win32/3rdparty/libxml2/trionan.c
8cf9b527
 /*************************************************************************
  *
  * $Id$
  *
  * Copyright (C) 2001 Bjorn Reese <breese@users.sourceforge.net>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
  * copyright notice and this permission notice appear in all copies.
  *
  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  * MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE AUTHORS AND
  * CONTRIBUTORS ACCEPT NO RESPONSIBILITY IN ANY CONCEIVABLE MANNER.
  *
  ************************************************************************
  *
  * Functions to handle special quantities in floating-point numbers
  * (that is, NaNs and infinity). They provide the capability to detect
  * and fabricate special quantities.
  *
  * Although written to be as portable as possible, it can never be
  * guaranteed to work on all platforms, as not all hardware supports
  * special quantities.
  *
  * The approach used here (approximately) is to:
  *
  *   1. Use C99 functionality when available.
  *   2. Use IEEE 754 bit-patterns if possible.
  *   3. Use platform-specific techniques.
  *
  ************************************************************************/
 
 /*
  * TODO:
  *  o Put all the magic into trio_fpclassify_and_signbit(), and use this from
  *    trio_isnan() etc.
  */
 
 /*************************************************************************
  * Include files
  */
 #include "triodef.h"
 #include "trionan.h"
 
 #include <math.h>
 #include <string.h>
 #include <limits.h>
 #include <float.h>
 #if defined(TRIO_PLATFORM_UNIX)
 # include <signal.h>
 #endif
 #if defined(TRIO_COMPILER_DECC)
 #  if defined(__linux__)
 #   include <cpml.h>
 #  else
 #   include <fp_class.h>
 #  endif
 #endif
 #include <assert.h>
 
 #if defined(TRIO_DOCUMENTATION)
 # include "doc/doc_nan.h"
 #endif
 /** @addtogroup SpecialQuantities
     @{
 */
 
 /*************************************************************************
  * Definitions
  */
 
 #define TRIO_TRUE (1 == 1)
 #define TRIO_FALSE (0 == 1)
 
 /*
  * We must enable IEEE floating-point on Alpha
  */
 #if defined(__alpha) && !defined(_IEEE_FP)
 # if defined(TRIO_COMPILER_DECC)
 #  if defined(TRIO_PLATFORM_VMS)
 #   error "Must be compiled with option /IEEE_MODE=UNDERFLOW_TO_ZERO/FLOAT=IEEE"
 #  else
 #   if !defined(_CFE)
 #    error "Must be compiled with option -ieee"
 #   endif
 #  endif
 # elif defined(TRIO_COMPILER_GCC) && (defined(__osf__) || defined(__linux__))
 #  error "Must be compiled with option -mieee"
 # endif
 #endif /* __alpha && ! _IEEE_FP */
 
 /*
  * In ANSI/IEEE 754-1985 64-bits double format numbers have the
  * following properties (amoungst others)
  *
  *   o FLT_RADIX == 2: binary encoding
  *   o DBL_MAX_EXP == 1024: 11 bits exponent, where one bit is used
  *     to indicate special numbers (e.g. NaN and Infinity), so the
  *     maximum exponent is 10 bits wide (2^10 == 1024).
  *   o DBL_MANT_DIG == 53: The mantissa is 52 bits wide, but because
  *     numbers are normalized the initial binary 1 is represented
  *     implicitly (the so-called "hidden bit"), which leaves us with
  *     the ability to represent 53 bits wide mantissa.
  */
 #if (FLT_RADIX == 2) && (DBL_MAX_EXP == 1024) && (DBL_MANT_DIG == 53)
 # define USE_IEEE_754
 #endif
 
 
 /*************************************************************************
  * Constants
  */
 
 static TRIO_CONST char rcsid[] = "@(#)$Id$";
 
 #if defined(USE_IEEE_754)
 
