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Diffstat (limited to 'contrib/gdtoa/qnan.c')
| -rw-r--r-- | contrib/gdtoa/qnan.c | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/contrib/gdtoa/qnan.c b/contrib/gdtoa/qnan.c new file mode 100644 index 0000000..118e749 --- /dev/null +++ b/contrib/gdtoa/qnan.c @@ -0,0 +1,110 @@ +/**************************************************************** + +The author of this software is David M. Gay. + +Copyright (C) 2005 by David M. Gay +All Rights Reserved + +Permission to use, copy, modify, and distribute this software and its +documentation for any purpose and without fee is hereby granted, +provided that the above copyright notice appear in all copies and that +both that the copyright notice and this permission notice and warranty +disclaimer appear in supporting documentation, and that the name of +the author or any of his current or former employers not be used in +advertising or publicity pertaining to distribution of the software +without specific, written prior permission. + +THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, +INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN +NO EVENT SHALL THE AUTHOR OR ANY OF HIS CURRENT OR FORMER EMPLOYERS BE +LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY +DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, +WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, +ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS +SOFTWARE. + +****************************************************************/ + +/* Please send bug reports to David M. Gay (dmg at acm dot org, + * with " at " changed at "@" and " dot " changed to "."). */ + +/* Program to compute quiet NaNs of various precisions (float, */ +/* double, and perhaps long double) on the current system, */ +/* provided the system uses binary IEEE (P754) arithmetic. */ +/* Note that one system's quiet NaN may be a signaling NaN on */ +/* another system. The IEEE arithmetic standards (P754, P854) */ +/* do not specify how to distinguish signaling NaNs from quiet */ +/* ones, and this detail varies across systems. The computed */ +/* NaN values are encoded in #defines for values for an */ +/* unsigned 32-bit integer type, called Ulong below, and */ +/* (for long double) perhaps as unsigned short values. Once */ +/* upon a time, there were PC compilers for Intel CPUs that */ +/* had sizeof(long double) = 10. Are such compilers still */ +/* distributed? */ + +#include <stdio.h> +#include "arith.h" + +#ifndef Long +#define Long long +#endif + +typedef unsigned Long Ulong; + +#undef HAVE_IEEE +#ifdef IEEE_8087 +#define _0 1 +#define _1 0 +#define HAVE_IEEE +#endif +#ifdef IEEE_MC68k +#define _0 0 +#define _1 1 +#define HAVE_IEEE +#endif + +#define UL (unsigned long) + + int +main(void) +{ +#ifdef HAVE_IEEE + typedef union { + float f; + double d; + Ulong L[4]; +#ifndef NO_LONG_LONG + unsigned short u[5]; + long double D; +#endif + } U; + U a, b, c; + int i; + + a.L[0] = b.L[0] = 0x7f800000; + c.f = a.f - b.f; + printf("#define f_QNAN 0x%lx\n", UL c.L[0]); + a.L[_0] = b.L[_0] = 0x7ff00000; + a.L[_1] = b.L[_1] = 0; + c.d = a.d - b.d; /* quiet NaN */ + printf("#define d_QNAN0 0x%lx\n", UL c.L[0]); + printf("#define d_QNAN1 0x%lx\n", UL c.L[1]); +#ifdef NO_LONG_LONG + for(i = 0; i < 4; i++) + printf("#define ld_QNAN%d 0xffffffff\n", i); + for(i = 0; i < 5; i++) + printf("#define ldus_QNAN%d 0xffff\n", i); +#else + b.D = c.D = a.d; + if (printf("") < 0) + c.D = 37; /* never executed; just defeat optimization */ + a.L[2] = a.L[3] = 0; + a.D = b.D - c.D; + for(i = 0; i < 4; i++) + printf("#define ld_QNAN%d 0x%lx\n", i, UL a.L[i]); + for(i = 0; i < 5; i++) + printf("#define ldus_QNAN%d 0x%x\n", i, a.u[i]); +#endif +#endif /* HAVE_IEEE */ + return 0; + } |
