/*
 * @(#)Long.java	1.79 04/05/11
 *
 * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package java.lang;

/**
 * The <code>Long</code> class wraps a value of the primitive type
 * <code>long</code> in an object. An object of type <code>Long</code>
 * contains a single field whose type is <code>long</code>.
 *
 * <p> 
 *
 * In addition, this class provides several methods for converting a
 * <code>long</code> to a <code>String</code> and a
 * <code>String</code> to a <code>long</code>, as well as other
 * constants and methods useful when dealing with a <code>long</code>.
 *
 * <p>Implementation note: The implementations of the "bit twiddling"
 * methods (such as {@link #highestOneBit(long) highestOneBit} and
 * {@link #numberOfTrailingZeros(long) numberOfTrailingZeros}) are
 * based on material from Henry S. Warren, Jr.'s <i>Hacker's
 * Delight</i>, (Addison Wesley, 2002).
 *
 * @author  Lee Boynton
 * @author  Arthur van Hoff
 * @author  Josh Bloch
 * @version 1.79, 05/11/04
 * @since   JDK1.0
 */
public final class Long extends Number implements Comparable<Long> {
    /**
     * A constant holding the minimum value a <code>long</code> can
     * have, -2<sup>63</sup>.
     */
    public static final long MIN_VALUE = 0x8000000000000000L;

    /**
     * A constant holding the maximum value a <code>long</code> can
     * have, 2<sup>63</sup>-1.
     */
    public static final long MAX_VALUE = 0x7fffffffffffffffL;

    /**
     * The <code>Class</code> instance representing the primitive type
     * <code>long</code>.
     *
     * @since   JDK1.1
     */
    public static final Class<Long>	TYPE = (Class<Long>) Class.getPrimitiveClass("long");

    /**
     * Returns a string representation of the first argument in the
     * radix specified by the second argument.
     * <p>
     * If the radix is smaller than <code>Character.MIN_RADIX</code>
     * or larger than <code>Character.MAX_RADIX</code>, then the radix
     * <code>10</code> is used instead.
     * <p>
     * If the first argument is negative, the first element of the
     * result is the ASCII minus sign <code>'-'</code>
     * (<code>'\u002d'</code>). If the first argument is not
     * negative, no sign character appears in the result.
     * <p>
     * The remaining characters of the result represent the magnitude
     * of the first argument. If the magnitude is zero, it is
     * represented by a single zero character <code>'0'</code>
     * (<code>'\u0030'</code>); otherwise, the first character of
     * the representation of the magnitude will not be the zero
     * character.  The following ASCII characters are used as digits:
     * <blockquote><pre>
     *   0123456789abcdefghijklmnopqrstuvwxyz
     * </pre></blockquote>
     * These are <code>'\u0030'</code> through
     * <code>'\u0039'</code> and <code>'\u0061'</code> through
     * <code>'\u007a'</code>. If <code>radix</code> is
     * <var>N</var>, then the first <var>N</var> of these characters
     * are used as radix-<var>N</var> digits in the order shown. Thus,
     * the digits for hexadecimal (radix 16) are
     * <code>0123456789abcdef</code>. If uppercase letters are
     * desired, the {@link java.lang.String#toUpperCase()} method may
     * be called on the result:
     * <blockquote><pre>
     * Long.toString(n, 16).toUpperCase()
     * </pre></blockquote>
     * 
     * @param   i       a <code>long</code>to be converted to a string.
     * @param   radix   the radix to use in the string representation.
     * @return  a string representation of the argument in the specified radix.
     * @see     java.lang.Character#MAX_RADIX
     * @see     java.lang.Character#MIN_RADIX
     */
    public static String toString(long i, int radix) {
        if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
	    radix = 10;
        if (radix == 10)
            return toString(i);
        char[] buf = new char[65];
        int charPos = 64;
        boolean negative = (i < 0);

        if (!negative) {
            i = -i;
        }

        while (i <= -radix) {
            buf[charPos--] = Integer.digits[(int)(-(i % radix))];
            i = i / radix;
        }
        buf[charPos] = Integer.digits[(int)(-i)];

        if (negative) { 
            buf[--charPos] = '-';
        }

        return new String(buf, charPos, (65 - charPos));
    }

    /**
     * Returns a string representation of the <code>long</code>
     * argument as an unsigned integer in base 16.
     * <p>
     * The unsigned <code>long</code> value is the argument plus
     * 2<sup>64</sup> if the argument is negative; otherwise, it is
     * equal to the argument.  This value is converted to a string of
     * ASCII digits in hexadecimal (base 16) with no extra
     * leading <code>0</code>s.  If the unsigned magnitude is zero, it
     * is represented by a single zero character <code>'0'</code>
     * (<code>'\u0030'</code>); otherwise, the first character of
     * the representation of the unsigned magnitude will not be the
     * zero character. The following characters are used as
     * hexadecimal digits:
     * <blockquote><pre>
     * 0123456789abcdef
     * </pre></blockquote>
     * These are the characters <code>'\u0030'</code> through
     * <code>'\u0039'</code> and  <code>'\u0061'</code> through
     * <code>'\u0066'</code>.  If uppercase letters are desired,
     * the {@link java.lang.String#toUpperCase()} method may be called
     * on the result:
     * <blockquote><pre>
     * Long.toHexString(n).toUpperCase()
     * </pre></blockquote>
     *
     * @param   i   a <code>long</code> to be converted to a string.
     * @return  the string representation of the unsigned <code>long</code>
     * 		value represented by the argument in hexadecimal
     *		(base 16).
     * @since   JDK 1.0.2
     */
    public static String toHexString(long i) {
	return toUnsignedString(i, 4);
    }

