1/****************************************************************
2
3The author of this software is David M. Gay.
4
5Copyright (C) 2005 by David M. Gay
6All Rights Reserved
7
8Permission to use, copy, modify, and distribute this software and its
9documentation for any purpose and without fee is hereby granted,
10provided that the above copyright notice appear in all copies and that
11both that the copyright notice and this permission notice and warranty
12disclaimer appear in supporting documentation, and that the name of
13the author or any of his current or former employers not be used in
14advertising or publicity pertaining to distribution of the software
15without specific, written prior permission.
16
17THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
18INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.  IN
19NO EVENT SHALL THE AUTHOR OR ANY OF HIS CURRENT OR FORMER EMPLOYERS BE
20LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY
21DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
22WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
23ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
24SOFTWARE.
25
26****************************************************************/
27
28/* Please send bug reports to David M. Gay (dmg at acm dot org,
29 * with " at " changed at "@" and " dot " changed to ".").	*/
30
31/* Program to compute quiet NaNs of various precisions (float,	*/
32/* double, and perhaps long double) on the current system,	*/
33/* provided the system uses binary IEEE (P754) arithmetic.	*/
34/* Note that one system's quiet NaN may be a signaling NaN on	*/
35/* another system.  The IEEE arithmetic standards (P754, P854)	*/
36/* do not specify how to distinguish signaling NaNs from quiet	*/
37/* ones, and this detail varies across systems.	 The computed	*/
38/* NaN values are encoded in #defines for values for an		*/
39/* unsigned 32-bit integer type, called Ulong below, and	*/
40/* (for long double) perhaps as unsigned short values.  Once	*/
41/* upon a time, there were PC compilers for Intel CPUs that	*/
42/* had sizeof(long double) = 10.  Are such compilers still	*/
43/* distributed?							*/
44
45#include <stdio.h>
46#include "arith.h"
47
48#ifndef Long
49#define Long long
50#endif
51
52typedef unsigned Long Ulong;
53
54#undef HAVE_IEEE
55#ifdef IEEE_8087
56#define _0 1
57#define _1 0
58#define HAVE_IEEE
59#endif
60#ifdef IEEE_MC68k
61#define _0 0
62#define _1 1
63#define HAVE_IEEE
64#endif
65
66#define UL (unsigned long)
67
68 int
69main(void)
70{
71#ifdef HAVE_IEEE
72	typedef union {
73		float f;
74		double d;
75		Ulong L[4];
76#ifndef NO_LONG_LONG
77		unsigned short u[5];
78		long double D;
79#endif
80		} U;
81	U a, b, c;
82	int i;
83
84	a.L[0] = b.L[0] = 0x7f800000;
85	c.f = a.f - b.f;
86	printf("#define f_QNAN 0x%lx\n", UL c.L[0]);
87	a.L[_0] = b.L[_0] = 0x7ff00000;
88	a.L[_1] = b.L[_1] = 0;
89	c.d = a.d - b.d;	/* quiet NaN */
90	printf("#define d_QNAN0 0x%lx\n", UL c.L[0]);
91	printf("#define d_QNAN1 0x%lx\n", UL c.L[1]);
92#ifdef NO_LONG_LONG
93	for(i = 0; i < 4; i++)
94		printf("#define ld_QNAN%d 0xffffffff\n", i);
95	for(i = 0; i < 5; i++)
96		printf("#define ldus_QNAN%d 0xffff\n", i);
97#else
98	b.D = c.D = a.d;
99	if (printf("") < 0)
100		c.D = 37;	/* never executed; just defeat optimization */
101	a.L[2] = a.L[3] = 0;
102	a.D = b.D - c.D;
103	for(i = 0; i < 4; i++)
104		printf("#define ld_QNAN%d 0x%lx\n", i, UL a.L[i]);
105	for(i = 0; i < 5; i++)
106		printf("#define ldus_QNAN%d 0x%x\n", i, a.u[i]);
107#endif
108#endif /* HAVE_IEEE */
109	return 0;
110	}
111