src/main/java/org/luaj/vm3/LoadState.java - minecraft/opencomputers - Rivoreo Source Code Repositories

 /*******************************************************************************
 * Copyright (c) 2009 Luaj.org. All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 ******************************************************************************/
 package org.luaj.vm3;

 import java.io.DataInputStream;
 import java.io.IOException;
 import java.io.InputStream;

 import org.luaj.vm3.compiler.DumpState;

 /**
 * Class to undump compiled lua bytecode into a {@link Prototype} instances.
 * <p>
 * The {@link LoadState} class implements {@link Globals#Undumper}
 * which is used to undump a string of bytes that represent a lua binary file
 * using either the C-based lua compiler, or luaj's {@link DumpState#dump} function.
 * <p>
 * The canonical method to load and execute code is done
 * indirectly using the Globals:
 * <pre> {@code
 * Globals globals = JsePlatform.standardGlobals();
 * LuaValue chunk = globasl.load("print('hello, world')", "main.lua");
 * chunk.call();
 * } </pre>
 * This should work regardless of which {@link Globals.Compiler}
 * has been installed.
 * <p>
 * By default, when using {@link JsePlatform} or {@JmePlatform}
 * to construct globals, the {@link LoadState} is installed
 * as the default {@link Globals#undumper}.
 * <p>
 *
 * A lua binary file is created via {@link DumpState#dump}:
 * <pre> {@code
 * Globals globals = JsePlatform.standardGlobals();
 * Prototype p = globals.compilePrototype(new StringReader("print('hello, world')"), "main.lua");
 * ByteArrayOutputStream o = new ByteArrayOutputStream();
 * DumpState.dump(p, o, false);
 * byte[] lua_binary_file_bytes = o.toByteArray();
 * } </pre>
 *
 * The {@link LoadState} may be used directly to undump these bytes:
 * <pre> {@code
 * Prototypep = LoadState.instance.undump(new ByteArrayInputStream(lua_binary_file_bytes), "main.lua");
 * LuaClosure c = new LuaClosure(p, globals);
 * c.call();
 * } </pre>
 *
 *
 * More commonly, the {@link Globals#undumper} may be used to undump them:
 * <pre> {@code
 * Prototype p = globals.loadPrototype(new ByteArrayInputStream(lua_binary_file_bytes), "main.lua", "b");
 * LuaClosure c = new LuaClosure(p, globals);
 * c.call();
 * } </pre>
 *
 * @see LuaCompiler
 * @see LuaClosure
 * @see LuaFunction
 * @see LoadState#compiler
 * @see LoadState#load(InputStream, String, LuaValue)
 * @see LuaC
 * @see LuaJC
 */
 public class LoadState implements Globals.Undumper {

 	/** Shared instance of Globals.Undumper to use loading prototypes from binary lua files */
 	public static final Globals.Undumper instance = new LoadState();

 	/** format corresponding to non-number-patched lua, all numbers are floats or doubles */
 	public static final int NUMBER_FORMAT_FLOATS_OR_DOUBLES = 0;

 	/** format corresponding to non-number-patched lua, all numbers are ints */
 	public static final int NUMBER_FORMAT_INTS_ONLY = 1;

 	/** format corresponding to number-patched lua, all numbers are 32-bit (4 byte) ints */
 	public static final int NUMBER_FORMAT_NUM_PATCH_INT32 = 4;

 	// type constants
 	public static final int LUA_TINT = (-2);
 	public static final int LUA_TNONE = (-1);
 	public static final int LUA_TNIL = 0;
 	public static final int LUA_TBOOLEAN = 1;
 	public static final int LUA_TLIGHTUSERDATA = 2;
 	public static final int LUA_TNUMBER = 3;
 	public static final int LUA_TSTRING = 4;
 	public static final int LUA_TTABLE = 5;
 	public static final int LUA_TFUNCTION = 6;
 	public static final int LUA_TUSERDATA = 7;
 	public static final int LUA_TTHREAD = 8;
 	public static final int LUA_TVALUE = 9;

