1 /*
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   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
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   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
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  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).
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  25 
  26 package java.lang;
  27 
  28 import java.lang.invoke.MethodHandles;
  29 import java.lang.constant.Constable;
  30 import java.lang.constant.ConstantDesc;
  31 import java.util.Optional;
  32 
  33 import jdk.internal.math.FloatConsts;
  34 import jdk.internal.math.FloatingDecimal;
  35 import jdk.internal.math.FloatToDecimal;
  36 import jdk.internal.vm.annotation.IntrinsicCandidate;
  37 
  38 /**
  39  * The {@code Float} class wraps a value of primitive type
  40  * {@code float} in an object. An object of type
  41  * {@code Float} contains a single field whose type is
  42  * {@code float}.
  43  *
  44  * <p>In addition, this class provides several methods for converting a
  45  * {@code float} to a {@code String} and a
  46  * {@code String} to a {@code float}, as well as other
  47  * constants and methods useful when dealing with a
  48  * {@code float}.
  49  *
  50  * <p>This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
  51  * class; programmers should treat instances that are
  52  * {@linkplain #equals(Object) equal} as interchangeable and should not
  53  * use instances for synchronization, or unpredictable behavior may
  54  * occur. For example, in a future release, synchronization may fail.
  55  *
  56  * <h2><a id=equivalenceRelation>Floating-point Equality, Equivalence,
  57  * and Comparison</a></h2>
  58  *
  59  * The class {@code java.lang.Double} has a {@linkplain
  60  * Double##equivalenceRelation discussion of equality,
  61  * equivalence, and comparison of floating-point values} that is
  62  * equally applicable to {@code float} values.
  63  *
  64  * <h2><a id=decimalToBinaryConversion>Decimal &harr; Binary Conversion Issues</a></h2>
  65  *
  66  * The {@linkplain Double##decimalToBinaryConversion discussion of binary to
  67  * decimal conversion issues} in {@code java.lang.Double} is also
  68  * applicable to {@code float} values.
  69  *
  70  * @see <a href="https://standards.ieee.org/ieee/754/6210/">
  71  *      <cite>IEEE Standard for Floating-Point Arithmetic</cite></a>
  72  *
  73  * @author  Lee Boynton
  74  * @author  Arthur van Hoff
  75  * @author  Joseph D. Darcy
  76  * @since 1.0
  77  */
  78 @jdk.internal.MigratedValueClass
  79 @jdk.internal.ValueBased
  80 public final class Float extends Number
  81         implements Comparable<Float>, Constable, ConstantDesc {
  82     /**
  83      * A constant holding the positive infinity of type
  84      * {@code float}. It is equal to the value returned by
  85      * {@code Float.intBitsToFloat(0x7f800000)}.
  86      */
  87     public static final float POSITIVE_INFINITY = 1.0f / 0.0f;
  88 
  89     /**
  90      * A constant holding the negative infinity of type
  91      * {@code float}. It is equal to the value returned by
  92      * {@code Float.intBitsToFloat(0xff800000)}.
  93      */
  94     public static final float NEGATIVE_INFINITY = -1.0f / 0.0f;
  95 
  96     /**
  97      * A constant holding a Not-a-Number (NaN) value of type
  98      * {@code float}.  It is equivalent to the value returned by
  99      * {@code Float.intBitsToFloat(0x7fc00000)}.
 100      */
 101     public static final float NaN = 0.0f / 0.0f;
 102 
 103     /**
 104      * A constant holding the largest positive finite value of type
 105      * {@code float}, (2-2<sup>-23</sup>)&middot;2<sup>127</sup>.
 106      * It is equal to the hexadecimal floating-point literal
 107      * {@code 0x1.fffffeP+127f} and also equal to
 108      * {@code Float.intBitsToFloat(0x7f7fffff)}.
 109      */
 110     public static final float MAX_VALUE = 0x1.fffffeP+127f; // 3.4028235e+38f
 111 
 112     /**
 113      * A constant holding the smallest positive normal value of type
 114      * {@code float}, 2<sup>-126</sup>.  It is equal to the
 115      * hexadecimal floating-point literal {@code 0x1.0p-126f} and also
 116      * equal to {@code Float.intBitsToFloat(0x00800000)}.
 117      *
 118      * @since 1.6
 119      */
 120     public static final float MIN_NORMAL = 0x1.0p-126f; // 1.17549435E-38f
 121 
 122     /**
 123      * A constant holding the smallest positive nonzero value of type
 124      * {@code float}, 2<sup>-149</sup>. It is equal to the
 125      * hexadecimal floating-point literal {@code 0x0.000002P-126f}
 126      * and also equal to {@code Float.intBitsToFloat(0x1)}.
 127      */
 128     public static final float MIN_VALUE = 0x0.000002P-126f; // 1.4e-45f
 129 
 130     /**
 131      * The number of bits used to represent a {@code float} value.
 132      *
 133      * @since 1.5
 134      */
 135     public static final int SIZE = 32;
 136 
 137     /**
 138      * The number of bits in the significand of a {@code float} value.
 139      * This is the parameter N in section {@jls 4.2.3} of
 140      * <cite>The Java Language Specification</cite>.
 141      *
 142      * @since 19
 143      */
 144     public static final int PRECISION = 24;
 145 
 146     /**
 147      * Maximum exponent a finite {@code float} variable may have.  It
 148      * is equal to the value returned by {@code
 149      * Math.getExponent(Float.MAX_VALUE)}.
 150      *
 151      * @since 1.6
 152      */
 153     public static final int MAX_EXPONENT = (1 << (SIZE - PRECISION - 1)) - 1; // 127
 154 
 155     /**
 156      * Minimum exponent a normalized {@code float} variable may have.
 157      * It is equal to the value returned by {@code
 158      * Math.getExponent(Float.MIN_NORMAL)}.
 159      *
 160      * @since 1.6
 161      */
 162     public static final int MIN_EXPONENT = 1 - MAX_EXPONENT; // -126
 163 
 164     /**
 165      * The number of bytes used to represent a {@code float} value.
 166      *
 167      * @since 1.8
 168      */
 169     public static final int BYTES = SIZE / Byte.SIZE;
 170 
 171     /**
 172      * The {@code Class} instance representing the primitive type
 173      * {@code float}.
 174      *
 175      * @since 1.1
 176      */
 177     @SuppressWarnings("unchecked")
 178     public static final Class<Float> TYPE = (Class<Float>) Class.getPrimitiveClass("float");
 179 
 180     /**
 181      * Returns a string representation of the {@code float}
 182      * argument. All characters mentioned below are ASCII characters.
 183      * <ul>
 184      * <li>If the argument is NaN, the result is the string
 185      * "{@code NaN}".
 186      * <li>Otherwise, the result is a string that represents the sign and
 187      *     magnitude (absolute value) of the argument. If the sign is
 188      *     negative, the first character of the result is
 189      *     '{@code -}' ({@code '\u005Cu002D'}); if the sign is
 190      *     positive, no sign character appears in the result. As for
 191      *     the magnitude <i>m</i>:
 192      * <ul>
 193      * <li>If <i>m</i> is infinity, it is represented by the characters
 194      *     {@code "Infinity"}; thus, positive infinity produces
 195      *     the result {@code "Infinity"} and negative infinity
 196      *     produces the result {@code "-Infinity"}.