    /**
     * Returns a string representation of the <code>long</code>
     * argument as an unsigned integer in base 8.
     * <p>
     * The unsigned <code>long</code> value is the argument plus
     * 2<sup>64</sup> if the argument is negative; otherwise, it is
     * equal to the argument.  This value is converted to a string of
     * ASCII digits in octal (base 8) with no extra leading
     * <code>0</code>s.
     * <p>
     * If the unsigned magnitude is zero, it is represented by a
     * single zero character <code>'0'</code>
     * (<code>'\u0030'</code>); otherwise, the first character of
     * the representation of the unsigned magnitude will not be the
     * zero character. The following characters are used as octal
     * digits:
     * <blockquote><pre>
     * 01234567
     * </pre></blockquote>
     * These are the characters <code>'\u0030'</code> through 
     * <code>'\u0037'</code>. 
     *
     * @param   i   a <code>long</code> to be converted to a string.
     * @return  the string representation of the unsigned <code>long</code> 
     *		value represented by the argument in octal (base 8).
     * @since   JDK 1.0.2
     */
    public static String toOctalString(long i) {
	return toUnsignedString(i, 3);
    }

    /**
     * Returns a string representation of the <code>long</code>
     * argument as an unsigned integer in base 2.
     * <p>
     * The unsigned <code>long</code> value is the argument plus
     * 2<sup>64</sup> if the argument is negative; otherwise, it is
     * equal to the argument.  This value is converted to a string of
     * ASCII digits in binary (base 2) with no extra leading
     * <code>0</code>s.  If the unsigned magnitude is zero, it is
     * represented by a single zero character <code>'0'</code>
     * (<code>'\u0030'</code>); otherwise, the first character of
     * the representation of the unsigned magnitude will not be the
     * zero character. The characters <code>'0'</code>
     * (<code>'\u0030'</code>) and <code>'1'</code>
     * (<code>'\u0031'</code>) are used as binary digits.
     *
     * @param   i   a <code>long</code> to be converted to a string.
     * @return  the string representation of the unsigned <code>long</code> 
     *          value represented by the argument in binary (base 2).
     * @since   JDK 1.0.2
     */
    public static String toBinaryString(long i) {
	return toUnsignedString(i, 1);
    }

    /**
     * Convert the integer to an unsigned number.
     */
    private static String toUnsignedString(long i, int shift) {
	char[] buf = new char[64];
	int charPos = 64;
	int radix = 1 << shift;
	long mask = radix - 1;
	do {
	    buf[--charPos] = Integer.digits[(int)(i & mask)];
	    i >>>= shift;
	} while (i != 0);
	return new String(buf, charPos, (64 - charPos));
    }

    /**
     * Returns a <code>String</code> object representing the specified
     * <code>long</code>.  The argument is converted to signed decimal
     * representation and returned as a string, exactly as if the
     * argument and the radix 10 were given as arguments to the {@link
     * #toString(long, int)} method.
     *
     * @param   i   a <code>long</code> to be converted.
     * @return  a string representation of the argument in base 10.
     */
    public static String toString(long i) {
        if (i == Long.MIN_VALUE)
            return "-9223372036854775808";
        int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
        char[] buf = new char[size];
        getChars(i, size, buf);
        return new String(0, size, buf);
    }

    /**
     * Places characters representing the integer i into the
     * character array buf. The characters are placed into
     * the buffer backwards starting with the least significant
     * digit at the specified index (exclusive), and working
     * backwards from there.
     *
     * Will fail if i == Long.MIN_VALUE
     */
    static void getChars(long i, int index, char[] buf) {
        long q;
        int r;
        int charPos = index;
        char sign = 0;

        if (i < 0) {
            sign = '-';
            i = -i;
        }

        // Get 2 digits/iteration using longs until quotient fits into an int
        while (i > Integer.MAX_VALUE) { 
            q = i / 100;
            // really: r = i - (q * 100);
            r = (int)(i - ((q << 6) + (q << 5) + (q << 2)));
            i = q;
            buf[--charPos] = Integer.DigitOnes[r];
            buf[--charPos] = Integer.DigitTens[r];
        }