 	/** The character encoding to use for file encoding.  Null means the default encoding */
 	public static String encoding = null;

 	/** Signature byte indicating the file is a compiled binary chunk */
 	public static final byte[] LUA_SIGNATURE = { '\033', 'L', 'u', 'a' };

 	/** Data to catch conversion errors */
 	public static final byte[] LUAC_TAIL = { (byte) 0x19, (byte) 0x93, '\r', '\n', (byte) 0x1a, '\n', };

 	/** Name for compiled chunks */
 	public static final String SOURCE_BINARY_STRING = "binary string";

 	/** for header of binary files -- this is Lua 5.2 */
 	public static final int LUAC_VERSION = 0x52;

 	/** for header of binary files -- this is the official format */
 	public static final int LUAC_FORMAT = 0;

 	/** size of header of binary files */
 	public static final int LUAC_HEADERSIZE = 12;

 	// values read from the header
 	private int luacVersion;
 	private int luacFormat;
 	private boolean luacLittleEndian;
 	private int luacSizeofInt;
 	private int luacSizeofSizeT;
 	private int luacSizeofInstruction;
 	private int luacSizeofLuaNumber;
 	private int luacNumberFormat;

 	/** input stream from which we are loading */
 	public final DataInputStream is;

 	/** Name of what is being loaded? */
 	String name;

 	private static final LuaValue[] NOVALUES = {};
 	private static final Prototype[] NOPROTOS = {};
 	private static final LocVars[] NOLOCVARS = {};
 	private static final LuaString[] NOSTRVALUES = {};
 	private static final Upvaldesc[] NOUPVALDESCS = {};
 	private static final int[] NOINTS = {};

 	/** Read buffer */
 	private byte[] buf = new byte[512];

 	/** Install this class as the standard Globals.Undumper for the supplied Globals */
 	public static void install(Globals globals) {
 		globals.undumper = instance;
 	}

 	/** Load a 4-byte int value from the input stream
 	 * @return the int value laoded.
 	 **/
 	int loadInt() throws IOException {
 		is.readFully(buf, 0, 4);
 		return luacLittleEndian ? (buf[3] << 24) | ((0xff & buf[2]) << 16) | ((0xff & buf[1]) << 8) | (0xff & buf[0]) : (buf[0] << 24) | ((0xff & buf[1]) << 16) | ((0xff & buf[2]) << 8) | (0xff & buf[3]);
 	}

 	/** Load an array of int values from the input stream
 	 * @return the array of int values laoded.
 	 **/
 	int[] loadIntArray() throws IOException {
 		int n = loadInt();
 		if (n == 0)
 			return NOINTS;

 		// read all data at once
 		int m = n << 2;
 		if (buf.length < m)
 			buf = new byte[m];
 		is.readFully(buf, 0, m);
 		int[] array = new int[n];
 		for (int i = 0, j = 0; i < n; ++i, j += 4)
 			array[i] = luacLittleEndian ? (buf[j + 3] << 24) | ((0xff & buf[j + 2]) << 16) | ((0xff & buf[j + 1]) << 8) | (0xff & buf[j + 0]) : (buf[j + 0] << 24) | ((0xff & buf[j + 1]) << 16) | ((0xff & buf[j + 2]) << 8) | (0xff & buf[j + 3]);

 		return array;
 	}

 	/** Load a long  value from the input stream
 	 * @return the long value laoded.
 	 **/
 	long loadInt64() throws IOException {
 		int a, b;
 		if (this.luacLittleEndian) {
 			a = loadInt();
 			b = loadInt();
 		} else {
 			b = loadInt();
 			a = loadInt();
 		}
 		return (((long) b) << 32) | (((long) a) & 0xffffffffL);
 	}