 197      * <li>If <i>m</i> is zero, it is represented by the characters
 198      *     {@code "0.0"}; thus, negative zero produces the result
 199      *     {@code "-0.0"} and positive zero produces the result
 200      *     {@code "0.0"}.
 201      *
 202      * <li> Otherwise <i>m</i> is positive and finite.
 203      * It is converted to a string in two stages:
 204      * <ul>
 205      * <li> <em>Selection of a decimal</em>:
 206      * A well-defined decimal <i>d</i><sub><i>m</i></sub>
 207      * is selected to represent <i>m</i>.
 208      * This decimal is (almost always) the <em>shortest</em> one that
 209      * rounds to <i>m</i> according to the round to nearest
 210      * rounding policy of IEEE 754 floating-point arithmetic.
 211      * <li> <em>Formatting as a string</em>:
 212      * The decimal <i>d</i><sub><i>m</i></sub> is formatted as a string,
 213      * either in plain or in computerized scientific notation,
 214      * depending on its value.
 215      * </ul>
 216      * </ul>
 217      * </ul>
 218      *
 219      * <p>A <em>decimal</em> is a number of the form
 220      * <i>s</i>&times;10<sup><i>i</i></sup>
 221      * for some (unique) integers <i>s</i> &gt; 0 and <i>i</i> such that
 222      * <i>s</i> is not a multiple of 10.
 223      * These integers are the <em>significand</em> and
 224      * the <em>exponent</em>, respectively, of the decimal.
 225      * The <em>length</em> of the decimal is the (unique)
 226      * positive integer <i>n</i> meeting
 227      * 10<sup><i>n</i>-1</sup> &le; <i>s</i> &lt; 10<sup><i>n</i></sup>.
 228      *
 229      * <p>The decimal <i>d</i><sub><i>m</i></sub> for a finite positive <i>m</i>
 230      * is defined as follows:
 231      * <ul>
 232      * <li>Let <i>R</i> be the set of all decimals that round to <i>m</i>
 233      * according to the usual <em>round to nearest</em> rounding policy of
 234      * IEEE 754 floating-point arithmetic.
 235      * <li>Let <i>p</i> be the minimal length over all decimals in <i>R</i>.
 236      * <li>When <i>p</i> &ge; 2, let <i>T</i> be the set of all decimals
 237      * in <i>R</i> with length <i>p</i>.
 238      * Otherwise, let <i>T</i> be the set of all decimals
 239      * in <i>R</i> with length 1 or 2.
 240      * <li>Define <i>d</i><sub><i>m</i></sub> as the decimal in <i>T</i>
 241      * that is closest to <i>m</i>.
 242      * Or if there are two such decimals in <i>T</i>,
 243      * select the one with the even significand.
 244      * </ul>
 245      *
 246      * <p>The (uniquely) selected decimal <i>d</i><sub><i>m</i></sub>
 247      * is then formatted.
 248      * Let <i>s</i>, <i>i</i> and <i>n</i> be the significand, exponent and
 249      * length of <i>d</i><sub><i>m</i></sub>, respectively.
 250      * Further, let <i>e</i> = <i>n</i> + <i>i</i> - 1 and let
 251      * <i>s</i><sub>1</sub>&hellip;<i>s</i><sub><i>n</i></sub>
 252      * be the usual decimal expansion of <i>s</i>.
 253      * Note that <i>s</i><sub>1</sub> &ne; 0
 254      * and <i>s</i><sub><i>n</i></sub> &ne; 0.
 255      * Below, the decimal point {@code '.'} is {@code '\u005Cu002E'}
 256      * and the exponent indicator {@code 'E'} is {@code '\u005Cu0045'}.
 257      * <ul>
 258      * <li>Case -3 &le; <i>e</i> &lt; 0:
 259      * <i>d</i><sub><i>m</i></sub> is formatted as
 260      * <code>0.0</code>&hellip;<code>0</code><!--
 261      * --><i>s</i><sub>1</sub>&hellip;<i>s</i><sub><i>n</i></sub>,
 262      * where there are exactly -(<i>n</i> + <i>i</i>) zeroes between
 263      * the decimal point and <i>s</i><sub>1</sub>.
 264      * For example, 123 &times; 10<sup>-4</sup> is formatted as
 265      * {@code 0.0123}.
 266      * <li>Case 0 &le; <i>e</i> &lt; 7:
 267      * <ul>
 268      * <li>Subcase <i>i</i> &ge; 0:
 269      * <i>d</i><sub><i>m</i></sub> is formatted as
 270      * <i>s</i><sub>1</sub>&hellip;<i>s</i><sub><i>n</i></sub><!--
 271      * --><code>0</code>&hellip;<code>0.0</code>,
 272      * where there are exactly <i>i</i> zeroes
 273      * between <i>s</i><sub><i>n</i></sub> and the decimal point.
 274      * For example, 123 &times; 10<sup>2</sup> is formatted as
 275      * {@code 12300.0}.
 276      * <li>Subcase <i>i</i> &lt; 0:
 277      * <i>d</i><sub><i>m</i></sub> is formatted as
 278      * <i>s</i><sub>1</sub>&hellip;<!--
 279      * --><i>s</i><sub><i>n</i>+<i>i</i></sub><code>.</code><!--
 280      * --><i>s</i><sub><i>n</i>+<i>i</i>+1</sub>&hellip;<!--
 281      * --><i>s</i><sub><i>n</i></sub>,
 282      * where there are exactly -<i>i</i> digits to the right of
 283      * the decimal point.
 284      * For example, 123 &times; 10<sup>-1</sup> is formatted as
 285      * {@code 12.3}.
 286      * </ul>
 287      * <li>Case <i>e</i> &lt; -3 or <i>e</i> &ge; 7:
 288      * computerized scientific notation is used to format
 289      * <i>d</i><sub><i>m</i></sub>.
 290      * Here <i>e</i> is formatted as by {@link Integer#toString(int)}.
 291      * <ul>
 292      * <li>Subcase <i>n</i> = 1:
 293      * <i>d</i><sub><i>m</i></sub> is formatted as
 294      * <i>s</i><sub>1</sub><code>.0E</code><i>e</i>.
 295      * For example, 1 &times; 10<sup>23</sup> is formatted as
 296      * {@code 1.0E23}.
 297      * <li>Subcase <i>n</i> &gt; 1:
 298      * <i>d</i><sub><i>m</i></sub> is formatted as
 299      * <i>s</i><sub>1</sub><code>.</code><i>s</i><sub>2</sub><!--
 300      * -->&hellip;<i>s</i><sub><i>n</i></sub><code>E</code><i>e</i>.
 301      * For example, 123 &times; 10<sup>-21</sup> is formatted as
 302      * {@code 1.23E-19}.
 303      * </ul>
 304      * </ul>
 305      *
 306      * <p>To create localized string representations of a floating-point
 307      * value, use subclasses of {@link java.text.NumberFormat}.
 308      *
 309      * @param   f   the {@code float} to be converted.
 310      * @return a string representation of the argument.