 /*
  * Endian-agnostic indexing macro.
  *
  * The value of internalEndianMagic, when converted into a 64-bit
  * integer, becomes 0x0706050403020100 (we could have used a 64-bit
  * integer value instead of a double, but not all platforms supports
  * that type). The value is automatically encoded with the correct
  * endianess by the compiler, which means that we can support any
  * kind of endianess. The individual bytes are then used as an index
  * for the IEEE 754 bit-patterns and masks.
  */
 #define TRIO_DOUBLE_INDEX(x) (((unsigned char *)&internalEndianMagic)[7-(x)])
 
 #if (defined(__BORLANDC__) && __BORLANDC__ >= 0x0590)
 static TRIO_CONST double internalEndianMagic = 7.949928895127362e-275;
 #else
 static TRIO_CONST double internalEndianMagic = 7.949928895127363e-275;
 #endif
 
 /* Mask for the exponent */
 static TRIO_CONST unsigned char ieee_754_exponent_mask[] = {
   0x7F, 0xF0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
 };
 
 /* Mask for the mantissa */
 static TRIO_CONST unsigned char ieee_754_mantissa_mask[] = {
   0x00, 0x0F, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
 };
 
 /* Mask for the sign bit */
 static TRIO_CONST unsigned char ieee_754_sign_mask[] = {
   0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
 };
 
 /* Bit-pattern for negative zero */
 static TRIO_CONST unsigned char ieee_754_negzero_array[] = {
   0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
 };
 
 /* Bit-pattern for infinity */
 static TRIO_CONST unsigned char ieee_754_infinity_array[] = {
   0x7F, 0xF0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
 };
 
 /* Bit-pattern for quiet NaN */
 static TRIO_CONST unsigned char ieee_754_qnan_array[] = {
   0x7F, 0xF8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
 };
 
 
 /*************************************************************************
  * Functions
  */
 
 /*
  * trio_make_double
  */
 TRIO_PRIVATE double
 trio_make_double
 TRIO_ARGS1((values),
 	   TRIO_CONST unsigned char *values)
 {
   TRIO_VOLATILE double result;
   int i;
 
   for (i = 0; i < (int)sizeof(double); i++) {
     ((TRIO_VOLATILE unsigned char *)&result)[TRIO_DOUBLE_INDEX(i)] = values[i];
   }
   return result;
 }
 
 /*
  * trio_is_special_quantity
  */
 TRIO_PRIVATE int
 trio_is_special_quantity
 TRIO_ARGS2((number, has_mantissa),
 	   double number,
 	   int *has_mantissa)
 {
   unsigned int i;
   unsigned char current;
   int is_special_quantity = TRIO_TRUE;
 
   *has_mantissa = 0;
 
   for (i = 0; i < (unsigned int)sizeof(double); i++) {
     current = ((unsigned char *)&number)[TRIO_DOUBLE_INDEX(i)];
     is_special_quantity
       &= ((current & ieee_754_exponent_mask[i]) == ieee_754_exponent_mask[i]);
     *has_mantissa |= (current & ieee_754_mantissa_mask[i]);
   }
   return is_special_quantity;
 }
 
 /*
  * trio_is_negative
  */
 TRIO_PRIVATE int
 trio_is_negative
 TRIO_ARGS1((number),
 	   double number)
 {
   unsigned int i;
   int is_negative = TRIO_FALSE;
 
   for (i = 0; i < (unsigned int)sizeof(double); i++) {
     is_negative |= (((unsigned char *)&number)[TRIO_DOUBLE_INDEX(i)]
 		    & ieee_754_sign_mask[i]);
   }
   return is_negative;
 }
 
 #endif /* USE_IEEE_754 */
 
 
 /**
    Generate negative zero.
 
    @return Floating-point representation of negative zero.
 */
 TRIO_PUBLIC double
 trio_nzero(TRIO_NOARGS)
 {
 #if defined(USE_IEEE_754)
   return trio_make_double(ieee_754_negzero_array);
 #else
   TRIO_VOLATILE double zero = 0.0;
 
   return -zero;
 #endif
 }
 
 /**
    Generate positive infinity.
 
