OpenCores
URL https://opencores.org/ocsvn/scarts/scarts/trunk

Subversion Repositories scarts

[/] [scarts/] [trunk/] [toolchain/] [scarts-gcc/] [gcc-4.1.1/] [libjava/] [classpath/] [java/] [lang/] [Float.java] - Blame information for rev 14

Details | Compare with Previous | View Log

Line No. Rev Author Line
1 14 jlechner
/* Float.java -- object wrapper for float
2
   Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2005
3
   Free Software Foundation, Inc.
4
 
5
This file is part of GNU Classpath.
6
 
7
GNU Classpath is free software; you can redistribute it and/or modify
8
it under the terms of the GNU General Public License as published by
9
the Free Software Foundation; either version 2, or (at your option)
10
any later version.
11
 
12
GNU Classpath is distributed in the hope that it will be useful, but
13
WITHOUT ANY WARRANTY; without even the implied warranty of
14
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15
General Public License for more details.
16
 
17
You should have received a copy of the GNU General Public License
18
along with GNU Classpath; see the file COPYING.  If not, write to the
19
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
20
02110-1301 USA.
21
 
22
Linking this library statically or dynamically with other modules is
23
making a combined work based on this library.  Thus, the terms and
24
conditions of the GNU General Public License cover the whole
25
combination.
26
 
27
As a special exception, the copyright holders of this library give you
28
permission to link this library with independent modules to produce an
29
executable, regardless of the license terms of these independent
30
modules, and to copy and distribute the resulting executable under
31
terms of your choice, provided that you also meet, for each linked
32
independent module, the terms and conditions of the license of that
33
module.  An independent module is a module which is not derived from
34
or based on this library.  If you modify this library, you may extend
35
this exception to your version of the library, but you are not
36
obligated to do so.  If you do not wish to do so, delete this
37
exception statement from your version. */
38
 
39
 
40
package java.lang;
41
 
42
/**
43
 * Instances of class <code>Float</code> represent primitive
44
 * <code>float</code> values.
45
 *
46
 * Additionally, this class provides various helper functions and variables
47
 * related to floats.
48
 *
49
 * @author Paul Fisher
50
 * @author Andrew Haley (aph@cygnus.com)
51
 * @author Eric Blake (ebb9@email.byu.edu)
52
 * @since 1.0
53
 * @status updated to 1.4
54
 */
55
public final class Float extends Number implements Comparable
56
{
57
  /**
58
   * Compatible with JDK 1.0+.
59
   */
60
  private static final long serialVersionUID = -2671257302660747028L;
61
 
62
  /**
63
   * The maximum positive value a <code>double</code> may represent
64
   * is 3.4028235e+38f.
65
   */
66
  public static final float MAX_VALUE = 3.4028235e+38f;
67
 
68
  /**
69
   * The minimum positive value a <code>float</code> may represent
70
   * is 1.4e-45.
71
   */
72
  public static final float MIN_VALUE = 1.4e-45f;
73
 
74
  /**
75
   * The value of a float representation -1.0/0.0, negative infinity.
76
   */
77
  public static final float NEGATIVE_INFINITY = -1.0f / 0.0f;
78
 
79
  /**
80
   * The value of a float representation 1.0/0.0, positive infinity.
81
   */
82
  public static final float POSITIVE_INFINITY = 1.0f / 0.0f;
83
 
84
  /**
85
   * All IEEE 754 values of NaN have the same value in Java.
86
   */
87
  public static final float NaN = 0.0f / 0.0f;
88
 
89
  /**
90
   * The primitive type <code>float</code> is represented by this
91
   * <code>Class</code> object.
92
   * @since 1.1
93
   */
94
  public static final Class TYPE = VMClassLoader.getPrimitiveClass('F');
95
 
96
  /**
97
   * The number of bits needed to represent a <code>float</code>.
98
   * @since 1.5
99
   */
100
  public static final int SIZE = 32;
101
 
102
  /**
103
   * The immutable value of this Float.
104
   *
105
   * @serial the wrapped float
106
   */
107
  private final float value;
108
 
109
  /**
110
   * Create a <code>Float</code> from the primitive <code>float</code>
111
   * specified.
112
   *
113
   * @param value the <code>float</code> argument
114
   */
115
  public Float(float value)
116
  {
117
    this.value = value;
118
  }
119
 
