1 /*
2 * Copyright (c) 1994, 2023, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.lang;
27
28 import java.lang.annotation.Native;
29 import java.lang.invoke.MethodHandles;
30 import java.lang.constant.Constable;
31 import java.lang.constant.ConstantDesc;
32 import java.math.*;
33 import java.util.Objects;
34 import java.util.Optional;
35
36 import jdk.internal.misc.CDS;
37 import jdk.internal.vm.annotation.ForceInline;
38 import jdk.internal.vm.annotation.IntrinsicCandidate;
39 import jdk.internal.vm.annotation.Stable;
40
41 import static java.lang.Character.digit;
42 import static java.lang.String.COMPACT_STRINGS;
43 import static java.lang.String.LATIN1;
44 import static java.lang.String.UTF16;
45
46 /**
47 * The {@code Long} class wraps a value of the primitive type {@code
48 * long} in an object. An object of type {@code Long} contains a
49 * single field whose type is {@code long}.
50 *
51 * <p> In addition, this class provides several methods for converting
52 * a {@code long} to a {@code String} and a {@code String} to a {@code
53 * long}, as well as other constants and methods useful when dealing
54 * with a {@code long}.
55 *
56 * <p>This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
57 * class; programmers should treat instances that are
58 * {@linkplain #equals(Object) equal} as interchangeable and should not
59 * use instances for synchronization, or unpredictable behavior may
60 * occur. For example, in a future release, synchronization may fail.
61 *
62 * <p>Implementation note: The implementations of the "bit twiddling"
63 * methods (such as {@link #highestOneBit(long) highestOneBit} and
64 * {@link #numberOfTrailingZeros(long) numberOfTrailingZeros}) are
65 * based on material from Henry S. Warren, Jr.'s <i>Hacker's
66 * Delight</i>, (Addison Wesley, 2002).
67 *
68 * @author Lee Boynton
69 * @author Arthur van Hoff
70 * @author Josh Bloch
71 * @author Joseph D. Darcy
72 * @since 1.0
73 */
74 @jdk.internal.ValueBased
75 public final class Long extends Number
76 implements Comparable<Long>, Constable, ConstantDesc {
77 /**
78 * A constant holding the minimum value a {@code long} can
79 * have, -2<sup>63</sup>.
80 */
81 @Native public static final long MIN_VALUE = 0x8000000000000000L;
82
83 /**
84 * A constant holding the maximum value a {@code long} can
85 * have, 2<sup>63</sup>-1.
86 */
87 @Native public static final long MAX_VALUE = 0x7fffffffffffffffL;
88
89 /**
90 * The {@code Class} instance representing the primitive type
91 * {@code long}.
92 *
93 * @since 1.1
94 */
95 @SuppressWarnings("unchecked")
96 public static final Class<Long> TYPE = (Class<Long>) Class.getPrimitiveClass("long");
97
98 /**
99 * Returns a string representation of the first argument in the
100 * radix specified by the second argument.
101 *
102 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
103 * or larger than {@code Character.MAX_RADIX}, then the radix
104 * {@code 10} is used instead.
105 *
106 * <p>If the first argument is negative, the first element of the
107 * result is the ASCII minus sign {@code '-'}
108 * ({@code '\u005Cu002d'}). If the first argument is not
109 * negative, no sign character appears in the result.
110 *
111 * <p>The remaining characters of the result represent the magnitude
112 * of the first argument. If the magnitude is zero, it is
113 * represented by a single zero character {@code '0'}
114 * ({@code '\u005Cu0030'}); otherwise, the first character of
115 * the representation of the magnitude will not be the zero
116 * character. The following ASCII characters are used as digits:
117 *
118 * <blockquote>
119 * {@code 0123456789abcdefghijklmnopqrstuvwxyz}
120 * </blockquote>
121 *
122 * These are {@code '\u005Cu0030'} through
123 * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
124 * {@code '\u005Cu007a'}. If {@code radix} is
125 * <var>N</var>, then the first <var>N</var> of these characters
126 * are used as radix-<var>N</var> digits in the order shown. Thus,
127 * the digits for hexadecimal (radix 16) are
128 * {@code 0123456789abcdef}. If uppercase letters are
129 * desired, the {@link java.lang.String#toUpperCase()} method may
130 * be called on the result:
131 *
132 * <blockquote>
133 * {@code Long.toString(n, 16).toUpperCase()}
134 * </blockquote>
135 *
136 * @param i a {@code long} to be converted to a string.
137 * @param radix the radix to use in the string representation.
138 * @return a string representation of the argument in the specified radix.
139 * @see java.lang.Character#MAX_RADIX
140 * @see java.lang.Character#MIN_RADIX
141 */
142 public static String toString(long i, int radix) {
143 if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
144 radix = 10;
145 if (radix == 10)
146 return toString(i);
147
148 if (COMPACT_STRINGS) {
149 byte[] buf = new byte[65];
150 int charPos = 64;
151 boolean negative = (i < 0);
152
153 if (!negative) {
154 i = -i;
155 }
156
157 while (i <= -radix) {
158 buf[charPos--] = (byte)Integer.digits[(int)(-(i % radix))];
159 i = i / radix;
160 }
161 buf[charPos] = (byte)Integer.digits[(int)(-i)];
162
163 if (negative) {
164 buf[--charPos] = '-';
165 }
166 return StringLatin1.newString(buf, charPos, (65 - charPos));
167 }
168 return toStringUTF16(i, radix);
169 }
170
171 private static String toStringUTF16(long i, int radix) {
172 byte[] buf = new byte[65 * 2];
173 int charPos = 64;
174 boolean negative = (i < 0);
175 if (!negative) {
176 i = -i;
177 }
178 while (i <= -radix) {
179 StringUTF16.putChar(buf, charPos--, Integer.digits[(int)(-(i % radix))]);
180 i = i / radix;
181 }
182 StringUTF16.putChar(buf, charPos, Integer.digits[(int)(-i)]);
183 if (negative) {
184 StringUTF16.putChar(buf, --charPos, '-');
185 }
186 return StringUTF16.newString(buf, charPos, (65 - charPos));
187 }
188
189 /**
190 * Returns a string representation of the first argument as an
191 * unsigned integer value in the radix specified by the second
192 * argument.
193 *
194 * <p>If the radix is smaller than {@code Character.MIN_RADIX}
195 * or larger than {@code Character.MAX_RADIX}, then the radix
196 * {@code 10} is used instead.
197 *
198 * <p>Note that since the first argument is treated as an unsigned
199 * value, no leading sign character is printed.
200 *
201 * <p>If the magnitude is zero, it is represented by a single zero
202 * character {@code '0'} ({@code '\u005Cu0030'}); otherwise,
203 * the first character of the representation of the magnitude will
204 * not be the zero character.
205 *
206 * <p>The behavior of radixes and the characters used as digits
207 * are the same as {@link #toString(long, int) toString}.
208 *
209 * @param i an integer to be converted to an unsigned string.
210 * @param radix the radix to use in the string representation.
211 * @return an unsigned string representation of the argument in the specified radix.
212 * @see #toString(long, int)
213 * @since 1.8
214 */
215 public static String toUnsignedString(long i, int radix) {
216 if (i >= 0)
217 return toString(i, radix);
218 else {
219 return switch (radix) {
220 case 2 -> toBinaryString(i);
221 case 4 -> toUnsignedString0(i, 2);
222 case 8 -> toOctalString(i);
223 case 10 -> {
224 /*
225 * We can get the effect of an unsigned division by 10
226 * on a long value by first shifting right, yielding a
227 * positive value, and then dividing by 5. This
228 * allows the last digit and preceding digits to be
229 * isolated more quickly than by an initial conversion
230 * to BigInteger.
231 */
232 long quot = (i >>> 1) / 5;
233 long rem = i - quot * 10;
234 yield toString(quot) + rem;
235 }
236 case 16 -> toHexString(i);
237 case 32 -> toUnsignedString0(i, 5);
238 default -> toUnsignedBigInteger(i).toString(radix);
239 };
240 }
241 }
242
243 /**
244 * Return a BigInteger equal to the unsigned value of the
245 * argument.
246 */
247 private static BigInteger toUnsignedBigInteger(long i) {
248 if (i >= 0L)
249 return BigInteger.valueOf(i);
250 else {
251 int upper = (int) (i >>> 32);
252 int lower = (int) i;
253
254 // return (upper << 32) + lower
255 return (BigInteger.valueOf(Integer.toUnsignedLong(upper))).shiftLeft(32).
256 add(BigInteger.valueOf(Integer.toUnsignedLong(lower)));
257 }
258 }
259
260 /**
261 * Returns a string representation of the {@code long}
262 * argument as an unsigned integer in base 16.
263 *
264 * <p>The unsigned {@code long} value is the argument plus
265 * 2<sup>64</sup> if the argument is negative; otherwise, it is
266 * equal to the argument. This value is converted to a string of
267 * ASCII digits in hexadecimal (base 16) with no extra
268 * leading {@code 0}s.
269 *
270 * <p>The value of the argument can be recovered from the returned
271 * string {@code s} by calling {@link
272 * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
273 * 16)}.
274 *
275 * <p>If the unsigned magnitude is zero, it is represented by a
276 * single zero character {@code '0'} ({@code '\u005Cu0030'});
277 * otherwise, the first character of the representation of the
278 * unsigned magnitude will not be the zero character. The
279 * following characters are used as hexadecimal digits:
280 *
281 * <blockquote>
282 * {@code 0123456789abcdef}
283 * </blockquote>
284 *
285 * These are the characters {@code '\u005Cu0030'} through
286 * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
287 * {@code '\u005Cu0066'}. If uppercase letters are desired,
288 * the {@link java.lang.String#toUpperCase()} method may be called
289 * on the result:
290 *
291 * <blockquote>
292 * {@code Long.toHexString(n).toUpperCase()}
293 * </blockquote>
294 *
295 * @apiNote
296 * The {@link java.util.HexFormat} class provides formatting and parsing
297 * of byte arrays and primitives to return a string or adding to an {@link Appendable}.