    @return Floating-point representation of positive infinity.
 */
 TRIO_PUBLIC double
 trio_pinf(TRIO_NOARGS)
 {
   /* Cache the result */
   static double result = 0.0;
 
   if (result == 0.0) {
 
 #if defined(INFINITY) && defined(__STDC_IEC_559__)
     result = (double)INFINITY;
 
 #elif defined(USE_IEEE_754)
     result = trio_make_double(ieee_754_infinity_array);
 
 #else
     /*
      * If HUGE_VAL is different from DBL_MAX, then HUGE_VAL is used
      * as infinity. Otherwise we have to resort to an overflow
      * operation to generate infinity.
      */
 # if defined(TRIO_PLATFORM_UNIX)
     void (*signal_handler)(int) = signal(SIGFPE, SIG_IGN);
 # endif
 
     result = HUGE_VAL;
     if (HUGE_VAL == DBL_MAX) {
       /* Force overflow */
       result += HUGE_VAL;
     }
 
 # if defined(TRIO_PLATFORM_UNIX)
     signal(SIGFPE, signal_handler);
 # endif
 
 #endif
   }
   return result;
 }
 
 /**
    Generate negative infinity.
 
    @return Floating-point value of negative infinity.
 */
 TRIO_PUBLIC double
 trio_ninf(TRIO_NOARGS)
 {
   static double result = 0.0;
 
   if (result == 0.0) {
     /*
      * Negative infinity is calculated by negating positive infinity,
      * which can be done because it is legal to do calculations on
      * infinity (for example,  1 / infinity == 0).
      */
     result = -trio_pinf();
   }
   return result;
 }
 
 /**
    Generate NaN.
 
    @return Floating-point representation of NaN.
 */
 TRIO_PUBLIC double
 trio_nan(TRIO_NOARGS)
 {
   /* Cache the result */
   static double result = 0.0;
 
   if (result == 0.0) {
 
 #if defined(TRIO_COMPILER_SUPPORTS_C99)
     result = nan("");
 
 #elif defined(NAN) && defined(__STDC_IEC_559__)
     result = (double)NAN;
 
 #elif defined(USE_IEEE_754)
     result = trio_make_double(ieee_754_qnan_array);
 
 #else
     /*
      * There are several ways to generate NaN. The one used here is
      * to divide infinity by infinity. I would have preferred to add
      * negative infinity to positive infinity, but that yields wrong
      * result (infinity) on FreeBSD.
      *
      * This may fail if the hardware does not support NaN, or if
      * the Invalid Operation floating-point exception is unmasked.
      */
 # if defined(TRIO_PLATFORM_UNIX)
     void (*signal_handler)(int) = signal(SIGFPE, SIG_IGN);
 # endif
 
     result = trio_pinf() / trio_pinf();
 
 # if defined(TRIO_PLATFORM_UNIX)
     signal(SIGFPE, signal_handler);
 # endif
 
 #endif
   }
   return result;
 }
 
 /**
    Check for NaN.
 
    @param number An arbitrary floating-point number.
    @return Boolean value indicating whether or not the number is a NaN.
 */
 TRIO_PUBLIC int
 trio_isnan
 TRIO_ARGS1((number),
 	   double number)
 {
 #if (defined(TRIO_COMPILER_SUPPORTS_C99) && defined(isnan)) \
  || defined(TRIO_COMPILER_SUPPORTS_UNIX95)
   /*
    * C99 defines isnan() as a macro. UNIX95 defines isnan() as a
    * function. This function was already present in XPG4, but this
    * is a bit tricky to detect with compiler defines, so we choose
    * the conservative approach and only use it for UNIX95.
    */
   return isnan(number);
 
