ModuleMD5Sums.java

/*
  ModuleMD5Sums.java

  (c) 2015 Edward Swartz

  All rights reserved. This program and the accompanying materials
  are made available under the terms of the Eclipse Public License v1.0
  which accompanies this distribution, and is available at
  http://www.eclipse.org/legal/epl-v10.html
 */
package v9t9.common.modules;

import java.util.Arrays;
import java.util.Comparator;

import v9t9.common.memory.MemoryEntryInfo;
import ejs.base.utils.FileUtils;
import ejs.base.utils.HexUtils;

/**
 * This class constructs "module MD5s" from module entries,
 * allowing a cheap and portable way of identifying a module,
 * short of encoding all its content.
 * @author ejs
 *
 */
public class ModuleMD5Sums {

	public static String createMD5(IModule module) {
		return createMD5(module.getMemoryEntryInfos());
	}
	
	public static String createMD5(MemoryEntryInfo[] ents) {
		Arrays.sort(ents, new Comparator<MemoryEntryInfo>() {

			@Override
			public int compare(MemoryEntryInfo arg0, MemoryEntryInfo arg1) {
				int diff = arg0.getDomainName().compareTo(arg1.getDomainName());
				if (diff != 0)
					return diff;
				
				diff = arg0.getAddress() - arg1.getAddress();
				if (diff != 0)
					return diff;
				
				diff = arg0.getAddress2() - arg1.getAddress2();
				if (diff != 0)
					return diff;
				
				diff = arg0.getBankSize() - arg1.getBankSize();
				if (diff != 0)
					return diff;
				
				diff = arg0.getSize() - arg1.getSize();
				if (diff != 0)
					return diff;
				
				return arg0.getName().compareTo(arg1.getName());
			}
			
		});
		
		StringBuilder sb = new StringBuilder();
		for (MemoryEntryInfo ent : ents) {
			sb.append(ent.getDomainName());
			sb.append(HexUtils.toHex4(ent.getAddress()));
			if (ent.getAddress2() != 0)
				sb.append(HexUtils.toHex4(ent.getAddress2()));
			if (ent.getFileMD5() != null) {
				String alg = ent.getEffectiveFileMD5Algorithm();
				sb.append(alg);
				sb.append(ent.getFileMD5());
			}
			if (ent.getFile2MD5() != null) {
				String alg = ent.getEffectiveFile2MD5Algorithm();
				sb.append(alg);
				sb.append(ent.getFile2MD5());
			}
		}

		return FileUtils.getMD5Hash(sb.toString().getBytes());
	}
}