 	/** Load a lua strin gvalue from the input stream
 	 * @return the {@link LuaString} value laoded.
 	 **/
 	LuaString loadString() throws IOException {
 		int size = this.luacSizeofSizeT == 8 ? (int) loadInt64() : loadInt();
 		if (size == 0)
 			return null;
 		byte[] bytes = new byte[size];
 		is.readFully(bytes, 0, size);
 		return LuaString.valueOf(bytes, 0, bytes.length - 1);
 	}

 	/**
 	 * Convert bits in a long value to a {@link LuaValue}.
 	 * @param bits long value containing the bits
 	 * @return {@link LuaInteger} or {@link LuaDouble} whose value corresponds to the bits provided.
 	 */
 	public static LuaValue longBitsToLuaNumber(long bits) {
 		if ((bits & ((1L << 63) - 1)) == 0L) {
 			return LuaValue.ZERO;
 		}

 		int e = (int) ((bits >> 52) & 0x7ffL) - 1023;

 		if (e >= 0 && e < 31) {
 			long f = bits & 0xFFFFFFFFFFFFFL;
 			int shift = 52 - e;
 			long intPrecMask = (1L << shift) - 1;
 			if ((f & intPrecMask) == 0) {
 				int intValue = (int) (f >> shift) | (1 << e);
 				return LuaInteger.valueOf(((bits >> 63) != 0) ? -intValue : intValue);
 			}
 		}

 		return LuaValue.valueOf(Double.longBitsToDouble(bits));
 	}

 	/**
 	 * Load a number from a binary chunk
 	 * @return the {@link LuaValue} loaded
 	 * @throws IOException if an i/o exception occurs
 	 */
 	LuaValue loadNumber() throws IOException {
 		if (luacNumberFormat == NUMBER_FORMAT_INTS_ONLY) {
 			return LuaInteger.valueOf(loadInt());
 		} else {
 			return longBitsToLuaNumber(loadInt64());
 		}
 	}

 	/**
 	 * Load a list of constants from a binary chunk
 	 * @param f the function prototype
 	 * @throws IOException if an i/o exception occurs
 	 */
 	void loadConstants(Prototype f) throws IOException {
 		int n = loadInt();
 		LuaValue[] values = n > 0 ? new LuaValue[n] : NOVALUES;
 		for (int i = 0; i < n; i++) {
 			switch (is.readByte()) {
 			case LUA_TNIL:
 				values[i] = LuaValue.NIL;
 				break;
 			case LUA_TBOOLEAN:
 				values[i] = (0 != is.readUnsignedByte() ? LuaValue.TRUE : LuaValue.FALSE);
 				break;
 			case LUA_TINT:
 				values[i] = LuaInteger.valueOf(loadInt());
 				break;
 			case LUA_TNUMBER:
 				values[i] = loadNumber();
 				break;
 			case LUA_TSTRING:
 				values[i] = loadString();
 				break;
 			default:
 				throw new IllegalStateException("bad constant");
 			}
 		}
 		f.k = values;

 		n = loadInt();
 		Prototype[] protos = n > 0 ? new Prototype[n] : NOPROTOS;
 		for (int i = 0; i < n; i++)
 			protos[i] = loadFunction(f.source);
 		f.p = protos;
 	}

 	void loadUpvalues(Prototype f) throws IOException {
 		int n = loadInt();
 		f.upvalues = n > 0 ? new Upvaldesc[n] : NOUPVALDESCS;
 		for (int i = 0; i < n; i++) {
 			boolean instack = is.readByte() != 0;
 			int idx = ((int) is.readByte()) & 0xff;
 			f.upvalues[i] = new Upvaldesc(null, instack, idx);
 		}
 	}