 #elif defined(TRIO_COMPILER_MSVC) || defined(TRIO_COMPILER_BCB)
   /*
    * Microsoft Visual C++ and Borland C++ Builder have an _isnan()
    * function.
    */
   return _isnan(number) ? TRIO_TRUE : TRIO_FALSE;
 
 #elif defined(USE_IEEE_754)
   /*
    * Examine IEEE 754 bit-pattern. A NaN must have a special exponent
    * pattern, and a non-empty mantissa.
    */
   int has_mantissa;
   int is_special_quantity;
 
   is_special_quantity = trio_is_special_quantity(number, &has_mantissa);
 
   return (is_special_quantity && has_mantissa);
 
 #else
   /*
    * Fallback solution
    */
   int status;
   double integral, fraction;
 
 # if defined(TRIO_PLATFORM_UNIX)
   void (*signal_handler)(int) = signal(SIGFPE, SIG_IGN);
 # endif
 
   status = (/*
 	     * NaN is the only number which does not compare to itself
 	     */
 	    ((TRIO_VOLATILE double)number != (TRIO_VOLATILE double)number) ||
 	    /*
 	     * Fallback solution if NaN compares to NaN
 	     */
 	    ((number != 0.0) &&
 	     (fraction = modf(number, &integral),
 	      integral == fraction)));
 
 # if defined(TRIO_PLATFORM_UNIX)
   signal(SIGFPE, signal_handler);
 # endif
 
   return status;
 
 #endif
 }
 
 /**
    Check for infinity.
 
    @param number An arbitrary floating-point number.
    @return 1 if positive infinity, -1 if negative infinity, 0 otherwise.
 */
 TRIO_PUBLIC int
 trio_isinf
 TRIO_ARGS1((number),
 	   double number)
 {
 #if defined(TRIO_COMPILER_DECC) && !defined(__linux__)
   /*
    * DECC has an isinf() macro, but it works differently than that
    * of C99, so we use the fp_class() function instead.
    */
   return ((fp_class(number) == FP_POS_INF)
 	  ? 1
 	  : ((fp_class(number) == FP_NEG_INF) ? -1 : 0));
 
 #elif defined(isinf)
   /*
    * C99 defines isinf() as a macro.
    */
   return isinf(number)
     ? ((number > 0.0) ? 1 : -1)
     : 0;
 
 #elif defined(TRIO_COMPILER_MSVC) || defined(TRIO_COMPILER_BCB)
   /*
    * Microsoft Visual C++ and Borland C++ Builder have an _fpclass()
    * function that can be used to detect infinity.
    */
   return ((_fpclass(number) == _FPCLASS_PINF)
 	  ? 1
 	  : ((_fpclass(number) == _FPCLASS_NINF) ? -1 : 0));
 
 #elif defined(USE_IEEE_754)
   /*
    * Examine IEEE 754 bit-pattern. Infinity must have a special exponent
    * pattern, and an empty mantissa.
    */
   int has_mantissa;
   int is_special_quantity;
 
   is_special_quantity = trio_is_special_quantity(number, &has_mantissa);
 
   return (is_special_quantity && !has_mantissa)
     ? ((number < 0.0) ? -1 : 1)
     : 0;
 
 #else
   /*
    * Fallback solution.
    */
   int status;
 
 # if defined(TRIO_PLATFORM_UNIX)
   void (*signal_handler)(int) = signal(SIGFPE, SIG_IGN);
 # endif
 
   double infinity = trio_pinf();
 
   status = ((number == infinity)
 	    ? 1
 	    : ((number == -infinity) ? -1 : 0));
 
 # if defined(TRIO_PLATFORM_UNIX)
   signal(SIGFPE, signal_handler);
 # endif
 
   return status;
 
 #endif
 }
 
 #if 0
 	/* Temporary fix - this routine is not used anywhere */
 /**
    Check for finity.
 