120
  /**
121
   * Create a <code>Float</code> from the primitive <code>double</code>
122
   * specified.
123
   *
124
   * @param value the <code>double</code> argument
125
   */
126
  public Float(double value)
127
  {
128
    this.value = (float) value;
129
  }
130
 
131
  /**
132
   * Create a <code>Float</code> from the specified <code>String</code>.
133
   * This method calls <code>Float.parseFloat()</code>.
134
   *
135
   * @param s the <code>String</code> to convert
136
   * @throws NumberFormatException if <code>s</code> cannot be parsed as a
137
   *         <code>float</code>
138
   * @throws NullPointerException if <code>s</code> is null
139
   * @see #parseFloat(String)
140
   */
141
  public Float(String s)
142
  {
143
    value = parseFloat(s);
144
  }
145
 
146
  /**
147
   * Convert the <code>float</code> to a <code>String</code>.
148
   * Floating-point string representation is fairly complex: here is a
149
   * rundown of the possible values.  "<code>[-]</code>" indicates that a
150
   * negative sign will be printed if the value (or exponent) is negative.
151
   * "<code>&lt;number&gt;</code>" means a string of digits ('0' to '9').
152
   * "<code>&lt;digit&gt;</code>" means a single digit ('0' to '9').<br>
153
   *
154
   * <table border=1>
155
   * <tr><th>Value of Float</th><th>String Representation</th></tr>
156
   * <tr><td>[+-] 0</td> <td><code>[-]0.0</code></td></tr>
157
   * <tr><td>Between [+-] 10<sup>-3</sup> and 10<sup>7</sup>, exclusive</td>
158
   *     <td><code>[-]number.number</code></td></tr>
159
   * <tr><td>Other numeric value</td>
160
   *     <td><code>[-]&lt;digit&gt;.&lt;number&gt;
161
   *          E[-]&lt;number&gt;</code></td></tr>
162
   * <tr><td>[+-] infinity</td> <td><code>[-]Infinity</code></td></tr>
163
   * <tr><td>NaN</td> <td><code>NaN</code></td></tr>
164
   * </table>
165
   *
166
   * Yes, negative zero <em>is</em> a possible value.  Note that there is
167
   * <em>always</em> a <code>.</code> and at least one digit printed after
168
   * it: even if the number is 3, it will be printed as <code>3.0</code>.
169
   * After the ".", all digits will be printed except trailing zeros. The
170
   * result is rounded to the shortest decimal number which will parse back
171
   * to the same float.
172
   *
173
   * <p>To create other output formats, use {@link java.text.NumberFormat}.
174
   *
175
   * @XXX specify where we are not in accord with the spec.
176
   *
177
   * @param f the <code>float</code> to convert
178
   * @return the <code>String</code> representing the <code>float</code>
179
   */
180
  public static String toString(float f)
181
  {
182
    return VMDouble.toString(f, true);
183
  }
184
 
185
  /**
186
   * Creates a new <code>Float</code> object using the <code>String</code>.
187
   *
188
   * @param s the <code>String</code> to convert
189
   * @return the new <code>Float</code>
190
   * @throws NumberFormatException if <code>s</code> cannot be parsed as a
191
   *         <code>float</code>
192
   * @throws NullPointerException if <code>s</code> is null
193
   * @see #parseFloat(String)
194
   */
195
  public static Float valueOf(String s)
196
  {
197
    return new Float(parseFloat(s));
198
  }
199
 
200
  /**
201
   * Returns a <code>Float</code> object wrapping the value.
202
   * In contrast to the <code>Float</code> constructor, this method
203
   * may cache some values.  It is used by boxing conversion.
204
   *
205
   * @param val the value to wrap
206
   * @return the <code>Float</code>
207
   *
208
   * @since 1.5
209
   */
210
  public static Float valueOf(float val)
211
  {
212
    // We don't actually cache, but we could.
213
    return new Float(val);
214
  }
215
 