 	/**
 	 * Load the debug info for a function prototype
 	 * @param f the function Prototype
 	 * @throws IOException if there is an i/o exception
 	 */
 	void loadDebug(Prototype f) throws IOException {
 		f.source = loadString();
 		f.lineinfo = loadIntArray();
 		int n = loadInt();
 		f.locvars = n > 0 ? new LocVars[n] : NOLOCVARS;
 		for (int i = 0; i < n; i++) {
 			LuaString varname = loadString();
 			int startpc = loadInt();
 			int endpc = loadInt();
 			f.locvars[i] = new LocVars(varname, startpc, endpc);
 		}

 		n = loadInt();
 		for (int i = 0; i < n; i++)
 			f.upvalues[i].name = loadString();
 	}

 	/**
 	 * Load a function prototype from the input stream
 	 * @param p name of the source
 	 * @return {@link Prototype} instance that was loaded
 	 * @throws IOException
 	 */
 	public Prototype loadFunction(LuaString p) throws IOException {
 		Prototype f = new Prototype();
 		////		this.L.push(f);
 		//		f.source = loadString();
 		//		if ( f.source == null )
 		//			f.source = p;
 		f.linedefined = loadInt();
 		f.lastlinedefined = loadInt();
 		f.numparams = is.readUnsignedByte();
 		f.is_vararg = is.readUnsignedByte();
 		f.maxstacksize = is.readUnsignedByte();
 		f.code = loadIntArray();
 		loadConstants(f);
 		loadUpvalues(f);
 		loadDebug(f);

 		// TODO: add check here, for debugging purposes, I believe
 		// see ldebug.c
 		//		 IF (!luaG_checkcode(f), "bad code");

 		//		 this.L.pop();
 		return f;
 	}

 	/**
 	 * Load the lua chunk header values.
 	 * @throws IOException if an i/o exception occurs.
 	 */
 	public void loadHeader() throws IOException {
 		luacVersion = is.readByte();
 		luacFormat = is.readByte();
 		luacLittleEndian = (0 != is.readByte());
 		luacSizeofInt = is.readByte();
 		luacSizeofSizeT = is.readByte();
 		luacSizeofInstruction = is.readByte();
 		luacSizeofLuaNumber = is.readByte();
 		luacNumberFormat = is.readByte();
 		for (int i = 0; i < LUAC_TAIL.length; ++i)
 			if (is.readByte() != LUAC_TAIL[i])
 				throw new LuaError("Unexpeted byte in luac tail of header, index=" + i);
 	}

 	/**
 	 * Load input stream as a lua binary chunk if the first 4 bytes are the lua binary signature.
 	 * @param stream InputStream to read, after having read the first byte already
 	 * @param name Name to apply to the loaded chunk
 	 * @return {@link Prototype} that was loaded, or null if the first 4 bytes were not the lua signature.
 	 * @throws IOException if an IOException occurs
 	 */
 	public Prototype undump(InputStream stream, String chunkname) throws IOException {
 		// check rest of signature
 		if (stream.read() != LUA_SIGNATURE[0] || stream.read() != LUA_SIGNATURE[1] || stream.read() != LUA_SIGNATURE[2] || stream.read() != LUA_SIGNATURE[3])
 			return null;

 		// load file as a compiled chunk
 		String sname = getSourceName(chunkname);
 		LoadState s = new LoadState(stream, sname);
 		s.loadHeader();

 		// check format
 		switch (s.luacNumberFormat) {
 		case NUMBER_FORMAT_FLOATS_OR_DOUBLES:
 		case NUMBER_FORMAT_INTS_ONLY:
 		case NUMBER_FORMAT_NUM_PATCH_INT32:
 			break;
 		default:
 			throw new LuaError("unsupported int size");
 		}
 		return s.loadFunction(LuaString.valueOf(sname));
 	}

 	/**
 	 * Construct a source name from a supplied chunk name
 	 * @param name String name that appears in the chunk
 	 * @return source file name
 	 */
 	public static String getSourceName(String name) {
 		String sname = name;
 		if (name.startsWith("@") || name.startsWith("="))
 			sname = name.substring(1);
 		else if (name.startsWith("\033"))
 			sname = SOURCE_BINARY_STRING;
 		return sname;
 	}