    @param number An arbitrary floating-point number.
    @return Boolean value indicating whether or not the number is a finite.
 */
 TRIO_PUBLIC int
 trio_isfinite
 TRIO_ARGS1((number),
 	   double number)
 {
 #if defined(TRIO_COMPILER_SUPPORTS_C99) && defined(isfinite)
   /*
    * C99 defines isfinite() as a macro.
    */
   return isfinite(number);
 
 #elif defined(TRIO_COMPILER_MSVC) || defined(TRIO_COMPILER_BCB)
   /*
    * Microsoft Visual C++ and Borland C++ Builder use _finite().
    */
   return _finite(number);
 
 #elif defined(USE_IEEE_754)
   /*
    * Examine IEEE 754 bit-pattern. For finity we do not care about the
    * mantissa.
    */
   int dummy;
 
   return (! trio_is_special_quantity(number, &dummy));
 
 #else
   /*
    * Fallback solution.
    */
   return ((trio_isinf(number) == 0) && (trio_isnan(number) == 0));
 
 #endif
 }
 
 #endif
 
 /*
  * The sign of NaN is always false
  */
 TRIO_PUBLIC int
 trio_fpclassify_and_signbit
 TRIO_ARGS2((number, is_negative),
 	   double number,
 	   int *is_negative)
 {
 #if defined(fpclassify) && defined(signbit)
   /*
    * C99 defines fpclassify() and signbit() as a macros
    */
   *is_negative = signbit(number);
   switch (fpclassify(number)) {
   case FP_NAN:
     return TRIO_FP_NAN;
   case FP_INFINITE:
     return TRIO_FP_INFINITE;
   case FP_SUBNORMAL:
     return TRIO_FP_SUBNORMAL;
   case FP_ZERO:
     return TRIO_FP_ZERO;
   default:
     return TRIO_FP_NORMAL;
   }
 
 #else
 # if defined(TRIO_COMPILER_DECC)
   /*
    * DECC has an fp_class() function.
    */
 #  define TRIO_FPCLASSIFY(n) fp_class(n)
 #  define TRIO_QUIET_NAN FP_QNAN
 #  define TRIO_SIGNALLING_NAN FP_SNAN
 #  define TRIO_POSITIVE_INFINITY FP_POS_INF
 #  define TRIO_NEGATIVE_INFINITY FP_NEG_INF
 #  define TRIO_POSITIVE_SUBNORMAL FP_POS_DENORM
 #  define TRIO_NEGATIVE_SUBNORMAL FP_NEG_DENORM
 #  define TRIO_POSITIVE_ZERO FP_POS_ZERO
 #  define TRIO_NEGATIVE_ZERO FP_NEG_ZERO
 #  define TRIO_POSITIVE_NORMAL FP_POS_NORM
 #  define TRIO_NEGATIVE_NORMAL FP_NEG_NORM
 
 # elif defined(TRIO_COMPILER_MSVC) || defined(TRIO_COMPILER_BCB)
   /*
    * Microsoft Visual C++ and Borland C++ Builder have an _fpclass()
    * function.
    */
 #  define TRIO_FPCLASSIFY(n) _fpclass(n)
 #  define TRIO_QUIET_NAN _FPCLASS_QNAN
 #  define TRIO_SIGNALLING_NAN _FPCLASS_SNAN
 #  define TRIO_POSITIVE_INFINITY _FPCLASS_PINF
 #  define TRIO_NEGATIVE_INFINITY _FPCLASS_NINF
 #  define TRIO_POSITIVE_SUBNORMAL _FPCLASS_PD
 #  define TRIO_NEGATIVE_SUBNORMAL _FPCLASS_ND
 #  define TRIO_POSITIVE_ZERO _FPCLASS_PZ
 #  define TRIO_NEGATIVE_ZERO _FPCLASS_NZ
 #  define TRIO_POSITIVE_NORMAL _FPCLASS_PN
 #  define TRIO_NEGATIVE_NORMAL _FPCLASS_NN
 
