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trionan.c

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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	* MERCHANTABILITY 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 (amongst 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	* endianness by the compiler, which means that we can support any
127	* kind of endianness. 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
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
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
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
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
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

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source: vbox/trunk/src/libs/libxml2-2.12.6/trionan.c

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