1 /*************************************************************************
2 *
3 * $Id$
4 *
5 * Copyright (C) 2001 Bjorn Reese <breese@users.sourceforge.net>
6 *
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
12 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
13 * MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE AUTHORS AND
14 * CONTRIBUTORS ACCEPT NO RESPONSIBILITY IN ANY CONCEIVABLE MANNER.
15 *
16 ************************************************************************
17 *
18 * Functions to handle special quantities in floating-point numbers
19 * (that is, NaNs and infinity). They provide the capability to detect
20 * and fabricate special quantities.
21 *
22 * Although written to be as portable as possible, it can never be
23 * guaranteed to work on all platforms, as not all hardware supports
24 * special quantities.
25 *
26 * The approach used here (approximately) is to:
27 *
28 * 1. Use C99 functionality when available.
29 * 2. Use IEEE 754 bit-patterns if possible.
30 * 3. Use platform-specific techniques.
31 *
32 ************************************************************************/
33
34 /*
35 * TODO:
36 * o Put all the magic into trio_fpclassify_and_signbit(), and use this from
37 * trio_isnan() etc.
38 */
39
40 /*************************************************************************
41 * Include files
42 */
43 #include "triodef.h"
44 #include "trionan.h"
45
46 #include <math.h>
47 #include <string.h>
48 #include <limits.h>
49 #include <float.h>
50 #if defined(TRIO_PLATFORM_UNIX)
51 # include <signal.h>
52 #endif
53 #if defined(TRIO_COMPILER_DECC)
54 # if defined(__linux__)
55 # include <cpml.h>
56 # else
57 # include <fp_class.h>
58 # endif
59 #endif
60 #include <assert.h>
61
62 #if defined(TRIO_DOCUMENTATION)
63 # include "doc/doc_nan.h"
64 #endif
65 /** @addtogroup SpecialQuantities
66 @{
67 */
68
69 /*************************************************************************
70 * Definitions
71 */
72
73 #define TRIO_TRUE (1 == 1)
74 #define TRIO_FALSE (0 == 1)
75
76 /*
77 * We must enable IEEE floating-point on Alpha
78 */
79 #if defined(__alpha) && !defined(_IEEE_FP)
80 # if defined(TRIO_COMPILER_DECC)
81 # if defined(TRIO_PLATFORM_VMS)
82 # error "Must be compiled with option /IEEE_MODE=UNDERFLOW_TO_ZERO/FLOAT=IEEE"
83 # else
84 # if !defined(_CFE)
85 # error "Must be compiled with option -ieee"
86 # endif
87 # endif
88 # elif defined(TRIO_COMPILER_GCC) && (defined(__osf__) || defined(__linux__))
89 # error "Must be compiled with option -mieee"
90 # endif
91 #endif /* __alpha && ! _IEEE_FP */
92
93 /*
94 * In ANSI/IEEE 754-1985 64-bits double format numbers have the
95 * following properties (amoungst others)
96 *
97 * o FLT_RADIX == 2: binary encoding
98 * o DBL_MAX_EXP == 1024: 11 bits exponent, where one bit is used
99 * to indicate special numbers (e.g. NaN and Infinity), so the
100 * maximum exponent is 10 bits wide (2^10 == 1024).
101 * o DBL_MANT_DIG == 53: The mantissa is 52 bits wide, but because
102 * numbers are normalized the initial binary 1 is represented
103 * implicitly (the so-called "hidden bit"), which leaves us with
104 * the ability to represent 53 bits wide mantissa.
105 */
106 #if (FLT_RADIX == 2) && (DBL_MAX_EXP == 1024) && (DBL_MANT_DIG == 53)
107 # define USE_IEEE_754
108 #endif
109
110
111 /*************************************************************************
112 * Constants
113 */
114
115 static TRIO_CONST char rcsid[] = "@(#)$Id$";
116
117 #if defined(USE_IEEE_754)
118
119 /*
120 * Endian-agnostic indexing macro.
