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%%	options

copyright owner	=	Dirk Krause
copyright year	=	2014-xxxx
license		=	bsd


%%	header

/**	@file	dk3mafpe.h	Floating point exception handling.

Before doing any floating point calculation, use dk3mafpe_get_handling_type()
to check whether an exception handling mechanism is available.

The function returns DK3_MA_FPE_HANDLING_CLEARFP on Windows systems
if _clearfp() and _statusfp() are available. It returns
DK3_MA_FPE_HANDLING_FETESTEXCEPT if the POSIX floating point exception
functions fetestexcept() and feclearexcept() are available.

If none of these mechanisms is available, DK3_MA_FPE_HANDLING_NONE is
returned. Your program should issue a warning.

Before doing a floating point calculation use dk3mafpe_clear() to
clear the FPU status word.

After doing a floating point calculation use dk3mafpe_get() or
dk3mafpe_get_and_clear() to retrieve the status word.
Check the status word against DK3MAFPE_ALL (and-combine them) to see
if any exception occured.

If your calculation results in just one double you can use
dk3mafpe_isfinite() and/or dk3mafpe_isnormal() to check the value.
If the dk3mafpe_isfinite() test fails, the value is of no use.
If the dk3mafpe_isnormal() test fails, the result is very small, it uses
denormalized representation and has probably and likely lost
much of it's precision.
*/

#include <dk3conf.h>

#if DK3_HAVE_FLOAT_H
#include <float.h>
#endif
#if DK3_HAVE_FENV_H
#include <fenv.h>
#endif



#if DK3_ON_WINDOWS
/**	Floating point exceptions set.
*/
typedef unsigned int	dk3_ma_fpe_t;

#if DK3_HAVE__CLEARFP

/**	Division by 0.
*/
#define	DK3MAFPE_DIVBYZERO	(_SW_ZERODIVIDE)

/**	Inexact result (either overflow or underflow).
*/
#define	DK3MAFPE_INEXACT	(_SW_INEXACT)

/**	Not a number (0/0 or infty - infty).
*/
#define	DK3MAFPE_INVALID	(_SW_INVALID)

/**	Result too large for representation.
*/
#define	DK3MAFPE_OVERFLOW	(_SW_OVERFLOW)

/**	Result too small for normalized representation.
*/
#define	DK3MAFPE_UNDERFLOW	(_SW_UNDERFLOW)

/**	Denormalized number.
*/
#define	DK3MAFPE_DENORMAL	(_SW_DENORMAL)

/**	Or-combination of all supported exceptions.
*/
#define	DK3MAFPE_ALL \
	((_SW_ZERODIVIDE) \
	| (_SW_INEXACT) \
	| (_SW_INVALID) \
	| (_SW_OVERFLOW) \
	| (_SW_UNDERFLOW) \
	| (_SW_DENORMAL))

#else

/**	Division by 0.
*/
#define	DK3MAFPE_DIVBYZERO	0

/**	Inexact result (either overflow or underflow).
*/
#define	DK3MAFPE_INEXACT	0

/**	Not a number (0/0 or infty - infty).
*/
#define	DK3MAFPE_INVALID	0

/**	Result too large for representation.
*/
#define	DK3MAFPE_OVERFLOW	0

/**	Result too small for normalized representation.
*/
#define	DK3MAFPE_UNDERFLOW	0

/**	Denormalized number.
*/
#define	DK3MAFPE_DENORMAL	0

/**	Or-combination of all supported exceptions.
*/
#define	DK3MAFPE_ALL		0

#endif
#else
/**	Floating point exceptions set.
*/
typedef int		dk3_ma_fpe_t;

#if DK3_HAVE_FETESTEXCEPT

/**	Division by 0.
*/
#define	DK3MAFPE_DIVBYZERO	(FE_DIVBYZERO)

/**	Inexact result (either overflow or underflow).
*/
#define	DK3MAFPE_INEXACT	(FE_INEXACT)

/**	Not a number (0/0 or infty - infty).
*/
#define	DK3MAFPE_INVALID	(FE_INVALID)

/**	Result too large for representation.
*/
#define	DK3MAFPE_OVERFLOW	(FE_OVERFLOW)

/**	Result too small for normalized representation.
*/
#define	DK3MAFPE_UNDERFLOW	(FE_UNDERFLOW)

/**	Denormalized number.
*/
#define	DK3MAFPE_DENORMAL	0

/**	Or-combination of all supported exceptions.
*/
#define	DK3MAFPE_ALL		(FE_ALL_EXCEPT)

#else

/**	Division by 0.
*/
#define	DK3MAFPE_DIVBYZERO	0

/**	Inexact result (either overflow or underflow).
*/
#define	DK3MAFPE_INEXACT	0

/**	Not a number (0/0 or infty - infty).
*/
#define	DK3MAFPE_INVALID	0

/**	Result too large for representation.
*/
#define	DK3MAFPE_OVERFLOW	0

/**	Result too small for normalized representation.
*/
#define	DK3MAFPE_UNDERFLOW	0

/**	Denormalized number.
*/
#define	DK3MAFPE_DENORMAL	0

/**	Or-combination of all supported exceptions.
*/
#define	DK3MAFPE_ALL		0

#endif
#endif



/**	Different handling types for floating point exceptions.
*/
enum {

  /**	No fpe exception handling available.
  */
  DK3_MA_FPE_HANDLING_NONE	=	0,

  /**	POSIX exception handling using fetestexcept() and friends.
  */
  DK3_MA_FPE_HANDLING_FETESTEXCEPT,