298 * {@code HexFormat} formats and parses uppercase or lowercase hexadecimal characters,
299 * with leading zeros and for byte arrays includes for each byte
300 * a delimiter, prefix, and suffix.
301 *
302 * @param i a {@code long} to be converted to a string.
303 * @return the string representation of the unsigned {@code long}
304 * value represented by the argument in hexadecimal
305 * (base 16).
306 * @see java.util.HexFormat
307 * @see #parseUnsignedLong(String, int)
308 * @see #toUnsignedString(long, int)
309 * @since 1.0.2
310 */
311 public static String toHexString(long i) {
312 return toUnsignedString0(i, 4);
313 }
314
315 /**
316 * Returns a string representation of the {@code long}
317 * argument as an unsigned integer in base 8.
318 *
319 * <p>The unsigned {@code long} value is the argument plus
320 * 2<sup>64</sup> if the argument is negative; otherwise, it is
321 * equal to the argument. This value is converted to a string of
322 * ASCII digits in octal (base 8) with no extra leading
323 * {@code 0}s.
324 *
325 * <p>The value of the argument can be recovered from the returned
326 * string {@code s} by calling {@link
327 * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
328 * 8)}.
329 *
330 * <p>If the unsigned magnitude is zero, it is represented by a
331 * single zero character {@code '0'} ({@code '\u005Cu0030'});
332 * otherwise, the first character of the representation of the
333 * unsigned magnitude will not be the zero character. The
334 * following characters are used as octal digits:
335 *
336 * <blockquote>
337 * {@code 01234567}
338 * </blockquote>
339 *
340 * These are the characters {@code '\u005Cu0030'} through
341 * {@code '\u005Cu0037'}.
342 *
343 * @param i a {@code long} to be converted to a string.
344 * @return the string representation of the unsigned {@code long}
345 * value represented by the argument in octal (base 8).
346 * @see #parseUnsignedLong(String, int)
347 * @see #toUnsignedString(long, int)
348 * @since 1.0.2
349 */
350 public static String toOctalString(long i) {
351 return toUnsignedString0(i, 3);
352 }
353
354 /**
355 * Returns a string representation of the {@code long}
356 * argument as an unsigned integer in base 2.
357 *
358 * <p>The unsigned {@code long} value is the argument plus
359 * 2<sup>64</sup> if the argument is negative; otherwise, it is
360 * equal to the argument. This value is converted to a string of
361 * ASCII digits in binary (base 2) with no extra leading
362 * {@code 0}s.
363 *
364 * <p>The value of the argument can be recovered from the returned
365 * string {@code s} by calling {@link
366 * Long#parseUnsignedLong(String, int) Long.parseUnsignedLong(s,
367 * 2)}.
368 *
369 * <p>If the unsigned magnitude is zero, it is represented by a
370 * single zero character {@code '0'} ({@code '\u005Cu0030'});
371 * otherwise, the first character of the representation of the
372 * unsigned magnitude will not be the zero character. The
373 * characters {@code '0'} ({@code '\u005Cu0030'}) and {@code
374 * '1'} ({@code '\u005Cu0031'}) are used as binary digits.
375 *
376 * @param i a {@code long} to be converted to a string.
377 * @return the string representation of the unsigned {@code long}
378 * value represented by the argument in binary (base 2).
379 * @see #parseUnsignedLong(String, int)
380 * @see #toUnsignedString(long, int)
381 * @since 1.0.2
382 */
383 public static String toBinaryString(long i) {
384 return toUnsignedString0(i, 1);
385 }
386
387 /**
388 * Format a long (treated as unsigned) into a String.
389 * @param val the value to format
390 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
391 */
392 static String toUnsignedString0(long val, int shift) {
393 // assert shift > 0 && shift <=5 : "Illegal shift value";
394 int mag = Long.SIZE - Long.numberOfLeadingZeros(val);
395 int chars = Math.max(((mag + (shift - 1)) / shift), 1);
396 if (COMPACT_STRINGS) {
397 byte[] buf = new byte[chars];
398 formatUnsignedLong0(val, shift, buf, 0, chars);
399 return new String(buf, LATIN1);
400 } else {
401 byte[] buf = new byte[chars * 2];
402 formatUnsignedLong0UTF16(val, shift, buf, 0, chars);
403 return new String(buf, UTF16);
404 }
405 }
406
407 /**
408 * Format a long (treated as unsigned) into a byte buffer (LATIN1 version). If
409 * {@code len} exceeds the formatted ASCII representation of {@code val},
410 * {@code buf} will be padded with leading zeroes.
411 *
412 * @param val the unsigned long to format
413 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
414 * @param buf the byte buffer to write to
415 * @param offset the offset in the destination buffer to start at
416 * @param len the number of characters to write
417 */
418 private static void formatUnsignedLong0(long val, int shift, byte[] buf, int offset, int len) {
419 int charPos = offset + len;
420 int radix = 1 << shift;
421 int mask = radix - 1;
422 do {
423 buf[--charPos] = (byte)Integer.digits[((int) val) & mask];
424 val >>>= shift;
425 } while (charPos > offset);
426 }
427
428 /**
429 * Format a long (treated as unsigned) into a byte buffer (UTF16 version). If
430 * {@code len} exceeds the formatted ASCII representation of {@code val},
431 * {@code buf} will be padded with leading zeroes.
432 *
433 * @param val the unsigned long to format
434 * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
435 * @param buf the byte buffer to write to
436 * @param offset the offset in the destination buffer to start at
437 * @param len the number of characters to write
438 */
439 private static void formatUnsignedLong0UTF16(long val, int shift, byte[] buf, int offset, int len) {
440 int charPos = offset + len;
441 int radix = 1 << shift;
442 int mask = radix - 1;
443 do {
444 StringUTF16.putChar(buf, --charPos, Integer.digits[((int) val) & mask]);
445 val >>>= shift;
446 } while (charPos > offset);
447 }
448
449 /**
450 * Returns a {@code String} object representing the specified
451 * {@code long}. The argument is converted to signed decimal
452 * representation and returned as a string, exactly as if the
453 * argument and the radix 10 were given as arguments to the {@link
454 * #toString(long, int)} method.
455 *
456 * @param i a {@code long} to be converted.
457 * @return a string representation of the argument in base 10.
458 */
459 public static String toString(long i) {
460 int size = stringSize(i);
461 if (COMPACT_STRINGS) {
462 byte[] buf = new byte[size];
463 StringLatin1.getChars(i, size, buf);
464 return new String(buf, LATIN1);
465 } else {
466 byte[] buf = new byte[size * 2];
467 StringUTF16.getChars(i, size, buf);
468 return new String(buf, UTF16);
469 }
470 }
471
472 /**
473 * Returns a string representation of the argument as an unsigned
474 * decimal value.
475 *
476 * The argument is converted to unsigned decimal representation
477 * and returned as a string exactly as if the argument and radix
478 * 10 were given as arguments to the {@link #toUnsignedString(long,
479 * int)} method.
480 *
481 * @param i an integer to be converted to an unsigned string.
482 * @return an unsigned string representation of the argument.
483 * @see #toUnsignedString(long, int)
484 * @since 1.8
485 */
486 public static String toUnsignedString(long i) {
487 return toUnsignedString(i, 10);
488 }
489
490 /**
491 * Returns the string representation size for a given long value.
492 *
493 * @param x long value
494 * @return string size
495 *
496 * @implNote There are other ways to compute this: e.g. binary search,
497 * but values are biased heavily towards zero, and therefore linear search
498 * wins. The iteration results are also routinely inlined in the generated
499 * code after loop unrolling.
500 */
501 static int stringSize(long x) {
502 int d = 1;
503 if (x >= 0) {
504 d = 0;
505 x = -x;
506 }
507 long p = -10;
508 for (int i = 1; i < 19; i++) {
509 if (x > p)
510 return i + d;
511 p = 10 * p;
512 }
513 return 19 + d;
514 }
515
516 /**
517 * Parses the string argument as a signed {@code long} in the
518 * radix specified by the second argument. The characters in the
519 * string must all be digits of the specified radix (as determined
520 * by whether {@link java.lang.Character#digit(char, int)} returns
521 * a nonnegative value), except that the first character may be an
522 * ASCII minus sign {@code '-'} ({@code '\u005Cu002D'}) to
523 * indicate a negative value or an ASCII plus sign {@code '+'}
524 * ({@code '\u005Cu002B'}) to indicate a positive value. The
525 * resulting {@code long} value is returned.
526 *
527 * <p>Note that neither the character {@code L}
528 * ({@code '\u005Cu004C'}) nor {@code l}
529 * ({@code '\u005Cu006C'}) is permitted to appear at the end
530 * of the string as a type indicator, as would be permitted in
531 * Java programming language source code - except that either
532 * {@code L} or {@code l} may appear as a digit for a
533 * radix greater than or equal to 22.
534 *
535 * <p>An exception of type {@code NumberFormatException} is
536 * thrown if any of the following situations occurs:
537 * <ul>
538 *
539 * <li>The first argument is {@code null} or is a string of
540 * length zero.
541 *
542 * <li>The {@code radix} is either smaller than {@link
543 * java.lang.Character#MIN_RADIX} or larger than {@link
544 * java.lang.Character#MAX_RADIX}.
545 *
546 * <li>Any character of the string is not a digit of the specified
547 * radix, except that the first character may be a minus sign
548 * {@code '-'} ({@code '\u005Cu002d'}) or plus sign {@code
549 * '+'} ({@code '\u005Cu002B'}) provided that the string is
550 * longer than length 1.