216
  /**
217
   * Parse the specified <code>String</code> as a <code>float</code>. The
218
   * extended BNF grammar is as follows:<br>
219
   * <pre>
220
   * <em>DecodableString</em>:
221
   *      ( [ <code>-</code> | <code>+</code> ] <code>NaN</code> )
222
   *    | ( [ <code>-</code> | <code>+</code> ] <code>Infinity</code> )
223
   *    | ( [ <code>-</code> | <code>+</code> ] <em>FloatingPoint</em>
224
   *              [ <code>f</code> | <code>F</code> | <code>d</code>
225
   *                | <code>D</code>] )
226
   * <em>FloatingPoint</em>:
227
   *      ( { <em>Digit</em> }+ [ <code>.</code> { <em>Digit</em> } ]
228
   *              [ <em>Exponent</em> ] )
229
   *    | ( <code>.</code> { <em>Digit</em> }+ [ <em>Exponent</em> ] )
230
   * <em>Exponent</em>:
231
   *      ( ( <code>e</code> | <code>E</code> )
232
   *              [ <code>-</code> | <code>+</code> ] { <em>Digit</em> }+ )
233
   * <em>Digit</em>: <em><code>'0'</code> through <code>'9'</code></em>
234
   * </pre>
235
   *
236
   * <p>NaN and infinity are special cases, to allow parsing of the output
237
   * of toString.  Otherwise, the result is determined by calculating
238
   * <em>n * 10<sup>exponent</sup></em> to infinite precision, then rounding
239
   * to the nearest float. Remember that many numbers cannot be precisely
240
   * represented in floating point. In case of overflow, infinity is used,
241
   * and in case of underflow, signed zero is used. Unlike Integer.parseInt,
242
   * this does not accept Unicode digits outside the ASCII range.
243
   *
244
   * <p>If an unexpected character is found in the <code>String</code>, a
245
   * <code>NumberFormatException</code> will be thrown.  Leading and trailing
246
   * 'whitespace' is ignored via <code>String.trim()</code>, but spaces
247
   * internal to the actual number are not allowed.
248
   *
249
   * <p>To parse numbers according to another format, consider using
250
   * {@link java.text.NumberFormat}.
251
   *
252
   * @XXX specify where/how we are not in accord with the spec.
253
   *
254
   * @param str the <code>String</code> to convert
255
   * @return the <code>float</code> value of <code>s</code>
256
   * @throws NumberFormatException if <code>s</code> cannot be parsed as a
257
   *         <code>float</code>
258
   * @throws NullPointerException if <code>s</code> is null
259
   * @see #MIN_VALUE
260
   * @see #MAX_VALUE
261
   * @see #POSITIVE_INFINITY
262
   * @see #NEGATIVE_INFINITY
263
   * @since 1.2
264
   */
265
  public static float parseFloat(String str)
266
  {
267
    // XXX Rounding parseDouble() causes some errors greater than 1 ulp from
268
    // the infinitely precise decimal.
269
    return (float) Double.parseDouble(str);
270
  }
271
 
272
  /**
273
   * Return <code>true</code> if the <code>float</code> has the same
274
   * value as <code>NaN</code>, otherwise return <code>false</code>.
275
   *
276
   * @param v the <code>float</code> to compare
277
   * @return whether the argument is <code>NaN</code>
278
   */
279
  public static boolean isNaN(float v)
280
  {
281
    // This works since NaN != NaN is the only reflexive inequality
282
    // comparison which returns true.
283
    return v != v;
284
  }
285
 
286
  /**
287
   * Return <code>true</code> if the <code>float</code> has a value
288
   * equal to either <code>NEGATIVE_INFINITY</code> or
289
   * <code>POSITIVE_INFINITY</code>, otherwise return <code>false</code>.
290
   *
291
   * @param v the <code>float</code> to compare
292
   * @return whether the argument is (-/+) infinity
293
   */
294
  public static boolean isInfinite(float v)
295
  {
296
    return v == POSITIVE_INFINITY || v == NEGATIVE_INFINITY;
297
  }
298
 
299
  /**
300
   * Return <code>true</code> if the value of this <code>Float</code>
301
   * is the same as <code>NaN</code>, otherwise return <code>false</code>.
302
   *
303
   * @return whether this <code>Float</code> is <code>NaN</code>
304
   */
305
  public boolean isNaN()
306
  {
307
    return isNaN(value);
308
  }
309
 