 311      */
 312     public static String toString(float f) {
 313         return FloatToDecimal.toString(f);
 314     }
 315 
 316     /**
 317      * Returns a hexadecimal string representation of the
 318      * {@code float} argument. All characters mentioned below are
 319      * ASCII characters.
 320      *
 321      * <ul>
 322      * <li>If the argument is NaN, the result is the string
 323      *     "{@code NaN}".
 324      * <li>Otherwise, the result is a string that represents the sign and
 325      * magnitude (absolute value) of the argument. If the sign is negative,
 326      * the first character of the result is '{@code -}'
 327      * ({@code '\u005Cu002D'}); if the sign is positive, no sign character
 328      * appears in the result. As for the magnitude <i>m</i>:
 329      *
 330      * <ul>
 331      * <li>If <i>m</i> is infinity, it is represented by the string
 332      * {@code "Infinity"}; thus, positive infinity produces the
 333      * result {@code "Infinity"} and negative infinity produces
 334      * the result {@code "-Infinity"}.
 335      *
 336      * <li>If <i>m</i> is zero, it is represented by the string
 337      * {@code "0x0.0p0"}; thus, negative zero produces the result
 338      * {@code "-0x0.0p0"} and positive zero produces the result
 339      * {@code "0x0.0p0"}.
 340      *
 341      * <li>If <i>m</i> is a {@code float} value with a
 342      * normalized representation, substrings are used to represent the
 343      * significand and exponent fields.  The significand is
 344      * represented by the characters {@code "0x1."}
 345      * followed by a lowercase hexadecimal representation of the rest
 346      * of the significand as a fraction.  Trailing zeros in the
 347      * hexadecimal representation are removed unless all the digits
 348      * are zero, in which case a single zero is used. Next, the
 349      * exponent is represented by {@code "p"} followed
 350      * by a decimal string of the unbiased exponent as if produced by
 351      * a call to {@link Integer#toString(int) Integer.toString} on the
 352      * exponent value.
 353      *
 354      * <li>If <i>m</i> is a {@code float} value with a subnormal
 355      * representation, the significand is represented by the
 356      * characters {@code "0x0."} followed by a
 357      * hexadecimal representation of the rest of the significand as a
 358      * fraction.  Trailing zeros in the hexadecimal representation are
 359      * removed. Next, the exponent is represented by
 360      * {@code "p-126"}.  Note that there must be at
 361      * least one nonzero digit in a subnormal significand.
 362      *
 363      * </ul>
 364      *
 365      * </ul>
 366      *
 367      * <table class="striped">
 368      * <caption>Examples</caption>
 369      * <thead>
 370      * <tr><th scope="col">Floating-point Value</th><th scope="col">Hexadecimal String</th>
 371      * </thead>
 372      * <tbody>
 373      * <tr><th scope="row">{@code 1.0}</th> <td>{@code 0x1.0p0}</td>
 374      * <tr><th scope="row">{@code -1.0}</th>        <td>{@code -0x1.0p0}</td>
 375      * <tr><th scope="row">{@code 2.0}</th> <td>{@code 0x1.0p1}</td>
 376      * <tr><th scope="row">{@code 3.0}</th> <td>{@code 0x1.8p1}</td>
 377      * <tr><th scope="row">{@code 0.5}</th> <td>{@code 0x1.0p-1}</td>
 378      * <tr><th scope="row">{@code 0.25}</th>        <td>{@code 0x1.0p-2}</td>
 379      * <tr><th scope="row">{@code Float.MAX_VALUE}</th>
 380      *     <td>{@code 0x1.fffffep127}</td>
 381      * <tr><th scope="row">{@code Minimum Normal Value}</th>
 382      *     <td>{@code 0x1.0p-126}</td>
 383      * <tr><th scope="row">{@code Maximum Subnormal Value}</th>
 384      *     <td>{@code 0x0.fffffep-126}</td>
 385      * <tr><th scope="row">{@code Float.MIN_VALUE}</th>
 386      *     <td>{@code 0x0.000002p-126}</td>
 387      * </tbody>
 388      * </table>
 389      * @param   f   the {@code float} to be converted.
 390      * @return a hex string representation of the argument.
 391      * @since 1.5
 392      * @author Joseph D. Darcy
 393      */
 394     public static String toHexString(float f) {
 395         if (Math.abs(f) < Float.MIN_NORMAL
 396             &&  f != 0.0f ) {// float subnormal
 397             // Adjust exponent to create subnormal double, then
 398             // replace subnormal double exponent with subnormal float
 399             // exponent
 400             String s = Double.toHexString(Math.scalb((double)f,
 401                                                      /* -1022+126 */
 402                                                      Double.MIN_EXPONENT-
 403                                                      Float.MIN_EXPONENT));
 404             return s.replaceFirst("p-1022$", "p-126");
 405         }
 406         else // double string will be the same as float string
 407             return Double.toHexString(f);
 408     }
 409 
 410     /**
 411      * Returns a {@code Float} object holding the
 412      * {@code float} value represented by the argument string
 413      * {@code s}.
 414      *
 415      * <p>If {@code s} is {@code null}, then a
 416      * {@code NullPointerException} is thrown.
 417      *
 418      * <p>Leading and trailing whitespace characters in {@code s}
 419      * are ignored.  Whitespace is removed as if by the {@link
 420      * String#trim} method; that is, both ASCII space and control
 421      * characters are removed. The rest of {@code s} should
 422      * constitute a <i>FloatValue</i> as described by the lexical
 423      * syntax rules:
 424      *
 425      * <blockquote>
 426      * <dl>
 427      * <dt><i>FloatValue:</i>
 428      * <dd><i>Sign<sub>opt</sub></i> {@code NaN}
 429      * <dd><i>Sign<sub>opt</sub></i> {@code Infinity}
 430      * <dd><i>Sign<sub>opt</sub> FloatingPointLiteral</i>
 431      * <dd><i>Sign<sub>opt</sub> HexFloatingPointLiteral</i>
 432      * <dd><i>SignedInteger</i>
 433      * </dl>
 434      *
 435      * <dl>
 436      * <dt><i>HexFloatingPointLiteral</i>:
 437      * <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i>
 438      * </dl>
 439      *
 440      * <dl>
 441      * <dt><i>HexSignificand:</i>
 442      * <dd><i>HexNumeral</i>
 443      * <dd><i>HexNumeral</i> {@code .}
 444      * <dd>{@code 0x} <i>HexDigits<sub>opt</sub>
 445      *     </i>{@code .}<i> HexDigits</i>
 446      * <dd>{@code 0X}<i> HexDigits<sub>opt</sub>
 447      *     </i>{@code .} <i>HexDigits</i>
 448      * </dl>
 449      *
 450      * <dl>
 451      * <dt><i>BinaryExponent:</i>
 452      * <dd><i>BinaryExponentIndicator SignedInteger</i>
 453      * </dl>
 454      *
 455      * <dl>
 456      * <dt><i>BinaryExponentIndicator:</i>
 457      * <dd>{@code p}
 458      * <dd>{@code P}
 459      * </dl>
 460      *
 461      * </blockquote>
 462      *
 463      * where <i>Sign</i>, <i>FloatingPointLiteral</i>,
 464      * <i>HexNumeral</i>, <i>HexDigits</i>, <i>SignedInteger</i> and
 465      * <i>FloatTypeSuffix</i> are as defined in the lexical structure
 466      * sections of
 467      * <cite>The Java Language Specification</cite>,
 468      * except that underscores are not accepted between digits.
