libm/include/amd64/fenv.h

/*-
 * Copyright (c) 2004-2005 David Schultz <das (at) FreeBSD.ORG>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef	_AMD64_FENV_H_
#define	_AMD64_FENV_H_

#include <sys/types.h>

/*
 * This file combines the OpenBSD include/fenv.h and machine/fenv.h to fit
 * the style of the other architectures (where we couldn't just take an
 * upstream fenv.h and had to write our own).
 */

__BEGIN_DECLS

/*
 * Each symbol representing a floating point exception expands to an integer
 * constant expression with values, such that bitwise-inclusive ORs of _all
 * combinations_ of the constants result in distinct values.
 *
 * We use such values that allow direct bitwise operations on FPU/SSE registers.
 */
#define	FE_INVALID		0x01
#define	FE_DENORMAL		0x02
#define	FE_DIVBYZERO		0x04
#define	FE_OVERFLOW		0x08
#define	FE_UNDERFLOW		0x10
#define	FE_INEXACT		0x20

/*
 * The following symbol is simply the bitwise-inclusive OR of all floating-point
 * exception constants defined above.
 */
#define	FE_ALL_EXCEPT		(FE_INVALID | FE_DENORMAL | FE_DIVBYZERO | \
				 FE_OVERFLOW | FE_UNDERFLOW | FE_INEXACT)
#define	_SSE_MASK_SHIFT		7

/*
 * Each symbol representing the rounding direction, expands to an integer
 * constant expression whose value is distinct non-negative value.
 *
 * We use such values that allow direct bitwise operations on FPU/SSE registers.
 */
#define	FE_TONEAREST		0x000
#define	FE_DOWNWARD		0x400
#define	FE_UPWARD		0x800
#define	FE_TOWARDZERO		0xc00

/*
 * The following symbol is simply the bitwise-inclusive OR of all floating-point
 * rounding direction constants defined above.
 */
#define	_X87_ROUND_MASK		(FE_TONEAREST | FE_DOWNWARD | FE_UPWARD | \
				 FE_TOWARDZERO)
#define	_SSE_ROUND_SHIFT	3

/*
 * fenv_t represents the entire floating-point environment.
 */
typedef	struct {
	struct {
		unsigned int __control;		/* Control word register */
		unsigned int __status;		/* Status word register */
		unsigned int __tag;		/* Tag word register */
		unsigned int __others[4];	/* EIP, Pointer Selector, etc */
	} __x87;
	unsigned int __mxcsr;			/* Control, status register */
} fenv_t;

/*
 * The following constant represents the default floating-point environment
 * (that is, the one installed at program startup) and has type pointer to
 * const-qualified fenv_t.
 *
 * It can be used as an argument to the functions within the <fenv.h> header
 * that manage the floating-point environment, namely fesetenv() and
 * feupdateenv().
 */
extern	fenv_t			__fe_dfl_env;
#define	FE_DFL_ENV		((const fenv_t *)&__fe_dfl_env)

/*
 * fexcept_t represents the floating-point status flags collectively, including
 * any status the implementation associates with the flags.
 *
 * A floating-point status flag is a system variable whose value is set (but
 * never cleared) when a floating-point exception is raised, which occurs as a
 * side effect of exceptional floating-point arithmetic to provide auxiliary
 * information.
 *
 * A floating-point control mode is a system variable whose value may be set by
 * the user to affect the subsequent behavior of floating-point arithmetic.
 */
typedef	unsigned int		fexcept_t;

/* C99 floating-point exception functions */
int feclearexcept(int excepts);
int fegetexceptflag(fexcept_t *flagp, int excepts);
int fesetexceptflag(const fexcept_t *flagp, int excepts);
/* feraiseexcept does not set the inexact flag on overflow/underflow */
int feraiseexcept(int excepts);
int fetestexcept(int excepts);

/* C99 rounding control functions */
int fegetround(void);
int fesetround(int round);

/* C99 floating-point environment functions */
int fegetenv(fenv_t *__envp);
int feholdexcept(fenv_t *__envp);
int fesetenv(const fenv_t *envp);
int feupdateenv(const fenv_t *__envp);

#if __BSD_VISIBLE
/* Additional support functions to set/query floating point traps */
int feenableexcept(int __mask);
int fedisableexcept(int __mask);
int fegetexcept(void);
#endif /* __BSD_VISIBLE */

__END_DECLS

#endif	/* !_AMD64_FENV_H_ */