551 *
552 * <li>The value represented by the string is not a value of type
553 * {@code long}.
554 * </ul>
555 *
556 * <p>Examples:
557 * <blockquote><pre>
558 * parseLong("0", 10) returns 0L
559 * parseLong("473", 10) returns 473L
560 * parseLong("+42", 10) returns 42L
561 * parseLong("-0", 10) returns 0L
562 * parseLong("-FF", 16) returns -255L
563 * parseLong("1100110", 2) returns 102L
564 * parseLong("99", 8) throws a NumberFormatException
565 * parseLong("Hazelnut", 10) throws a NumberFormatException
566 * parseLong("Hazelnut", 36) returns 1356099454469L
567 * </pre></blockquote>
568 *
569 * @param s the {@code String} containing the
570 * {@code long} representation to be parsed.
571 * @param radix the radix to be used while parsing {@code s}.
572 * @return the {@code long} represented by the string argument in
573 * the specified radix.
574 * @throws NumberFormatException if the string does not contain a
575 * parsable {@code long}.
576 */
577 public static long parseLong(String s, int radix)
578 throws NumberFormatException {
579 if (s == null) {
580 throw new NumberFormatException("Cannot parse null string");
581 }
582
583 if (radix < Character.MIN_RADIX) {
584 throw new NumberFormatException(String.format(
585 "radix %s less than Character.MIN_RADIX", radix));
586 }
587
588 if (radix > Character.MAX_RADIX) {
589 throw new NumberFormatException(String.format(
590 "radix %s greater than Character.MAX_RADIX", radix));
591 }
592
593 int len = s.length();
594 if (len == 0) {
595 throw NumberFormatException.forInputString("", radix);
596 }
597 int digit = ~0xFF;
598 int i = 0;
599 char firstChar = s.charAt(i++);
600 if (firstChar != '-' && firstChar != '+') {
601 digit = digit(firstChar, radix);
602 }
603 if (digit >= 0 || digit == ~0xFF && len > 1) {
604 long limit = firstChar != '-' ? MIN_VALUE + 1 : MIN_VALUE;
605 long multmin = limit / radix;
606 long result = -(digit & 0xFF);
607 boolean inRange = true;
608 /* Accumulating negatively avoids surprises near MAX_VALUE */
609 while (i < len && (digit = digit(s.charAt(i++), radix)) >= 0
610 && (inRange = result > multmin
611 || result == multmin && digit <= (int) (radix * multmin - limit))) {
612 result = radix * result - digit;
613 }
614 if (inRange && i == len && digit >= 0) {
615 return firstChar != '-' ? -result : result;
616 }
617 }
618 throw NumberFormatException.forInputString(s, radix);
619 }
620
621 /**
622 * Parses the {@link CharSequence} argument as a signed {@code long} in
623 * the specified {@code radix}, beginning at the specified
624 * {@code beginIndex} and extending to {@code endIndex - 1}.
625 *
626 * <p>The method does not take steps to guard against the
627 * {@code CharSequence} being mutated while parsing.
628 *
629 * @param s the {@code CharSequence} containing the {@code long}
630 * representation to be parsed
631 * @param beginIndex the beginning index, inclusive.
632 * @param endIndex the ending index, exclusive.
633 * @param radix the radix to be used while parsing {@code s}.
634 * @return the signed {@code long} represented by the subsequence in
635 * the specified radix.
636 * @throws NullPointerException if {@code s} is null.
637 * @throws IndexOutOfBoundsException if {@code beginIndex} is
638 * negative, or if {@code beginIndex} is greater than
639 * {@code endIndex} or if {@code endIndex} is greater than
640 * {@code s.length()}.
641 * @throws NumberFormatException if the {@code CharSequence} does not
642 * contain a parsable {@code long} in the specified
643 * {@code radix}, or if {@code radix} is either smaller than
644 * {@link java.lang.Character#MIN_RADIX} or larger than
645 * {@link java.lang.Character#MAX_RADIX}.
646 * @since 9
647 */
648 public static long parseLong(CharSequence s, int beginIndex, int endIndex, int radix)
649 throws NumberFormatException {
650 Objects.requireNonNull(s);
651 Objects.checkFromToIndex(beginIndex, endIndex, s.length());
652
653 if (radix < Character.MIN_RADIX) {
654 throw new NumberFormatException(String.format(
655 "radix %s less than Character.MIN_RADIX", radix));
656 }
657
658 if (radix > Character.MAX_RADIX) {
659 throw new NumberFormatException(String.format(
660 "radix %s greater than Character.MAX_RADIX", radix));
661 }
662
663 /*
664 * While s can be concurrently modified, it is ensured that each
665 * of its characters is read at most once, from lower to higher indices.
666 * This is obtained by reading them using the pattern s.charAt(i++),
667 * and by not updating i anywhere else.
668 */
669 if (beginIndex == endIndex) {
670 throw NumberFormatException.forInputString("", radix);
671 }
672 int digit = ~0xFF; // ~0xFF means firstChar char is sign
673 int i = beginIndex;
674 char firstChar = s.charAt(i++);
675 if (firstChar != '-' && firstChar != '+') {
676 digit = digit(firstChar, radix);
677 }
678 if (digit >= 0 || digit == ~0xFF && endIndex - beginIndex > 1) {
679 long limit = firstChar != '-' ? MIN_VALUE + 1 : MIN_VALUE;
680 long multmin = limit / radix;
681 long result = -(digit & 0xFF);
682 boolean inRange = true;
683 /* Accumulating negatively avoids surprises near MAX_VALUE */
684 while (i < endIndex && (digit = digit(s.charAt(i++), radix)) >= 0
685 && (inRange = result > multmin
686 || result == multmin && digit <= (int) (radix * multmin - limit))) {
687 result = radix * result - digit;
688 }
689 if (inRange && i == endIndex && digit >= 0) {
690 return firstChar != '-' ? -result : result;
691 }
692 }
693 throw NumberFormatException.forCharSequence(s, beginIndex,
694 endIndex, i - (digit < -1 ? 0 : 1));
695 }
696
697 /**
698 * Parses the string argument as a signed decimal {@code long}.
699 * The characters in the string must all be decimal digits, except
700 * that the first character may be an ASCII minus sign {@code '-'}
701 * ({@code \u005Cu002D'}) to indicate a negative value or an
702 * ASCII plus sign {@code '+'} ({@code '\u005Cu002B'}) to
703 * indicate a positive value. The resulting {@code long} value is
704 * returned, exactly as if the argument and the radix {@code 10}
705 * were given as arguments to the {@link
706 * #parseLong(java.lang.String, int)} method.
707 *
708 * <p>Note that neither the character {@code L}
709 * ({@code '\u005Cu004C'}) nor {@code l}
710 * ({@code '\u005Cu006C'}) is permitted to appear at the end
711 * of the string as a type indicator, as would be permitted in
712 * Java programming language source code.
713 *
714 * @param s a {@code String} containing the {@code long}
715 * representation to be parsed
716 * @return the {@code long} represented by the argument in
717 * decimal.
718 * @throws NumberFormatException if the string does not contain a
719 * parsable {@code long}.
720 */
721 public static long parseLong(String s) throws NumberFormatException {
722 return parseLong(s, 10);
723 }
724
725 /**
726 * Parses the string argument as an unsigned {@code long} in the
727 * radix specified by the second argument. An unsigned integer
728 * maps the values usually associated with negative numbers to
729 * positive numbers larger than {@code MAX_VALUE}.
730 *
731 * The characters in the string must all be digits of the
732 * specified radix (as determined by whether {@link
733 * java.lang.Character#digit(char, int)} returns a nonnegative
734 * value), except that the first character may be an ASCII plus
735 * sign {@code '+'} ({@code '\u005Cu002B'}). The resulting
736 * integer value is returned.
737 *
738 * <p>An exception of type {@code NumberFormatException} is
739 * thrown if any of the following situations occurs:
740 * <ul>
741 * <li>The first argument is {@code null} or is a string of
742 * length zero.
743 *
744 * <li>The radix is either smaller than
745 * {@link java.lang.Character#MIN_RADIX} or
746 * larger than {@link java.lang.Character#MAX_RADIX}.
747 *
748 * <li>Any character of the string is not a digit of the specified
749 * radix, except that the first character may be a plus sign
750 * {@code '+'} ({@code '\u005Cu002B'}) provided that the
751 * string is longer than length 1.
752 *
753 * <li>The value represented by the string is larger than the
754 * largest unsigned {@code long}, 2<sup>64</sup>-1.
755 *
756 * </ul>
757 *
758 *
759 * @param s the {@code String} containing the unsigned integer
760 * representation to be parsed
761 * @param radix the radix to be used while parsing {@code s}.
762 * @return the unsigned {@code long} represented by the string
763 * argument in the specified radix.
764 * @throws NumberFormatException if the {@code String}
765 * does not contain a parsable {@code long}.
