/*

 * Copyright (c) 1994, 2013, 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.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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 java.lang;

import java.lang.annotation.Native;

import java.math.*;

import java.util.Objects;

/**

 * The {@code Long} class wraps a value of the primitive type {@code

 * long} in an object. An object of type {@code Long} contains a

 * single field whose type is {@code long}.

 *

 * <p> In addition, this class provides several methods for converting

 * a {@code long} to a {@code String} and a {@code String} to a {@code

 * long}, as well as other constants and methods useful when dealing

 * with a {@code long}.

 *

 * <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

 * @author  Joseph D. Darcy

 * @since   1.0

 */

public final class Long extends Number implements Comparable<Long> {

    /**

     * A constant holding the minimum value a {@code long} can

     * have, -2<sup>63</sup>.

     */

    @Native public static final long MIN_VALUE = 0x8000000000000000L;

    /**

     * A constant holding the maximum value a {@code long} can

     * have, 2<sup>63</sup>-1.

     */

    @Native public static final long MAX_VALUE = 0x7fffffffffffffffL;

    /**

     * The {@code Class} instance representing the primitive type

     * {@code long}.

     *

     * @since   1.1

     */

    @SuppressWarnings("unchecked")

    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}

     * or larger than {@code Character.MAX_RADIX}, then the radix

     * {@code 10} is used instead.

     *

     * <p>If the first argument is negative, the first element of the

     * result is the ASCII minus sign {@code '-'}

     * ({@code '\u005Cu002d'}). 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 '\u005Cu0030'}); 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>

     *   {@code 0123456789abcdefghijklmnopqrstuvwxyz}

     * </blockquote>

     *

     * These are {@code '\u005Cu0030'} through

     * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through

     * {@code '\u005Cu007a'}. If {@code radix} 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}. If uppercase letters are

     * desired, the {@link java.lang.String#toUpperCase()} method may

     * be called on the result:

     *

     * <blockquote>

     *  {@code Long.toString(n, 16).toUpperCase()}

     * </blockquote>

     *

     * @param   i       a {@code long} 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 first argument as an

     * unsigned integer value in the radix specified by the second

     * argument.

     *

     * <p>If the radix is smaller than {@code Character.MIN_RADIX}

     * or larger than {@code Character.MAX_RADIX}, then the radix

     * {@code 10} is used instead.

     *

     * <p>Note that since the first argument is treated as an unsigned

     * value, no leading sign character is printed.

     *

     * <p>If the magnitude is zero, it is represented by a single zero

     * character {@code '0'} ({@code '\u005Cu0030'}); otherwise,

     * the first character of the representation of the magnitude will

     * not be the zero character.

     *

     * <p>The behavior of radixes and the characters used as digits

     * are the same as {@link #toString(long, int) toString}.

     *

     * @param   i       an integer to be converted to an unsigned string.

     * @param   radix   the radix to use in the string representation.

     * @return  an unsigned string representation of the argument in the specified radix.

     * @see     #toString(long, int)

     * @since 1.8

     */

    public static String toUnsignedString(long i, int radix) {

        if (i >= 0)

            return toString(i, radix);

        else {

            switch (radix) {

            case 2:

                return toBinaryString(i);

            case 4:

                return toUnsignedString0(i, 2);

            case 8:

                return toOctalString(i);

            case 10:

                /*

                 * We can get the effect of an unsigned division by 10

                 * on a long value by first shifting right, yielding a

                 * positive value, and then dividing by 5.  This

                 * allows the last digit and preceding digits to be

                 * isolated more quickly than by an initial conversion

                 * to BigInteger.

                 */

                long quot = (i >>> 1) / 5;

                long rem = i - quot * 10;

                return toString(quot) + rem;

            case 16:

                return toHexString(i);

            case 32:

                return toUnsignedString0(i, 5);

            default:

                return toUnsignedBigInteger(i).toString(radix);

            }

        }

    }

    /**

     * Return a BigInteger equal to the unsigned value of the

     * argument.

     */

    private static BigInteger toUnsignedBigInteger(long i) {

        if (i >= 0L)

            return BigInteger.valueOf(i);

        else {

            int upper = (int) (i >>> 32);

            int lower = (int) i;

            // return (upper << 32) + lower

            return (BigInteger.valueOf(Integer.toUnsignedLong(upper))).shiftLeft(32).

                add(BigInteger.valueOf(Integer.toUnsignedLong(lower)));

        }

    }

    /**

     * Returns a string representation of the {@code long}

     * argument as an unsigned integer in base 16.

     *

     * <p>The unsigned {@code long} 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}s.

     *

     * <p>The value of the argument can be recovered from the returned

     * string {@code s} by calling {@link

     * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,

     * 16)}.

     *

     * <p>If the unsigned magnitude is zero, it is represented by a

     * single zero character {@code '0'} ({@code '\u005Cu0030'});

     * 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>

     *  {@code 0123456789abcdef}

     * </blockquote>

     *

     * These are the characters {@code '\u005Cu0030'} through

     * {@code '\u005Cu0039'} and  {@code '\u005Cu0061'} through

     * {@code '\u005Cu0066'}.  If uppercase letters are desired,

     * the {@link java.lang.String#toUpperCase()} method may be called

     * on the result:

     *

     * <blockquote>

     *  {@code Long.toHexString(n).toUpperCase()}

     * </blockquote>

     *

     * @param   i   a {@code long} to be converted to a string.

