vmobject.java

来自「纯java操作系统jnode,安装简单和操作简单的个人使用的Java操作系统」· Java 代码 · 共 47 行

/**
 * $Id: VmObject.java,v 1.2 2003/11/28 09:12:34 epr Exp $
 */
package org.jnode.vm.classmgr;

/**
 * <description>
 * 
 * @author epr
 */
public class VmObject {
	
	/**
	 * The offset of the size of an object from the start of the object. This
	 * value must be multipled by SLOT_SIZE to get the offset in bytes.
	 */
	public static final int SIZE_OFFSET = -2;

	/**
	 * The offset of the VMT of an object from the start of the object. This
	 * value must be multipled by SLOT_SIZE to get the offset in bytes.
	 */
	public static final int VMT_OFFSET = -1;
	
	/**
	 * The size of the header of an object. This value must be multipled by
	 * SLOT_SIZE to get the size in bytes.
	 */
	public static final int HEADER_SIZE = 2;
	
	/**
	 * The number of bytes object are aligned on in memory.
	 */
	public static final int OBJECT_ALIGN = 8;
	
	public static final int SIZE_MASK = 0xFFFFFFFC;
	
	/**
	 * Returns the given value aligned to OBJECT_ALIGN. 
	 * @param value
	 * @return int
	 */
	public static int objectAlign(int value) {
		return (value + OBJECT_ALIGN - 1) & ~(OBJECT_ALIGN - 1);
	}
}