structs in Java objects. A subclass of
* Structure must implement the method sizeof() to define the size of the
* struct it wraps.
*/
static abstract class Structure {
final ByteBuffer b;
final long p;
/** Create a new Structure wrapping a new C struct */
protected Structure() {
b = ByteBuffer.allocateDirect(sizeof());
p = getC().GetDirectBufferAddress(b);
}
/**
* Create a new Structure wrapping the C struct at the given location
* in memory
* @param ptr The memory address of the C struct to wrap
*/
protected Structure(long ptr) {
b = getC().NewDirectByteBuffer(ptr, sizeof());
p = ptr;
}
/** The size of the C struct in bytes. Must be overridden by subclasses. */
abstract int sizeof();
}
/** Create a new ByteBuffer that provides access to the memory at a given
* address
*
* @param ptr The memory address for which to create a ByteBuffer.
* @param size The byte length of memory to be wrapped in the ByteBuffer.
* @return a new ByteBuffer providing direct access to the requested
* memory region
*/
native ByteBuffer NewDirectByteBuffer(long ptr, int size);
/**
* Finds the memory address pointed to by a direct ByteBuffer
*
* @param b a direct ByteBuffer
* @return the memory address referenced by b
*/
native long GetDirectBufferAddress(ByteBuffer b);
}