  /**	Windows exception handling using _clearfp() and friends.
  */
  DK3_MA_FPE_HANDLING_CLEARFP

};



#ifdef __cplusplus
extern "C" {
#endif

/**	Retrieve exception set.
	@return	Exceptions found.
*/
dk3_ma_fpe_t
dk3mafpe_get(void);

/**	Clear exception set.
*/
void
dk3mafpe_clear(void);

/**	Retrieve exception set and clear.
	@return	Exceptions found.
*/
dk3_ma_fpe_t
dk3mafpe_get_and_clear(void);

/**	Get exception handling type.
	@return	One from DK3_MA_FPE_HANDLING_NONE,
	DK3_MA_FPE_HANDLING_FETESTEXCEPT, DK3_MA_FPE_HANDLING_CLEARFP.
*/
int
dk3mafpe_get_handling_type(void);

/**	Check whether a number is normalized.
	@param	x	Number to check.
	@return	Non-null result on success, 0 on error.
*/
int
dk3mafpe_isnormal(double x);

/**	Check whether a number is finite (not NAN, not INF).
	@param	x	Number to check.
	@return	Non-null result on success, 0 on error.
*/
int
dk3mafpe_isfinite(double x);

#ifdef __cplusplus
}
#endif


%%	module

#include "dk3mafpe.h"



$!trace-include



#if TRACE_DEBUG

static
void
dk3mafpe_debug(dk3_ma_fpe_t fpes)
{
  $? "+ dk3mafpe_debug"
  if (NULL != dktrace_file()) {
    if (0 != (fpes & DK3MAFPE_DIVBYZERO)) {
      fputs("DIVBYZERO\n", dktrace_file());
    }
    if (0 != (fpes & DK3MAFPE_INEXACT)) {
      fputs("INEXACT\n", dktrace_file());
    }
    if (0 != (fpes & DK3MAFPE_OVERFLOW)) {
      fputs("OVERFLOW\n", dktrace_file());
    }
    if (0 != (fpes & DK3MAFPE_UNDERFLOW)) {
      fputs("UNDERFLOW\n", dktrace_file());
    }
    if (0 != (fpes & DK3MAFPE_INVALID)) {
      fputs("INVALID\n", dktrace_file());
    }
  }
  $? "- dk3mafpe_debug"
}

#endif

dk3_ma_fpe_t
dk3mafpe_get(void)
{
#if DK3_ON_WINDOWS
#if DK3_HAVE__CLEARFP
#if TRACE_DEBUG
  dk3_ma_fpe_t	back;
  back = _statusfp();
  dk3mafpe_debug(back);
  return back;
#else
  return (_statusfp());
#endif
#else
  return 0;
#endif
#else
#if DK3_HAVE_FETESTEXCEPT
#if TRACE_DEBUG
  dk3_ma_fpe_t	back;
  back = fetestexcept(FE_ALL_EXCEPT);
  dk3mafpe_debug(back);
  return back;
#else
  return (fetestexcept(FE_ALL_EXCEPT));
#endif
#else
  return 0;
#endif
#endif
}



void
dk3mafpe_clear(void)
{
#if DK3_ON_WINDOWS
#if DK3_HAVE__CLEARFP
  (void)_clearfp();
#else

#endif
#else
#if DK3_HAVE_FETESTEXCEPT
  feclearexcept(FE_ALL_EXCEPT);
#else

#endif
#endif
}



dk3_ma_fpe_t
dk3mafpe_get_and_clear(void)
{
#if DK3_ON_WINDOWS
#if DK3_HAVE__CLEARFP
#if TRACE_DEBUG
  dk3_ma_fpe_t	back;
  back = _clearfp();
  dk3mafpe_debug(back);
  return back;
#else
  return (_clearfp());
#endif
#else
  return 0;
#endif
#else
#if DK3_HAVE_FETESTEXCEPT
  dk3_ma_fpe_t	back;
  back = fetestexcept(FE_ALL_EXCEPT);
  feclearexcept(FE_ALL_EXCEPT);
#if TRACE_DEBUG
  dk3mafpe_debug(back);
#endif
  return back;
#else
  return 0;
#endif
#endif
}



int
dk3mafpe_get_handling_type(void)
{
#if DK3_ON_WINDOWS
#if DK3_HAVE__CLEARFP
  return DK3_MA_FPE_HANDLING_CLEARFP;
#else
  return DK3_MA_FPE_HANDLING_NONE;
#endif
#else
#if DK3_HAVE_FETESTEXCEPT
  return DK3_MA_FPE_HANDLING_FETESTEXCEPT;
#else
  return DK3_MA_FPE_HANDLING_NONE;
#endif
#endif
}



int
dk3mafpe_isfinite(double x)
{
#if DK3_ON_WINDOWS
  int back = 0;
  if (_finite(x)) {
    back = 1;
  }
  return back;
#else
#if DK3_HAVE_ISFINITE
  int back = 0;
  if (isfinite(x)) {
    back = 1;
  }
  return back;
#else
#error "No function or macro isfinite(x) available!"
  return 1;
#endif
#endif
}




int
dk3mafpe_isnormal(double x)
{
#if DK3_ON_WINDOWS
  int	back	=	0;
  if (_finite(x)) {
    back = 1;
    switch (_fpclass(x)) {
      case _FPCLASS_ND: case _FPCLASS_PD: {
        back = 0;
      } break;
    }
  }
  return back;
#else
#if DK3_HAVE_ISNORMAL
  int	back = 0;
  if (isnormal(x)) {
    back = 1;
  }
  return back;
#else
#error "No function or macro isnormal(x) available!"
  return 1;
#endif
#endif
}