        // Get 2 digits/iteration using ints
        int q2;
        int i2 = (int)i;
        while (i2 >= 65536) {
            q2 = i2 / 100;
            // really: r = i2 - (q * 100);
            r = i2 - ((q2 << 6) + (q2 << 5) + (q2 << 2));
            i2 = q2;
            buf[--charPos] = Integer.DigitOnes[r];
            buf[--charPos] = Integer.DigitTens[r];
        }

        // Fall thru to fast mode for smaller numbers
        // assert(i2 <= 65536, i2);
        for (;;) {
            q2 = (i2 * 52429) >>> (16+3);
            r = i2 - ((q2 << 3) + (q2 << 1));  // r = i2-(q2*10) ...
            buf[--charPos] = Integer.digits[r];
            i2 = q2;
            if (i2 == 0) break;
        }
        if (sign != 0) {
            buf[--charPos] = sign;
        }
    }

    // Requires positive x
    static int stringSize(long x) {
        long p = 10;
        for (int i=1; i<19; i++) {
            if (x < p)
                return i;
            p = 10*p;
        }
        return 19;
    }

    /**
     * Parses the string argument as a signed <code>long</code> in the
     * radix specified by the second argument. The characters in the
     * string must all be digits of the specified radix (as determined
     * by whether {@link java.lang.Character#digit(char, int)} returns
     * a nonnegative value), except that the first character may be an
     * ASCII minus sign <code>'-'</code> (<code>'\u002D'</code>) to
     * indicate a negative value. The resulting <code>long</code>
     * value is returned.
     * <p>
     * Note that neither the character <code>L</code>
     * (<code>'\u004C'</code>) nor <code>l</code>
     * (<code>'\u006C'</code>) is permitted to appear at the end
     * of the string as a type indicator, as would be permitted in
     * Java programming language source code - except that either
     * <code>L</code> or <code>l</code> may appear as a digit for a
     * radix greater than 22.
     * <p>
     * An exception of type <code>NumberFormatException</code> is
     * thrown if any of the following situations occurs:
     * <ul>
     * <li>The first argument is <code>null</code> or is a string of
     * length zero.
     * <li>The <code>radix</code> is either smaller than {@link
     * java.lang.Character#MIN_RADIX} or larger than {@link
     * java.lang.Character#MAX_RADIX}.
     * <li>Any character of the string is not a digit of the specified
     * radix, except that the first character may be a minus sign
     * <code>'-'</code> (<code>'\u002d'</code>) provided that the
     * string is longer than length 1.
     * <li>The value represented by the string is not a value of type
     *      <code>long</code>. 
     * </ul><p>
     * Examples:
     * <blockquote><pre>
     * parseLong("0", 10) returns 0L
     * parseLong("473", 10) returns 473L
     * parseLong("-0", 10) returns 0L
     * parseLong("-FF", 16) returns -255L
     * parseLong("1100110", 2) returns 102L
     * parseLong("99", 8) throws a NumberFormatException
     * parseLong("Hazelnut", 10) throws a NumberFormatException
     * parseLong("Hazelnut", 36) returns 1356099454469L
     * </pre></blockquote>
     * 
     * @param      s       the <code>String</code> containing the
     *                     <code>long</code> representation to be parsed.
     * @param      radix   the radix to be used while parsing <code>s</code>.
     * @return     the <code>long</code> represented by the string argument in
     *             the specified radix.
     * @exception  NumberFormatException  if the string does not contain a
     *               parsable <code>long</code>.
     */
    public static long parseLong(String s, int radix)
              throws NumberFormatException
    {
        if (s == null) {
            throw new NumberFormatException("null");
        }

	if (radix < Character.MIN_RADIX) {
	    throw new NumberFormatException("radix " + radix +
					    " less than Character.MIN_RADIX");
	}
	if (radix > Character.MAX_RADIX) {
	    throw new NumberFormatException("radix " + radix +
					    " greater than Character.MAX_RADIX");
	}

	long result = 0;
	boolean negative = false;
	int i = 0, max = s.length();
	long limit;
	long multmin;
	int digit;

	if (max > 0) {
	    if (s.charAt(0) == '-') {
		negative = true;
		limit = Long.MIN_VALUE;
		i++;
	    } else {
		limit = -Long.MAX_VALUE;
	    }
	    multmin = limit / radix;
            if (i < max) {
                digit = Character.digit(s.charAt(i++),radix);
		if (digit < 0) {
		    throw NumberFormatException.forInputString(s);
		} else {
		    result = -digit;
		}
	    }
	    while (i < max) {
		// Accumulating negatively avoids surprises near MAX_VALUE
		digit = Character.digit(s.charAt(i++),radix);
		if (digit < 0) {
		    throw NumberFormatException.forInputString(s);
		}
		if (result < multmin) {
		    throw NumberFormatException.forInputString(s);
		}
		result *= radix;
		if (result < limit + digit) {
		    throw NumberFormatException.forInputString(s);
		}
		result -= digit;
	    }
	} else {
	    throw NumberFormatException.forInputString(s);
	}
	if (negative) {
	    if (i > 1) {
		return result;
	    } else {	/* Only got "-" */
		throw NumberFormatException.forInputString(s);
	    }
	} else {
	    return -result;
	}
    }

