/*-
 * Copyright (c) 2004 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/cdefs.h>
#include <sys/_types.h>

typedef struct {
	__uint32_t	__control;
	__uint32_t	__status;
	__uint32_t	__tag;
	char		__other[16];
} fenv_t;

typedef	__uint16_t	fexcept_t;

/* Exception flags */
#define	FE_INVALID	0x01
#define	FE_DENORMAL	0x02
#define	FE_DIVBYZERO	0x04
#define	FE_OVERFLOW	0x08
#define	FE_UNDERFLOW	0x10
#define	FE_INEXACT	0x20
#define	FE_ALL_EXCEPT	(FE_DIVBYZERO | FE_DENORMAL | FE_INEXACT | \
			 FE_INVALID | FE_OVERFLOW | FE_UNDERFLOW)

/* Rounding modes */
#define	FE_TONEAREST	0x0000
#define	FE_DOWNWARD	0x0400
#define	FE_UPWARD	0x0800
#define	FE_TOWARDZERO	0x0c00
#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)

#define	__fldcw(__cw)		__asm __volatile("fldcw %0" : : "m" (__cw))
#define	__fldenv(__env)		__asm __volatile("fldenv %0" : : "m" (__env))
#define	__fnclex()		__asm __volatile("fnclex")
#define	__fnstenv(__env)	__asm("fnstenv %0" : "=m" (*(__env)))
#define	__fnstcw(__cw)		__asm("fnstcw %0" : "=m" (*(__cw)))
#define	__fnstsw(__sw)		__asm("fnstsw %0" : "=am" (*(__sw)))
#define	__fwait()		__asm __volatile("fwait")

static __inline int
feclearexcept(int __excepts)
{
	fenv_t __env;

	if (__excepts == FE_ALL_EXCEPT) {
		__fnclex();
	} else {
		__fnstenv(&__env);
		__env.__status &= ~__excepts;
		__fldenv(__env);
	}
	return (0);
}

static __inline int
fegetexceptflag(fexcept_t *__flagp, int __excepts)
{
	int __status;

	__fnstsw(&__status);
	*__flagp = __status & __excepts;
	return (0);
}

static __inline int
fesetexceptflag(const fexcept_t *__flagp, int __excepts)
{
	fenv_t __env;

	__fnstenv(&__env);
	__env.__status &= ~__excepts;
	__env.__status |= *__flagp & __excepts;
	__fldenv(__env);
	return (0);
}

static __inline int
feraiseexcept(int __excepts)
{
	fexcept_t __ex = __excepts;

	fesetexceptflag(&__ex, __excepts);
	__fwait();
	return (0);
}

static __inline int
fetestexcept(int __excepts)
{
	int __status;

	__fnstsw(&__status);
	return (__status & __excepts);
}

static __inline int
fegetround(void)
{
	int __control;

	__fnstcw(&__control);
	return (__control & _ROUND_MASK);
}

static __inline int
fesetround(int __round)
{
	int __control;

	if (__round & ~_ROUND_MASK)
		return (-1);
	__fnstcw(&__control);
	__control &= ~_ROUND_MASK;
	__control |= __round;
	__fldcw(__control);
	return (0);
}

static __inline int
fegetenv(fenv_t *__envp)
{
	int __control;

	/*
	 * fnstenv masks all exceptions, so we need to save and
	 * restore the control word to avoid this side effect.
	 */
	__fnstcw(&__control);
	__fnstenv(__envp);
	__fldcw(__control);
	return (0);
}

static __inline int
feholdexcept(fenv_t *__envp)
{

	__fnstenv(__envp);
	__fnclex();
	return (0);
}

static __inline int
fesetenv(const fenv_t *__envp)
{

	__fldenv(*__envp);
	return (0);
}

static __inline int
feupdateenv(const fenv_t *__envp)
{
	int __status;

	__fnstsw(&__status);
	__fldenv(*__envp);
	feraiseexcept(__status & FE_ALL_EXCEPT);
	return (0);
}

#if __BSD_VISIBLE

static __inline int
fesetmask(int __mask)
{
	int __control;

	__fnstcw(&__control);
	__mask = (__control | FE_ALL_EXCEPT) & ~__mask;
	__fldcw(__mask);
	return (~__control & FE_ALL_EXCEPT);
}

static __inline int
fegetmask(void)
{
	int __control;

	__fnstcw(&__control);
	return (~__control & FE_ALL_EXCEPT);
}

#endif /* __BSD_VISIBLE */

__END_DECLS

#endif	/* !_FENV_H_ */