121 *
122 * The value of internalEndianMagic, when converted into a 64-bit
123 * integer, becomes 0x0706050403020100 (we could have used a 64-bit
124 * integer value instead of a double, but not all platforms supports
125 * that type). The value is automatically encoded with the correct
126 * endianess by the compiler, which means that we can support any
127 * kind of endianess. The individual bytes are then used as an index
128 * for the IEEE 754 bit-patterns and masks.
129 */
130 #define TRIO_DOUBLE_INDEX(x) (((unsigned char *)&internalEndianMagic)[7-(x)])
131
132 #if (defined(__BORLANDC__) && __BORLANDC__ >= 0x0590)
133 static TRIO_CONST double internalEndianMagic = 7.949928895127362e-275;
134 #else
135 static TRIO_CONST double internalEndianMagic = 7.949928895127363e-275;
136 #endif
137
138 /* Mask for the exponent */
139 static TRIO_CONST unsigned char ieee_754_exponent_mask[] = {
140 0x7F, 0xF0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
141 };
142
143 /* Mask for the mantissa */
144 static TRIO_CONST unsigned char ieee_754_mantissa_mask[] = {
145 0x00, 0x0F, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
146 };
147
148 /* Mask for the sign bit */
149 static TRIO_CONST unsigned char ieee_754_sign_mask[] = {
150 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
151 };
152
153 /* Bit-pattern for negative zero */
154 static TRIO_CONST unsigned char ieee_754_negzero_array[] = {
155 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
156 };
157
158 /* Bit-pattern for infinity */
159 static TRIO_CONST unsigned char ieee_754_infinity_array[] = {
160 0x7F, 0xF0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
161 };
162
163 /* Bit-pattern for quiet NaN */
164 static TRIO_CONST unsigned char ieee_754_qnan_array[] = {
165 0x7F, 0xF8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
166 };
167
168
169 /*************************************************************************
170 * Functions
171 */
172
173 /*
174 * trio_make_double
175 */
176 TRIO_PRIVATE double
177 trio_make_double
178 TRIO_ARGS1((values),
179 TRIO_CONST unsigned char *values)
180 {
181 TRIO_VOLATILE double result;
182 int i;
183
184 for (i = 0; i < (int)sizeof(double); i++) {
185 ((TRIO_VOLATILE unsigned char *)&result)[TRIO_DOUBLE_INDEX(i)] = values[i];
186 }
187 return result;
188 }
189
190 /*
191 * trio_is_special_quantity
192 */
193 TRIO_PRIVATE int
194 trio_is_special_quantity
195 TRIO_ARGS2((number, has_mantissa),
196 double number,
197 int *has_mantissa)
198 {
199 unsigned int i;
200 unsigned char current;
201 int is_special_quantity = TRIO_TRUE;
202
203 *has_mantissa = 0;
204
205 for (i = 0; i < (unsigned int)sizeof(double); i++) {
206 current = ((unsigned char *)&number)[TRIO_DOUBLE_INDEX(i)];
207 is_special_quantity
208 &= ((current & ieee_754_exponent_mask[i]) == ieee_754_exponent_mask[i]);
209 *has_mantissa |= (current & ieee_754_mantissa_mask[i]);
210 }
211 return is_special_quantity;
212 }
213
214 /*
215 * trio_is_negative
216 */
217 TRIO_PRIVATE int
218 trio_is_negative
219 TRIO_ARGS1((number),
220 double number)
221 {
222 unsigned int i;
223 int is_negative = TRIO_FALSE;
224
225 for (i = 0; i < (unsigned int)sizeof(double); i++) {
226 is_negative |= (((unsigned char *)&number)[TRIO_DOUBLE_INDEX(i)]
227 & ieee_754_sign_mask[i]);
228 }
229 return is_negative;
230 }
231
232 #endif /* USE_IEEE_754 */
233
234
235 /**
236 Generate negative zero.
237
238 @return Floating-point representation of negative zero.
239 */
240 TRIO_PUBLIC double
trio_nzero(TRIO_NOARGS)241 trio_nzero(TRIO_NOARGS)
242 {
243 #if defined(USE_IEEE_754)
244 return trio_make_double(ieee_754_negzero_array);
245 #else
246 TRIO_VOLATILE double zero = 0.0;
247
248 return -zero;
249 #endif
250 }
251
252 /**
253 Generate positive infinity.
254
255 @return Floating-point representation of positive infinity.