 	/** Private constructor for create a load state */
 	private LoadState(InputStream stream, String name) {
 		this.name = name;
 		this.is = new DataInputStream(stream);
 	}

 	private LoadState() {
 		this.name = "";
 		this.is = null;
 	}
 }
	/*******************************************************************************
	* Copyright (c) 2009 Luaj.org. All rights reserved.
	*
	* Permission is hereby granted, free of charge, to any person obtaining a copy
	* of this software and associated documentation files (the "Software"), to deal
	* in the Software without restriction, including without limitation the rights
	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	* copies of the Software, and to permit persons to whom the Software is
	* furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	* THE SOFTWARE.
	******************************************************************************/
	package org.luaj.vm3;

	import java.io.DataInputStream;
	import java.io.IOException;
	import java.io.InputStream;

	import org.luaj.vm3.compiler.DumpState;

	/**
	* Class to undump compiled lua bytecode into a {@link Prototype} instances.
	* <p>
	* The {@link LoadState} class implements {@link Globals#Undumper}
	* which is used to undump a string of bytes that represent a lua binary file
	* using either the C-based lua compiler, or luaj's {@link DumpState#dump} function.
	* <p>
	* The canonical method to load and execute code is done
	* indirectly using the Globals:
	* <pre> {@code
	* Globals globals = JsePlatform.standardGlobals();
	* LuaValue chunk = globasl.load("print('hello, world')", "main.lua");
	* chunk.call();
	* } </pre>
	* This should work regardless of which {@link Globals.Compiler}
	* has been installed.
	* <p>
	* By default, when using {@link JsePlatform} or {@JmePlatform}
	* to construct globals, the {@link LoadState} is installed
	* as the default {@link Globals#undumper}.
	* <p>
	*
	* A lua binary file is created via {@link DumpState#dump}:
	* <pre> {@code
	* Globals globals = JsePlatform.standardGlobals();
	* Prototype p = globals.compilePrototype(new StringReader("print('hello, world')"), "main.lua");
	* ByteArrayOutputStream o = new ByteArrayOutputStream();
	* DumpState.dump(p, o, false);
	* byte[] lua_binary_file_bytes = o.toByteArray();
	* } </pre>
	*
	* The {@link LoadState} may be used directly to undump these bytes:
	* <pre> {@code
	* Prototypep = LoadState.instance.undump(new ByteArrayInputStream(lua_binary_file_bytes), "main.lua");
	* LuaClosure c = new LuaClosure(p, globals);
	* c.call();
	* } </pre>
	*
	*
	* More commonly, the {@link Globals#undumper} may be used to undump them:
	* <pre> {@code
	* Prototype p = globals.loadPrototype(new ByteArrayInputStream(lua_binary_file_bytes), "main.lua", "b");
	* LuaClosure c = new LuaClosure(p, globals);
	* c.call();
	* } </pre>
	*
	* @see LuaCompiler
	* @see LuaClosure
	* @see LuaFunction
	* @see LoadState#compiler
	* @see LoadState#load(InputStream, String, LuaValue)
	* @see LuaC
	* @see LuaJC
	*/
	public class LoadState implements Globals.Undumper {

	/** Shared instance of Globals.Undumper to use loading prototypes from binary lua files */
	public static final Globals.Undumper instance = new LoadState();

	/** format corresponding to non-number-patched lua, all numbers are floats or doubles */
	public static final int NUMBER_FORMAT_FLOATS_OR_DOUBLES = 0;

	/** format corresponding to non-number-patched lua, all numbers are ints */
	public static final int NUMBER_FORMAT_INTS_ONLY = 1;

	/** format corresponding to number-patched lua, all numbers are 32-bit (4 byte) ints */
	public static final int NUMBER_FORMAT_NUM_PATCH_INT32 = 4;

