fenv.h

/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (c) 2004-2005 David Schultz <das@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.
 *
 * $FreeBSD$
 */

#ifndef	_FENV_H_
#define	_FENV_H_

#include <sys/_types.h>
#include <machine/endian.h>

#ifndef	__fenv_static
#define	__fenv_static	static
#endif

typedef	__uint32_t	fenv_t;
typedef	__uint32_t	fexcept_t;

/* Exception flags */
#define	FE_INEXACT	0x02000000
#define	FE_DIVBYZERO	0x04000000
#define	FE_UNDERFLOW	0x08000000
#define	FE_OVERFLOW	0x10000000
#define	FE_INVALID	0x20000000	/* all types of invalid FP ops */

/*
 * The PowerPC architecture has extra invalid flags that indicate the
 * specific type of invalid operation occurred.  These flags may be
 * tested, set, and cleared---but not masked---separately.  All of
 * these bits are cleared when FE_INVALID is cleared, but only
 * FE_VXSOFT is set when FE_INVALID is explicitly set in software.
 */
#define	FE_VXCVI	0x00000100	/* invalid integer convert */
#define	FE_VXSQRT	0x00000200	/* square root of a negative */
#define	FE_VXSOFT	0x00000400	/* software-requested exception */
#define	FE_VXVC		0x00080000	/* ordered comparison involving NaN */
#define	FE_VXIMZ	0x00100000	/* inf * 0 */
#define	FE_VXZDZ	0x00200000	/* 0 / 0 */
#define	FE_VXIDI	0x00400000	/* inf / inf */
#define	FE_VXISI	0x00800000	/* inf - inf */
#define	FE_VXSNAN	0x01000000	/* operation on a signalling NaN */
#define	FE_ALL_INVALID	(FE_VXCVI | FE_VXSQRT | FE_VXSOFT | FE_VXVC | \
			 FE_VXIMZ | FE_VXZDZ | FE_VXIDI | FE_VXISI | \
			 FE_VXSNAN | FE_INVALID)
#define	FE_ALL_EXCEPT	(FE_DIVBYZERO | FE_INEXACT | \
			 FE_ALL_INVALID | FE_OVERFLOW | FE_UNDERFLOW)

/* Rounding modes */
#define	FE_TONEAREST	0x0000
#define	FE_TOWARDZERO	0x0001
#define	FE_UPWARD	0x0002
#define	FE_DOWNWARD	0x0003
#define	_ROUND_MASK	(FE_TONEAREST | FE_DOWNWARD | \
			 FE_UPWARD | FE_TOWARDZERO)

__BEGIN_DECLS

/* Default floating-point environment */
extern const fenv_t	__fe_dfl_env;
#define	FE_DFL_ENV	(&__fe_dfl_env)

/* We need to be able to map status flag positions to mask flag positions */
#define	_FPUSW_SHIFT	22
#define	_ENABLE_MASK	((FE_DIVBYZERO | FE_INEXACT | FE_INVALID | \
			 FE_OVERFLOW | FE_UNDERFLOW) >> _FPUSW_SHIFT)

#ifndef _SOFT_FLOAT
#ifdef __SPE__
#define	__mffs(__env) \
	__asm __volatile("mfspr %0, 512" : "=r" ((__env)->__bits.__reg))
#define	__mtfsf(__env) \
	__asm __volatile("mtspr 512,%0;isync" :: "r" ((__env).__bits.__reg))
#else
#define	__mffs(__env) \
	__asm __volatile("mffs %0" : "=f" ((__env)->__d))
#define	__mtfsf(__env) \
	__asm __volatile("mtfsf 255,%0" :: "f" ((__env).__d))
#endif
#else
#define	__mffs(__env)
#define	__mtfsf(__env)
#endif

union __fpscr {
	double __d;
	struct {
#if _BYTE_ORDER == _LITTLE_ENDIAN
		fenv_t __reg;
		__uint32_t __junk;
#else
		__uint32_t __junk;
		fenv_t __reg;
#endif
	} __bits;
};