 469      * If {@code s} does not have the form of
 470      * a <i>FloatValue</i>, then a {@code NumberFormatException}
 471      * is thrown. Otherwise, {@code s} is regarded as
 472      * representing an exact decimal value in the usual
 473      * "computerized scientific notation" or as an exact
 474      * hexadecimal value; this exact numerical value is then
 475      * conceptually converted to an "infinitely precise"
 476      * binary value that is then rounded to type {@code float}
 477      * by the usual round-to-nearest rule of IEEE 754 floating-point
 478      * arithmetic, which includes preserving the sign of a zero
 479      * value.
 480      *
 481      * Note that the round-to-nearest rule also implies overflow and
 482      * underflow behaviour; if the exact value of {@code s} is large
 483      * enough in magnitude (greater than or equal to ({@link
 484      * #MAX_VALUE} + {@link Math#ulp(float) ulp(MAX_VALUE)}/2),
 485      * rounding to {@code float} will result in an infinity and if the
 486      * exact value of {@code s} is small enough in magnitude (less
 487      * than or equal to {@link #MIN_VALUE}/2), rounding to float will
 488      * result in a zero.
 489      *
 490      * Finally, after rounding a {@code Float} object representing
 491      * this {@code float} value is returned.
 492      *
 493      * <p>Note that trailing format specifiers, specifiers that
 494      * determine the type of a floating-point literal
 495      * ({@code 1.0f} is a {@code float} value;
 496      * {@code 1.0d} is a {@code double} value), do
 497      * <em>not</em> influence the results of this method.  In other
 498      * words, the numerical value of the input string is converted
 499      * directly to the target floating-point type.  In general, the
 500      * two-step sequence of conversions, string to {@code double}
 501      * followed by {@code double} to {@code float}, is
 502      * <em>not</em> equivalent to converting a string directly to
 503      * {@code float}.  For example, if first converted to an
 504      * intermediate {@code double} and then to
 505      * {@code float}, the string<br>
 506      * {@code "1.00000017881393421514957253748434595763683319091796875001d"}<br>
 507      * results in the {@code float} value
 508      * {@code 1.0000002f}; if the string is converted directly to
 509      * {@code float}, <code>1.000000<b>1</b>f</code> results.
 510      *
 511      * <p>To avoid calling this method on an invalid string and having
 512      * a {@code NumberFormatException} be thrown, the documentation
 513      * for {@link Double#valueOf Double.valueOf} lists a regular
 514      * expression which can be used to screen the input.
 515      *
 516      * @apiNote To interpret localized string representations of a
 517      * floating-point value, or string representations that have
 518      * non-ASCII digits, use {@link java.text.NumberFormat}. For
 519      * example,
 520      * {@snippet lang="java" :
 521      *     NumberFormat.getInstance(l).parse(s).floatValue();
 522      * }
 523      * where {@code l} is the desired locale, or
 524      * {@link java.util.Locale#ROOT} if locale insensitive.
 525      *
 526      * @param   s   the string to be parsed.
 527      * @return  a {@code Float} object holding the value
 528      *          represented by the {@code String} argument.
 529      * @throws  NumberFormatException  if the string does not contain a
 530      *          parsable number.
 531      * @see Double##decimalToBinaryConversion Decimal &harr; Binary Conversion Issues
 532      */
 533     public static Float valueOf(String s) throws NumberFormatException {
 534         return new Float(parseFloat(s));
 535     }
 536 
 537     /**
 538      * Returns a {@code Float} instance representing the specified
 539      * {@code float} value.
 540      * If a new {@code Float} instance is not required, this method
 541      * should generally be used in preference to the constructor
 542      * {@link #Float(float)}, as this method is likely to yield
 543      * significantly better space and time performance by caching
 544      * frequently requested values.
 545      *
 546      * @param  f a float value.
 547      * @return a {@code Float} instance representing {@code f}.
 548      * @since  1.5
 549      */
 550     @IntrinsicCandidate
 551     public static Float valueOf(float f) {
 552         return new Float(f);
 553     }
 554 
 555     /**
 556      * Returns a new {@code float} initialized to the value
 557      * represented by the specified {@code String}, as performed
 558      * by the {@code valueOf} method of class {@code Float}.
 559      *
 560      * @param  s the string to be parsed.
 561      * @return the {@code float} value represented by the string
 562      *         argument.
 563      * @throws NullPointerException  if the string is null
 564      * @throws NumberFormatException if the string does not contain a
 565      *               parsable {@code float}.
 566      * @see    java.lang.Float#valueOf(String)
 567      * @see    Double##decimalToBinaryConversion Decimal &harr; Binary Conversion Issues
 568      * @since 1.2
 569      */
 570     public static float parseFloat(String s) throws NumberFormatException {
 571         return FloatingDecimal.parseFloat(s);
 572     }
 573 
 574     /**
 575      * Returns {@code true} if the specified number is a
 576      * Not-a-Number (NaN) value, {@code false} otherwise.
 577      *
 578      * @apiNote
 579      * This method corresponds to the isNaN operation defined in IEEE
 580      * 754.
 581      *
 582      * @param   v   the value to be tested.
 583      * @return  {@code true} if the argument is NaN;
 584      *          {@code false} otherwise.
 585      */
 586     public static boolean isNaN(float v) {
 587         return (v != v);
 588     }
 589 
 590     /**
 591      * Returns {@code true} if the specified number is infinitely
 592      * large in magnitude, {@code false} otherwise.
 593      *
 594      * @apiNote
 595      * This method corresponds to the isInfinite operation defined in
 596      * IEEE 754.
 597      *
 598      * @param   v   the value to be tested.
 599      * @return  {@code true} if the argument is positive infinity or
 600      *          negative infinity; {@code false} otherwise.
 601      */
 602     @IntrinsicCandidate
 603     public static boolean isInfinite(float v) {
 604         return Math.abs(v) > MAX_VALUE;
 605     }
 606 
 607 
 608     /**
 609      * Returns {@code true} if the argument is a finite floating-point
 610      * value; returns {@code false} otherwise (for NaN and infinity
 611      * arguments).
 612      *
 613      * @apiNote
 614      * This method corresponds to the isFinite operation defined in
 615      * IEEE 754.
 616      *
 617      * @param f the {@code float} value to be tested
 618      * @return {@code true} if the argument is a finite
 619      * floating-point value, {@code false} otherwise.
 620      * @since 1.8
 621      */
 622      @IntrinsicCandidate
 623      public static boolean isFinite(float f) {
 624         return Math.abs(f) <= Float.MAX_VALUE;
 625     }
 626 
 627     /**
 628      * The value of the Float.
 629      *
 630      * @serial
 631      */
 632     private final float value;
 633 
 634     /**
 635      * Constructs a newly allocated {@code Float} object that
 636      * represents the primitive {@code float} argument.
 637      *
 638      * @param   value   the value to be represented by the {@code Float}.
