arraybackedinstructionsource.java

JPC: x86 PC Hardware Emulator. 牛津大学开发的一个纯JAVA的x86系统结构硬件模拟器。

/*
    JPC: A x86 PC Hardware Emulator for a pure Java Virtual Machine
    Release Version 2.0

    A project from the Physics Dept, The University of Oxford

    Copyright (C) 2007 Isis Innovation Limited

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License version 2 as published by
    the Free Software Foundation.

    This program 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 for more details.

    You should have received a copy of the GNU General Public License along
    with this program; if not, write to the Free Software Foundation, Inc.,
    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
    Details (including contact information) can be found at: 

    www.physics.ox.ac.uk/jpc
*/

package org.jpc.emulator.memory.codeblock;

public class ArrayBackedInstructionSource implements InstructionSource
{
    private int[] microcodes;
    private int[] positions;

    private int readOffset;
    private int operationLength;
    private int operationEnd;
    private int operationStart;

    private int x86Start;
    private int x86End;

    public ArrayBackedInstructionSource(int[] microcodes, int[] positions)
    {
	this.microcodes = microcodes;
	this.positions = positions;

	x86Start = 0;
	x86End = 0;
    }

    public boolean getNext()
    {
	if (operationEnd >= microcodes.length)
	    return false;

	operationStart = readOffset = operationEnd++;
	x86Start = x86End;

	while ((operationEnd < microcodes.length) && (positions[operationEnd] == positions[operationEnd - 1])) {
	    operationEnd++;
	}

	x86End = positions[operationEnd - 1];

	return true;
    }
 
    public int getMicrocode()
    {
	if (readOffset < operationEnd)
	    return microcodes[readOffset++];
	else
	    throw new IllegalStateException();
    }
 
    public int getLength()
    {
	return operationEnd - operationStart;
    }
 
    public int getX86Length()
    {
	return x86End - x86Start;
    }
}