766 * @since 1.8
767 */
768 public static long parseUnsignedLong(String s, int radix)
769 throws NumberFormatException {
770 if (s == null) {
771 throw new NumberFormatException("Cannot parse null string");
772 }
773
774 if (radix < Character.MIN_RADIX) {
775 throw new NumberFormatException(String.format(
776 "radix %s less than Character.MIN_RADIX", radix));
777 }
778
779 if (radix > Character.MAX_RADIX) {
780 throw new NumberFormatException(String.format(
781 "radix %s greater than Character.MAX_RADIX", radix));
782 }
783
784 int len = s.length();
785 if (len == 0) {
786 throw NumberFormatException.forInputString(s, radix);
787 }
788 int i = 0;
789 char firstChar = s.charAt(i++);
790 if (firstChar == '-') {
791 throw new NumberFormatException(String.format(
792 "Illegal leading minus sign on unsigned string %s.", s));
793 }
794 int digit = ~0xFF;
795 if (firstChar != '+') {
796 digit = digit(firstChar, radix);
797 }
798 if (digit >= 0 || digit == ~0xFF && len > 1) {
799 long multmax = divideUnsigned(-1L, radix); // -1L is max unsigned long
800 long result = digit & 0xFF;
801 boolean inRange = true;
802 while (i < len && (digit = digit(s.charAt(i++), radix)) >= 0
803 && (inRange = compareUnsigned(result, multmax) < 0
804 || result == multmax && digit < (int) (-radix * multmax))) {
805 result = radix * result + digit;
806 }
807 if (inRange && i == len && digit >= 0) {
808 return result;
809 }
810 }
811 if (digit < 0) {
812 throw NumberFormatException.forInputString(s, radix);
813 }
814 throw new NumberFormatException(String.format(
815 "String value %s exceeds range of unsigned long.", s));
816 }
817
818 /**
819 * Parses the {@link CharSequence} argument as an unsigned {@code long} in
820 * the specified {@code radix}, beginning at the specified
821 * {@code beginIndex} and extending to {@code endIndex - 1}.
822 *
823 * <p>The method does not take steps to guard against the
824 * {@code CharSequence} being mutated while parsing.
825 *
826 * @param s the {@code CharSequence} containing the unsigned
827 * {@code long} representation to be parsed
828 * @param beginIndex the beginning index, inclusive.
829 * @param endIndex the ending index, exclusive.
830 * @param radix the radix to be used while parsing {@code s}.
831 * @return the unsigned {@code long} represented by the subsequence in
832 * the specified radix.
833 * @throws NullPointerException if {@code s} is null.
834 * @throws IndexOutOfBoundsException if {@code beginIndex} is
835 * negative, or if {@code beginIndex} is greater than
836 * {@code endIndex} or if {@code endIndex} is greater than
837 * {@code s.length()}.
838 * @throws NumberFormatException if the {@code CharSequence} does not
839 * contain a parsable unsigned {@code long} in the specified
840 * {@code radix}, or if {@code radix} is either smaller than
841 * {@link java.lang.Character#MIN_RADIX} or larger than
842 * {@link java.lang.Character#MAX_RADIX}.
843 * @since 9
844 */
845 public static long parseUnsignedLong(CharSequence s, int beginIndex, int endIndex, int radix)
846 throws NumberFormatException {
847 Objects.requireNonNull(s);
848 Objects.checkFromToIndex(beginIndex, endIndex, s.length());
849
850 if (radix < Character.MIN_RADIX) {
851 throw new NumberFormatException(String.format(
852 "radix %s less than Character.MIN_RADIX", radix));
853 }
854
855 if (radix > Character.MAX_RADIX) {
856 throw new NumberFormatException(String.format(
857 "radix %s greater than Character.MAX_RADIX", radix));
858 }
859
860 /*
861 * While s can be concurrently modified, it is ensured that each
862 * of its characters is read at most once, from lower to higher indices.
863 * This is obtained by reading them using the pattern s.charAt(i++),
864 * and by not updating i anywhere else.
865 */
866 if (beginIndex == endIndex) {
867 throw NumberFormatException.forInputString("", radix);
868 }
869 int i = beginIndex;
870 char firstChar = s.charAt(i++);
871 if (firstChar == '-') {
872 throw new NumberFormatException(
873 "Illegal leading minus sign on unsigned string " + s + ".");
874 }
875 int digit = ~0xFF;
876 if (firstChar != '+') {
877 digit = digit(firstChar, radix);
878 }
879 if (digit >= 0 || digit == ~0xFF && endIndex - beginIndex > 1) {
880 long multmax = divideUnsigned(-1L, radix); // -1L is max unsigned long
881 long result = digit & 0xFF;
882 boolean inRange = true;
883 while (i < endIndex && (digit = digit(s.charAt(i++), radix)) >= 0
884 && (inRange = compareUnsigned(result, multmax) < 0
885 || result == multmax && digit < (int) (-radix * multmax))) {
886 result = radix * result + digit;
887 }
888 if (inRange && i == endIndex && digit >= 0) {
889 return result;
890 }
891 }
892 if (digit < 0) {
893 throw NumberFormatException.forCharSequence(s, beginIndex,
894 endIndex, i - (digit < -1 ? 0 : 1));
895 }
896 throw new NumberFormatException(String.format(
897 "String value %s exceeds range of unsigned long.", s));
898 }
899
900 /**
901 * Parses the string argument as an unsigned decimal {@code long}. The
902 * characters in the string must all be decimal digits, except
903 * that the first character may be an ASCII plus sign {@code
904 * '+'} ({@code '\u005Cu002B'}). The resulting integer value
905 * is returned, exactly as if the argument and the radix 10 were
906 * given as arguments to the {@link
907 * #parseUnsignedLong(java.lang.String, int)} method.
908 *
909 * @param s a {@code String} containing the unsigned {@code long}
910 * representation to be parsed
911 * @return the unsigned {@code long} value represented by the decimal string argument
912 * @throws NumberFormatException if the string does not contain a
913 * parsable unsigned integer.
914 * @since 1.8
915 */
916 public static long parseUnsignedLong(String s) throws NumberFormatException {
917 return parseUnsignedLong(s, 10);
918 }
919
920 /**
921 * Returns a {@code Long} object holding the value
922 * extracted from the specified {@code String} when parsed
923 * with the radix given by the second argument. The first
924 * argument is interpreted as representing a signed
925 * {@code long} in the radix specified by the second
926 * argument, exactly as if the arguments were given to the {@link
927 * #parseLong(java.lang.String, int)} method. The result is a
928 * {@code Long} object that represents the {@code long}
929 * value specified by the string.
930 *
931 * <p>In other words, this method returns a {@code Long} object equal
932 * to the value of:
933 *
934 * <blockquote>
935 * {@code Long.valueOf(Long.parseLong(s, radix))}
936 * </blockquote>
937 *
938 * @param s the string to be parsed
939 * @param radix the radix to be used in interpreting {@code s}
940 * @return a {@code Long} object holding the value
941 * represented by the string argument in the specified
942 * radix.
943 * @throws NumberFormatException If the {@code String} does not
944 * contain a parsable {@code long}.
945 */
946 public static Long valueOf(String s, int radix) throws NumberFormatException {
947 return Long.valueOf(parseLong(s, radix));
948 }
949
950 /**
951 * Returns a {@code Long} object holding the value
952 * of the specified {@code String}. The argument is
953 * interpreted as representing a signed decimal {@code long},
954 * exactly as if the argument were given to the {@link
955 * #parseLong(java.lang.String)} method. The result is a
956 * {@code Long} object that represents the integer value
957 * specified by the string.
958 *
959 * <p>In other words, this method returns a {@code Long} object
960 * equal to the value of:
961 *
962 * <blockquote>
963 * {@code Long.valueOf(Long.parseLong(s))}
964 * </blockquote>
965 *
966 * @param s the string to be parsed.
967 * @return a {@code Long} object holding the value
968 * represented by the string argument.
969 * @throws NumberFormatException If the string cannot be parsed
970 * as a {@code long}.
971 */
972 public static Long valueOf(String s) throws NumberFormatException
973 {
974 return Long.valueOf(parseLong(s, 10));
975 }
976
977 private static final class LongCache {
978 private LongCache() {}
979
980 @Stable
981 static final Long[] cache;
982 static Long[] archivedCache;
983
984 static {
985 int size = -(-128) + 127 + 1;
986
987 // Load and use the archived cache if it exists
988 CDS.initializeFromArchive(LongCache.class);
989 if (archivedCache == null || archivedCache.length != size) {
990 Long[] c = new Long[size];
991 long value = -128;
992 for(int i = 0; i < size; i++) {
993 c[i] = new Long(value++);
994 }
995 archivedCache = c;
996 }
997 cache = archivedCache;
998 }
999 }
1000
1001 /**
1002 * Returns a {@code Long} instance representing the specified
1003 * {@code long} value.
1004 * If a new {@code Long} instance is not required, this method
1005 * should generally be used in preference to the constructor
1006 * {@link #Long(long)}, as this method is likely to yield
1007 * significantly better space and time performance by caching
1008 * frequently requested values.
1009 *
1010 * This method will always cache values in the range -128 to 127,
1011 * inclusive, and may cache other values outside of this range.
1012 *
1013 * @param l a long value.
1014 * @return a {@code Long} instance representing {@code l}.
1015 * @since 1.5
1016 */
1017 @IntrinsicCandidate
1018 public static Long valueOf(long l) {
1019 final int offset = 128;
1020 if (l >= -128 && l <= 127) { // will cache
1021 return LongCache.cache[(int)l + offset];
1022 }
1023 return new Long(l);
1024 }
1025
1026 /**
1027 * Decodes a {@code String} into a {@code Long}.
1028 * Accepts decimal, hexadecimal, and octal numbers given by the
1029 * following grammar:
1030 *
1031 * <blockquote>
1032 * <dl>
1033 * <dt><i>DecodableString:</i>
1034 * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
1035 * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
1036 * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
1037 * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
1038 * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
1039 *
1040 * <dt><i>Sign:</i>
1041 * <dd>{@code -}
1042 * <dd>{@code +}
1043 * </dl>
1044 * </blockquote>
1045 *
1046 * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
1047 * are as defined in section {@jls 3.10.1} of
1048 * <cite>The Java Language Specification</cite>,
1049 * except that underscores are not accepted between digits.
1050 *
1051 * <p>The sequence of characters following an optional
1052 * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
1053 * "{@code #}", or leading zero) is parsed as by the {@code
1054 * Long.parseLong} method with the indicated radix (10, 16, or 8).