310
  /**
311
   * Return <code>true</code> if the value of this <code>Float</code>
312
   * is the same as <code>NEGATIVE_INFINITY</code> or
313
   * <code>POSITIVE_INFINITY</code>, otherwise return <code>false</code>.
314
   *
315
   * @return whether this <code>Float</code> is (-/+) infinity
316
   */
317
  public boolean isInfinite()
318
  {
319
    return isInfinite(value);
320
  }
321
 
322
  /**
323
   * Convert the <code>float</code> value of this <code>Float</code>
324
   * to a <code>String</code>.  This method calls
325
   * <code>Float.toString(float)</code> to do its dirty work.
326
   *
327
   * @return the <code>String</code> representation
328
   * @see #toString(float)
329
   */
330
  public String toString()
331
  {
332
    return toString(value);
333
  }
334
 
335
  /**
336
   * Return the value of this <code>Float</code> as a <code>byte</code>.
337
   *
338
   * @return the byte value
339
   * @since 1.1
340
   */
341
  public byte byteValue()
342
  {
343
    return (byte) value;
344
  }
345
 
346
  /**
347
   * Return the value of this <code>Float</code> as a <code>short</code>.
348
   *
349
   * @return the short value
350
   * @since 1.1
351
   */
352
  public short shortValue()
353
  {
354
    return (short) value;
355
  }
356
 
357
  /**
358
   * Return the value of this <code>Integer</code> as an <code>int</code>.
359
   *
360
   * @return the int value
361
   */
362
  public int intValue()
363
  {
364
    return (int) value;
365
  }
366
 
367
  /**
368
   * Return the value of this <code>Integer</code> as a <code>long</code>.
369
   *
370
   * @return the long value
371
   */
372
  public long longValue()
373
  {
374
    return (long) value;
375
  }
376
 
377
  /**
378
   * Return the value of this <code>Float</code>.
379
   *
380
   * @return the float value
381
   */
382
  public float floatValue()
383
  {
384
    return value;
385
  }
386
 
387
  /**
388
   * Return the value of this <code>Float</code> as a <code>double</code>
389
   *
390
   * @return the double value
391
   */
392
  public double doubleValue()
393
  {
394
    return value;
395
  }
396
 
397
  /**
398
   * Return a hashcode representing this Object. <code>Float</code>'s hash
399
   * code is calculated by calling <code>floatToIntBits(floatValue())</code>.
400
   *
401
   * @return this Object's hash code
402
   * @see #floatToIntBits(float)
403
   */
404
  public int hashCode()
405
  {
406
    return floatToIntBits(value);
407
  }
408
 
409
  /**
410
   * Returns <code>true</code> if <code>obj</code> is an instance of
411
   * <code>Float</code> and represents the same float value. Unlike comparing
412
   * two floats with <code>==</code>, this treats two instances of
413
   * <code>Float.NaN</code> as equal, but treats <code>0.0</code> and
414
   * <code>-0.0</code> as unequal.
415
   *
416
   * <p>Note that <code>f1.equals(f2)</code> is identical to
417
   * <code>floatToIntBits(f1.floatValue()) ==
418
   *    floatToIntBits(f2.floatValue())</code>.
419
   *
420
   * @param obj the object to compare
421
   * @return whether the objects are semantically equal
422
   */
423
  public boolean equals(Object obj)
424
  {
425
    if (! (obj instanceof Float))
426
      return false;
427
 
428
    float f = ((Float) obj).value;
429
 
430
    // Avoid call to native method. However, some implementations, like gcj,
431
    // are better off using floatToIntBits(value) == floatToIntBits(f).
432
    // Check common case first, then check NaN and 0.
433
    if (value == f)
434
      return (value != 0) || (1 / value == 1 / f);
435
    return isNaN(value) && isNaN(f);
436
  }
437
 