    /**
     * Parses the string argument as a signed decimal
     * <code>long</code>.  The characters in the string must all be
     * decimal digits, except that the first character may be an ASCII
     * minus sign <code>'-'</code> (<code>\u002D'</code>) to
     * indicate a negative value. The resulting <code>long</code>
     * value is returned, exactly as if the argument and the radix
     * <code>10</code> were given as arguments to the {@link
     * #parseLong(java.lang.String, int)} method.
     * <p>
     * Note that neither the character <code>L</code>
     * (<code>'\u004C'</code>) nor <code>l</code>
     * (<code>'\u006C'</code>) is permitted to appear at the end
     * of the string as a type indicator, as would be permitted in
     * Java programming language source code.
     *
     * @param      s   a <code>String</code> containing the <code>long</code>
     *             representation to be parsed
     * @return     the <code>long</code> represented by the argument in 
     *		   decimal.
     * @exception  NumberFormatException  if the string does not contain a
     *               parsable <code>long</code>.
     */
    public static long parseLong(String s) throws NumberFormatException {
	return parseLong(s, 10);
    }

    /**
     * Returns a <code>Long</code> object holding the value
     * extracted from the specified <code>String</code> when parsed
     * with the radix given by the second argument.  The first
     * argument is interpreted as representing a signed
     * <code>long</code> in the radix specified by the second
     * argument, exactly as if the arguments were given to the {@link
     * #parseLong(java.lang.String, int)} method. The result is a
     * <code>Long</code> object that represents the <code>long</code>
     * value specified by the string.
     * <p>
     * In other words, this method returns a <code>Long</code> object equal 
     * to the value of:
     *
     * <blockquote><code>
     * new Long(Long.parseLong(s, radix))
     * </code></blockquote>
     *
     * @param      s       the string to be parsed
     * @param      radix   the radix to be used in interpreting <code>s</code>
     * @return     a <code>Long</code> object holding the value
     *             represented by the string argument in the specified
     *             radix.
     * @exception  NumberFormatException  If the <code>String</code> does not
     *             contain a parsable <code>long</code>.
     */
    public static Long valueOf(String s, int radix) throws NumberFormatException {
	return new Long(parseLong(s, radix));
    }

    /**
     * Returns a <code>Long</code> object holding the value
     * of the specified <code>String</code>. The argument is
     * interpreted as representing a signed decimal <code>long</code>,
     * exactly as if the argument were given to the {@link
     * #parseLong(java.lang.String)} method. The result is a
     * <code>Long</code> object that represents the integer value
     * specified by the string.
     * <p>
     * In other words, this method returns a <code>Long</code> object
     * equal to the value of:
     *
     * <blockquote><pre>
     * new Long(Long.parseLong(s))
     * </pre></blockquote>
     *
     * @param      s   the string to be parsed.
     * @return     a <code>Long</code> object holding the value
     *             represented by the string argument.
     * @exception  NumberFormatException  If the string cannot be parsed
     *              as a <code>long</code>.
     */
    public static Long valueOf(String s) throws NumberFormatException
    {
	return new Long(parseLong(s, 10));
    }

    private static class LongCache {
	private LongCache(){}

	static final Long cache[] = new Long[-(-128) + 127 + 1];

	static {
	    for(int i = 0; i < cache.length; i++)
		cache[i] = new Long(i - 128);
	}
    }

    /**
     * Returns a <tt>Long</tt> instance representing the specified
     * <tt>long</tt> value.
     * If a new <tt>Long</tt> instance is not required, this method
     * should generally be used in preference to the constructor
     * {@link #Long(long)}, as this method is likely to yield
     * significantly better space and time performance by caching
     * frequently requested values.
     *
     * @param  l a long value.
     * @return a <tt>Long</tt> instance representing <tt>l</tt>.
     * @since  1.5
     */
    public static Long valueOf(long l) {
	final int offset = 128;
	if (l >= -128 && l <= 127) { // will cache
	    return LongCache.cache[(int)l + offset];
	}
        return new Long(l);
    }