 # elif defined(FP_PLUS_NORM)
   /*
    * HP-UX 9.x and 10.x have an fpclassify() function, that is different
    * from the C99 fpclassify() macro supported on HP-UX 11.x.
    *
    * AIX has class() for C, and _class() for C++, which returns the
    * same values as the HP-UX fpclassify() function.
    */
 #  if defined(TRIO_PLATFORM_AIX)
 #   if defined(__cplusplus)
 #    define TRIO_FPCLASSIFY(n) _class(n)
 #   else
 #    define TRIO_FPCLASSIFY(n) class(n)
 #   endif
 #  else
 #   define TRIO_FPCLASSIFY(n) fpclassify(n)
 #  endif
 #  define TRIO_QUIET_NAN FP_QNAN
 #  define TRIO_SIGNALLING_NAN FP_SNAN
 #  define TRIO_POSITIVE_INFINITY FP_PLUS_INF
 #  define TRIO_NEGATIVE_INFINITY FP_MINUS_INF
 #  define TRIO_POSITIVE_SUBNORMAL FP_PLUS_DENORM
 #  define TRIO_NEGATIVE_SUBNORMAL FP_MINUS_DENORM
 #  define TRIO_POSITIVE_ZERO FP_PLUS_ZERO
 #  define TRIO_NEGATIVE_ZERO FP_MINUS_ZERO
 #  define TRIO_POSITIVE_NORMAL FP_PLUS_NORM
 #  define TRIO_NEGATIVE_NORMAL FP_MINUS_NORM
 # endif
 
 # if defined(TRIO_FPCLASSIFY)
   switch (TRIO_FPCLASSIFY(number)) {
   case TRIO_QUIET_NAN:
   case TRIO_SIGNALLING_NAN:
     *is_negative = TRIO_FALSE; /* NaN has no sign */
     return TRIO_FP_NAN;
   case TRIO_POSITIVE_INFINITY:
     *is_negative = TRIO_FALSE;
     return TRIO_FP_INFINITE;
   case TRIO_NEGATIVE_INFINITY:
     *is_negative = TRIO_TRUE;
     return TRIO_FP_INFINITE;
   case TRIO_POSITIVE_SUBNORMAL:
     *is_negative = TRIO_FALSE;
     return TRIO_FP_SUBNORMAL;
   case TRIO_NEGATIVE_SUBNORMAL:
     *is_negative = TRIO_TRUE;
     return TRIO_FP_SUBNORMAL;
   case TRIO_POSITIVE_ZERO:
     *is_negative = TRIO_FALSE;
     return TRIO_FP_ZERO;
   case TRIO_NEGATIVE_ZERO:
     *is_negative = TRIO_TRUE;
     return TRIO_FP_ZERO;
   case TRIO_POSITIVE_NORMAL:
     *is_negative = TRIO_FALSE;
     return TRIO_FP_NORMAL;
   case TRIO_NEGATIVE_NORMAL:
     *is_negative = TRIO_TRUE;
     return TRIO_FP_NORMAL;
   default:
     /* Just in case... */
     *is_negative = (number < 0.0);
     return TRIO_FP_NORMAL;
   }
 
 # else
   /*
    * Fallback solution.
    */
   int rc;
 
   if (number == 0.0) {
     /*
      * In IEEE 754 the sign of zero is ignored in comparisons, so we
      * have to handle this as a special case by examining the sign bit
      * directly.
      */
 #  if defined(USE_IEEE_754)
     *is_negative = trio_is_negative(number);
 #  else
     *is_negative = TRIO_FALSE; /* FIXME */
 #  endif
     return TRIO_FP_ZERO;
   }
   if (trio_isnan(number)) {
     *is_negative = TRIO_FALSE;
     return TRIO_FP_NAN;
   }
   if ((rc = trio_isinf(number))) {
     *is_negative = (rc == -1);
     return TRIO_FP_INFINITE;
   }
   if ((number > 0.0) && (number < DBL_MIN)) {
     *is_negative = TRIO_FALSE;
     return TRIO_FP_SUBNORMAL;
   }
   if ((number < 0.0) && (number > -DBL_MIN)) {
     *is_negative = TRIO_TRUE;
     return TRIO_FP_SUBNORMAL;
   }
   *is_negative = (number < 0.0);
   return TRIO_FP_NORMAL;
 
 # endif
 #endif
 }
 
 /**
    Examine the sign of a number.
 
