xref: /freebsd-11.0-release/sys/i386/include/floatingpoint.h

/*-
 * Copyright (c) 1993 Andrew Moore, Talke Studio
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 *
 *	from: @(#) floatingpoint.h	1.0 (Berkeley) 9/23/93
 * $FreeBSD: head/sys/i386/include/floatingpoint.h 97713 2002-06-01 17:39:46Z bde $
 */

#ifndef _FLOATINGPOINT_H_
#define _FLOATINGPOINT_H_

/*
 * IEEE floating point structure and function definitions
 */

/*-
 * XXX the following undocumented pollution is exported:
 *	fpsetsticky().
 *	FP*FLD, FP*OFF and FP*REG from <machine/ieeefp.h>
 */

#include <sys/cdefs.h>
#include <machine/ieeefp.h>

#ifdef __GNUC__

#define __fldenv(addr)	__asm __volatile("fldenv %0" : : "m" (*(addr)))
#define __fnstenv(addr)	__asm __volatile("fnstenv %0" : "=m" (*(addr)))
#define __fnstcw(addr)	__asm __volatile("fnstcw %0" : "=m" (*(addr)))
#define __fnstsw(addr)	__asm __volatile("fnstsw %0" : "=m" (*(addr)))

/*
 * return the contents of a FP register
 */
static __inline__ int
__fpgetreg(int _reg)
{
	unsigned short _mem;

	/*-
	 * This is more efficient than it looks.  The switch gets optimized
	 * away if _reg is constant.
	 *
	 * The default case only supports _reg == 0.  We could handle more
	 * registers (e.g., tags) using fnstenv, but the interface doesn't
	 * support more.
	 */
	switch(_reg) {
	default:
		__fnstcw(&_mem);
		break;
	case FP_STKY_REG:
		__fnstsw(&_mem);
		break;
	}
	return _mem;
}

/*
 * set a FP mode; return previous mode
 */
static __inline__ int
__fpsetreg(int _m, int _reg, int _fld, int _off)
{
	unsigned _env[7];
	unsigned _p;

	/*
	 * _reg == 0 could be handled better using fnstcw/fldcw.
	 */
	__fnstenv(_env);
	_p =  (_env[_reg] & _fld) >> _off;
	_env[_reg] = (_env[_reg] & ~_fld) | (_m << _off & _fld);
	__fldenv(_env);
	return _p;
}

#endif /* __GNUC__ */

/*
 * SysV/386 FP control interface
 */
#define	fpgetround()	((fp_rnd_t)					\
	((__fpgetreg(FP_RND_REG) & FP_RND_FLD) >> FP_RND_OFF))
#define	fpsetround(m)	((fp_rnd_t)					\
	__fpsetreg((m), FP_RND_REG, FP_RND_FLD, FP_RND_OFF))
#define	fpgetprec()	((fp_prec_t)					\
	((__fpgetreg(FP_PRC_REG) & FP_PRC_FLD) >> FP_PRC_OFF))
#define	fpsetprec(m)	((fp_prec_t)					\
	__fpsetreg((m), FP_PRC_REG, FP_PRC_FLD, FP_PRC_OFF))
#define	fpgetmask()	((fp_except_t)					\
	((~__fpgetreg(FP_MSKS_REG) & FP_MSKS_FLD) >> FP_MSKS_OFF))
#define	fpsetmask(m)	((fp_except_t)					\
	(~__fpsetreg(~(m), FP_MSKS_REG, FP_MSKS_FLD, FP_MSKS_OFF)) &	\
	    (FP_MSKS_FLD >> FP_MSKS_OFF))
#define	fpgetsticky()	((fp_except_t)					\
	((__fpgetreg(FP_STKY_REG) & FP_STKY_FLD) >> FP_STKY_OFF))
#define	fpresetsticky(m) ((fp_except_t)					\
	__fpsetreg(0, FP_STKY_REG, (m), FP_STKY_OFF))
#define	fpsetsticky(m)	fpresetsticky(m)

#endif /* !_FLOATINGPOINT_H_ */