256 */
257 TRIO_PUBLIC double
trio_pinf(TRIO_NOARGS)258 trio_pinf(TRIO_NOARGS)
259 {
260 /* Cache the result */
261 static double result = 0.0;
262
263 if (result == 0.0) {
264
265 #if defined(INFINITY) && defined(__STDC_IEC_559__)
266 result = (double)INFINITY;
267
268 #elif defined(USE_IEEE_754)
269 result = trio_make_double(ieee_754_infinity_array);
270
271 #else
272 /*
273 * If HUGE_VAL is different from DBL_MAX, then HUGE_VAL is used
274 * as infinity. Otherwise we have to resort to an overflow
275 * operation to generate infinity.
276 */
277 # if defined(TRIO_PLATFORM_UNIX)
278 void (*signal_handler)(int) = signal(SIGFPE, SIG_IGN);
279 # endif
280
281 result = HUGE_VAL;
282 if (HUGE_VAL == DBL_MAX) {
283 /* Force overflow */
284 result += HUGE_VAL;
285 }
286
287 # if defined(TRIO_PLATFORM_UNIX)
288 signal(SIGFPE, signal_handler);
289 # endif
290
291 #endif
292 }
293 return result;
294 }
295
296 /**
297 Generate negative infinity.
298
299 @return Floating-point value of negative infinity.
300 */
301 TRIO_PUBLIC double
trio_ninf(TRIO_NOARGS)302 trio_ninf(TRIO_NOARGS)
303 {
304 static double result = 0.0;
305
306 if (result == 0.0) {
307 /*
308 * Negative infinity is calculated by negating positive infinity,
309 * which can be done because it is legal to do calculations on
310 * infinity (for example, 1 / infinity == 0).
311 */
312 result = -trio_pinf();
313 }
314 return result;
315 }
316
317 /**
318 Generate NaN.
319
320 @return Floating-point representation of NaN.
321 */
322 TRIO_PUBLIC double
trio_nan(TRIO_NOARGS)323 trio_nan(TRIO_NOARGS)
324 {
325 /* Cache the result */
326 static double result = 0.0;
327
328 if (result == 0.0) {
329
330 #if defined(TRIO_COMPILER_SUPPORTS_C99)
331 result = nan("");
332
333 #elif defined(NAN) && defined(__STDC_IEC_559__)
334 result = (double)NAN;
335
336 #elif defined(USE_IEEE_754)
337 result = trio_make_double(ieee_754_qnan_array);
338
339 #else
340 /*
341 * There are several ways to generate NaN. The one used here is
342 * to divide infinity by infinity. I would have preferred to add
343 * negative infinity to positive infinity, but that yields wrong
344 * result (infinity) on FreeBSD.
345 *
346 * This may fail if the hardware does not support NaN, or if
347 * the Invalid Operation floating-point exception is unmasked.
348 */
349 # if defined(TRIO_PLATFORM_UNIX)
350 void (*signal_handler)(int) = signal(SIGFPE, SIG_IGN);
351 # endif
352
353 result = trio_pinf() / trio_pinf();
354
355 # if defined(TRIO_PLATFORM_UNIX)
356 signal(SIGFPE, signal_handler);
357 # endif
358
359 #endif
360 }
361 return result;
362 }
363
364 /**
365 Check for NaN.
366
367 @param number An arbitrary floating-point number.
368 @return Boolean value indicating whether or not the number is a NaN.
369 */
370 TRIO_PUBLIC int
371 trio_isnan
372 TRIO_ARGS1((number),
373 double number)
374 {
375 #if (defined(TRIO_COMPILER_SUPPORTS_C99) && defined(isnan)) \
376 || defined(TRIO_COMPILER_SUPPORTS_UNIX95)
377 /*
378 * C99 defines isnan() as a macro. UNIX95 defines isnan() as a
379 * function. This function was already present in XPG4, but this
380 * is a bit tricky to detect with compiler defines, so we choose
381 * the conservative approach and only use it for UNIX95.