1055 * This sequence of characters must represent a positive value or
1056 * a {@link NumberFormatException} will be thrown. The result is
1057 * negated if first character of the specified {@code String} is
1058 * the minus sign. No whitespace characters are permitted in the
1059 * {@code String}.
1060 *
1061 * @param nm the {@code String} to decode.
1062 * @return a {@code Long} object holding the {@code long}
1063 * value represented by {@code nm}
1064 * @throws NumberFormatException if the {@code String} does not
1065 * contain a parsable {@code long}.
1066 * @see java.lang.Long#parseLong(String, int)
1067 * @since 1.2
1068 */
1069 public static Long decode(String nm) throws NumberFormatException {
1070 int radix = 10;
1071 int index = 0;
1072 boolean negative = false;
1073 long result;
1074
1075 if (nm.isEmpty())
1076 throw new NumberFormatException("Zero length string");
1077 char firstChar = nm.charAt(0);
1078 // Handle sign, if present
1079 if (firstChar == '-') {
1080 negative = true;
1081 index++;
1082 } else if (firstChar == '+')
1083 index++;
1084
1085 // Handle radix specifier, if present
1086 if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
1087 index += 2;
1088 radix = 16;
1089 }
1090 else if (nm.startsWith("#", index)) {
1091 index ++;
1092 radix = 16;
1093 }
1094 else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
1095 index ++;
1096 radix = 8;
1097 }
1098
1099 if (nm.startsWith("-", index) || nm.startsWith("+", index))
1100 throw new NumberFormatException("Sign character in wrong position");
1101
1102 try {
1103 result = parseLong(nm, index, nm.length(), radix);
1104 result = negative ? -result : result;
1105 } catch (NumberFormatException e) {
1106 // If number is Long.MIN_VALUE, we'll end up here. The next line
1107 // handles this case, and causes any genuine format error to be
1108 // rethrown.
1109 String constant = negative ? ("-" + nm.substring(index))
1110 : nm.substring(index);
1111 result = parseLong(constant, radix);
1112 }
1113 return result;
1114 }
1115
1116 /**
1117 * The value of the {@code Long}.
1118 *
1119 * @serial
1120 */
1121 private final long value;
1122
1123 /**
1124 * Constructs a newly allocated {@code Long} object that
1125 * represents the specified {@code long} argument.
1126 *
1127 * @param value the value to be represented by the
1128 * {@code Long} object.
1129 *
1130 * @deprecated
1131 * It is rarely appropriate to use this constructor. The static factory
1132 * {@link #valueOf(long)} is generally a better choice, as it is
1133 * likely to yield significantly better space and time performance.
1134 */
1135 @Deprecated(since="9", forRemoval = true)
1136 public Long(long value) {
1137 this.value = value;
1138 }
1139
1140 /**
1141 * Constructs a newly allocated {@code Long} object that
1142 * represents the {@code long} value indicated by the
1143 * {@code String} parameter. The string is converted to a
1144 * {@code long} value in exactly the manner used by the
1145 * {@code parseLong} method for radix 10.
1146 *
1147 * @param s the {@code String} to be converted to a
1148 * {@code Long}.
1149 * @throws NumberFormatException if the {@code String} does not
1150 * contain a parsable {@code long}.
1151 *
1152 * @deprecated
1153 * It is rarely appropriate to use this constructor.
1154 * Use {@link #parseLong(String)} to convert a string to a
1155 * {@code long} primitive, or use {@link #valueOf(String)}
1156 * to convert a string to a {@code Long} object.
1157 */
1158 @Deprecated(since="9", forRemoval = true)
1159 public Long(String s) throws NumberFormatException {
1160 this.value = parseLong(s, 10);
1161 }
1162
1163 /**
1164 * Returns the value of this {@code Long} as a {@code byte} after
1165 * a narrowing primitive conversion.
1166 * @jls 5.1.3 Narrowing Primitive Conversion
1167 */
1168 public byte byteValue() {
1169 return (byte)value;
1170 }
1171
1172 /**
1173 * Returns the value of this {@code Long} as a {@code short} after
1174 * a narrowing primitive conversion.
1175 * @jls 5.1.3 Narrowing Primitive Conversion
1176 */
1177 public short shortValue() {
1178 return (short)value;
1179 }
1180
1181 /**
1182 * Returns the value of this {@code Long} as an {@code int} after
1183 * a narrowing primitive conversion.
1184 * @jls 5.1.3 Narrowing Primitive Conversion
1185 */
1186 public int intValue() {
1187 return (int)value;
1188 }
1189
1190 /**
1191 * Returns the value of this {@code Long} as a
1192 * {@code long} value.
1193 */
1194 @IntrinsicCandidate
1195 public long longValue() {
1196 return value;
1197 }
1198
1199 /**
1200 * Returns the value of this {@code Long} as a {@code float} after
1201 * a widening primitive conversion.
1202 * @jls 5.1.2 Widening Primitive Conversion
1203 */
1204 public float floatValue() {
1205 return (float)value;
1206 }
1207
1208 /**
1209 * Returns the value of this {@code Long} as a {@code double}
1210 * after a widening primitive conversion.
1211 * @jls 5.1.2 Widening Primitive Conversion
1212 */
1213 public double doubleValue() {
1214 return (double)value;
1215 }
1216
1217 /**
1218 * Returns a {@code String} object representing this
1219 * {@code Long}'s value. The value is converted to signed
1220 * decimal representation and returned as a string, exactly as if
1221 * the {@code long} value were given as an argument to the
1222 * {@link java.lang.Long#toString(long)} method.
1223 *
1224 * @return a string representation of the value of this object in
1225 * base 10.
1226 */
1227 public String toString() {
1228 return toString(value);
1229 }
1230
1231 /**
1232 * Returns a hash code for this {@code Long}. The result is
1233 * the exclusive OR of the two halves of the primitive
1234 * {@code long} value held by this {@code Long}
1235 * object. That is, the hashcode is the value of the expression:
1236 *
1237 * <blockquote>
1238 * {@code (int)(this.longValue()^(this.longValue()>>>32))}
1239 * </blockquote>
1240 *
1241 * @return a hash code value for this object.
1242 */
1243 @Override
1244 public int hashCode() {
1245 return Long.hashCode(value);
1246 }
1247
1248 /**
1249 * Returns a hash code for a {@code long} value; compatible with
1250 * {@code Long.hashCode()}.
1251 *
1252 * @param value the value to hash
1253 * @return a hash code value for a {@code long} value.
1254 * @since 1.8
1255 */
1256 public static int hashCode(long value) {
1257 return (int)(value ^ (value >>> 32));
1258 }
1259
1260 /**
1261 * Compares this object to the specified object. The result is
1262 * {@code true} if and only if the argument is not
1263 * {@code null} and is a {@code Long} object that
1264 * contains the same {@code long} value as this object.
1265 *
1266 * @param obj the object to compare with.
1267 * @return {@code true} if the objects are the same;
1268 * {@code false} otherwise.
1269 */
1270 public boolean equals(Object obj) {
1271 if (obj instanceof Long) {
1272 return value == ((Long)obj).longValue();
1273 }
1274 return false;
1275 }
1276
1277 /**
1278 * Determines the {@code long} value of the system property
1279 * with the specified name.
1280 *
1281 * <p>The first argument is treated as the name of a system
1282 * property. System properties are accessible through the {@link
1283 * java.lang.System#getProperty(java.lang.String)} method. The
1284 * string value of this property is then interpreted as a {@code
1285 * long} value using the grammar supported by {@link Long#decode decode}
1286 * and a {@code Long} object representing this value is returned.
1287 *
1288 * <p>If there is no property with the specified name, if the
1289 * specified name is empty or {@code null}, or if the property
1290 * does not have the correct numeric format, then {@code null} is
1291 * returned.
1292 *
1293 * <p>In other words, this method returns a {@code Long} object
1294 * equal to the value of:
1295 *
1296 * <blockquote>
1297 * {@code getLong(nm, null)}
1298 * </blockquote>
1299 *
1300 * @param nm property name.
1301 * @return the {@code Long} value of the property.
1302 * @throws SecurityException for the same reasons as
1303 * {@link System#getProperty(String) System.getProperty}
1304 * @see java.lang.System#getProperty(java.lang.String)
1305 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1306 */
1307 public static Long getLong(String nm) {
1308 return getLong(nm, null);
1309 }
1310
1311 /**
1312 * Determines the {@code long} value of the system property
1313 * with the specified name.
1314 *
1315 * <p>The first argument is treated as the name of a system
1316 * property. System properties are accessible through the {@link
1317 * java.lang.System#getProperty(java.lang.String)} method. The
1318 * string value of this property is then interpreted as a {@code
1319 * long} value using the grammar supported by {@link Long#decode decode}
1320 * and a {@code Long} object representing this value is returned.
1321 *
1322 * <p>The second argument is the default value. A {@code Long} object
1323 * that represents the value of the second argument is returned if there
1324 * is no property of the specified name, if the property does not have
1325 * the correct numeric format, or if the specified name is empty or null.
1326 *
1327 * <p>In other words, this method returns a {@code Long} object equal
1328 * to the value of:
1329 *
1330 * <blockquote>
1331 * {@code getLong(nm, Long.valueOf(val))}
1332 * </blockquote>
1333 *
1334 * but in practice it may be implemented in a manner such as:
1335 *
1336 * <blockquote><pre>
1337 * Long result = getLong(nm, null);
1338 * return (result == null) ? Long.valueOf(val) : result;
1339 * </pre></blockquote>
1340 *
1341 * to avoid the unnecessary allocation of a {@code Long} object when
1342 * the default value is not needed.
1343 *
1344 * @param nm property name.
1345 * @param val default value.
1346 * @return the {@code Long} value of the property.