	// type constants
	public static final int LUA_TINT = (-2);
	public static final int LUA_TNONE = (-1);
	public static final int LUA_TNIL = 0;
	public static final int LUA_TBOOLEAN = 1;
	public static final int LUA_TLIGHTUSERDATA = 2;
	public static final int LUA_TNUMBER = 3;
	public static final int LUA_TSTRING = 4;
	public static final int LUA_TTABLE = 5;
	public static final int LUA_TFUNCTION = 6;
	public static final int LUA_TUSERDATA = 7;
	public static final int LUA_TTHREAD = 8;
	public static final int LUA_TVALUE = 9;

	/** The character encoding to use for file encoding. Null means the default encoding */
	public static String encoding = null;

	/** Signature byte indicating the file is a compiled binary chunk */
	public static final byte[] LUA_SIGNATURE = { '\033', 'L', 'u', 'a' };

	/** Data to catch conversion errors */
	public static final byte[] LUAC_TAIL = { (byte) 0x19, (byte) 0x93, '\r', '\n', (byte) 0x1a, '\n', };

	/** Name for compiled chunks */
	public static final String SOURCE_BINARY_STRING = "binary string";

	/** for header of binary files -- this is Lua 5.2 */
	public static final int LUAC_VERSION = 0x52;

	/** for header of binary files -- this is the official format */
	public static final int LUAC_FORMAT = 0;

	/** size of header of binary files */
	public static final int LUAC_HEADERSIZE = 12;

	// values read from the header
	private int luacVersion;
	private int luacFormat;
	private boolean luacLittleEndian;
	private int luacSizeofInt;
	private int luacSizeofSizeT;
	private int luacSizeofInstruction;
	private int luacSizeofLuaNumber;
	private int luacNumberFormat;

	/** input stream from which we are loading */
	public final DataInputStream is;

	/** Name of what is being loaded? */
	String name;

	private static final LuaValue[] NOVALUES = {};
	private static final Prototype[] NOPROTOS = {};
	private static final LocVars[] NOLOCVARS = {};
	private static final LuaString[] NOSTRVALUES = {};
	private static final Upvaldesc[] NOUPVALDESCS = {};
	private static final int[] NOINTS = {};

	/** Read buffer */
	private byte[] buf = new byte[512];

	/** Install this class as the standard Globals.Undumper for the supplied Globals */
	public static void install(Globals globals) {
	globals.undumper = instance;
	}

	/** Load a 4-byte int value from the input stream
	* @return the int value laoded.
	**/
	int loadInt() throws IOException {
	is.readFully(buf, 0, 4);
	return luacLittleEndian ? (buf[3] << 24) \| ((0xff & buf[2]) << 16) \| ((0xff & buf[1]) << 8) \| (0xff & buf[0]) : (buf[0] << 24) \| ((0xff & buf[1]) << 16) \| ((0xff & buf[2]) << 8) \| (0xff & buf[3]);
	}

	/** Load an array of int values from the input stream
	* @return the array of int values laoded.
	**/
	int[] loadIntArray() throws IOException {
	int n = loadInt();
	if (n == 0)
	return NOINTS;

	// read all data at once
	int m = n << 2;
	if (buf.length < m)
	buf = new byte[m];
	is.readFully(buf, 0, m);
	int[] array = new int[n];
	for (int i = 0, j = 0; i < n; ++i, j += 4)
	array[i] = luacLittleEndian ? (buf[j + 3] << 24) \| ((0xff & buf[j + 2]) << 16) \| ((0xff & buf[j + 1]) << 8) \| (0xff & buf[j + 0]) : (buf[j + 0] << 24) \| ((0xff & buf[j + 1]) << 16) \| ((0xff & buf[j + 2]) << 8) \| (0xff & buf[j + 3]);

	return array;
	}

	/** Load a long value from the input stream
	* @return the long value laoded.
	**/
	long loadInt64() throws IOException {
	int a, b;
	if (this.luacLittleEndian) {
	a = loadInt();
	b = loadInt();
	} else {
	b = loadInt();
	a = loadInt();
	}
	return (((long) b) << 32) \| (((long) a) & 0xffffffffL);
	}