382 */
383 return isnan(number);
384
385 #elif defined(TRIO_COMPILER_MSVC) || defined(TRIO_COMPILER_BCB)
386 /*
387 * Microsoft Visual C++ and Borland C++ Builder have an _isnan()
388 * function.
389 */
390 return _isnan(number) ? TRIO_TRUE : TRIO_FALSE;
391
392 #elif defined(USE_IEEE_754)
393 /*
394 * Examine IEEE 754 bit-pattern. A NaN must have a special exponent
395 * pattern, and a non-empty mantissa.
396 */
397 int has_mantissa;
398 int is_special_quantity;
399
400 is_special_quantity = trio_is_special_quantity(number, &has_mantissa);
401
402 return (is_special_quantity && has_mantissa);
403
404 #else
405 /*
406 * Fallback solution
407 */
408 int status;
409 double integral, fraction;
410
411 # if defined(TRIO_PLATFORM_UNIX)
412 void (*signal_handler)(int) = signal(SIGFPE, SIG_IGN);
413 # endif
414
415 status = (/*
416 * NaN is the only number which does not compare to itself
417 */
418 ((TRIO_VOLATILE double)number != (TRIO_VOLATILE double)number) ||
419 /*
420 * Fallback solution if NaN compares to NaN
421 */
422 ((number != 0.0) &&
423 (fraction = modf(number, &integral),
424 integral == fraction)));
425
426 # if defined(TRIO_PLATFORM_UNIX)
427 signal(SIGFPE, signal_handler);
428 # endif
429
430 return status;
431
432 #endif
433 }
434
435 /**
436 Check for infinity.
437
438 @param number An arbitrary floating-point number.
439 @return 1 if positive infinity, -1 if negative infinity, 0 otherwise.
440 */
441 TRIO_PUBLIC int
442 trio_isinf
443 TRIO_ARGS1((number),
444 double number)
445 {
446 #if defined(TRIO_COMPILER_DECC) && !defined(__linux__)
447 /*
448 * DECC has an isinf() macro, but it works differently than that
449 * of C99, so we use the fp_class() function instead.
450 */
451 return ((fp_class(number) == FP_POS_INF)
452 ? 1
453 : ((fp_class(number) == FP_NEG_INF) ? -1 : 0));
454
455 #elif defined(isinf)
456 /*
457 * C99 defines isinf() as a macro.
458 */
459 return isinf(number)
460 ? ((number > 0.0) ? 1 : -1)
461 : 0;
462
463 #elif defined(TRIO_COMPILER_MSVC) || defined(TRIO_COMPILER_BCB)
464 /*
465 * Microsoft Visual C++ and Borland C++ Builder have an _fpclass()
466 * function that can be used to detect infinity.
467 */
468 return ((_fpclass(number) == _FPCLASS_PINF)
469 ? 1
470 : ((_fpclass(number) == _FPCLASS_NINF) ? -1 : 0));
471
472 #elif defined(USE_IEEE_754)
473 /*
474 * Examine IEEE 754 bit-pattern. Infinity must have a special exponent
475 * pattern, and an empty mantissa.
476 */
477 int has_mantissa;
478 int is_special_quantity;
479
480 is_special_quantity = trio_is_special_quantity(number, &has_mantissa);
481
482 return (is_special_quantity && !has_mantissa)
483 ? ((number < 0.0) ? -1 : 1)
484 : 0;
485
486 #else
487 /*
488 * Fallback solution.
489 */
490 int status;
491
492 # if defined(TRIO_PLATFORM_UNIX)
493 void (*signal_handler)(int) = signal(SIGFPE, SIG_IGN);
494 # endif
495
496 double infinity = trio_pinf();
497
498 status = ((number == infinity)
499 ? 1
500 : ((number == -infinity) ? -1 : 0));
501
502 # if defined(TRIO_PLATFORM_UNIX)
503 signal(SIGFPE, signal_handler);
504 # endif
505
506 return status;
507
508 #endif
509 }
510
511 #if 0
512 /* Temporary fix - this routine is not used anywhere */
513 /**
514 Check for finity.
515
516 @param number An arbitrary floating-point number.