1347 * @throws SecurityException for the same reasons as
1348 * {@link System#getProperty(String) System.getProperty}
1349 * @see java.lang.System#getProperty(java.lang.String)
1350 * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
1351 */
1352 public static Long getLong(String nm, long val) {
1353 Long result = Long.getLong(nm, null);
1354 return (result == null) ? Long.valueOf(val) : result;
1355 }
1356
1357 /**
1358 * Returns the {@code long} value of the system property with
1359 * the specified name. The first argument is treated as the name
1360 * of a system property. System properties are accessible through
1361 * the {@link java.lang.System#getProperty(java.lang.String)}
1362 * method. The string value of this property is then interpreted
1363 * as a {@code long} value, as per the
1364 * {@link Long#decode decode} method, and a {@code Long} object
1365 * representing this value is returned; in summary:
1366 *
1367 * <ul>
1368 * <li>If the property value begins with the two ASCII characters
1369 * {@code 0x} or the ASCII character {@code #}, not followed by
1370 * a minus sign, then the rest of it is parsed as a hexadecimal integer
1371 * exactly as for the method {@link #valueOf(java.lang.String, int)}
1372 * with radix 16.
1373 * <li>If the property value begins with the ASCII character
1374 * {@code 0} followed by another character, it is parsed as
1375 * an octal integer exactly as by the method {@link
1376 * #valueOf(java.lang.String, int)} with radix 8.
1377 * <li>Otherwise the property value is parsed as a decimal
1378 * integer exactly as by the method
1379 * {@link #valueOf(java.lang.String, int)} with radix 10.
1380 * </ul>
1381 *
1382 * <p>Note that, in every case, neither {@code L}
1383 * ({@code '\u005Cu004C'}) nor {@code l}
1384 * ({@code '\u005Cu006C'}) is permitted to appear at the end
1385 * of the property value as a type indicator, as would be
1386 * permitted in Java programming language source code.
1387 *
1388 * <p>The second argument is the default value. The default value is
1389 * returned if there is no property of the specified name, if the
1390 * property does not have the correct numeric format, or if the
1391 * specified name is empty or {@code null}.
1392 *
1393 * @param nm property name.
1394 * @param val default value.
1395 * @return the {@code Long} value of the property.
1396 * @throws SecurityException for the same reasons as
1397 * {@link System#getProperty(String) System.getProperty}
1398 * @see System#getProperty(java.lang.String)
1399 * @see System#getProperty(java.lang.String, java.lang.String)
1400 */
1401 public static Long getLong(String nm, Long val) {
1402 String v = null;
1403 try {
1404 v = System.getProperty(nm);
1405 } catch (IllegalArgumentException | NullPointerException e) {
1406 }
1407 if (v != null) {
1408 try {
1409 return Long.decode(v);
1410 } catch (NumberFormatException e) {
1411 }
1412 }
1413 return val;
1414 }
1415
1416 /**
1417 * Compares two {@code Long} objects numerically.
1418 *
1419 * @param anotherLong the {@code Long} to be compared.
1420 * @return the value {@code 0} if this {@code Long} is
1421 * equal to the argument {@code Long}; a value less than
1422 * {@code 0} if this {@code Long} is numerically less
1423 * than the argument {@code Long}; and a value greater
1424 * than {@code 0} if this {@code Long} is numerically
1425 * greater than the argument {@code Long} (signed
1426 * comparison).
1427 * @since 1.2
1428 */
1429 public int compareTo(Long anotherLong) {
1430 return compare(this.value, anotherLong.value);
1431 }
1432
1433 /**
1434 * Compares two {@code long} values numerically.
1435 * The value returned is identical to what would be returned by:
1436 * <pre>
1437 * Long.valueOf(x).compareTo(Long.valueOf(y))
1438 * </pre>
1439 *
1440 * @param x the first {@code long} to compare
1441 * @param y the second {@code long} to compare
1442 * @return the value {@code 0} if {@code x == y};
1443 * a value less than {@code 0} if {@code x < y}; and
1444 * a value greater than {@code 0} if {@code x > y}
1445 * @since 1.7
1446 */
1447 public static int compare(long x, long y) {
1448 return (x < y) ? -1 : ((x == y) ? 0 : 1);
1449 }
1450
1451 /**
1452 * Compares two {@code long} values numerically treating the values
1453 * as unsigned.
1454 *
1455 * @param x the first {@code long} to compare
1456 * @param y the second {@code long} to compare
1457 * @return the value {@code 0} if {@code x == y}; a value less
1458 * than {@code 0} if {@code x < y} as unsigned values; and
1459 * a value greater than {@code 0} if {@code x > y} as
1460 * unsigned values
1461 * @since 1.8
1462 */
1463 @IntrinsicCandidate
1464 public static int compareUnsigned(long x, long y) {
1465 return compare(x + MIN_VALUE, y + MIN_VALUE);
1466 }
1467
1468
1469 /**
1470 * Returns the unsigned quotient of dividing the first argument by
1471 * the second where each argument and the result is interpreted as
1472 * an unsigned value.
1473 *
1474 * <p>Note that in two's complement arithmetic, the three other
1475 * basic arithmetic operations of add, subtract, and multiply are
1476 * bit-wise identical if the two operands are regarded as both
1477 * being signed or both being unsigned. Therefore separate {@code
1478 * addUnsigned}, etc. methods are not provided.
1479 *
1480 * @param dividend the value to be divided
1481 * @param divisor the value doing the dividing
1482 * @return the unsigned quotient of the first argument divided by
1483 * the second argument
1484 * @see #remainderUnsigned
1485 * @since 1.8
1486 */
1487 @IntrinsicCandidate
1488 public static long divideUnsigned(long dividend, long divisor) {
1489 /* See Hacker's Delight (2nd ed), section 9.3 */
1490 if (divisor >= 0) {
1491 final long q = (dividend >>> 1) / divisor << 1;
1492 final long r = dividend - q * divisor;
1493 return q + ((r | ~(r - divisor)) >>> (Long.SIZE - 1));
1494 }
1495 return (dividend & ~(dividend - divisor)) >>> (Long.SIZE - 1);
1496 }
1497
1498 /**
1499 * Returns the unsigned remainder from dividing the first argument
1500 * by the second where each argument and the result is interpreted
1501 * as an unsigned value.
1502 *
1503 * @param dividend the value to be divided
1504 * @param divisor the value doing the dividing
1505 * @return the unsigned remainder of the first argument divided by
1506 * the second argument
1507 * @see #divideUnsigned
1508 * @since 1.8
1509 */
1510 @IntrinsicCandidate
1511 public static long remainderUnsigned(long dividend, long divisor) {
1512 /* See Hacker's Delight (2nd ed), section 9.3 */
1513 if (divisor >= 0) {
1514 final long q = (dividend >>> 1) / divisor << 1;
1515 final long r = dividend - q * divisor;
1516 /*
1517 * Here, 0 <= r < 2 * divisor
1518 * (1) When 0 <= r < divisor, the remainder is simply r.
1519 * (2) Otherwise the remainder is r - divisor.
1520 *
1521 * In case (1), r - divisor < 0. Applying ~ produces a long with
1522 * sign bit 0, so >> produces 0. The returned value is thus r.
1523 *
1524 * In case (2), a similar reasoning shows that >> produces -1,
1525 * so the returned value is r - divisor.
1526 */
1527 return r - ((~(r - divisor) >> (Long.SIZE - 1)) & divisor);
1528 }
1529 /*
1530 * (1) When dividend >= 0, the remainder is dividend.
1531 * (2) Otherwise
1532 * (2.1) When dividend < divisor, the remainder is dividend.
1533 * (2.2) Otherwise the remainder is dividend - divisor
1534 *
1535 * A reasoning similar to the above shows that the returned value
1536 * is as expected.
1537 */
1538 return dividend - (((dividend & ~(dividend - divisor)) >> (Long.SIZE - 1)) & divisor);
1539 }
1540
1541 // Bit Twiddling
1542
1543 /**
1544 * The number of bits used to represent a {@code long} value in two's
1545 * complement binary form.
1546 *
1547 * @since 1.5
1548 */
1549 @Native public static final int SIZE = 64;
1550
1551 /**
1552 * The number of bytes used to represent a {@code long} value in two's
1553 * complement binary form.
1554 *
1555 * @since 1.8
1556 */
1557 public static final int BYTES = SIZE / Byte.SIZE;
1558
1559 /**
1560 * Returns a {@code long} value with at most a single one-bit, in the
1561 * position of the highest-order ("leftmost") one-bit in the specified
1562 * {@code long} value. Returns zero if the specified value has no
1563 * one-bits in its two's complement binary representation, that is, if it
1564 * is equal to zero.
1565 *
1566 * @param i the value whose highest one bit is to be computed
1567 * @return a {@code long} value with a single one-bit, in the position
1568 * of the highest-order one-bit in the specified value, or zero if
1569 * the specified value is itself equal to zero.
1570 * @since 1.5
1571 */
1572 public static long highestOneBit(long i) {
1573 return i & (MIN_VALUE >>> numberOfLeadingZeros(i));
1574 }
1575
1576 /**
1577 * Returns a {@code long} value with at most a single one-bit, in the
1578 * position of the lowest-order ("rightmost") one-bit in the specified
1579 * {@code long} value. Returns zero if the specified value has no
1580 * one-bits in its two's complement binary representation, that is, if it
1581 * is equal to zero.
1582 *
1583 * @param i the value whose lowest one bit is to be computed
1584 * @return a {@code long} value with a single one-bit, in the position
1585 * of the lowest-order one-bit in the specified value, or zero if
1586 * the specified value is itself equal to zero.