     * @return  the string representation of the unsigned {@code long}

     *          value represented by the argument in hexadecimal

     *          (base 16).

     * @see #parseUnsignedLong(String, int)

     * @see #toUnsignedString(long, int)

     * @since   1.0.2

     */

    public static String toHexString(long i) {

        return toUnsignedString0(i, 4);

    }

    /**

     * Returns a string representation of the {@code long}

     * argument as an unsigned integer in base 8.

     *

     * <p>The unsigned {@code long} 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}s.

     *

     * <p>The value of the argument can be recovered from the returned

     * string {@code s} by calling {@link

     * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,

     * 8)}.

     *

     * <p>If the unsigned magnitude is zero, it is represented by a

     * single zero character {@code '0'} ({@code '\u005Cu0030'});

     * 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>

     *  {@code 01234567}

     * </blockquote>

     *

     * These are the characters {@code '\u005Cu0030'} through

     * {@code '\u005Cu0037'}.

     *

     * @param   i   a {@code long} to be converted to a string.

     * @return  the string representation of the unsigned {@code long}

     *          value represented by the argument in octal (base 8).

     * @see #parseUnsignedLong(String, int)

     * @see #toUnsignedString(long, int)

     * @since   1.0.2

     */

    public static String toOctalString(long i) {

        return toUnsignedString0(i, 3);

    }

    /**

     * Returns a string representation of the {@code long}

     * argument as an unsigned integer in base 2.

     *

     * <p>The unsigned {@code long} 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}s.

     *

     * <p>The value of the argument can be recovered from the returned

     * string {@code s} by calling {@link

     * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,

     * 2)}.

     *

     * <p>If the unsigned magnitude is zero, it is represented by a

     * single zero character {@code '0'} ({@code '\u005Cu0030'});

     * otherwise, the first character of the representation of the

     * unsigned magnitude will not be the zero character. The

     * characters {@code '0'} ({@code '\u005Cu0030'}) and {@code

     * '1'} ({@code '\u005Cu0031'}) are used as binary digits.

     *

     * @param   i   a {@code long} to be converted to a string.

     * @return  the string representation of the unsigned {@code long}

     *          value represented by the argument in binary (base 2).

     * @see #parseUnsignedLong(String, int)

     * @see #toUnsignedString(long, int)

     * @since   1.0.2

     */

    public static String toBinaryString(long i) {

        return toUnsignedString0(i, 1);

    }

    /**

     * Format a long (treated as unsigned) into a String.

     * @param val the value to format

     * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)

     */

    static String toUnsignedString0(long val, int shift) {

        // assert shift > 0 && shift <=5 : "Illegal shift value";

        int mag = Long.SIZE - Long.numberOfLeadingZeros(val);

        int chars = Math.max(((mag + (shift - 1)) / shift), 1);

        char[] buf = new char[chars];

        formatUnsignedLong(val, shift, buf, 0, chars);

        return new String(buf, true);

    }

    /**

     * Format a long (treated as unsigned) into a character buffer. If

     * {@code len} exceeds the formatted ASCII representation of {@code val},

     * {@code buf} will be padded with leading zeroes.

     *

     * @param val the unsigned long to format

     * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)

     * @param buf the character buffer to write to

     * @param offset the offset in the destination buffer to start at

     * @param len the number of characters to write

     */

     static void formatUnsignedLong(long val, int shift, char[] buf, int offset, int len) {

        // assert shift > 0 && shift <=5 : "Illegal shift value";

        // assert offset >= 0 && offset < buf.length : "illegal offset";

        // assert len > 0 && (offset + len) <= buf.length : "illegal length";

        int charPos = offset + len;

        int radix = 1 << shift;

        int mask = radix - 1;

        do {

            buf[--charPos] = Integer.digits[((int) val) & mask];

            val >>>= shift;

        } while (charPos > offset);

    }

    /**

     * Returns a {@code String} object representing the specified

     * {@code long}.  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} 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(buf, true);

    }

    /**

     * Returns a string representation of the argument as an unsigned

     * decimal value.

     *

     * The argument is converted to unsigned decimal representation

     * and returned as a string exactly as if the argument and radix

     * 10 were given as arguments to the {@link #toUnsignedString(long,

     * int)} method.

     *

     * @param   i  an integer to be converted to an unsigned string.

     * @return  an unsigned string representation of the argument.

     * @see     #toUnsignedString(long, int)

     * @since 1.8

     */

    public static String toUnsignedString(long i) {

        return toUnsignedString(i, 10);

    }

    /**

     * 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} 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 '\u005Cu002D'}) to

     * indicate a negative value or an ASCII plus sign {@code '+'}

     * ({@code '\u005Cu002B'}) to indicate a positive value. The

     * resulting {@code long} value is returned.

     *

     * <p>Note that neither the character {@code L}

     * ({@code '\u005Cu004C'}) nor {@code l}

     * ({@code '\u005Cu006C'}) 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} or {@code l} may appear as a digit for a

     * radix greater than or equal to 22.