1 /* $NetBSD: qnan.c,v 1.2 2006/01/25 15:27:42 kleink Exp $ */ 2 3 /**************************************************************** 4 5 The author of this software is David M. Gay. 6 7 Copyright (C) 2005 by David M. Gay 8 All Rights Reserved 9 10 Permission to use, copy, modify, and distribute this software and its 11 documentation for any purpose and without fee is hereby granted, 12 provided that the above copyright notice appear in all copies and that 13 both that the copyright notice and this permission notice and warranty 14 disclaimer appear in supporting documentation, and that the name of 15 the author or any of his current or former employers not be used in 16 advertising or publicity pertaining to distribution of the software 17 without specific, written prior permission. 18 19 THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, 20 INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN 21 NO EVENT SHALL THE AUTHOR OR ANY OF HIS CURRENT OR FORMER EMPLOYERS BE 22 LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY 23 DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, 24 WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, 25 ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 26 SOFTWARE. 27 28 ****************************************************************/ 29 30 /* Please send bug reports to David M. Gay (dmg at acm dot org, 31 * with " at " changed at "@" and " dot " changed to "."). */ 32 33 /* Program to compute quiet NaNs of various precisions (float, */ 34 /* double, and perhaps long double) on the current system, */ 35 /* provided the system uses binary IEEE (P754) arithmetic. */ 36 /* Note that one system's quiet NaN may be a signaling NaN on */ 37 /* another system. The IEEE arithmetic standards (P754, P854) */ 38 /* do not specify how to distinguish signaling NaNs from quiet */ 39 /* ones, and this detail varies across systems. The computed */ 40 /* NaN values are encoded in #defines for values for an */ 41 /* unsigned 32-bit integer type, called Ulong below, and */ 42 /* (for long double) perhaps as unsigned short values. Once */ 43 /* upon a time, there were PC compilers for Intel CPUs that */ 44 /* had sizeof(long double) = 10. Are such compilers still */ 45 /* distributed? */ 46 47 #include <stdio.h> 48 #include "arith.h" 49 50 #ifndef Long 51 #define Long long 52 #endif 53 54 typedef unsigned Long Ulong; 55 56 #undef HAVE_IEEE 57 #ifdef IEEE_LITTLE_ENDIAN 58 #define _0 1 59 #define _1 0 60 #define HAVE_IEEE 61 #endif 62 #ifdef IEEE_BIG_ENDIAN 63 #define _0 0 64 #define _1 1 65 #define HAVE_IEEE 66 #endif 67 68 #define UL (unsigned long) 69 70 int 71 main(void) 72 { 73 #ifdef HAVE_IEEE 74 typedef union { 75 float f; 76 double d; 77 Ulong L[4]; 78 #ifndef NO_LONG_LONG 79 unsigned short u[5]; 80 long double D; 81 #endif 82 } U; 83 U a, b, c; 84 int i; 85 86 a.L[0] = b.L[0] = 0x7f800000; 87 c.f = a.f - b.f; 88 printf("#define f_QNAN 0x%lx\n", UL c.L[0]); 89 a.L[_0] = b.L[_0] = 0x7ff00000; 90 a.L[_1] = b.L[_1] = 0; 91 c.d = a.d - b.d; /* quiet NaN */ 92 printf("#define d_QNAN0 0x%lx\n", UL c.L[0]); 93 printf("#define d_QNAN1 0x%lx\n", UL c.L[1]); 94 #ifdef NO_LONG_LONG 95 for(i = 0; i < 4; i++) 96 printf("#define ld_QNAN%d 0xffffffff\n", i); 97 for(i = 0; i < 5; i++) 98 printf("#define ldus_QNAN%d 0xffff\n", i); 99 #else 100 b.D = c.D = a.d; 101 if (printf("") < 0) 102 c.D = 37; /* never executed; just defeat optimization */ 103 a.L[2] = a.L[3] = 0; 104 a.D = b.D - c.D; 105 for(i = 0; i < 4; i++) 106 printf("#define ld_QNAN%d 0x%lx\n", i, UL a.L[i]); 107 for(i = 0; i < 5; i++) 108 printf("#define ldus_QNAN%d 0x%x\n", i, a.u[i]); 109 #endif 110 #endif /* HAVE_IEEE */ 111 return 0; 112 } 113