438
  /**
439
   * Convert the float to the IEEE 754 floating-point "single format" bit
440
   * layout. Bit 31 (the most significant) is the sign bit, bits 30-23
441
   * (masked by 0x7f800000) represent the exponent, and bits 22-0
442
   * (masked by 0x007fffff) are the mantissa. This function collapses all
443
   * versions of NaN to 0x7fc00000. The result of this function can be used
444
   * as the argument to <code>Float.intBitsToFloat(int)</code> to obtain the
445
   * original <code>float</code> value.
446
   *
447
   * @param value the <code>float</code> to convert
448
   * @return the bits of the <code>float</code>
449
   * @see #intBitsToFloat(int)
450
   */
451
  public static int floatToIntBits(float value)
452
  {
453
    return VMFloat.floatToIntBits(value);
454
  }
455
 
456
  /**
457
   * Convert the float to the IEEE 754 floating-point "single format" bit
458
   * layout. Bit 31 (the most significant) is the sign bit, bits 30-23
459
   * (masked by 0x7f800000) represent the exponent, and bits 22-0
460
   * (masked by 0x007fffff) are the mantissa. This function leaves NaN alone,
461
   * rather than collapsing to a canonical value. The result of this function
462
   * can be used as the argument to <code>Float.intBitsToFloat(int)</code> to
463
   * obtain the original <code>float</code> value.
464
   *
465
   * @param value the <code>float</code> to convert
466
   * @return the bits of the <code>float</code>
467
   * @see #intBitsToFloat(int)
468
   */
469
  public static int floatToRawIntBits(float value)
470
  {
471
    return VMFloat.floatToRawIntBits(value);
472
  }
473
 
474
  /**
475
   * Convert the argument in IEEE 754 floating-point "single format" bit
476
   * layout to the corresponding float. Bit 31 (the most significant) is the
477
   * sign bit, bits 30-23 (masked by 0x7f800000) represent the exponent, and
478
   * bits 22-0 (masked by 0x007fffff) are the mantissa. This function leaves
479
   * NaN alone, so that you can recover the bit pattern with
480
   * <code>Float.floatToRawIntBits(float)</code>.
481
   *
482
   * @param bits the bits to convert
483
   * @return the <code>float</code> represented by the bits
484
   * @see #floatToIntBits(float)
485
   * @see #floatToRawIntBits(float)
486
   */
487
  public static float intBitsToFloat(int bits)
488
  {
489
    return VMFloat.intBitsToFloat(bits);
490
  }
491
 
492
  /**
493
   * Compare two Floats numerically by comparing their <code>float</code>
494
   * values. The result is positive if the first is greater, negative if the
495
   * second is greater, and 0 if the two are equal. However, this special
496
   * cases NaN and signed zero as follows: NaN is considered greater than
497
   * all other floats, including <code>POSITIVE_INFINITY</code>, and positive
498
   * zero is considered greater than negative zero.
499
   *
500
   * @param f the Float to compare
501
   * @return the comparison
502
   * @since 1.2
503
   */
504
  public int compareTo(Float f)
505
  {
506
    return compare(value, f.value);
507
  }
508
 
509
  /**
510
   * Behaves like <code>compareTo(Float)</code> unless the Object
511
   * is not an <code>Float</code>.
512
   *
513
   * @param o the object to compare
514
   * @return the comparison
515
   * @throws ClassCastException if the argument is not a <code>Float</code>
516
   * @see #compareTo(Float)
517
   * @see Comparable
518
   * @since 1.2
519
   */
520
  public int compareTo(Object o)
521
  {
522
    return compare(value, ((Float) o).value);
523
  }
524
 
525
  /**
526
   * Behaves like <code>new Float(x).compareTo(new Float(y))</code>; in
527
   * other words this compares two floats, special casing NaN and zero,
528
   * without the overhead of objects.
529
   *
530
   * @param x the first float to compare
531
   * @param y the second float to compare
532
   * @return the comparison
533
   * @since 1.4
534
   */
535
  public static int compare(float x, float y)
536
  {
537
    if (isNaN(x))
538
      return isNaN(y) ? 0 : 1;
539
    if (isNaN(y))
540
      return -1;
541
    // recall that 0.0 == -0.0, so we convert to infinities and try again
542
    if (x == 0 && y == 0)
543
      return (int) (1 / x - 1 / y);
544
    if (x == y)
545
      return 0;
546
 
547
    return x > y ? 1 : -1;
548
  }
549
}

powered by: WebSVN 2.1.0

© copyright 1999-2024 OpenCores.org, equivalent to Oliscience, all rights reserved. OpenCores®, registered trademark.