1587 * @since 1.5
1588 */
1589 public static long lowestOneBit(long i) {
1590 // HD, Section 2-1
1591 return i & -i;
1592 }
1593
1594 /**
1595 * Returns the number of zero bits preceding the highest-order
1596 * ("leftmost") one-bit in the two's complement binary representation
1597 * of the specified {@code long} value. Returns 64 if the
1598 * specified value has no one-bits in its two's complement representation,
1599 * in other words if it is equal to zero.
1600 *
1601 * <p>Note that this method is closely related to the logarithm base 2.
1602 * For all positive {@code long} values x:
1603 * <ul>
1604 * <li>floor(log<sub>2</sub>(x)) = {@code 63 - numberOfLeadingZeros(x)}
1605 * <li>ceil(log<sub>2</sub>(x)) = {@code 64 - numberOfLeadingZeros(x - 1)}
1606 * </ul>
1607 *
1608 * @param i the value whose number of leading zeros is to be computed
1609 * @return the number of zero bits preceding the highest-order
1610 * ("leftmost") one-bit in the two's complement binary representation
1611 * of the specified {@code long} value, or 64 if the value
1612 * is equal to zero.
1613 * @since 1.5
1614 */
1615 @IntrinsicCandidate
1616 public static int numberOfLeadingZeros(long i) {
1617 int x = (int)(i >>> 32);
1618 return x == 0 ? 32 + Integer.numberOfLeadingZeros((int)i)
1619 : Integer.numberOfLeadingZeros(x);
1620 }
1621
1622 /**
1623 * Returns the number of zero bits following the lowest-order ("rightmost")
1624 * one-bit in the two's complement binary representation of the specified
1625 * {@code long} value. Returns 64 if the specified value has no
1626 * one-bits in its two's complement representation, in other words if it is
1627 * equal to zero.
1628 *
1629 * @param i the value whose number of trailing zeros is to be computed
1630 * @return the number of zero bits following the lowest-order ("rightmost")
1631 * one-bit in the two's complement binary representation of the
1632 * specified {@code long} value, or 64 if the value is equal
1633 * to zero.
1634 * @since 1.5
1635 */
1636 @IntrinsicCandidate
1637 public static int numberOfTrailingZeros(long i) {
1638 int x = (int)i;
1639 return x == 0 ? 32 + Integer.numberOfTrailingZeros((int)(i >>> 32))
1640 : Integer.numberOfTrailingZeros(x);
1641 }
1642
1643 /**
1644 * Returns the number of one-bits in the two's complement binary
1645 * representation of the specified {@code long} value. This function is
1646 * sometimes referred to as the <i>population count</i>.
1647 *
1648 * @param i the value whose bits are to be counted
1649 * @return the number of one-bits in the two's complement binary
1650 * representation of the specified {@code long} value.
1651 * @since 1.5
1652 */
1653 @IntrinsicCandidate
1654 public static int bitCount(long i) {
1655 // HD, Figure 5-2
1656 i = i - ((i >>> 1) & 0x5555555555555555L);
1657 i = (i & 0x3333333333333333L) + ((i >>> 2) & 0x3333333333333333L);
1658 i = (i + (i >>> 4)) & 0x0f0f0f0f0f0f0f0fL;
1659 i = i + (i >>> 8);
1660 i = i + (i >>> 16);
1661 i = i + (i >>> 32);
1662 return (int)i & 0x7f;
1663 }
1664
1665 /**
1666 * Returns the value obtained by rotating the two's complement binary
1667 * representation of the specified {@code long} value left by the
1668 * specified number of bits. (Bits shifted out of the left hand, or
1669 * high-order, side reenter on the right, or low-order.)
1670 *
1671 * <p>Note that left rotation with a negative distance is equivalent to
1672 * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val,
1673 * distance)}. Note also that rotation by any multiple of 64 is a
1674 * no-op, so all but the last six bits of the rotation distance can be
1675 * ignored, even if the distance is negative: {@code rotateLeft(val,
1676 * distance) == rotateLeft(val, distance & 0x3F)}.
1677 *
1678 * @param i the value whose bits are to be rotated left
1679 * @param distance the number of bit positions to rotate left
1680 * @return the value obtained by rotating the two's complement binary
1681 * representation of the specified {@code long} value left by the
1682 * specified number of bits.
1683 * @since 1.5
1684 */
1685 public static long rotateLeft(long i, int distance) {
1686 return (i << distance) | (i >>> -distance);
1687 }
1688
1689 /**
1690 * Returns the value obtained by rotating the two's complement binary
1691 * representation of the specified {@code long} value right by the
1692 * specified number of bits. (Bits shifted out of the right hand, or
1693 * low-order, side reenter on the left, or high-order.)
1694 *
1695 * <p>Note that right rotation with a negative distance is equivalent to
1696 * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val,
1697 * distance)}. Note also that rotation by any multiple of 64 is a
1698 * no-op, so all but the last six bits of the rotation distance can be
1699 * ignored, even if the distance is negative: {@code rotateRight(val,
1700 * distance) == rotateRight(val, distance & 0x3F)}.
1701 *
1702 * @param i the value whose bits are to be rotated right
1703 * @param distance the number of bit positions to rotate right
1704 * @return the value obtained by rotating the two's complement binary
1705 * representation of the specified {@code long} value right by the
1706 * specified number of bits.
1707 * @since 1.5
1708 */
1709 public static long rotateRight(long i, int distance) {
1710 return (i >>> distance) | (i << -distance);
1711 }
1712
1713 /**
1714 * Returns the value obtained by reversing the order of the bits in the
1715 * two's complement binary representation of the specified {@code long}
1716 * value.
1717 *
1718 * @param i the value to be reversed
1719 * @return the value obtained by reversing order of the bits in the
1720 * specified {@code long} value.
1721 * @since 1.5
1722 */
1723 @IntrinsicCandidate
1724 public static long reverse(long i) {
1725 // HD, Figure 7-1
1726 i = (i & 0x5555555555555555L) << 1 | (i >>> 1) & 0x5555555555555555L;
1727 i = (i & 0x3333333333333333L) << 2 | (i >>> 2) & 0x3333333333333333L;
1728 i = (i & 0x0f0f0f0f0f0f0f0fL) << 4 | (i >>> 4) & 0x0f0f0f0f0f0f0f0fL;
1729
1730 return reverseBytes(i);
1731 }
1732
1733 /**
1734 * Returns the value obtained by compressing the bits of the
1735 * specified {@code long} value, {@code i}, in accordance with
1736 * the specified bit mask.
1737 * <p>
1738 * For each one-bit value {@code mb} of the mask, from least
1739 * significant to most significant, the bit value of {@code i} at
1740 * the same bit location as {@code mb} is assigned to the compressed
1741 * value contiguously starting from the least significant bit location.
1742 * All the upper remaining bits of the compressed value are set
1743 * to zero.
1744 *
1745 * @apiNote
1746 * Consider the simple case of compressing the digits of a hexadecimal
1747 * value:
1748 * {@snippet lang="java" :
1749 * // Compressing drink to food
1750 * compress(0xCAFEBABEL, 0xFF00FFF0L) == 0xCABABL
1751 * }
1752 * Starting from the least significant hexadecimal digit at position 0
1753 * from the right, the mask {@code 0xFF00FFF0} selects hexadecimal digits
1754 * at positions 1, 2, 3, 6 and 7 of {@code 0xCAFEBABE}. The selected digits
1755 * occur in the resulting compressed value contiguously from digit position
1756 * 0 in the same order.
1757 * <p>
1758 * The following identities all return {@code true} and are helpful to
1759 * understand the behaviour of {@code compress}:
1760 * {@snippet lang="java" :
1761 * // Returns 1 if the bit at position n is one
1762 * compress(x, 1L << n) == (x >> n & 1)
1763 *
1764 * // Logical shift right
1765 * compress(x, -1L << n) == x >>> n
1766 *
1767 * // Any bits not covered by the mask are ignored
1768 * compress(x, m) == compress(x & m, m)
1769 *
1770 * // Compressing a value by itself
1771 * compress(m, m) == (m == -1 || m == 0) ? m : (1L << bitCount(m)) - 1
1772 *
1773 * // Expanding then compressing with the same mask
1774 * compress(expand(x, m), m) == x & compress(m, m)
1775 * }
1776 * <p>
1777 * The Sheep And Goats (SAG) operation (see Hacker's Delight, section 7.7)
1778 * can be implemented as follows:
1779 * {@snippet lang="java" :
1780 * long compressLeft(long i, long mask) {
1781 * // This implementation follows the description in Hacker's Delight which
1782 * // is informative. A more optimal implementation is:
1783 * // Long.compress(i, mask) << -Long.bitCount(mask)
1784 * return Long.reverse(
1785 * Long.compress(Long.reverse(i), Long.reverse(mask)));
1786 * }
1787 *
1788 * long sag(long i, long mask) {
1789 * return compressLeft(i, mask) | Long.compress(i, ~mask);
1790 * }
1791 *
1792 * // Separate the sheep from the goats
1793 * sag(0x00000000_CAFEBABEL, 0xFFFFFFFF_FF00FFF0L) == 0x00000000_CABABFEEL
1794 * }
1795 *
1796 * @param i the value whose bits are to be compressed
1797 * @param mask the bit mask
1798 * @return the compressed value
1799 * @see #expand
1800 * @since 19
1801 */
1802 @IntrinsicCandidate
1803 public static long compress(long i, long mask) {
1804 // See Hacker's Delight (2nd ed) section 7.4 Compress, or Generalized Extract
1805
1806 i = i & mask; // Clear irrelevant bits
1807 long maskCount = ~mask << 1; // Count 0's to right
1808
1809 for (int j = 0; j < 6; j++) {
1810 // Parallel prefix
1811 // Mask prefix identifies bits of the mask that have an odd number of 0's to the right
1812 long maskPrefix = parallelSuffix(maskCount);
1813 // Bits to move
1814 long maskMove = maskPrefix & mask;
1815 // Compress mask
1816 mask = (mask ^ maskMove) | (maskMove >>> (1 << j));
1817 // Bits of i to be moved
1818 long t = i & maskMove;
1819 // Compress i
1820 i = (i ^ t) | (t >>> (1 << j));
1821 // Adjust the mask count by identifying bits that have 0 to the right
1822 maskCount = maskCount & ~maskPrefix;
1823 }
1824 return i;
1825 }
1826
1827 /**
1828 * Returns the value obtained by expanding the bits of the
1829 * specified {@code long} value, {@code i}, in accordance with
1830 * the specified bit mask.