 639      *
 640      * @deprecated
 641      * It is rarely appropriate to use this constructor. The static factory
 642      * {@link #valueOf(float)} is generally a better choice, as it is
 643      * likely to yield significantly better space and time performance.
 644      */
 645     @Deprecated(since="9", forRemoval = true)
 646     public Float(float value) {
 647         this.value = value;
 648     }
 649 
 650     /**
 651      * Constructs a newly allocated {@code Float} object that
 652      * represents the argument converted to type {@code float}.
 653      *
 654      * @param   value   the value to be represented by the {@code Float}.
 655      *
 656      * @deprecated
 657      * It is rarely appropriate to use this constructor. Instead, use the
 658      * static factory method {@link #valueOf(float)} method as follows:
 659      * {@code Float.valueOf((float)value)}.
 660      */
 661     @Deprecated(since="9", forRemoval = true)
 662     public Float(double value) {
 663         this.value = (float)value;
 664     }
 665 
 666     /**
 667      * Constructs a newly allocated {@code Float} object that
 668      * represents the floating-point value of type {@code float}
 669      * represented by the string. The string is converted to a
 670      * {@code float} value as if by the {@code valueOf} method.
 671      *
 672      * @param   s   a string to be converted to a {@code Float}.
 673      * @throws      NumberFormatException if the string does not contain a
 674      *              parsable number.
 675      *
 676      * @deprecated
 677      * It is rarely appropriate to use this constructor.
 678      * Use {@link #parseFloat(String)} to convert a string to a
 679      * {@code float} primitive, or use {@link #valueOf(String)}
 680      * to convert a string to a {@code Float} object.
 681      */
 682     @Deprecated(since="9", forRemoval = true)
 683     public Float(String s) throws NumberFormatException {
 684         value = parseFloat(s);
 685     }
 686 
 687     /**
 688      * Returns {@code true} if this {@code Float} value is a
 689      * Not-a-Number (NaN), {@code false} otherwise.
 690      *
 691      * @return  {@code true} if the value represented by this object is
 692      *          NaN; {@code false} otherwise.
 693      */
 694     public boolean isNaN() {
 695         return isNaN(value);
 696     }
 697 
 698     /**
 699      * Returns {@code true} if this {@code Float} value is
 700      * infinitely large in magnitude, {@code false} otherwise.
 701      *
 702      * @return  {@code true} if the value represented by this object is
 703      *          positive infinity or negative infinity;
 704      *          {@code false} otherwise.
 705      */
 706     public boolean isInfinite() {
 707         return isInfinite(value);
 708     }
 709 
 710     /**
 711      * Returns a string representation of this {@code Float} object.
 712      * The primitive {@code float} value represented by this object
 713      * is converted to a {@code String} exactly as if by the method
 714      * {@code toString} of one argument.
 715      *
 716      * @return  a {@code String} representation of this object.
 717      * @see java.lang.Float#toString(float)
 718      */
 719     public String toString() {
 720         return Float.toString(value);
 721     }
 722 
 723     /**
 724      * Returns the value of this {@code Float} as a {@code byte} after
 725      * a narrowing primitive conversion.
 726      *
 727      * @return  the {@code float} value represented by this object
 728      *          converted to type {@code byte}
 729      * @jls 5.1.3 Narrowing Primitive Conversion
 730      */
 731     public byte byteValue() {
 732         return (byte)value;
 733     }
 734 
 735     /**
 736      * Returns the value of this {@code Float} as a {@code short}
 737      * after a narrowing primitive conversion.
 738      *
 739      * @return  the {@code float} value represented by this object
 740      *          converted to type {@code short}
 741      * @jls 5.1.3 Narrowing Primitive Conversion
 742      * @since 1.1
 743      */
 744     public short shortValue() {
 745         return (short)value;
 746     }
 747 
 748     /**
 749      * Returns the value of this {@code Float} as an {@code int} after
 750      * a narrowing primitive conversion.
 751      *
 752      * @return  the {@code float} value represented by this object
 753      *          converted to type {@code int}
 754      * @jls 5.1.3 Narrowing Primitive Conversion
 755      */
 756     public int intValue() {
 757         return (int)value;
 758     }
 759 
 760     /**
 761      * Returns value of this {@code Float} as a {@code long} after a
 762      * narrowing primitive conversion.
 763      *
 764      * @return  the {@code float} value represented by this object
 765      *          converted to type {@code long}
 766      * @jls 5.1.3 Narrowing Primitive Conversion
 767      */
 768     public long longValue() {
 769         return (long)value;
 770     }
 771 
 772     /**
 773      * Returns the {@code float} value of this {@code Float} object.
 774      *
 775      * @return the {@code float} value represented by this object
 776      */
 777     @IntrinsicCandidate
 778     public float floatValue() {
 779         return value;
 780     }
 781 
 782     /**
 783      * Returns the value of this {@code Float} as a {@code double}
 784      * after a widening primitive conversion.
 785      *
 786      * @apiNote
 787      * This method corresponds to the convertFormat operation defined
 788      * in IEEE 754.
 789      *
 790      * @return the {@code float} value represented by this
 791      *         object converted to type {@code double}
 792      * @jls 5.1.2 Widening Primitive Conversion
 793      */
 794     public double doubleValue() {
 795         return (double)value;
 796     }
 797 
 798     /**
 799      * Returns a hash code for this {@code Float} object. The
 800      * result is the integer bit representation, exactly as produced
 801      * by the method {@link #floatToIntBits(float)}, of the primitive
 802      * {@code float} value represented by this {@code Float}
 803      * object.
 804      *
 805      * @return a hash code value for this object.
 806      */
 807     @Override
 808     public int hashCode() {
 809         return Float.hashCode(value);
 810     }
 811 
 812     /**
 813      * Returns a hash code for a {@code float} value; compatible with
 814      * {@code Float.hashCode()}.
 815      *
 816      * @param value the value to hash
 817      * @return a hash code value for a {@code float} value.
 818      * @since 1.8
 819      */
 820     public static int hashCode(float value) {
 821         return floatToIntBits(value);
 822     }
 823 
 824     /**
 825      * Compares this object against the specified object.  The result
 826      * is {@code true} if and only if the argument is not
 827      * {@code null} and is a {@code Float} object that
 828      * represents a {@code float} with the same value as the
 829      * {@code float} represented by this object. For this
 830      * purpose, two {@code float} values are considered to be the
 831      * same if and only if the method {@link #floatToIntBits(float)}
 832      * returns the identical {@code int} value when applied to
 833      * each.
 834      *
 835      * @apiNote
 836      * This method is defined in terms of {@link
 837      * #floatToIntBits(float)} rather than the {@code ==} operator on
 838      * {@code float} values since the {@code ==} operator does
 839      * <em>not</em> define an equivalence relation and to satisfy the
 840      * {@linkplain Object#equals equals contract} an equivalence
 841      * relation must be implemented; see <a
 842      * href="Double.html#equivalenceRelation">this discussion</a> for
 843      * details of floating-point equality and equivalence.
 844      *
 845      * @param obj the object to be compared
 846      * @return  {@code true} if the objects are the same;
 847      *          {@code false} otherwise.