517 @return Boolean value indicating whether or not the number is a finite.
518 */
519 TRIO_PUBLIC int
520 trio_isfinite
521 TRIO_ARGS1((number),
522 double number)
523 {
524 #if defined(TRIO_COMPILER_SUPPORTS_C99) && defined(isfinite)
525 /*
526 * C99 defines isfinite() as a macro.
527 */
528 return isfinite(number);
529
530 #elif defined(TRIO_COMPILER_MSVC) || defined(TRIO_COMPILER_BCB)
531 /*
532 * Microsoft Visual C++ and Borland C++ Builder use _finite().
533 */
534 return _finite(number);
535
536 #elif defined(USE_IEEE_754)
537 /*
538 * Examine IEEE 754 bit-pattern. For finity we do not care about the
539 * mantissa.
540 */
541 int dummy;
542
543 return (! trio_is_special_quantity(number, &dummy));
544
545 #else
546 /*
547 * Fallback solution.
548 */
549 return ((trio_isinf(number) == 0) && (trio_isnan(number) == 0));
550
551 #endif
552 }
553
554 #endif
555
556 /*
557 * The sign of NaN is always false
558 */
559 TRIO_PUBLIC int
560 trio_fpclassify_and_signbit
561 TRIO_ARGS2((number, is_negative),
562 double number,
563 int *is_negative)
564 {
565 #if defined(fpclassify) && defined(signbit)
566 /*
567 * C99 defines fpclassify() and signbit() as a macros
568 */
569 *is_negative = signbit(number);
570 switch (fpclassify(number)) {
571 case FP_NAN:
572 return TRIO_FP_NAN;
573 case FP_INFINITE:
574 return TRIO_FP_INFINITE;
575 case FP_SUBNORMAL:
576 return TRIO_FP_SUBNORMAL;
577 case FP_ZERO:
578 return TRIO_FP_ZERO;
579 default:
580 return TRIO_FP_NORMAL;
581 }
582
583 #else
584 # if defined(TRIO_COMPILER_DECC)
585 /*
586 * DECC has an fp_class() function.
587 */
588 # define TRIO_FPCLASSIFY(n) fp_class(n)
589 # define TRIO_QUIET_NAN FP_QNAN
590 # define TRIO_SIGNALLING_NAN FP_SNAN
591 # define TRIO_POSITIVE_INFINITY FP_POS_INF
592 # define TRIO_NEGATIVE_INFINITY FP_NEG_INF
593 # define TRIO_POSITIVE_SUBNORMAL FP_POS_DENORM
594 # define TRIO_NEGATIVE_SUBNORMAL FP_NEG_DENORM
595 # define TRIO_POSITIVE_ZERO FP_POS_ZERO
596 # define TRIO_NEGATIVE_ZERO FP_NEG_ZERO
597 # define TRIO_POSITIVE_NORMAL FP_POS_NORM
598 # define TRIO_NEGATIVE_NORMAL FP_NEG_NORM
599
600 # elif defined(TRIO_COMPILER_MSVC) || defined(TRIO_COMPILER_BCB)
601 /*
602 * Microsoft Visual C++ and Borland C++ Builder have an _fpclass()
603 * function.
604 */
605 # define TRIO_FPCLASSIFY(n) _fpclass(n)
606 # define TRIO_QUIET_NAN _FPCLASS_QNAN
607 # define TRIO_SIGNALLING_NAN _FPCLASS_SNAN
608 # define TRIO_POSITIVE_INFINITY _FPCLASS_PINF
609 # define TRIO_NEGATIVE_INFINITY _FPCLASS_NINF
610 # define TRIO_POSITIVE_SUBNORMAL _FPCLASS_PD
611 # define TRIO_NEGATIVE_SUBNORMAL _FPCLASS_ND
612 # define TRIO_POSITIVE_ZERO _FPCLASS_PZ
613 # define TRIO_NEGATIVE_ZERO _FPCLASS_NZ
614 # define TRIO_POSITIVE_NORMAL _FPCLASS_PN
615 # define TRIO_NEGATIVE_NORMAL _FPCLASS_NN
616
617 # elif defined(FP_PLUS_NORM)
618 /*
619 * HP-UX 9.x and 10.x have an fpclassify() function, that is different
620 * from the C99 fpclassify() macro supported on HP-UX 11.x.
