control_w.h

freebsd v4.4内核源码

/*
 *  control_w.h
 *
 *
 * Copyright (C) 1992,1993,1994
 *                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,
 *                       Australia.  E-mail   [e-mail]
 * All rights reserved.
 *
 * This copyright notice covers the redistribution and use of the
 * FPU emulator developed by W. Metzenthen. It covers only its use
 * in the 386BSD, FreeBSD and NetBSD operating systems. Any other
 * use is not permitted under this copyright.
 *
 * 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 include information specifying
 *    that source code for the emulator is freely available and include
 *    either:
 *      a) an offer to provide the source code for a nominal distribution
 *         fee, or
 *      b) list at least two alternative methods whereby the source
 *         can be obtained, e.g. a publically accessible bulletin board
 *         and an anonymous ftp site from which the software can be
 *         downloaded.
 * 3. All advertising materials specifically mentioning features or use of
 *    this emulator must acknowledge that it was developed by W. Metzenthen.
 * 4. The name of W. Metzenthen may not be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED ``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
 * W. METZENTHEN 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.
 *
 *
 * The purpose of this copyright, based upon the Berkeley copyright, is to
 * ensure that the covered software remains freely available to everyone.
 *
 * The software (with necessary differences) is also available, but under
 * the terms of the GNU copyleft, for the Linux operating system and for
 * the djgpp ms-dos extender.
 *
 * W. Metzenthen   June 1994.
 *
 *
 * $FreeBSD: src/sys/gnu/i386/fpemul/control_w.h,v 1.4.8.1 1999/09/05 08:09:33 peter Exp $
 *
 */

#ifndef _CONTROLW_H_
#define _CONTROLW_H_

#ifdef LOCORE
#define	_Const_(x)	$/**/x
#else
#define	_Const_(x)	x
#endif

#define CW_RC		_Const_(0x0C00)	/* rounding control */
#define CW_PC		_Const_(0x0300)	/* precision control */

#define CW_Precision	Const_(0x0020)	/* loss of precision mask */
#define CW_Underflow	Const_(0x0010)	/* underflow mask */
#define CW_Overflow	Const_(0x0008)	/* overflow mask */
#define CW_ZeroDiv	Const_(0x0004)	/* divide by zero mask */
#define CW_Denormal	Const_(0x0002)	/* denormalized operand mask */
#define CW_Invalid	Const_(0x0001)	/* invalid operation mask */

#define CW_Exceptions  	_Const_(0x003f)	/* all masks */

#define RC_RND		_Const_(0x0000)
#define RC_DOWN		_Const_(0x0400)
#define RC_UP		_Const_(0x0800)
#define RC_CHOP		_Const_(0x0C00)

/* p 15-5: Precision control bits affect only the following:
   ADD, SUB(R), MUL, DIV(R), and SQRT */
#define PR_24_BITS      _Const_(0x000)
#define PR_53_BITS      _Const_(0x200)
#define PR_64_BITS      _Const_(0x300)
/* FULL_PRECISION simulates all exceptions masked */
#define FULL_PRECISION  (PR_64_BITS | RC_RND | 0x3f)

#endif				/* _CONTROLW_H_ */