    /**
     * Decodes a <code>String</code> into a <code>Long</code>.
     * Accepts decimal, hexadecimal, and octal numbers given by the
     * following grammar:
     *
     * <blockquote>
     * <dl>
     * <dt><i>DecodableString:</i>
     * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
     * <dd><i>Sign<sub>opt</sub></i> <code>0x</code> <i>HexDigits</i>
     * <dd><i>Sign<sub>opt</sub></i> <code>0X</code> <i>HexDigits</i>
     * <dd><i>Sign<sub>opt</sub></i> <code>#</code> <i>HexDigits</i>
     * <dd><i>Sign<sub>opt</sub></i> <code>0</code> <i>OctalDigits</i>
     * <p>
     * <dt><i>Sign:</i>
     * <dd><code>-</code>
     * </dl>
     * </blockquote>
     *
     * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
     * are defined in <a href="http://java.sun.com/docs/books/jls/second_edition/html/lexical.doc.html#48282">§3.10.1</a> 
     * of the <a href="http://java.sun.com/docs/books/jls/html/">Java 
     * Language Specification</a>.
     * <p>
     * The sequence of characters following an (optional) negative
     * sign and/or radix specifier ("<code>0x</code>",
     * "<code>0X</code>", "<code>#</code>", or
     * leading zero) is parsed as by the <code>Long.parseLong</code>
     * method with the indicated radix (10, 16, or 8).  This sequence
     * of characters must represent a positive value or a {@link
     * NumberFormatException} will be thrown.  The result is negated
     * if first character of the specified <code>String</code> is the
     * minus sign.  No whitespace characters are permitted in the
     * <code>String</code>.
     *
     * @param     nm the <code>String</code> to decode.
     * @return    a <code>Long</code> object holding the <code>long</code>
     *		  value represented by <code>nm</code>
     * @exception NumberFormatException  if the <code>String</code> does not
     *            contain a parsable <code>long</code>.
     * @see java.lang.Long#parseLong(String, int)
     * @since 1.2
     */
    public static Long decode(String nm) throws NumberFormatException {
        int radix = 10;
        int index = 0;
        boolean negative = false;
        Long result;

        // Handle minus sign, if present
        if (nm.startsWith("-")) {
            negative = true;
            index++;
        }

        // Handle radix specifier, if present
	if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
	    index += 2;
            radix = 16;
	}
	else if (nm.startsWith("#", index)) {
	    index ++;
            radix = 16;
	}
	else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
	    index ++;
            radix = 8;
	}

        if (nm.startsWith("-", index))
            throw new NumberFormatException("Negative sign in wrong position");

        try {
            result = Long.valueOf(nm.substring(index), radix);
            result = negative ? new Long((long)-result.longValue()) : result;
        } catch (NumberFormatException e) {
            // If number is Long.MIN_VALUE, we'll end up here. The next line
            // handles this case, and causes any genuine format error to be
            // rethrown.
            String constant = negative ? new String("-" + nm.substring(index))
                                       : nm.substring(index);
            result = Long.valueOf(constant, radix);
        }
        return result;
    }

    /**
     * The value of the <code>Long</code>.
     *
     * @serial
     */
    private final long value;

    /**
     * Constructs a newly allocated <code>Long</code> object that
     * represents the specified <code>long</code> argument.
     *
     * @param   value   the value to be represented by the 
     *          <code>Long</code> object.
     */
    public Long(long value) {
	this.value = value;
    }

    /**
     * Constructs a newly allocated <code>Long</code> object that
     * represents the <code>long</code> value indicated by the
     * <code>String</code> parameter. The string is converted to a
     * <code>long</code> value in exactly the manner used by the
     * <code>parseLong</code> method for radix 10.
     *
     * @param      s   the <code>String</code> to be converted to a 
     *		   <code>Long</code>.
     * @exception  NumberFormatException  if the <code>String</code> does not
     *               contain a parsable <code>long</code>.
     * @see        java.lang.Long#parseLong(java.lang.String, int)
     */
    public Long(String s) throws NumberFormatException {
	this.value = parseLong(s, 10);
    }

    /**
     * Returns the value of this <code>Long</code> as a
     * <code>byte</code>.
     */
    public byte byteValue() {
	return (byte)value;
    }

    /**
     * Returns the value of this <code>Long</code> as a
     * <code>short</code>.
     */
    public short shortValue() {
	return (short)value;
    }

    /**
     * Returns the value of this <code>Long</code> as an
     * <code>int</code>.
     */
    public int intValue() {
	return (int)value;
    }

    /**
     * Returns the value of this <code>Long</code> as a
     * <code>long</code> value.
     */
    public long longValue() {
	return (long)value;
    }

    /**
     * Returns the value of this <code>Long</code> as a
     * <code>float</code>.
     */
    public float floatValue() {
	return (float)value;
    }

    /**
     * Returns the value of this <code>Long</code> as a
     * <code>double</code>.
     */
    public double doubleValue() {
	return (double)value;
    }

    /**
     * Returns a <code>String</code> object representing this
     * <code>Long</code>'s value.  The value is converted to signed
     * decimal representation and returned as a string, exactly as if
     * the <code>long</code> value were given as an argument to the
     * {@link java.lang.Long#toString(long)} method.
     *
     * @return  a string representation of the value of this object in
     *		base 10.
     */
    public String toString() {
	return String.valueOf(value);
    }

    /**
     * Returns a hash code for this <code>Long</code>. The result is
     * the exclusive OR of the two halves of the primitive
     * <code>long</code> value held by this <code>Long</code>
     * object. That is, the hashcode is the value of the expression:
     * <blockquote><pre>
     * (int)(this.longValue()^(this.longValue()>>>32))
     * </pre></blockquote>
     *
     * @return  a hash code value for this object.
     */
    public int hashCode() {
	return (int)(value ^ (value >>> 32));
    }