621 *
622 * AIX has class() for C, and _class() for C++, which returns the
623 * same values as the HP-UX fpclassify() function.
624 */
625 # if defined(TRIO_PLATFORM_AIX)
626 # if defined(__cplusplus)
627 # define TRIO_FPCLASSIFY(n) _class(n)
628 # else
629 # define TRIO_FPCLASSIFY(n) class(n)
630 # endif
631 # else
632 # define TRIO_FPCLASSIFY(n) fpclassify(n)
633 # endif
634 # define TRIO_QUIET_NAN FP_QNAN
635 # define TRIO_SIGNALLING_NAN FP_SNAN
636 # define TRIO_POSITIVE_INFINITY FP_PLUS_INF
637 # define TRIO_NEGATIVE_INFINITY FP_MINUS_INF
638 # define TRIO_POSITIVE_SUBNORMAL FP_PLUS_DENORM
639 # define TRIO_NEGATIVE_SUBNORMAL FP_MINUS_DENORM
640 # define TRIO_POSITIVE_ZERO FP_PLUS_ZERO
641 # define TRIO_NEGATIVE_ZERO FP_MINUS_ZERO
642 # define TRIO_POSITIVE_NORMAL FP_PLUS_NORM
643 # define TRIO_NEGATIVE_NORMAL FP_MINUS_NORM
644 # endif
645
646 # if defined(TRIO_FPCLASSIFY)
647 switch (TRIO_FPCLASSIFY(number)) {
648 case TRIO_QUIET_NAN:
649 case TRIO_SIGNALLING_NAN:
650 *is_negative = TRIO_FALSE; /* NaN has no sign */
651 return TRIO_FP_NAN;
652 case TRIO_POSITIVE_INFINITY:
653 *is_negative = TRIO_FALSE;
654 return TRIO_FP_INFINITE;
655 case TRIO_NEGATIVE_INFINITY:
656 *is_negative = TRIO_TRUE;
657 return TRIO_FP_INFINITE;
658 case TRIO_POSITIVE_SUBNORMAL:
659 *is_negative = TRIO_FALSE;
660 return TRIO_FP_SUBNORMAL;
661 case TRIO_NEGATIVE_SUBNORMAL:
662 *is_negative = TRIO_TRUE;
663 return TRIO_FP_SUBNORMAL;
664 case TRIO_POSITIVE_ZERO:
665 *is_negative = TRIO_FALSE;
666 return TRIO_FP_ZERO;
667 case TRIO_NEGATIVE_ZERO:
668 *is_negative = TRIO_TRUE;
669 return TRIO_FP_ZERO;
670 case TRIO_POSITIVE_NORMAL:
671 *is_negative = TRIO_FALSE;
672 return TRIO_FP_NORMAL;
673 case TRIO_NEGATIVE_NORMAL:
674 *is_negative = TRIO_TRUE;
675 return TRIO_FP_NORMAL;
676 default:
677 /* Just in case... */
678 *is_negative = (number < 0.0);
679 return TRIO_FP_NORMAL;
680 }
681
682 # else
683 /*
684 * Fallback solution.
685 */
686 int rc;
687
688 if (number == 0.0) {
689 /*
690 * In IEEE 754 the sign of zero is ignored in comparisons, so we
691 * have to handle this as a special case by examining the sign bit
692 * directly.