 848      * @see java.lang.Float#floatToIntBits(float)
 849      * @jls 15.21.1 Numerical Equality Operators == and !=
 850      */
 851     public boolean equals(Object obj) {
 852         return (obj instanceof Float)
 853                && (floatToIntBits(((Float)obj).value) == floatToIntBits(value));
 854     }
 855 
 856     /**
 857      * Returns a representation of the specified floating-point value
 858      * according to the IEEE 754 floating-point "single format" bit
 859      * layout.
 860      *
 861      * <p>Bit 31 (the bit that is selected by the mask
 862      * {@code 0x80000000}) represents the sign of the floating-point
 863      * number.
 864      * Bits 30-23 (the bits that are selected by the mask
 865      * {@code 0x7f800000}) represent the exponent.
 866      * Bits 22-0 (the bits that are selected by the mask
 867      * {@code 0x007fffff}) represent the significand (sometimes called
 868      * the mantissa) of the floating-point number.
 869      *
 870      * <p>If the argument is positive infinity, the result is
 871      * {@code 0x7f800000}.
 872      *
 873      * <p>If the argument is negative infinity, the result is
 874      * {@code 0xff800000}.
 875      *
 876      * <p>If the argument is NaN, the result is {@code 0x7fc00000}.
 877      *
 878      * <p>In all cases, the result is an integer that, when given to the
 879      * {@link #intBitsToFloat(int)} method, will produce a floating-point
 880      * value the same as the argument to {@code floatToIntBits}
 881      * (except all NaN values are collapsed to a single
 882      * "canonical" NaN value).
 883      *
 884      * @param   value   a floating-point number.
 885      * @return the bits that represent the floating-point number.
 886      */
 887     @IntrinsicCandidate
 888     public static int floatToIntBits(float value) {
 889         if (!isNaN(value)) {
 890             return floatToRawIntBits(value);
 891         }
 892         return 0x7fc00000;
 893     }
 894 
 895     /**
 896      * Returns a representation of the specified floating-point value
 897      * according to the IEEE 754 floating-point "single format" bit
 898      * layout, preserving Not-a-Number (NaN) values.
 899      *
 900      * <p>Bit 31 (the bit that is selected by the mask
 901      * {@code 0x80000000}) represents the sign of the floating-point
 902      * number.
 903      * Bits 30-23 (the bits that are selected by the mask
 904      * {@code 0x7f800000}) represent the exponent.
 905      * Bits 22-0 (the bits that are selected by the mask
 906      * {@code 0x007fffff}) represent the significand (sometimes called
 907      * the mantissa) of the floating-point number.
 908      *
 909      * <p>If the argument is positive infinity, the result is
 910      * {@code 0x7f800000}.
 911      *
 912      * <p>If the argument is negative infinity, the result is
 913      * {@code 0xff800000}.
 914      *
 915      * <p>If the argument is NaN, the result is the integer representing
 916      * the actual NaN value.  Unlike the {@code floatToIntBits}
 917      * method, {@code floatToRawIntBits} does not collapse all the
 918      * bit patterns encoding a NaN to a single "canonical"
 919      * NaN value.
 920      *
 921      * <p>In all cases, the result is an integer that, when given to the
 922      * {@link #intBitsToFloat(int)} method, will produce a
 923      * floating-point value the same as the argument to
 924      * {@code floatToRawIntBits}.
 925      *
 926      * @param   value   a floating-point number.
 927      * @return the bits that represent the floating-point number.
 928      * @since 1.3
 929      */
 930     @IntrinsicCandidate
 931     public static native int floatToRawIntBits(float value);
 932 
 933     /**
 934      * Returns the {@code float} value corresponding to a given
 935      * bit representation.
 936      * The argument is considered to be a representation of a
 937      * floating-point value according to the IEEE 754 floating-point
 938      * "single format" bit layout.
 939      *
 940      * <p>If the argument is {@code 0x7f800000}, the result is positive
 941      * infinity.
 942      *
 943      * <p>If the argument is {@code 0xff800000}, the result is negative
 944      * infinity.
 945      *
 946      * <p>If the argument is any value in the range
 947      * {@code 0x7f800001} through {@code 0x7fffffff} or in
 948      * the range {@code 0xff800001} through
 949      * {@code 0xffffffff}, the result is a NaN.  No IEEE 754
 950      * floating-point operation provided by Java can distinguish
 951      * between two NaN values of the same type with different bit
 952      * patterns.  Distinct values of NaN are only distinguishable by
 953      * use of the {@code Float.floatToRawIntBits} method.
 954      *
 955      * <p>In all other cases, let <i>s</i>, <i>e</i>, and <i>m</i> be three
 956      * values that can be computed from the argument:
 957      *
 958      * {@snippet lang="java" :
 959      * int s = ((bits >> 31) == 0) ? 1 : -1;
 960      * int e = ((bits >> 23) & 0xff);
 961      * int m = (e == 0) ?
 962      *                 (bits & 0x7fffff) << 1 :
 963      *                 (bits & 0x7fffff) | 0x800000;
 964      * }
 965      *
 966      * Then the floating-point result equals the value of the mathematical
 967      * expression <i>s</i>&middot;<i>m</i>&middot;2<sup><i>e</i>-150</sup>.
 968      *
 969      * <p>Note that this method may not be able to return a
 970      * {@code float} NaN with exactly same bit pattern as the
 971      * {@code int} argument.  IEEE 754 distinguishes between two
 972      * kinds of NaNs, quiet NaNs and <i>signaling NaNs</i>.  The
 973      * differences between the two kinds of NaN are generally not
 974      * visible in Java.  Arithmetic operations on signaling NaNs turn
 975      * them into quiet NaNs with a different, but often similar, bit
 976      * pattern.  However, on some processors merely copying a
 977      * signaling NaN also performs that conversion.  In particular,
 978      * copying a signaling NaN to return it to the calling method may
 979      * perform this conversion.  So {@code intBitsToFloat} may
 980      * not be able to return a {@code float} with a signaling NaN
 981      * bit pattern.  Consequently, for some {@code int} values,
 982      * {@code floatToRawIntBits(intBitsToFloat(start))} may
 983      * <i>not</i> equal {@code start}.  Moreover, which
 984      * particular bit patterns represent signaling NaNs is platform
 985      * dependent; although all NaN bit patterns, quiet or signaling,
 986      * must be in the NaN range identified above.
 987      *
 988      * @param   bits   an integer.
 989      * @return  the {@code float} floating-point value with the same bit
 990      *          pattern.
 991      */
 992     @IntrinsicCandidate
 993     public static native float intBitsToFloat(int bits);
 994 
 995     /**
 996      * {@return the {@code float} value closest to the numerical value
 997      * of the argument, a floating-point binary16 value encoded in a
 998      * {@code short}} The conversion is exact; all binary16 values can
 999      * be exactly represented in {@code float}.
1000      *
1001      * Special cases:
1002      * <ul>
1003      * <li> If the argument is zero, the result is a zero with the
1004      * same sign as the argument.
1005      * <li> If the argument is infinite, the result is an infinity
1006      * with the same sign as the argument.
1007      * <li> If the argument is a NaN, the result is a NaN.
