/*	$OpenBSD: fenv.h,v 1.2 2021/05/12 02:28:25 jsg Exp $	*/

/*
 * Copyright (c) 2011 Martynas Venckus <martynas@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#ifndef	_MACHINE_FENV_H_
#define	_MACHINE_FENV_H_

/*
 * 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 registers.
 */
#define	FE_INVALID		0x10
#define	FE_DIVBYZERO		0x08
#define	FE_OVERFLOW		0x04
#define	FE_UNDERFLOW		0x02
#define	FE_INEXACT		0x01

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

/*
 * 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 registers.
 */
#define	FE_TONEAREST		0x0
#define	FE_TOWARDZERO		0x1
#define	FE_DOWNWARD		0x2
#define	FE_UPWARD		0x3
#define	FE_TONEARESTFROMZERO	0x4

/*
 * The following symbol is simply the bitwise-inclusive OR of all floating-point
 * rounding direction constants defined above.
 */
#define	_ROUND_MASK		(FE_TONEAREST | FE_TOWARDZERO | FE_DOWNWARD | \
				 FE_UPWARD | FE_TONEARESTFROMZERO)
#define	_ROUND_SHIFT		5

/*
 * fenv_t represents the entire floating-point environment.
 */
typedef	unsigned int		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().
 */
__BEGIN_DECLS
extern	fenv_t			__fe_dfl_env;
__END_DECLS
#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;

#endif	/* !_MACHINE_FENV_H_ */