    @param number An arbitrary floating-point number.
    @return Boolean value indicating whether or not the number has the
    sign bit set (i.e. is negative).
 */
 TRIO_PUBLIC int
 trio_signbit
 TRIO_ARGS1((number),
 	   double number)
 {
   int is_negative;
 
   (void)trio_fpclassify_and_signbit(number, &is_negative);
   return is_negative;
 }
 
 #if 0
 	/* Temporary fix - this routine is not used in libxml */
 /**
    Examine the class of a number.
 
    @param number An arbitrary floating-point number.
    @return Enumerable value indicating the class of @p number
 */
 TRIO_PUBLIC int
 trio_fpclassify
 TRIO_ARGS1((number),
 	   double number)
 {
   int dummy;
 
   return trio_fpclassify_and_signbit(number, &dummy);
 }
 
 #endif
 
 /** @} SpecialQuantities */
 
 /*************************************************************************
  * For test purposes.
  *
  * Add the following compiler option to include this test code.
  *
  *  Unix : -DSTANDALONE
  *  VMS  : /DEFINE=(STANDALONE)
  */
 #if defined(STANDALONE)
 # include <stdio.h>
 
 static TRIO_CONST char *
 getClassification
 TRIO_ARGS1((type),
 	   int type)
 {
   switch (type) {
   case TRIO_FP_INFINITE:
     return "FP_INFINITE";
   case TRIO_FP_NAN:
     return "FP_NAN";
   case TRIO_FP_NORMAL:
     return "FP_NORMAL";
   case TRIO_FP_SUBNORMAL:
     return "FP_SUBNORMAL";
   case TRIO_FP_ZERO:
     return "FP_ZERO";
   default:
     return "FP_UNKNOWN";
   }
 }
 
 static void
 print_class
 TRIO_ARGS2((prefix, number),
 	   TRIO_CONST char *prefix,
 	   double number)
 {
   printf("%-6s: %s %-15s %g\n",
 	 prefix,
 	 trio_signbit(number) ? "-" : "+",
 	 getClassification(TRIO_FPCLASSIFY(number)),
 	 number);
 }
 
 int main(TRIO_NOARGS)
 {
   double my_nan;
   double my_pinf;
   double my_ninf;
 # if defined(TRIO_PLATFORM_UNIX)
   void (*signal_handler) TRIO_PROTO((int));
 # endif
 
   my_nan = trio_nan();
   my_pinf = trio_pinf();
   my_ninf = trio_ninf();
 
   print_class("Nan", my_nan);
   print_class("PInf", my_pinf);
   print_class("NInf", my_ninf);
   print_class("PZero", 0.0);
   print_class("NZero", -0.0);
   print_class("PNorm", 1.0);
   print_class("NNorm", -1.0);
   print_class("PSub", 1.01e-307 - 1.00e-307);
   print_class("NSub", 1.00e-307 - 1.01e-307);
 