    /**
     * Compares this object to the specified object.  The result is
     * <code>true</code> if and only if the argument is not
     * <code>null</code> and is a <code>Long</code> object that
     * contains the same <code>long</code> value as this object.
     *
     * @param   obj   the object to compare with.
     * @return  <code>true</code> if the objects are the same;
     *          <code>false</code> otherwise.
     */
    public boolean equals(Object obj) {
	if (obj instanceof Long) {
	    return value == ((Long)obj).longValue();
	}
	return false;
    }

    /**
     * Determines the <code>long</code> value of the system property
     * with the specified name.
     * <p>
     * The first argument is treated as the name of a system property.
     * System properties are accessible through the {@link
     * java.lang.System#getProperty(java.lang.String)} method. The
     * string value of this property is then interpreted as a
     * <code>long</code> value and a <code>Long</code> object
     * representing this value is returned.  Details of possible
     * numeric formats can be found with the definition of
     * <code>getProperty</code>.
     * <p>
     * If there is no property with the specified name, if the
     * specified name is empty or <code>null</code>, or if the
     * property does not have the correct numeric format, then
     * <code>null</code> is returned.
     * <p>
     * In other words, this method returns a <code>Long</code> object equal to 
     * the value of:
     * <blockquote><code>
     * getLong(nm, null)
     * </code></blockquote>
     *
     * @param   nm   property name.
     * @return  the <code>Long</code> value of the property.
     * @see     java.lang.System#getProperty(java.lang.String)
     * @see     java.lang.System#getProperty(java.lang.String, java.lang.String)
     */
    public static Long getLong(String nm) {
	return getLong(nm, null);
    }

    /**
     * Determines the <code>long</code> value of the system property
     * with the specified name.
     * <p>
     * The first argument is treated as the name of a system property.
     * System properties are accessible through the {@link
     * java.lang.System#getProperty(java.lang.String)} method. The
     * string value of this property is then interpreted as a
     * <code>long</code> value and a <code>Long</code> object
     * representing this value is returned.  Details of possible
     * numeric formats can be found with the definition of
     * <code>getProperty</code>.
     * <p>
     * The second argument is the default value. A <code>Long</code> object
     * that represents the value of the second argument is returned if there
     * is no property of the specified name, if the property does not have
     * the correct numeric format, or if the specified name is empty or null.
     * <p>
     * In other words, this method returns a <code>Long</code> object equal 
     * to the value of:
     * <blockquote><code>
     * getLong(nm, new Long(val))
     * </code></blockquote>
     * but in practice it may be implemented in a manner such as: 
     * <blockquote><pre>
     * Long result = getLong(nm, null);
     * return (result == null) ? new Long(val) : result;
     * </pre></blockquote>
     * to avoid the unnecessary allocation of a <code>Long</code> object when 
     * the default value is not needed. 
     *
     * @param   nm    property name.
     * @param   val   default value.
     * @return  the <code>Long</code> value of the property.
     * @see     java.lang.System#getProperty(java.lang.String)
     * @see     java.lang.System#getProperty(java.lang.String, java.lang.String)
     */
    public static Long getLong(String nm, long val) {
        Long result = Long.getLong(nm, null);
        return (result == null) ? new Long(val) : result;
    }

    /**
     * Returns the <code>long</code> value of the system property with
     * the specified name.  The first argument is treated as the name
     * of a system property.  System properties are accessible through
     * the {@link java.lang.System#getProperty(java.lang.String)}
     * method. The string value of this property is then interpreted
     * as a <code>long</code> value, as per the
     * <code>Long.decode</code> method, and a <code>Long</code> object
     * representing this value is returned.
     * <p><ul>
     * <li>If the property value begins with the two ASCII characters
     * <code>0x</code> or the ASCII character <code>#</code>, not followed by 
     * a minus sign, then the rest of it is parsed as a hexadecimal integer
     * exactly as for the method {@link #valueOf(java.lang.String, int)} 
     * with radix 16. 
     * <li>If the property value begins with the ASCII character
     * <code>0</code> followed by another character, it is parsed as
     * an octal integer exactly as by the method {@link
     * #valueOf(java.lang.String, int)} with radix 8.
     * <li>Otherwise the property value is parsed as a decimal
     * integer exactly as by the method 
     * {@link #valueOf(java.lang.String, int)} with radix 10.
     * </ul>
     * <p>
     * Note that, in every case, neither <code>L</code>
     * (<code>'\u004C'</code>) nor <code>l</code>
     * (<code>'\u006C'</code>) is permitted to appear at the end
     * of the property value as a type indicator, as would be
     * permitted in Java programming language source code.
     * <p>
     * The second argument is the default value. The default value is
     * returned if there is no property of the specified name, if the
     * property does not have the correct numeric format, or if the
     * specified name is empty or <code>null</code>.
     *
     * @param   nm   property name.
     * @param   val   default value.
     * @return  the <code>Long</code> value of the property.
     * @see     java.lang.System#getProperty(java.lang.String)
     * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
     * @see java.lang.Long#decode
     */
    public static Long getLong(String nm, Long val) {
        String v = null;
        try {
            v = System.getProperty(nm);
        } catch (IllegalArgumentException e) {
        } catch (NullPointerException e) {
        }
	if (v != null) {
	    try {
		return Long.decode(v);
	    } catch (NumberFormatException e) {
	    }
	}
	return val;
    }