	/** Load a lua strin gvalue from the input stream
	* @return the {@link LuaString} value laoded.
	**/
	LuaString loadString() throws IOException {
	int size = this.luacSizeofSizeT == 8 ? (int) loadInt64() : loadInt();
	if (size == 0)
	return null;
	byte[] bytes = new byte[size];
	is.readFully(bytes, 0, size);
	return LuaString.valueOf(bytes, 0, bytes.length - 1);
	}

	/**
	* Convert bits in a long value to a {@link LuaValue}.
	* @param bits long value containing the bits
	* @return {@link LuaInteger} or {@link LuaDouble} whose value corresponds to the bits provided.
	*/
	public static LuaValue longBitsToLuaNumber(long bits) {
	if ((bits & ((1L << 63) - 1)) == 0L) {
	return LuaValue.ZERO;
	}

	int e = (int) ((bits >> 52) & 0x7ffL) - 1023;

	if (e >= 0 && e < 31) {
	long f = bits & 0xFFFFFFFFFFFFFL;
	int shift = 52 - e;
	long intPrecMask = (1L << shift) - 1;
	if ((f & intPrecMask) == 0) {
	int intValue = (int) (f >> shift) \| (1 << e);
	return LuaInteger.valueOf(((bits >> 63) != 0) ? -intValue : intValue);
	}
	}

	return LuaValue.valueOf(Double.longBitsToDouble(bits));
	}

	/**
	* Load a number from a binary chunk
	* @return the {@link LuaValue} loaded
	* @throws IOException if an i/o exception occurs
	*/
	LuaValue loadNumber() throws IOException {
	if (luacNumberFormat == NUMBER_FORMAT_INTS_ONLY) {
	return LuaInteger.valueOf(loadInt());
	} else {
	return longBitsToLuaNumber(loadInt64());
	}
	}

	/**
	* Load a list of constants from a binary chunk
	* @param f the function prototype
	* @throws IOException if an i/o exception occurs
	*/
	void loadConstants(Prototype f) throws IOException {
	int n = loadInt();
	LuaValue[] values = n > 0 ? new LuaValue[n] : NOVALUES;
	for (int i = 0; i < n; i++) {
	switch (is.readByte()) {
	case LUA_TNIL:
	values[i] = LuaValue.NIL;
	break;
	case LUA_TBOOLEAN:
	values[i] = (0 != is.readUnsignedByte() ? LuaValue.TRUE : LuaValue.FALSE);
	break;
	case LUA_TINT:
	values[i] = LuaInteger.valueOf(loadInt());
	break;
	case LUA_TNUMBER:
	values[i] = loadNumber();
	break;
	case LUA_TSTRING:
	values[i] = loadString();
	break;
	default:
	throw new IllegalStateException("bad constant");
	}
	}
	f.k = values;

	n = loadInt();
	Prototype[] protos = n > 0 ? new Prototype[n] : NOPROTOS;
	for (int i = 0; i < n; i++)
	protos[i] = loadFunction(f.source);
	f.p = protos;
	}

	void loadUpvalues(Prototype f) throws IOException {
	int n = loadInt();
	f.upvalues = n > 0 ? new Upvaldesc[n] : NOUPVALDESCS;
	for (int i = 0; i < n; i++) {
	boolean instack = is.readByte() != 0;
	int idx = ((int) is.readByte()) & 0xff;
	f.upvalues[i] = new Upvaldesc(null, instack, idx);
	}
	}

