float.h

众所周知

/* 
 * float.h
 * This file has no copyright assigned and is placed in the Public Domain.
 * This file is a part of the mingw-runtime package.
 * No warranty is given; refer to the file DISCLAIMER within the package.
 *
 * Constants related to floating point arithmetic.
 *
 * Also included here are some non-ANSI bits for accessing the floating
 * point controller.
 *
 * NOTE: GCC provides float.h, but it doesn't include the non-standard
 *       stuff for accessing the fp controller. We include_next the
 *       GCC-supplied header and just define the MS-specific extensions
 *       here.     
 *
 */

#include_next<float.h>

#ifndef _MINGW_FLOAT_H_
#define _MINGW_FLOAT_H_

/* All the headers include this file. */
#include <_mingw.h>

/*
 * Functions and definitions for controlling the FPU.
 */
#ifndef	__STRICT_ANSI__

/* TODO: These constants are only valid for x86 machines */

/* Control word masks for unMask */
#define	_MCW_EM		0x0008001F	/* Error masks */
#define	_MCW_IC		0x00040000	/* Infinity */
#define	_MCW_RC		0x00000300	/* Rounding */
#define	_MCW_PC		0x00030000	/* Precision */

/* Control word values for unNew (use with related unMask above) */
#define	_EM_INVALID	0x00000010
#define	_EM_DENORMAL	0x00080000
#define	_EM_ZERODIVIDE	0x00000008
#define	_EM_OVERFLOW	0x00000004
#define	_EM_UNDERFLOW	0x00000002
#define	_EM_INEXACT	0x00000001
#define	_IC_AFFINE	0x00040000
#define	_IC_PROJECTIVE	0x00000000
#define	_RC_CHOP	0x00000300
#define	_RC_UP		0x00000200
#define	_RC_DOWN	0x00000100
#define	_RC_NEAR	0x00000000
#define	_PC_24		0x00020000
#define	_PC_53		0x00010000
#define	_PC_64		0x00000000

/* These are also defined in Mingw math.h, needed to work around
   GCC build issues.  */
/* Return values for fpclass. */
#ifndef __MINGW_FPCLASS_DEFINED
#define __MINGW_FPCLASS_DEFINED 1
#define	_FPCLASS_SNAN	0x0001	/* Signaling "Not a Number" */
#define	_FPCLASS_QNAN	0x0002	/* Quiet "Not a Number" */
#define	_FPCLASS_NINF	0x0004	/* Negative Infinity */
#define	_FPCLASS_NN	0x0008	/* Negative Normal */
#define	_FPCLASS_ND	0x0010	/* Negative Denormal */
#define	_FPCLASS_NZ	0x0020	/* Negative Zero */
#define	_FPCLASS_PZ	0x0040	/* Positive Zero */
#define	_FPCLASS_PD	0x0080	/* Positive Denormal */
#define	_FPCLASS_PN	0x0100	/* Positive Normal */
#define	_FPCLASS_PINF	0x0200	/* Positive Infinity */
#endif /* __MINGW_FPCLASS_DEFINED */

/* invalid subconditions (_SW_INVALID also set) */
#define _SW_UNEMULATED		0x0040  /* unemulated instruction */
#define _SW_SQRTNEG		0x0080  /* square root of a neg number */
#define _SW_STACKOVERFLOW	0x0200  /* FP stack overflow */
#define _SW_STACKUNDERFLOW	0x0400  /* FP stack underflow */

/*  Floating point error signals and return codes */
#define _FPE_INVALID		0x81
#define _FPE_DENORMAL		0x82
#define _FPE_ZERODIVIDE		0x83
#define _FPE_OVERFLOW		0x84
#define _FPE_UNDERFLOW		0x85
#define _FPE_INEXACT		0x86
#define _FPE_UNEMULATED		0x87
#define _FPE_SQRTNEG		0x88
#define _FPE_STACKOVERFLOW	0x8a
#define _FPE_STACKUNDERFLOW	0x8b
#define _FPE_EXPLICITGEN	0x8c    /* raise( SIGFPE ); */

#ifndef RC_INVOKED

#ifdef	__cplusplus
extern "C" {
#endif

/* Set the FPU control word as cw = (cw & ~unMask) | (unNew & unMask),
 * i.e. change the bits in unMask to have the values they have in unNew,
 * leaving other bits unchanged. */
_CRTIMP unsigned int __cdecl __MINGW_NOTHROW _controlfp (unsigned int unNew, unsigned int unMask);
_CRTIMP unsigned int __cdecl __MINGW_NOTHROW _control87 (unsigned int unNew, unsigned int unMask);


_CRTIMP unsigned int __cdecl __MINGW_NOTHROW _clearfp (void);	/* Clear the FPU status word */
_CRTIMP unsigned int __cdecl __MINGW_NOTHROW _statusfp (void);	/* Report the FPU status word */
#define		_clear87	_clearfp
#define		_status87	_statusfp


/*
   MSVCRT.dll _fpreset initializes the control register to 0x27f,
   the status register to zero and the tag word to 0FFFFh.
   This differs from asm instruction finit/fninit which set control
   word to 0x37f (64 bit mantissa precison rather than 53 bit).
   By default, the mingw version of _fpreset sets fp control as
   per fninit. To use the MSVCRT.dll _fpreset, include CRT_fp8.o when
   building your application.	 
*/
void __cdecl __MINGW_NOTHROW _fpreset (void);
void __cdecl __MINGW_NOTHROW fpreset (void);

/* Global 'variable' for the current floating point error code. */
_CRTIMP int * __cdecl __MINGW_NOTHROW __fpecode(void);
#define	_fpecode	(*(__fpecode()))

/*
 * IEEE recommended functions.  MS puts them in float.h
 * but they really belong in math.h.
 */

_CRTIMP double __cdecl __MINGW_NOTHROW _chgsign	(double);
_CRTIMP double __cdecl __MINGW_NOTHROW _copysign (double, double);
_CRTIMP double __cdecl __MINGW_NOTHROW _logb (double);
_CRTIMP double __cdecl __MINGW_NOTHROW _nextafter (double, double);
_CRTIMP double __cdecl __MINGW_NOTHROW _scalb (double, long);

_CRTIMP int __cdecl __MINGW_NOTHROW _finite (double);
_CRTIMP int __cdecl __MINGW_NOTHROW _fpclass (double);
_CRTIMP int __cdecl __MINGW_NOTHROW _isnan (double);

#ifdef	__cplusplus
}
#endif

#endif	/* Not RC_INVOKED */

#endif	/* Not __STRICT_ANSI__ */

#endif /* _FLOAT_H_ */