1/*	$NetBSD: fenv.h,v 1.2 2014/02/12 23:04:43 dsl Exp $	*/
  2/*-
  3 * Copyright (c) 2004-2005 David Schultz <das (at) FreeBSD.ORG>
  4 * All rights reserved.
  5 *
  6 * Redistribution and use in source and binary forms, with or without
  7 * modification, are permitted provided that the following conditions
  8 * are met:
  9 * 1. Redistributions of source code must retain the above copyright
 10 *    notice, this list of conditions and the following disclaimer.
 11 * 2. Redistributions in binary form must reproduce the above copyright
 12 *    notice, this list of conditions and the following disclaimer in the
 13 *    documentation and/or other materials provided with the distribution.
 14 *
 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 18 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 25 * SUCH DAMAGE.
 26 */
 27
 28#ifndef	_X86_FENV_H_
 29#define	_X86_FENV_H_
 30
 31#ifndef _KERNEL
 32#include <sys/stdint.h>
 33#endif
 34
 35/* Default x87 control word. */
 36#define __INITIAL_NPXCW__       0x037f  
 37/* Modern NetBSD uses the default control word.. */
 38#define __NetBSD_NPXCW__        __INITIAL_NPXCW__
 39/* NetBSD before 6.99.26 forced IEEE double precision. */
 40#define __NetBSD_COMPAT_NPXCW__ 0x127f
 41
 42/* Default values for the mxcsr. All traps masked. */
 43#define __INITIAL_MXCSR__       0x1f80
 44
 45#ifndef _KERNEL
 46/*
 47 * Each symbol representing a floating point exception expands to an integer
 48 * constant expression with values, such that bitwise-inclusive ORs of _all
 49 * combinations_ of the constants result in distinct values.
 50 *
 51 * We use such values that allow direct bitwise operations on FPU/SSE registers.
 52 */
 53#define	FE_INVALID	0x01	/* 000000000001 */
 54#define	FE_DENORMAL	0x02	/* 000000000010 */
 55#define	FE_DIVBYZERO	0x04	/* 000000000100 */
 56#define	FE_OVERFLOW	0x08	/* 000000001000 */
 57#define	FE_UNDERFLOW	0x10	/* 000000010000 */
 58#define	FE_INEXACT	0x20	/* 000000100000 */
 59
 60/*
 61 * The following symbol is simply the bitwise-inclusive OR of all floating-point
 62 * exception constants defined above.
 63 */
 64#define FE_ALL_EXCEPT	(FE_DIVBYZERO | FE_DENORMAL | FE_INEXACT | \
 65			 FE_INVALID | FE_OVERFLOW | FE_UNDERFLOW)
 66
 67/*
 68 * Each symbol representing the rounding direction, expands to an integer
 69 * constant expression whose value is distinct non-negative value.
 70 *
 71 * We use such values that allow direct bitwise operations on FPU/SSE registers.
 72 */
 73#define	FE_TONEAREST	0x000	/* 000000000000 */
 74#define	FE_DOWNWARD	0x400	/* 010000000000 */
 75#define	FE_UPWARD	0x800	/* 100000000000 */
 76#define	FE_TOWARDZERO	0xC00	/* 110000000000 */
 77
 78/*
 79 * As compared to the x87 control word, the SSE unit's control has the rounding
 80 * control bits offset by 3 and the exception mask bits offset by 7
 81 */
 82#define	__X87_ROUND_MASK	0xC00		/* 110000000000 */
 83#define	__SSE_ROUND_SHIFT	3
 84#define	__SSE_EMASK_SHIFT	7
 85
 86/*
 87 * fenv_t represents the entire floating-point environment
 88 */
 89typedef struct {
 90	struct {
 91		uint16_t control;	/* Control word register */
 92		uint16_t unused1;
 93		uint16_t status;	/* Status word register */
 94		uint16_t unused2;
 95		uint16_t tag;		/* Tag word register */
 96		uint16_t unused3;
 97		uint32_t others[4];	/* EIP, Pointer Selector, etc */
 98	} x87;
 99		
100	uint32_t mxcsr;			/* Control and status register */
101} fenv_t;
102
103/*
104 * The following constant represents the default floating-point environment
105 * (that is, the one installed at program startup) and has type pointer to
106 * const-qualified fenv_t.
107 *
108 * It can be used as an argument to the functions within the <fenv.h> header
109 * that manage the floating-point environment.
110 */
111extern  fenv_t		__fe_dfl_env;
112#define FE_DFL_ENV      ((const fenv_t *) &__fe_dfl_env)
113
114/*
115 * fexcept_t represents the floating-point status flags collectively, including
116 * any status the implementation associates with the flags.
117 *
118 * A floating-point status flag is a system variable whose value is set (but
119 * never cleared) when a floating-point exception is raised, which occurs as a
120 * side effect of exceptional floating-point arithmetic to provide auxiliary
121 * information.
122 *
123 * A floating-point control mode is a system variable whose value may be set by
124 * the user to affect the subsequent behavior of floating-point arithmetic.
125 */
126typedef uint32_t fexcept_t;
127#endif
128
129#endif	/* ! _X86_FENV_H_ */