693 */
694 # if defined(USE_IEEE_754)
695 *is_negative = trio_is_negative(number);
696 # else
697 *is_negative = TRIO_FALSE; /* FIXME */
698 # endif
699 return TRIO_FP_ZERO;
700 }
701 if (trio_isnan(number)) {
702 *is_negative = TRIO_FALSE;
703 return TRIO_FP_NAN;
704 }
705 if ((rc = trio_isinf(number))) {
706 *is_negative = (rc == -1);
707 return TRIO_FP_INFINITE;
708 }
709 if ((number > 0.0) && (number < DBL_MIN)) {
710 *is_negative = TRIO_FALSE;
711 return TRIO_FP_SUBNORMAL;
712 }
713 if ((number < 0.0) && (number > -DBL_MIN)) {
714 *is_negative = TRIO_TRUE;
715 return TRIO_FP_SUBNORMAL;
716 }
717 *is_negative = (number < 0.0);
718 return TRIO_FP_NORMAL;
719
720 # endif
721 #endif
722 }
723
724 /**
725 Examine the sign of a number.
726
727 @param number An arbitrary floating-point number.
728 @return Boolean value indicating whether or not the number has the
729 sign bit set (i.e. is negative).
730 */
731 TRIO_PUBLIC int
732 trio_signbit
733 TRIO_ARGS1((number),
734 double number)
735 {
736 int is_negative;
737
738 (void)trio_fpclassify_and_signbit(number, &is_negative);
739 return is_negative;
740 }
741
742 #if 0
743 /* Temporary fix - this routine is not used in libxml */
744 /**
745 Examine the class of a number.
746
747 @param number An arbitrary floating-point number.
748 @return Enumerable value indicating the class of @p number
749 */
750 TRIO_PUBLIC int
751 trio_fpclassify
752 TRIO_ARGS1((number),
753 double number)
754 {
755 int dummy;
756
757 return trio_fpclassify_and_signbit(number, &dummy);
758 }
759
760 #endif
761
762 /** @} SpecialQuantities */
763
764 /*************************************************************************
765 * For test purposes.
766 *
767 * Add the following compiler option to include this test code.
768 *
769 * Unix : -DSTANDALONE
770 * VMS : /DEFINE=(STANDALONE)
771 */
772 #if defined(STANDALONE)
773 # include <stdio.h>
774
775 static TRIO_CONST char *
776 getClassification
777 TRIO_ARGS1((type),
778 int type)
779 {
780 switch (type) {
781 case TRIO_FP_INFINITE:
782 return "FP_INFINITE";
783 case TRIO_FP_NAN:
784 return "FP_NAN";
785 case TRIO_FP_NORMAL:
786 return "FP_NORMAL";
787 case TRIO_FP_SUBNORMAL:
788 return "FP_SUBNORMAL";
789 case TRIO_FP_ZERO:
790 return "FP_ZERO";
791 default:
792 return "FP_UNKNOWN";
793 }
794 }
795
796 static void
797 print_class
798 TRIO_ARGS2((prefix, number),
799 TRIO_CONST char *prefix,
800 double number)
801 {
802 printf("%-6s: %s %-15s %g\n",
803 prefix,
804 trio_signbit(number) ? "-" : "+",
805 getClassification(TRIO_FPCLASSIFY(number)),
806 number);
807 }
808
main(TRIO_NOARGS)809 int main(TRIO_NOARGS)
810 {
811 double my_nan;
812 double my_pinf;
813 double my_ninf;
814 # if defined(TRIO_PLATFORM_UNIX)
815 void (*signal_handler) TRIO_PROTO((int));
816 # endif
817
818 my_nan = trio_nan();
819 my_pinf = trio_pinf();
820 my_ninf = trio_ninf();
821
822 print_class("Nan", my_nan);
823 print_class("PInf", my_pinf);
824 print_class("NInf", my_ninf);
825 print_class("PZero", 0.0);