1831 * <p>
1832 * For each one-bit value {@code mb} of the mask, from least
1833 * significant to most significant, the next contiguous bit value
1834 * of {@code i} starting at the least significant bit is assigned
1835 * to the expanded value at the same bit location as {@code mb}.
1836 * All other remaining bits of the expanded value are set to zero.
1837 *
1838 * @apiNote
1839 * Consider the simple case of expanding the digits of a hexadecimal
1840 * value:
1841 * {@snippet lang="java" :
1842 * expand(0x0000CABABL, 0xFF00FFF0L) == 0xCA00BAB0L
1843 * }
1844 * Starting from the least significant hexadecimal digit at position 0
1845 * from the right, the mask {@code 0xFF00FFF0} selects the first five
1846 * hexadecimal digits of {@code 0x0000CABAB}. The selected digits occur
1847 * in the resulting expanded value in order at positions 1, 2, 3, 6, and 7.
1848 * <p>
1849 * The following identities all return {@code true} and are helpful to
1850 * understand the behaviour of {@code expand}:
1851 * {@snippet lang="java" :
1852 * // Logically shift right the bit at position 0
1853 * expand(x, 1L << n) == (x & 1) << n
1854 *
1855 * // Logically shift right
1856 * expand(x, -1L << n) == x << n
1857 *
1858 * // Expanding all bits returns the mask
1859 * expand(-1L, m) == m
1860 *
1861 * // Any bits not covered by the mask are ignored
1862 * expand(x, m) == expand(x, m) & m
1863 *
1864 * // Compressing then expanding with the same mask
1865 * expand(compress(x, m), m) == x & m
1866 * }
1867 * <p>
1868 * The select operation for determining the position of the one-bit with
1869 * index {@code n} in a {@code long} value can be implemented as follows:
1870 * {@snippet lang="java" :
1871 * long select(long i, long n) {
1872 * // the one-bit in i (the mask) with index n
1873 * long nthBit = Long.expand(1L << n, i);
1874 * // the bit position of the one-bit with index n
1875 * return Long.numberOfTrailingZeros(nthBit);
1876 * }
1877 *
1878 * // The one-bit with index 0 is at bit position 1
1879 * select(0b10101010_10101010, 0) == 1
1880 * // The one-bit with index 3 is at bit position 7
1881 * select(0b10101010_10101010, 3) == 7
1882 * }
1883 *
1884 * @param i the value whose bits are to be expanded
1885 * @param mask the bit mask
1886 * @return the expanded value
1887 * @see #compress
1888 * @since 19
1889 */
1890 @IntrinsicCandidate
1891 public static long expand(long i, long mask) {
1892 // Save original mask
1893 long originalMask = mask;
1894 // Count 0's to right
1895 long maskCount = ~mask << 1;
1896 long maskPrefix = parallelSuffix(maskCount);
1897 // Bits to move
1898 long maskMove1 = maskPrefix & mask;
1899 // Compress mask
1900 mask = (mask ^ maskMove1) | (maskMove1 >>> (1 << 0));
1901 maskCount = maskCount & ~maskPrefix;
1902
1903 maskPrefix = parallelSuffix(maskCount);
1904 // Bits to move
1905 long maskMove2 = maskPrefix & mask;
1906 // Compress mask
1907 mask = (mask ^ maskMove2) | (maskMove2 >>> (1 << 1));
1908 maskCount = maskCount & ~maskPrefix;
1909
1910 maskPrefix = parallelSuffix(maskCount);
1911 // Bits to move
1912 long maskMove3 = maskPrefix & mask;
1913 // Compress mask
1914 mask = (mask ^ maskMove3) | (maskMove3 >>> (1 << 2));
1915 maskCount = maskCount & ~maskPrefix;
1916
1917 maskPrefix = parallelSuffix(maskCount);
1918 // Bits to move
1919 long maskMove4 = maskPrefix & mask;
1920 // Compress mask
1921 mask = (mask ^ maskMove4) | (maskMove4 >>> (1 << 3));
1922 maskCount = maskCount & ~maskPrefix;
1923
1924 maskPrefix = parallelSuffix(maskCount);
1925 // Bits to move
1926 long maskMove5 = maskPrefix & mask;
1927 // Compress mask
1928 mask = (mask ^ maskMove5) | (maskMove5 >>> (1 << 4));
1929 maskCount = maskCount & ~maskPrefix;
1930
1931 maskPrefix = parallelSuffix(maskCount);
1932 // Bits to move
1933 long maskMove6 = maskPrefix & mask;
1934
1935 long t = i << (1 << 5);
1936 i = (i & ~maskMove6) | (t & maskMove6);
1937 t = i << (1 << 4);
1938 i = (i & ~maskMove5) | (t & maskMove5);
1939 t = i << (1 << 3);
1940 i = (i & ~maskMove4) | (t & maskMove4);
1941 t = i << (1 << 2);
1942 i = (i & ~maskMove3) | (t & maskMove3);
1943 t = i << (1 << 1);
1944 i = (i & ~maskMove2) | (t & maskMove2);
1945 t = i << (1 << 0);
1946 i = (i & ~maskMove1) | (t & maskMove1);
1947
1948 // Clear irrelevant bits
1949 return i & originalMask;
1950 }
1951
1952 @ForceInline
1953 private static long parallelSuffix(long maskCount) {
1954 long maskPrefix = maskCount ^ (maskCount << 1);
1955 maskPrefix = maskPrefix ^ (maskPrefix << 2);
1956 maskPrefix = maskPrefix ^ (maskPrefix << 4);
1957 maskPrefix = maskPrefix ^ (maskPrefix << 8);
1958 maskPrefix = maskPrefix ^ (maskPrefix << 16);
1959 maskPrefix = maskPrefix ^ (maskPrefix << 32);
1960 return maskPrefix;
1961 }
1962
1963 /**
1964 * Returns the signum function of the specified {@code long} value. (The
1965 * return value is -1 if the specified value is negative; 0 if the
1966 * specified value is zero; and 1 if the specified value is positive.)
1967 *
1968 * @param i the value whose signum is to be computed
1969 * @return the signum function of the specified {@code long} value.
1970 * @since 1.5
1971 */
1972 public static int signum(long i) {
1973 // HD, Section 2-7
1974 return (int) ((i >> 63) | (-i >>> 63));
1975 }
1976
1977 /**
1978 * Returns the value obtained by reversing the order of the bytes in the
1979 * two's complement representation of the specified {@code long} value.
1980 *
1981 * @param i the value whose bytes are to be reversed
1982 * @return the value obtained by reversing the bytes in the specified
1983 * {@code long} value.
1984 * @since 1.5
1985 */
1986 @IntrinsicCandidate
1987 public static long reverseBytes(long i) {
1988 i = (i & 0x00ff00ff00ff00ffL) << 8 | (i >>> 8) & 0x00ff00ff00ff00ffL;
1989 return (i << 48) | ((i & 0xffff0000L) << 16) |
1990 ((i >>> 16) & 0xffff0000L) | (i >>> 48);
1991 }
1992
1993 /**
1994 * Adds two {@code long} values together as per the + operator.
1995 *
1996 * @param a the first operand
1997 * @param b the second operand
1998 * @return the sum of {@code a} and {@code b}
1999 * @see java.util.function.BinaryOperator
2000 * @since 1.8
2001 */
2002 public static long sum(long a, long b) {
2003 return a + b;
2004 }
2005
2006 /**
2007 * Returns the greater of two {@code long} values
2008 * as if by calling {@link Math#max(long, long) Math.max}.
2009 *
2010 * @param a the first operand
2011 * @param b the second operand
2012 * @return the greater of {@code a} and {@code b}
2013 * @see java.util.function.BinaryOperator
2014 * @since 1.8
2015 */
2016 public static long max(long a, long b) {
2017 return Math.max(a, b);
2018 }
2019
2020 /**
2021 * Returns the smaller of two {@code long} values
2022 * as if by calling {@link Math#min(long, long) Math.min}.
2023 *
2024 * @param a the first operand
2025 * @param b the second operand
2026 * @return the smaller of {@code a} and {@code b}
2027 * @see java.util.function.BinaryOperator
2028 * @since 1.8
2029 */
2030 public static long min(long a, long b) {
2031 return Math.min(a, b);
2032 }
2033
2034 /**
2035 * Returns an {@link Optional} containing the nominal descriptor for this
2036 * instance, which is the instance itself.
2037 *
2038 * @return an {@link Optional} describing the {@linkplain Long} instance
2039 * @since 12
2040 */
2041 @Override
2042 public Optional<Long> describeConstable() {
2043 return Optional.of(this);
2044 }
2045
2046 /**
2047 * Resolves this instance as a {@link ConstantDesc}, the result of which is
2048 * the instance itself.
2049 *
2050 * @param lookup ignored
2051 * @return the {@linkplain Long} instance
2052 * @since 12
2053 */
2054 @Override
2055 public Long resolveConstantDesc(MethodHandles.Lookup lookup) {
2056 return this;
2057 }
2058
2059 /** use serialVersionUID from JDK 1.0.2 for interoperability */
2060 @java.io.Serial
2061 @Native private static final long serialVersionUID = 4290774380558885855L;
2062 }