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/* $NetBSD: npx.h,v 1.11 1994/10/27 04:16:11 cgd Exp $ */
/*-
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* William Jolitz.
*
* 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.
*
* @(#)npx.h 5.3 (Berkeley) 1/18/91
*/
/*
* 287/387 NPX Coprocessor Data Structures and Constants
* W. Jolitz 1/90
*/
#ifndef _I386_NPX_H_
#define _I386_NPX_H_
/* Environment information of floating point unit */
struct env87 {
long en_cw; /* control word (16bits) */
long en_sw; /* status word (16bits) */
long en_tw; /* tag word (16bits) */
long en_fip; /* floating point instruction pointer */
u_short en_fcs; /* floating code segment selector */
u_short en_opcode; /* opcode last executed (11 bits ) */
long en_foo; /* floating operand offset */
long en_fos; /* floating operand segment selector */
};
/* Contents of each floating point accumulator */
struct fpacc87 {
#ifdef dontdef /* too unportable */
u_long fp_mantlo; /* mantissa low (31:0) */
u_long fp_manthi; /* mantissa high (63:32) */
int fp_exp:15; /* exponent */
int fp_sgn:1; /* mantissa sign */
#else
u_char fp_bytes[10];
#endif
};
/* Floating point context */
struct save87 {
struct env87 sv_env; /* floating point control/status */
struct fpacc87 sv_ac[8]; /* accumulator contents, 0-7 */
#ifndef dontdef
u_long sv_ex_sw; /* status word for last exception (was pad) */
u_long sv_ex_tw; /* tag word for last exception (was pad) */
u_char sv_pad[8 * 2 - 2 * 4]; /* bogus historical padding */
#endif
};
/* Cyrix EMC memory - mapped coprocessor context switch information */
struct emcsts {
long em_msw; /* memory mapped status register when swtched */
long em_tar; /* memory mapped temp A register when swtched */
long em_dl; /* memory mapped D low register when swtched */
};
/* Intel prefers long real (53 bit) precision */
#define __iBCS_NPXCW__ 0x262
#define __NetBSD_NPXCW__ 0x127f
/*
* The standard control word from finit is 0x37F, giving:
* round to nearest
* 64-bit precision
* all exceptions masked.
*
* Now we want:
* affine mode (if we decide to support 287's)
* round to nearest
* 53-bit precision
* all exceptions masked.
*
* 64-bit precision often gives bad results with high level languages
* because it makes the results of calculations depend on whether
* intermediate values are stored in memory or in FPU registers.
*
* The iBCS control word has underflow, overflow, zero divide, and invalid
* operation exceptions unmasked. But that causes an unexpected exception
* in the test program 'paranoia' and makes denormals useless (DBL_MIN / 2
* underflows). It doesn't make a lot of sense to trap underflow without
* trapping denormals.
*/
#define __INITIAL_NPXCW__ __NetBSD_NPXCW__
#endif /* !_I386_NPX_H_ */
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