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fenv.h revision 1.1.4.2 
      1 /*	$NetBSD: fenv.h,v 1.1.4.2 2010/08/17 06:44:37 uebayasi 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 #include <sys/stdint.h>
     32 #include <i386/npx.h>
     33 
     34 /*
     35  * Each symbol representing a floating point exception expands to an integer
     36  * constant expression with values, such that bitwise-inclusive ORs of _all
     37  * combinations_ of the constants result in distinct values.
     38  *
     39  * We use such values that allow direct bitwise operations on FPU/SSE registers.
     40  */
     41 #define	FE_INVALID	0x01	/* 000000000001 */
     42 #define	FE_DENORMAL	0x02	/* 000000000010 */
     43 #define	FE_DIVBYZERO	0x04	/* 000000000100 */
     44 #define	FE_OVERFLOW	0x08	/* 000000001000 */
     45 #define	FE_UNDERFLOW	0x10	/* 000000010000 */
     46 #define	FE_INEXACT	0x20	/* 000000100000 */
     47 
     48 /*
     49  * The following symbol is simply the bitwise-inclusive OR of all floating-point
     50  * exception constants defined above.
     51  */
     52 #define FE_ALL_EXCEPT	(FE_DIVBYZERO | FE_DENORMAL | FE_INEXACT | \
     53 			 FE_INVALID | FE_OVERFLOW | FE_UNDERFLOW)
     54 
     55 /*
     56  * Each symbol representing the rounding direction, expands to an integer
     57  * constant expression whose value is distinct non-negative value.
     58  *
     59  * We use such values that allow direct bitwise operations on FPU/SSE registers.
     60  */
     61 #define	FE_TONEAREST	0x000	/* 000000000000 */
     62 #define	FE_DOWNWARD	0x400	/* 010000000000 */
     63 #define	FE_UPWARD	0x800	/* 100000000000 */
     64 #define	FE_TOWARDZERO	0xC00	/* 110000000000 */
     65 
     66 /*
     67  * As compared to the x87 control word, the SSE unit's control has the rounding
     68  * control bits offset by 3 and the exception mask bits offset by 7
     69  */
     70 #define	__X87_ROUND_MASK	0xC00		/* 110000000000 */
     71 #define	__SSE_ROUND_SHIFT	3
     72 #define	__SSE_EMASK_SHIFT	7
     73 
     74 /*
     75  * fenv_t represents the entire floating-point environment
     76  */
     77 typedef struct {
     78 	struct {
     79 		uint16_t control;	/* Control word register */
     80 		uint16_t unused1;
     81 		uint16_t status;	/* Status word register */
     82 		uint16_t unused2;
     83 		uint16_t tag;		/* Tag word register */
     84 		uint16_t unused3;
     85 		uint32_t others[4];	/* EIP, Pointer Selector, etc */
     86 	} x87;
     87 
     88 	uint32_t mxcsr;			/* Control and status register */
     89 } fenv_t;
     90 
     91 /*
     92  * The following constant represents the default floating-point environment
     93  * (that is, the one installed at program startup) and has type pointer to
     94  * const-qualified fenv_t.
     95  *
     96  * It can be used as an argument to the functions within the <fenv.h> header
     97  * that manage the floating-point environment.
     98  */
     99 extern  fenv_t		__fe_dfl_env;
    100 #define FE_DFL_ENV      ((const fenv_t *) &__fe_dfl_env)
    101 
    102 /*
    103  * fexcept_t represents the floating-point status flags collectively, including
    104  * any status the implementation associates with the flags.
    105  *
    106  * A floating-point status flag is a system variable whose value is set (but
    107  * never cleared) when a floating-point exception is raised, which occurs as a
    108  * side effect of exceptional floating-point arithmetic to provide auxiliary
    109  * information.
    110  *
    111  * A floating-point control mode is a system variable whose value may be set by
    112  * the user to affect the subsequent behavior of floating-point arithmetic.
    113  */
    114 typedef uint32_t fexcept_t;
    115 
    116 #endif	/* ! _X86_FENV_H_ */
    117