__fenv_static inline int
feclearexcept(int __excepts)
{
	union __fpscr __r;

	if (__excepts & FE_INVALID)
		__excepts |= FE_ALL_INVALID;
	__mffs(&__r);
	__r.__bits.__reg &= ~__excepts;
	__mtfsf(__r);
	return (0);
}

__fenv_static inline int
fegetexceptflag(fexcept_t *__flagp, int __excepts)
{
	union __fpscr __r;

	__mffs(&__r);
	*__flagp = __r.__bits.__reg & __excepts;
	return (0);
}

__fenv_static inline int
fesetexceptflag(const fexcept_t *__flagp, int __excepts)
{
	union __fpscr __r;

	if (__excepts & FE_INVALID)
		__excepts |= FE_ALL_INVALID;
	__mffs(&__r);
	__r.__bits.__reg &= ~__excepts;
	__r.__bits.__reg |= *__flagp & __excepts;
	__mtfsf(__r);
	return (0);
}

__fenv_static inline int
feraiseexcept(int __excepts)
{
	union __fpscr __r;

	if (__excepts & FE_INVALID)
		__excepts |= FE_VXSOFT;
	__mffs(&__r);
	__r.__bits.__reg |= __excepts;
	__mtfsf(__r);
	return (0);
}

__fenv_static inline int
fetestexcept(int __excepts)
{
	union __fpscr __r;

	__mffs(&__r);
	return (__r.__bits.__reg & __excepts);
}

__fenv_static inline int
fegetround(void)
{
	union __fpscr __r;

	__mffs(&__r);
	return (__r.__bits.__reg & _ROUND_MASK);
}

__fenv_static inline int
fesetround(int __round)
{
	union __fpscr __r;

	if (__round & ~_ROUND_MASK)
		return (-1);
	__mffs(&__r);
	__r.__bits.__reg &= ~_ROUND_MASK;
	__r.__bits.__reg |= __round;
	__mtfsf(__r);
	return (0);
}

__fenv_static inline int
fegetenv(fenv_t *__envp)
{
	union __fpscr __r;

	__mffs(&__r);
	*__envp = __r.__bits.__reg;
	return (0);
}

__fenv_static inline int
feholdexcept(fenv_t *__envp)
{
	union __fpscr __r;

	__mffs(&__r);
	*__envp = __r.__bits.__reg;
	__r.__bits.__reg &= ~(FE_ALL_EXCEPT | _ENABLE_MASK);
	__mtfsf(__r);
	return (0);
}

__fenv_static inline int
fesetenv(const fenv_t *__envp)
{
	union __fpscr __r;

	__r.__bits.__reg = *__envp;
	__mtfsf(__r);
	return (0);
}

__fenv_static inline int
feupdateenv(const fenv_t *__envp)
{
	union __fpscr __r;

	__mffs(&__r);
	__r.__bits.__reg &= FE_ALL_EXCEPT;
	__r.__bits.__reg |= *__envp;
	__mtfsf(__r);
	return (0);
}

#if __BSD_VISIBLE

/* We currently provide no external definitions of the functions below. */

static inline int
feenableexcept(int __mask)
{
	union __fpscr __r;
	fenv_t __oldmask;

	__mffs(&__r);
	__oldmask = __r.__bits.__reg;
	__r.__bits.__reg |= (__mask & FE_ALL_EXCEPT) >> _FPUSW_SHIFT;
	__mtfsf(__r);
	return ((__oldmask & _ENABLE_MASK) << _FPUSW_SHIFT);
}

static inline int
fedisableexcept(int __mask)
{
	union __fpscr __r;
	fenv_t __oldmask;

	__mffs(&__r);
	__oldmask = __r.__bits.__reg;
	__r.__bits.__reg &= ~((__mask & FE_ALL_EXCEPT) >> _FPUSW_SHIFT);
	__mtfsf(__r);
	return ((__oldmask & _ENABLE_MASK) << _FPUSW_SHIFT);
}

static inline int
fegetexcept(void)
{
	union __fpscr __r;

	__mffs(&__r);
	return ((__r.__bits.__reg & _ENABLE_MASK) << _FPUSW_SHIFT);
}

#endif /* __BSD_VISIBLE */

__END_DECLS

#endif	/* !_FENV_H_ */