1008      * </ul>
1009      *
1010      * <h4><a id=binary16Format>IEEE 754 binary16 format</a></h4>
1011      * The IEEE 754 standard defines binary16 as a 16-bit format, along
1012      * with the 32-bit binary32 format (corresponding to the {@code
1013      * float} type) and the 64-bit binary64 format (corresponding to
1014      * the {@code double} type). The binary16 format is similar to the
1015      * other IEEE 754 formats, except smaller, having all the usual
1016      * IEEE 754 values such as NaN, signed infinities, signed zeros,
1017      * and subnormals. The parameters (JLS {@jls 4.2.3}) for the
1018      * binary16 format are N = 11 precision bits, K = 5 exponent bits,
1019      * <i>E</i><sub><i>max</i></sub> = 15, and
1020      * <i>E</i><sub><i>min</i></sub> = -14.
1021      *
1022      * @apiNote
1023      * This method corresponds to the convertFormat operation defined
1024      * in IEEE 754 from the binary16 format to the binary32 format.
1025      * The operation of this method is analogous to a primitive
1026      * widening conversion (JLS {@jls 5.1.2}).
1027      *
1028      * @param floatBinary16 the binary16 value to convert to {@code float}
1029      * @since 20
1030      */
1031     @IntrinsicCandidate
1032     public static float float16ToFloat(short floatBinary16) {
1033         /*
1034          * The binary16 format has 1 sign bit, 5 exponent bits, and 10
1035          * significand bits. The exponent bias is 15.
1036          */
1037         int bin16arg = (int)floatBinary16;
1038         int bin16SignBit     = 0x8000 & bin16arg;
1039         int bin16ExpBits     = 0x7c00 & bin16arg;
1040         int bin16SignifBits  = 0x03FF & bin16arg;
1041 
1042         // Shift left difference in the number of significand bits in
1043         // the float and binary16 formats
1044         final int SIGNIF_SHIFT = (FloatConsts.SIGNIFICAND_WIDTH - 11);
1045 
1046         float sign = (bin16SignBit != 0) ? -1.0f : 1.0f;
1047 
1048         // Extract binary16 exponent, remove its bias, add in the bias
1049         // of a float exponent and shift to correct bit location
1050         // (significand width includes the implicit bit so shift one
1051         // less).
1052         int bin16Exp = (bin16ExpBits >> 10) - 15;
1053         if (bin16Exp == -15) {
1054             // For subnormal binary16 values and 0, the numerical
1055             // value is 2^24 * the significand as an integer (no
1056             // implicit bit).
1057             return sign * (0x1p-24f * bin16SignifBits);
1058         } else if (bin16Exp == 16) {
1059             return (bin16SignifBits == 0) ?
1060                 sign * Float.POSITIVE_INFINITY :
1061                 Float.intBitsToFloat((bin16SignBit << 16) |
1062                                      0x7f80_0000 |
1063                                      // Preserve NaN signif bits
1064                                      ( bin16SignifBits << SIGNIF_SHIFT ));
1065         }
1066 
1067         assert -15 < bin16Exp  && bin16Exp < 16;
1068 
1069         int floatExpBits = (bin16Exp + FloatConsts.EXP_BIAS)
1070             << (FloatConsts.SIGNIFICAND_WIDTH - 1);
1071 
1072         // Compute and combine result sign, exponent, and significand bits.
1073         return Float.intBitsToFloat((bin16SignBit << 16) |
1074                                     floatExpBits |
1075                                     (bin16SignifBits << SIGNIF_SHIFT));
1076     }
1077 
1078     /**
1079      * {@return the floating-point binary16 value, encoded in a {@code
1080      * short}, closest in value to the argument}
1081      * The conversion is computed under the {@linkplain
1082      * java.math.RoundingMode#HALF_EVEN round to nearest even rounding
1083      * mode}.
1084      *
1085      * Special cases:
1086      * <ul>
1087      * <li> If the argument is zero, the result is a zero with the
1088      * same sign as the argument.
1089      * <li> If the argument is infinite, the result is an infinity
1090      * with the same sign as the argument.
1091      * <li> If the argument is a NaN, the result is a NaN.
1092      * </ul>
1093      *
1094      * The <a href="#binary16Format">binary16 format</a> is discussed in
1095      * more detail in the {@link #float16ToFloat} method.
1096      *
1097      * @apiNote
1098      * This method corresponds to the convertFormat operation defined
1099      * in IEEE 754 from the binary32 format to the binary16 format.
1100      * The operation of this method is analogous to a primitive
1101      * narrowing conversion (JLS {@jls 5.1.3}).
1102      *
1103      * @param f the {@code float} value to convert to binary16
1104      * @since 20
1105      */
1106     @IntrinsicCandidate
1107     public static short floatToFloat16(float f) {
1108         int doppel = Float.floatToRawIntBits(f);
1109         short sign_bit = (short)((doppel & 0x8000_0000) >> 16);
1110 
1111         if (Float.isNaN(f)) {
1112             // Preserve sign and attempt to preserve significand bits
1113             return (short)(sign_bit
1114                     | 0x7c00 // max exponent + 1
1115                     // Preserve high order bit of float NaN in the
1116                     // binary16 result NaN (tenth bit); OR in remaining
1117                     // bits into lower 9 bits of binary 16 significand.
1118                     | (doppel & 0x007f_e000) >> 13 // 10 bits
1119                     | (doppel & 0x0000_1ff0) >> 4  //  9 bits
1120                     | (doppel & 0x0000_000f));     //  4 bits
1121         }
1122 
1123         float abs_f = Math.abs(f);
1124 
1125         // The overflow threshold is binary16 MAX_VALUE + 1/2 ulp
1126         if (abs_f >= (0x1.ffcp15f + 0x0.002p15f) ) {
1127             return (short)(sign_bit | 0x7c00); // Positive or negative infinity
1128         }
1129 
1130         // Smallest magnitude nonzero representable binary16 value
1131         // is equal to 0x1.0p-24; half-way and smaller rounds to zero.
1132         if (abs_f <= 0x1.0p-24f * 0.5f) { // Covers float zeros and subnormals.
1133             return sign_bit; // Positive or negative zero
1134         }
1135 
1136         // Dealing with finite values in exponent range of binary16
1137         // (when rounding is done, could still round up)
1138         int exp = Math.getExponent(f);
1139         assert -25 <= exp && exp <= 15;
1140 
1141         // For binary16 subnormals, beside forcing exp to -15, retain
1142         // the difference expdelta = E_min - exp.  This is the excess
1143         // shift value, in addition to 13, to be used in the
1144         // computations below.  Further the (hidden) msb with value 1
1145         // in f must be involved as well.
1146         int expdelta = 0;
1147         int msb = 0x0000_0000;
1148         if (exp < -14) {
1149             expdelta = -14 - exp;
1150             exp = -15;
1151             msb = 0x0080_0000;
1152         }
1153         int f_signif_bits = doppel & 0x007f_ffff | msb;
1154 
1155         // Significand bits as if using rounding to zero (truncation).