   printf("NaN : %4g 0x%02x%02x%02x%02x%02x%02x%02x%02x (%2d, %2d)\n",
 	 my_nan,
 	 ((unsigned char *)&my_nan)[0],
 	 ((unsigned char *)&my_nan)[1],
 	 ((unsigned char *)&my_nan)[2],
 	 ((unsigned char *)&my_nan)[3],
 	 ((unsigned char *)&my_nan)[4],
 	 ((unsigned char *)&my_nan)[5],
 	 ((unsigned char *)&my_nan)[6],
 	 ((unsigned char *)&my_nan)[7],
 	 trio_isnan(my_nan), trio_isinf(my_nan));
   printf("PInf: %4g 0x%02x%02x%02x%02x%02x%02x%02x%02x (%2d, %2d)\n",
 	 my_pinf,
 	 ((unsigned char *)&my_pinf)[0],
 	 ((unsigned char *)&my_pinf)[1],
 	 ((unsigned char *)&my_pinf)[2],
 	 ((unsigned char *)&my_pinf)[3],
 	 ((unsigned char *)&my_pinf)[4],
 	 ((unsigned char *)&my_pinf)[5],
 	 ((unsigned char *)&my_pinf)[6],
 	 ((unsigned char *)&my_pinf)[7],
 	 trio_isnan(my_pinf), trio_isinf(my_pinf));
   printf("NInf: %4g 0x%02x%02x%02x%02x%02x%02x%02x%02x (%2d, %2d)\n",
 	 my_ninf,
 	 ((unsigned char *)&my_ninf)[0],
 	 ((unsigned char *)&my_ninf)[1],
 	 ((unsigned char *)&my_ninf)[2],
 	 ((unsigned char *)&my_ninf)[3],
 	 ((unsigned char *)&my_ninf)[4],
 	 ((unsigned char *)&my_ninf)[5],
 	 ((unsigned char *)&my_ninf)[6],
 	 ((unsigned char *)&my_ninf)[7],
 	 trio_isnan(my_ninf), trio_isinf(my_ninf));
 
 # if defined(TRIO_PLATFORM_UNIX)
   signal_handler = signal(SIGFPE, SIG_IGN);
 # endif
 
   my_pinf = DBL_MAX + DBL_MAX;
   my_ninf = -my_pinf;
   my_nan = my_pinf / my_pinf;
 
 # if defined(TRIO_PLATFORM_UNIX)
   signal(SIGFPE, signal_handler);
 # endif
 
   printf("NaN : %4g 0x%02x%02x%02x%02x%02x%02x%02x%02x (%2d, %2d)\n",
 	 my_nan,
 	 ((unsigned char *)&my_nan)[0],
 	 ((unsigned char *)&my_nan)[1],
 	 ((unsigned char *)&my_nan)[2],
 	 ((unsigned char *)&my_nan)[3],
 	 ((unsigned char *)&my_nan)[4],
 	 ((unsigned char *)&my_nan)[5],
 	 ((unsigned char *)&my_nan)[6],
 	 ((unsigned char *)&my_nan)[7],
 	 trio_isnan(my_nan), trio_isinf(my_nan));
   printf("PInf: %4g 0x%02x%02x%02x%02x%02x%02x%02x%02x (%2d, %2d)\n",
 	 my_pinf,
 	 ((unsigned char *)&my_pinf)[0],
 	 ((unsigned char *)&my_pinf)[1],
 	 ((unsigned char *)&my_pinf)[2],
 	 ((unsigned char *)&my_pinf)[3],
 	 ((unsigned char *)&my_pinf)[4],
 	 ((unsigned char *)&my_pinf)[5],
 	 ((unsigned char *)&my_pinf)[6],
 	 ((unsigned char *)&my_pinf)[7],
 	 trio_isnan(my_pinf), trio_isinf(my_pinf));
   printf("NInf: %4g 0x%02x%02x%02x%02x%02x%02x%02x%02x (%2d, %2d)\n",
 	 my_ninf,
 	 ((unsigned char *)&my_ninf)[0],
 	 ((unsigned char *)&my_ninf)[1],
 	 ((unsigned char *)&my_ninf)[2],
 	 ((unsigned char *)&my_ninf)[3],
 	 ((unsigned char *)&my_ninf)[4],
 	 ((unsigned char *)&my_ninf)[5],
 	 ((unsigned char *)&my_ninf)[6],
 	 ((unsigned char *)&my_ninf)[7],
 	 trio_isnan(my_ninf), trio_isinf(my_ninf));
 
   return 0;
 }
 #endif