826 print_class("NZero", -0.0);
827 print_class("PNorm", 1.0);
828 print_class("NNorm", -1.0);
829 print_class("PSub", 1.01e-307 - 1.00e-307);
830 print_class("NSub", 1.00e-307 - 1.01e-307);
831
832 printf("NaN : %4g 0x%02x%02x%02x%02x%02x%02x%02x%02x (%2d, %2d)\n",
833 my_nan,
834 ((unsigned char *)&my_nan)[0],
835 ((unsigned char *)&my_nan)[1],
836 ((unsigned char *)&my_nan)[2],
837 ((unsigned char *)&my_nan)[3],
838 ((unsigned char *)&my_nan)[4],
839 ((unsigned char *)&my_nan)[5],
840 ((unsigned char *)&my_nan)[6],
841 ((unsigned char *)&my_nan)[7],
842 trio_isnan(my_nan), trio_isinf(my_nan));
843 printf("PInf: %4g 0x%02x%02x%02x%02x%02x%02x%02x%02x (%2d, %2d)\n",
844 my_pinf,
845 ((unsigned char *)&my_pinf)[0],
846 ((unsigned char *)&my_pinf)[1],
847 ((unsigned char *)&my_pinf)[2],
848 ((unsigned char *)&my_pinf)[3],
849 ((unsigned char *)&my_pinf)[4],
850 ((unsigned char *)&my_pinf)[5],
851 ((unsigned char *)&my_pinf)[6],
852 ((unsigned char *)&my_pinf)[7],
853 trio_isnan(my_pinf), trio_isinf(my_pinf));
854 printf("NInf: %4g 0x%02x%02x%02x%02x%02x%02x%02x%02x (%2d, %2d)\n",
855 my_ninf,
856 ((unsigned char *)&my_ninf)[0],
857 ((unsigned char *)&my_ninf)[1],
858 ((unsigned char *)&my_ninf)[2],
859 ((unsigned char *)&my_ninf)[3],
860 ((unsigned char *)&my_ninf)[4],
861 ((unsigned char *)&my_ninf)[5],
862 ((unsigned char *)&my_ninf)[6],
863 ((unsigned char *)&my_ninf)[7],
864 trio_isnan(my_ninf), trio_isinf(my_ninf));
865
866 # if defined(TRIO_PLATFORM_UNIX)
867 signal_handler = signal(SIGFPE, SIG_IGN);
868 # endif
869
870 my_pinf = DBL_MAX + DBL_MAX;
871 my_ninf = -my_pinf;
872 my_nan = my_pinf / my_pinf;
873
874 # if defined(TRIO_PLATFORM_UNIX)
875 signal(SIGFPE, signal_handler);
876 # endif
877
878 printf("NaN : %4g 0x%02x%02x%02x%02x%02x%02x%02x%02x (%2d, %2d)\n",
879 my_nan,
880 ((unsigned char *)&my_nan)[0],
881 ((unsigned char *)&my_nan)[1],
882 ((unsigned char *)&my_nan)[2],
883 ((unsigned char *)&my_nan)[3],
884 ((unsigned char *)&my_nan)[4],
885 ((unsigned char *)&my_nan)[5],
886 ((unsigned char *)&my_nan)[6],
887 ((unsigned char *)&my_nan)[7],
888 trio_isnan(my_nan), trio_isinf(my_nan));
889 printf("PInf: %4g 0x%02x%02x%02x%02x%02x%02x%02x%02x (%2d, %2d)\n",
890 my_pinf,
891 ((unsigned char *)&my_pinf)[0],
892 ((unsigned char *)&my_pinf)[1],
893 ((unsigned char *)&my_pinf)[2],
894 ((unsigned char *)&my_pinf)[3],
895 ((unsigned char *)&my_pinf)[4],
896 ((unsigned char *)&my_pinf)[5],
897 ((unsigned char *)&my_pinf)[6],
898 ((unsigned char *)&my_pinf)[7],
899 trio_isnan(my_pinf), trio_isinf(my_pinf));
900 printf("NInf: %4g 0x%02x%02x%02x%02x%02x%02x%02x%02x (%2d, %2d)\n",
901 my_ninf,
902 ((unsigned char *)&my_ninf)[0],
903 ((unsigned char *)&my_ninf)[1],
904 ((unsigned char *)&my_ninf)[2],
905 ((unsigned char *)&my_ninf)[3],
906 ((unsigned char *)&my_ninf)[4],
907 ((unsigned char *)&my_ninf)[5],
908 ((unsigned char *)&my_ninf)[6],
909 ((unsigned char *)&my_ninf)[7],
910 trio_isnan(my_ninf), trio_isinf(my_ninf));
911
912 return 0;
913 }
914 #endif
915