    /**
     * Compares two <code>Long</code> objects numerically.
     *
     * @param   anotherLong   the <code>Long</code> to be compared.
     * @return	the value <code>0</code> if this <code>Long</code> is
     * 		equal to the argument <code>Long</code> a value less than
     * 		<code>0</code> if this <code>Long</code> is numerically less
     * 		than the argument <code>Long</code> and a value greater 
     * 		than <code>0</code> if this <code>Long</code> is numerically
     * 		 greater than the argument <code>Long</code> (signed
     * 		 comparison).
     * @since   1.2
     */
    public int compareTo(Long anotherLong) {
	long thisVal = this.value;
	long anotherVal = anotherLong.value;
	return (thisVal<anotherVal ? -1 : (thisVal==anotherVal ? 0 : 1));
    }


    // Bit Twiddling

    /**
     * The number of bits used to represent a <tt>long</tt> value in two's
     * complement binary form.
     *
     * @since 1.5
     */
    public static final int SIZE = 64;
 
    /**
     * Returns an <tt>long</tt> value with at most a single one-bit, in the
     * position of the highest-order ("leftmost") one-bit in the specified
     * <tt>long</tt> value.  Returns zero if the specified value has no
     * one-bits in its two's complement binary representation, that is, if it
     * is equal to zero.
     *
     * @return an <tt>long</tt> value with a single one-bit, in the position
     *     of the highest-order one-bit in the specified value, or zero if
     *     the specified value is itself equal to zero.
     * @since 1.5
     */
    public static long highestOneBit(long i) {
        // HD, Figure 3-1
        i |= (i >>  1);
        i |= (i >>  2);
        i |= (i >>  4);
        i |= (i >>  8);
        i |= (i >> 16);
        i |= (i >> 32);
        return i - (i >>> 1);
    }

    /**
     * Returns an <tt>long</tt> value with at most a single one-bit, in the
     * position of the lowest-order ("rightmost") one-bit in the specified
     * <tt>long</tt> value.  Returns zero if the specified value has no
     * one-bits in its two's complement binary representation, that is, if it
     * is equal to zero.
     *
     * @return an <tt>long</tt> value with a single one-bit, in the position
     *     of the lowest-order one-bit in the specified value, or zero if
     *     the specified value is itself equal to zero.
     * @since 1.5
     */
    public static long lowestOneBit(long i) {
        // HD, Section 2-1
        return i & -i;
    }
 
    /**
     * Returns the number of zero bits preceding the highest-order
     * ("leftmost") one-bit in the two's complement binary representation
     * of the specified <tt>long</tt> value.  Returns 64 if the
     * specified value has no one-bits in its two's complement representation,
     * in other words if it is equal to zero.
     *
     * <p>Note that this method is closely related to the logarithm base 2.
     * For all positive <tt>long</tt> values x:
     * <ul>
     * <li>floor(log<sub>2</sub>(x)) = <tt>63 - numberOfLeadingZeros(x)</tt>
     * <li>ceil(log<sub>2</sub>(x)) = <tt>64 - numberOfLeadingZeros(x - 1)</tt>
     * </ul>
     *
     * @return the number of zero bits preceding the highest-order
     *     ("leftmost") one-bit in the two's complement binary representation
     *     of the specified <tt>long</tt> value, or 64 if the value
     *     is equal to zero.
     * @since 1.5
     */
    public static int numberOfLeadingZeros(long i) {
        // HD, Figure 5-6
         if (i == 0)
            return 64;
        int n = 1;
	int x = (int)(i >>> 32);
        if (x == 0) { n += 32; x = (int)i; }
        if (x >>> 16 == 0) { n += 16; x <<= 16; }
        if (x >>> 24 == 0) { n +=  8; x <<=  8; }
        if (x >>> 28 == 0) { n +=  4; x <<=  4; }
        if (x >>> 30 == 0) { n +=  2; x <<=  2; }
        n -= x >>> 31;
        return n;
    }
 
    /**
     * Returns the number of zero bits following the lowest-order ("rightmost")
     * one-bit in the two's complement binary representation of the specified
     * <tt>long</tt> value.  Returns 64 if the specified value has no
     * one-bits in its two's complement representation, in other words if it is
     * equal to zero.
     *
     * @return the number of zero bits following the lowest-order ("rightmost")
     *     one-bit in the two's complement binary representation of the
     *     specified <tt>long</tt> value, or 64 if the value is equal
     *     to zero.
     * @since 1.5
     */
    public static int numberOfTrailingZeros(long i) {
        // HD, Figure 5-14
	int x, y;
	if (i == 0) return 64;
	int n = 63;
	y = (int)i; if (y != 0) { n = n -32; x = y; } else x = (int)(i>>>32);
	y = x <<16; if (y != 0) { n = n -16; x = y; }
	y = x << 8; if (y != 0) { n = n - 8; x = y; }
	y = x << 4; if (y != 0) { n = n - 4; x = y; }
	y = x << 2; if (y != 0) { n = n - 2; x = y; }
	return n - ((x << 1) >>> 31);
    }

