/*
* Copyright (c) 2007, 2011, 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.
*
* 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.max.asm;
/**
* Represents an offset between two positions (represented by given labels) in the assembled code.
*/
public class OffsetLiteral extends MutableAssembledObject {
/**
* Creates an offset between two positions (represented by given labels) in the assembled code.
*
* @param base the label whose position marks the base of the offset
* @param target the label whose position marks the target of the offset
*/
protected OffsetLiteral(Assembler assembler, int startPosition, int endPosition, Label target, Label base) {
super(assembler, startPosition, endPosition);
assembler.addFixedSizeAssembledObject(this);
this.target = target;
this.base = base;
}
private final Label target;
private final Label base;
@Override
protected final void assemble() throws AssemblyException {
final Assembler assembler = assembler();
final long offset = offset();
// select the correct assembler function to emit the offset.
// The assembler knows the endianness to use
switch(size()) {
case 1:
assembler.emitByte((byte) (offset & 0xFF));
break;
case 2:
assembler.emitShort((short) (offset & 0xFFFF));
break;
case 4:
assembler.emitInt((int) (offset & 0xFFFFFFFF));
break;
case 8:
assembler.emitLong(offset);
break;
default:
throw new AssemblyException("Invalid size for offset literal");
}
}
public final long offset() throws AssemblyException {
return target.position() - base.position();
}
public final boolean isCode() {
return false;
}
}