1156         short signif_bits = (short)(f_signif_bits >> (13 + expdelta));
1157 
1158         // For round to nearest even, determining whether or not to
1159         // round up (in magnitude) is a function of the least
1160         // significant bit (LSB), the next bit position (the round
1161         // position), and the sticky bit (whether there are any
1162         // nonzero bits in the exact result to the right of the round
1163         // digit). An increment occurs in three cases:
1164         //
1165         // LSB  Round Sticky
1166         // 0    1     1
1167         // 1    1     0
1168         // 1    1     1
1169         // See "Computer Arithmetic Algorithms," Koren, Table 4.9
1170 
1171         int lsb    = f_signif_bits & (1 << 13 + expdelta);
1172         int round  = f_signif_bits & (1 << 12 + expdelta);
1173         int sticky = f_signif_bits & ((1 << 12 + expdelta) - 1);
1174 
1175         if (round != 0 && ((lsb | sticky) != 0 )) {
1176             signif_bits++;
1177         }
1178 
1179         // No bits set in significand beyond the *first* exponent bit,
1180         // not just the significand; quantity is added to the exponent
1181         // to implement a carry out from rounding the significand.
1182         assert (0xf800 & signif_bits) == 0x0;
1183 
1184         return (short)(sign_bit | ( ((exp + 15) << 10) + signif_bits ) );
1185     }
1186 
1187     /**
1188      * Compares two {@code Float} objects numerically.
1189      *
1190      * This method imposes a total order on {@code Float} objects
1191      * with two differences compared to the incomplete order defined by
1192      * the Java language numerical comparison operators ({@code <, <=,
1193      * ==, >=, >}) on {@code float} values.
1194      *
1195      * <ul><li> A NaN is <em>unordered</em> with respect to other
1196      *          values and unequal to itself under the comparison
1197      *          operators.  This method chooses to define {@code
1198      *          Float.NaN} to be equal to itself and greater than all
1199      *          other {@code double} values (including {@code
1200      *          Float.POSITIVE_INFINITY}).
1201      *
1202      *      <li> Positive zero and negative zero compare equal
1203      *      numerically, but are distinct and distinguishable values.
1204      *      This method chooses to define positive zero ({@code +0.0f}),
1205      *      to be greater than negative zero ({@code -0.0f}).
1206      * </ul>
1207      *
1208      * This ensures that the <i>natural ordering</i> of {@code Float}
1209      * objects imposed by this method is <i>consistent with
1210      * equals</i>; see <a href="Double.html#equivalenceRelation">this
1211      * discussion</a> for details of floating-point comparison and
1212      * ordering.
1213      *
1214      *
1215      * @param   anotherFloat   the {@code Float} to be compared.
1216      * @return  the value {@code 0} if {@code anotherFloat} is
1217      *          numerically equal to this {@code Float}; a value
1218      *          less than {@code 0} if this {@code Float}
1219      *          is numerically less than {@code anotherFloat};
1220      *          and a value greater than {@code 0} if this
1221      *          {@code Float} is numerically greater than
1222      *          {@code anotherFloat}.
1223      *
1224      * @jls 15.20.1 Numerical Comparison Operators {@code <}, {@code <=}, {@code >}, and {@code >=}
1225      * @since   1.2
1226      */
1227     public int compareTo(Float anotherFloat) {
1228         return Float.compare(value, anotherFloat.value);
1229     }
1230 
1231     /**
1232      * Compares the two specified {@code float} values. The sign
1233      * of the integer value returned is the same as that of the
1234      * integer that would be returned by the call:
1235      * <pre>
1236      *    Float.valueOf(f1).compareTo(Float.valueOf(f2))
1237      * </pre>
1238      *
1239      * @param   f1        the first {@code float} to compare.
1240      * @param   f2        the second {@code float} to compare.
1241      * @return  the value {@code 0} if {@code f1} is
1242      *          numerically equal to {@code f2}; a value less than
1243      *          {@code 0} if {@code f1} is numerically less than
1244      *          {@code f2}; and a value greater than {@code 0}
1245      *          if {@code f1} is numerically greater than
1246      *          {@code f2}.
1247      * @since 1.4
1248      */
1249     public static int compare(float f1, float f2) {
1250         if (f1 < f2)
1251             return -1;           // Neither val is NaN, thisVal is smaller
1252         if (f1 > f2)
1253             return 1;            // Neither val is NaN, thisVal is larger
1254 
1255         // Cannot use floatToRawIntBits because of possibility of NaNs.
1256         int thisBits    = Float.floatToIntBits(f1);
1257         int anotherBits = Float.floatToIntBits(f2);
1258 
1259         return (thisBits == anotherBits ?  0 : // Values are equal
1260                 (thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN)
1261                  1));                          // (0.0, -0.0) or (NaN, !NaN)
1262     }
1263 
1264     /**
1265      * Adds two {@code float} values together as per the + operator.
1266      *
1267      * @apiNote This method corresponds to the addition operation
1268      * defined in IEEE 754.
1269      *
1270      * @param a the first operand
1271      * @param b the second operand
1272      * @return the sum of {@code a} and {@code b}
1273      * @jls 4.2.4 Floating-Point Operations
1274      * @see java.util.function.BinaryOperator
1275      * @since 1.8
1276      */
1277     public static float sum(float a, float b) {
1278         return a + b;
1279     }
1280 
1281     /**
1282      * Returns the greater of two {@code float} values
1283      * as if by calling {@link Math#max(float, float) Math.max}.
1284      *
1285      * @apiNote
1286      * This method corresponds to the maximum operation defined in
1287      * IEEE 754.
1288      *
1289      * @param a the first operand
1290      * @param b the second operand
1291      * @return the greater of {@code a} and {@code b}
1292      * @see java.util.function.BinaryOperator
1293      * @since 1.8
1294      */
1295     public static float max(float a, float b) {
1296         return Math.max(a, b);
1297     }
1298 
1299     /**
1300      * Returns the smaller of two {@code float} values
1301      * as if by calling {@link Math#min(float, float) Math.min}.
1302      *
1303      * @apiNote
1304      * This method corresponds to the minimum operation defined in
1305      * IEEE 754.
1306      *
1307      * @param a the first operand
1308      * @param b the second operand
1309      * @return the smaller of {@code a} and {@code b}
1310      * @see java.util.function.BinaryOperator
1311      * @since 1.8
1312      */
1313     public static float min(float a, float b) {
1314         return Math.min(a, b);
1315     }
1316 
1317     /**
1318      * Returns an {@link Optional} containing the nominal descriptor for this
1319      * instance, which is the instance itself.
1320      *
1321      * @return an {@link Optional} describing the {@linkplain Float} instance
1322      * @since 12
1323      */
1324     @Override
1325     public Optional<Float> describeConstable() {
1326         return Optional.of(this);
1327     }
1328 
1329     /**
1330      * Resolves this instance as a {@link ConstantDesc}, the result of which is
1331      * the instance itself.
1332      *
1333      * @param lookup ignored
1334      * @return the {@linkplain Float} instance
1335      * @since 12
1336      */
1337     @Override
1338     public Float resolveConstantDesc(MethodHandles.Lookup lookup) {
1339         return this;
1340     }
1341 
1342     /** use serialVersionUID from JDK 1.0.2 for interoperability */
1343     @java.io.Serial
1344     private static final long serialVersionUID = -2671257302660747028L;
1345 }