    /**
     * Returns the number of one-bits in the two's complement binary
     * representation of the specified <tt>long</tt> value.  This function is
     * sometimes referred to as the <i>population count</i>.
     *
     * @return the number of one-bits in the two's complement binary
     *     representation of the specified <tt>long</tt> value.
     * @since 1.5
     */
     public static int bitCount(long i) {
        // HD, Figure 5-14
	i = i - ((i >>> 1) & 0x5555555555555555L);
	i = (i & 0x3333333333333333L) + ((i >>> 2) & 0x3333333333333333L);
	i = (i + (i >>> 4)) & 0x0f0f0f0f0f0f0f0fL;
	i = i + (i >>> 8);
	i = i + (i >>> 16);
	i = i + (i >>> 32);
	return (int)i & 0x7f;
     }
 
    /**
     * Returns the value obtained by rotating the two's complement binary
     * representation of the specified <tt>long</tt> value left by the
     * specified number of bits.  (Bits shifted out of the left hand, or
     * high-order, side reenter on the right, or low-order.)
     *
     * <p>Note that left rotation with a negative distance is equivalent to
     * right rotation: <tt>rotateLeft(val, -distance) == rotateRight(val,
     * distance)</tt>.  Note also that rotation by any multiple of 64 is a
     * no-op, so all but the last six bits of the rotation distance can be
     * ignored, even if the distance is negative: <tt>rotateLeft(val,
     * distance) == rotateLeft(val, distance & 0x3F)</tt>.
     *
     * @return the value obtained by rotating the two's complement binary
     *     representation of the specified <tt>long</tt> value left by the
     *     specified number of bits.
     * @since 1.5
     */
    public static long rotateLeft(long i, int distance) {
        return (i << distance) | (i >>> -distance);
    }
 
    /**
     * Returns the value obtained by rotating the two's complement binary
     * representation of the specified <tt>long</tt> value right by the
     * specified number of bits.  (Bits shifted out of the right hand, or
     * low-order, side reenter on the left, or high-order.)
     *
     * <p>Note that right rotation with a negative distance is equivalent to
     * left rotation: <tt>rotateRight(val, -distance) == rotateLeft(val,
     * distance)</tt>.  Note also that rotation by any multiple of 64 is a
     * no-op, so all but the last six bits of the rotation distance can be
     * ignored, even if the distance is negative: <tt>rotateRight(val,
     * distance) == rotateRight(val, distance & 0x3F)</tt>.
     *
     * @return the value obtained by rotating the two's complement binary
     *     representation of the specified <tt>long</tt> value right by the
     *     specified number of bits.
     * @since 1.5
     */
    public static long rotateRight(long i, int distance) {
        return (i >>> distance) | (i << -distance);
    }
 
    /**
     * Returns the value obtained by reversing the order of the bits in the
     * two's complement binary representation of the specified <tt>long</tt>
     * value.
     *
     * @return the value obtained by reversing order of the bits in the
     *     specified <tt>long</tt> value.
     * @since 1.5
     */
    public static long reverse(long i) {
        // HD, Figure 7-1
	i = (i & 0x5555555555555555L) << 1 | (i >>> 1) & 0x5555555555555555L;
	i = (i & 0x3333333333333333L) << 2 | (i >>> 2) & 0x3333333333333333L;
	i = (i & 0x0f0f0f0f0f0f0f0fL) << 4 | (i >>> 4) & 0x0f0f0f0f0f0f0f0fL;
	i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL;
	i = (i << 48) | ((i & 0xffff0000L) << 16) |
	    ((i >>> 16) & 0xffff0000L) | (i >>> 48);
	return i;
    }
 
    /**
     * Returns the signum function of the specified <tt>long</tt> value.  (The
     * return value is -1 if the specified value is negative; 0 if the
     * specified value is zero; and 1 if the specified value is positive.)
     *
     * @return the signum function of the specified <tt>long</tt> value.
     * @since 1.5
     */
    public static int signum(long i) {
        // HD, Section 2-7
        return (int) ((i >> 63) | (-i >>> 63));
    }
 
    /**
     * Returns the value obtained by reversing the order of the bytes in the
     * two's complement representation of the specified <tt>long</tt> value.
     *
     * @return the value obtained by reversing the bytes in the specified
     *     <tt>long</tt> value.
     * @since 1.5
     */
    public static long reverseBytes(long i) {
        i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL;
        return (i << 48) | ((i & 0xffff0000L) << 16) |
            ((i >>> 16) & 0xffff0000L) | (i >>> 48);
    }

    /** use serialVersionUID from JDK 1.0.2 for interoperability */
    private static final long serialVersionUID = 4290774380558885855L;
}