/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * 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.
 */

#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	femode_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	_FPUSW_SHIFT	22
#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)

/* Default floating-point control modes */
extern const femode_t	__fe_dfl_mode;
#define	FE_DFL_MODE	(&__fe_dfl_mode)

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

#ifndef _SOFT_FLOAT
#define	__mffs(__env) \
	__asm __volatile("mffs %0" : "=f" ((__env)->__d))
#define	__mtfsf(__env) \
	__asm __volatile("mtfsf 255,%0" :: "f" ((__env).__d))
#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;
};

int feclearexcept(int);
int fegetexceptflag(fexcept_t *, int);
int fesetexceptflag(const fexcept_t *, int);
int feraiseexcept(int);
int fetestexcept(int);
int fegetround(void);
int fesetround(int);
int fegetmode(femode_t *);
int fesetmode(const femode_t *);
int fegetenv(fenv_t *);
int feholdexcept(fenv_t *);
int fesetenv(const fenv_t *);
int feupdateenv(const fenv_t *);

/*
 * C permits a standard library function to also be exposed as a function-like
 * macro (C23 7.1.4), and msun uses that here to inline the fast path.  C++
 * forbids it: <cfenv> imports these names into namespace std (using
 * ::feclearexcept; etc.), so std::feclearexcept() and friends must denote the
 * actual functions.  Expose the inlining macros to C only; C++ uses the real
 * extern functions (defined in the matching lib/msun/<arch>/fenv.c).
 */
#ifndef __cplusplus
#define	feclearexcept(a)	__feclearexcept_int(a)
#define	fegetexceptflag(e, a)	__fegetexceptflag_int(e, a)
#define	fesetexceptflag(e, a)	__fesetexceptflag_int(e, a)
#define	feraiseexcept(a)	__feraiseexcept_int(a)
#define	fetestexcept(a)		__fetestexcept_int(a)
#define	fegetround()		__fegetround_int()
#define	fesetround(a)		__fesetround_int(a)
#define	fegetmode(m)		__fegetmode_int(m)
#define	fesetmode(m)		__fesetmode_int(m)
#define	fegetenv(e)		__fegetenv_int(e)
#define	feholdexcept(e)		__feholdexcept_int(e)
#define	fesetenv(e)		__fesetenv_int(e)
#define	feupdateenv(e)		__feupdateenv_int(e)
#endif /* !__cplusplus */

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

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

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

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

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

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

__fenv_static inline int
__fesetround_int(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
__fegetmode_int(femode_t *__modep)
{
	union __fpscr __r;

	__mffs(&__r);
	*__modep = __r.__bits.__reg & ~FE_ALL_EXCEPT;
	return (0);
}

__fenv_static inline int
__fesetmode_int(const femode_t *__modep)
{
	union __fpscr __r;

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

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

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

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

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

__fenv_static inline int
__feupdateenv_int(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

int feenableexcept(int);
int fedisableexcept(int);

#ifndef __cplusplus	/* see the note above; C++ uses the real functions */
#define	feenableexcept(a)	__feenableexcept_int(a)
#define	fedisableexcept(a)	__fedisableexcept_int(a)
#endif

__fenv_static inline int
__feenableexcept_int(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);
}

__fenv_static inline int
__fedisableexcept_int(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);
}

/* We currently provide no external definition of fegetexcept(). */
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_ */