	/**
	* Load the debug info for a function prototype
	* @param f the function Prototype
	* @throws IOException if there is an i/o exception
	*/
	void loadDebug(Prototype f) throws IOException {
	f.source = loadString();
	f.lineinfo = loadIntArray();
	int n = loadInt();
	f.locvars = n > 0 ? new LocVars[n] : NOLOCVARS;
	for (int i = 0; i < n; i++) {
	LuaString varname = loadString();
	int startpc = loadInt();
	int endpc = loadInt();
	f.locvars[i] = new LocVars(varname, startpc, endpc);
	}

	n = loadInt();
	for (int i = 0; i < n; i++)
	f.upvalues[i].name = loadString();
	}

	/**
	* Load a function prototype from the input stream
	* @param p name of the source
	* @return {@link Prototype} instance that was loaded
	* @throws IOException
	*/
	public Prototype loadFunction(LuaString p) throws IOException {
	Prototype f = new Prototype();
	//// this.L.push(f);
	// f.source = loadString();
	// if ( f.source == null )
	// f.source = p;
	f.linedefined = loadInt();
	f.lastlinedefined = loadInt();
	f.numparams = is.readUnsignedByte();
	f.is_vararg = is.readUnsignedByte();
	f.maxstacksize = is.readUnsignedByte();
	f.code = loadIntArray();
	loadConstants(f);
	loadUpvalues(f);
	loadDebug(f);

	// TODO: add check here, for debugging purposes, I believe
	// see ldebug.c
	// IF (!luaG_checkcode(f), "bad code");

	// this.L.pop();
	return f;
	}

	/**
	* Load the lua chunk header values.
	* @throws IOException if an i/o exception occurs.
	*/
	public void loadHeader() throws IOException {
	luacVersion = is.readByte();
	luacFormat = is.readByte();
	luacLittleEndian = (0 != is.readByte());
	luacSizeofInt = is.readByte();
	luacSizeofSizeT = is.readByte();
	luacSizeofInstruction = is.readByte();
	luacSizeofLuaNumber = is.readByte();
	luacNumberFormat = is.readByte();
	for (int i = 0; i < LUAC_TAIL.length; ++i)
	if (is.readByte() != LUAC_TAIL[i])
	throw new LuaError("Unexpeted byte in luac tail of header, index=" + i);
	}

	/**
	* Load input stream as a lua binary chunk if the first 4 bytes are the lua binary signature.
	* @param stream InputStream to read, after having read the first byte already
	* @param name Name to apply to the loaded chunk
	* @return {@link Prototype} that was loaded, or null if the first 4 bytes were not the lua signature.
	* @throws IOException if an IOException occurs
	*/
	public Prototype undump(InputStream stream, String chunkname) throws IOException {
	// check rest of signature
	if (stream.read() != LUA_SIGNATURE[0] \|\| stream.read() != LUA_SIGNATURE[1] \|\| stream.read() != LUA_SIGNATURE[2] \|\| stream.read() != LUA_SIGNATURE[3])
	return null;

	// load file as a compiled chunk
	String sname = getSourceName(chunkname);
	LoadState s = new LoadState(stream, sname);
	s.loadHeader();

	// check format
	switch (s.luacNumberFormat) {
	case NUMBER_FORMAT_FLOATS_OR_DOUBLES:
	case NUMBER_FORMAT_INTS_ONLY:
	case NUMBER_FORMAT_NUM_PATCH_INT32:
	break;
	default:
	throw new LuaError("unsupported int size");
	}
	return s.loadFunction(LuaString.valueOf(sname));
	}

	/**
	* Construct a source name from a supplied chunk name
	* @param name String name that appears in the chunk
	* @return source file name
	*/
	public static String getSourceName(String name) {
	String sname = name;
	if (name.startsWith("@") \|\| name.startsWith("="))
	sname = name.substring(1);
	else if (name.startsWith("\033"))
	sname = SOURCE_BINARY_STRING;
	return sname;
	}

	/** Private constructor for create a load state */
	private LoadState(InputStream stream, String name) {
	this.name = name;
	this.is = new DataInputStream(stream);
	}

	private LoadState() {
	this.name = "";
	this.is = null;
	}
	}