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fenv.h

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/** @file
 * IPRT / No-CRT - fenv.h, X86.
 */

/*
 * Copyright (C) 2006-2007 Oracle Corporation
 *
 * This file is part of VirtualBox Open Source Edition (OSE), as
 * available from http://www.virtualbox.org. This file is free software;
 * you can redistribute it and/or modify it under the terms of the GNU
 * General Public License (GPL) as published by the Free Software
 * Foundation, in version 2 as it comes in the "COPYING" file of the
 * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
 * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
 *
 * The contents of this file may alternatively be used under the terms
 * of the Common Development and Distribution License Version 1.0
 * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
 * VirtualBox OSE distribution, in which case the provisions of the
 * CDDL are applicable instead of those of the GPL.
 *
 * You may elect to license modified versions of this file under the
 * terms and conditions of either the GPL or the CDDL or both.
 * --------------------------------------------------------------------
 *
 * This code is based on:
 *
 * Copyright (c) 2004-2005 David Schultz <das@FreeBSD.ORG>
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 *
 * $FreeBSD: src/lib/msun/i387/fenv.h,v 1.4 2005/03/17 22:21:46 das Exp $
 */

#ifndef ___iprt_nocrt_x86_fenv_h
#define ___iprt_nocrt_x86_fenv_h

#include <iprt/types.h>

/*
 * To preserve binary compatibility with FreeBSD 5.3, we pack the
 * mxcsr into some reserved fields, rather than changing sizeof(fenv_t).
 */
typedef struct {
    uint16_t    __control;
    uint16_t      __mxcsr_hi;
    uint16_t    __status;
    uint16_t      __mxcsr_lo;
    uint32_t    __tag;
    char        __other[16];
} fenv_t;

#define __get_mxcsr(env)    (((env).__mxcsr_hi << 16) | \
                 ((env).__mxcsr_lo))
#define __set_mxcsr(env, x) do {                \
    (env).__mxcsr_hi = (uint32_t)(x) >> 16;     \
    (env).__mxcsr_lo = (uint16_t)(x);           \
} while (0)

typedef uint16_t    fexcept_t;

/* Exception flags */
#define FE_INVALID  0x01
#define FE_DENORMAL 0x02
#define FE_DIVBYZERO    0x04
#define FE_OVERFLOW 0x08
#define FE_UNDERFLOW    0x10
#define FE_INEXACT  0x20
#define FE_ALL_EXCEPT   (FE_DIVBYZERO | FE_DENORMAL | FE_INEXACT | \
             FE_INVALID | FE_OVERFLOW | FE_UNDERFLOW)

/* Rounding modes */
#define FE_TONEAREST    0x0000
#define FE_DOWNWARD 0x0400
#define FE_UPWARD   0x0800
#define FE_TOWARDZERO   0x0c00
#define _ROUND_MASK (FE_TONEAREST | FE_DOWNWARD | \
             FE_UPWARD | FE_TOWARDZERO)

/*
 * As compared to the x87 control word, the SSE unit's control word
 * has the rounding control bits offset by 3 and the exception mask
 * bits offset by 7.
 */
#define _SSE_ROUND_SHIFT    3
#define _SSE_EMASK_SHIFT    7

/* After testing for SSE support once, we cache the result in __has_sse. */
enum __sse_support { __SSE_YES, __SSE_NO, __SSE_UNK };
extern enum __sse_support RT_NOCRT(__has_sse);
int RT_NOCRT(__test_sse)(void);
#ifdef __SSE__
#define __HAS_SSE() 1
#else
#define __HAS_SSE() (RT_NOCRT(__has_sse) == __SSE_YES ||          \
             (RT_NOCRT(__has_sse) == __SSE_UNK && RT_NOCRT(__test_sse)()))
#endif

RT_C_DECLS_BEGIN

/* Default floating-point environment */
extern const fenv_t __fe_dfl_env;
#define FE_DFL_ENV  (&__fe_dfl_env)

#define __fldcw(__cw)       __asm __volatile("fldcw %0" : : "m" (__cw))
#define __fldenv(__env)     __asm __volatile("fldenv %0" : : "m" (__env))
#define __fnclex()      __asm __volatile("fnclex")
#define __fnstenv(__env)    __asm __volatile("fnstenv %0" : "=m" (*(__env)))
#define __fnstcw(__cw)      __asm __volatile("fnstcw %0" : "=m" (*(__cw)))
#define __fnstsw(__sw)      __asm __volatile("fnstsw %0" : "=am" (*(__sw)))
#define __fwait()       __asm __volatile("fwait")
#define __ldmxcsr(__csr)    __asm __volatile("ldmxcsr %0" : : "m" (__csr))
#define __stmxcsr(__csr)    __asm __volatile("stmxcsr %0" : "=m" (*(__csr)))

DECLINLINE(int)
feclearexcept(int __excepts)
{
    fenv_t __env;
    int __mxcsr;

    if (__excepts == FE_ALL_EXCEPT) {
        __fnclex();
    } else {
        __fnstenv(&__env);
        __env.__status &= ~__excepts;
        __fldenv(__env);
    }
    if (__HAS_SSE()) {
        __stmxcsr(&__mxcsr);
        __mxcsr &= ~__excepts;
        __ldmxcsr(__mxcsr);
    }
    return (0);
}

DECLINLINE(int)
fegetexceptflag(fexcept_t *__flagp, int __excepts)
{
    int __mxcsr, __status;

    __fnstsw(&__status);
    if (__HAS_SSE())
        __stmxcsr(&__mxcsr);
    else
        __mxcsr = 0;
    *__flagp = (__mxcsr | __status) & __excepts;
    return (0);
}

int RT_NOCRT(fesetexceptflag)(const fexcept_t *__flagp, int __excepts);
int RT_NOCRT(feraiseexcept)(int __excepts);

DECLINLINE(int)
fetestexcept(int __excepts)
{
    int __mxcsr, __status;

    __fnstsw(&__status);
    if (__HAS_SSE())
        __stmxcsr(&__mxcsr);
    else
        __mxcsr = 0;
    return ((__status | __mxcsr) & __excepts);
}

DECLINLINE(int)
fegetround(void)
{
    int __control;

    /*
     * We assume that the x87 and the SSE unit agree on the
     * rounding mode.  Reading the control word on the x87 turns
     * out to be about 5 times faster than reading it on the SSE
     * unit on an Opteron 244.
     */
    __fnstcw(&__control);
    return (__control & _ROUND_MASK);
}

DECLINLINE(int)
fesetround(int __round)
{
    int __mxcsr, __control;

    if (__round & ~_ROUND_MASK)
        return (-1);

    __fnstcw(&__control);
    __control &= ~_ROUND_MASK;
    __control |= __round;
    __fldcw(__control);

    if (__HAS_SSE()) {
        __stmxcsr(&__mxcsr);
        __mxcsr &= ~(_ROUND_MASK << _SSE_ROUND_SHIFT);
        __mxcsr |= __round << _SSE_ROUND_SHIFT;
        __ldmxcsr(__mxcsr);
    }

    return (0);
}

int RT_NOCRT(fegetenv)(fenv_t *__envp);
int RT_NOCRT(feholdexcept)(fenv_t *__envp);

DECLINLINE(int)
fesetenv(const fenv_t *__envp)
{
    fenv_t __env = *__envp;
    int __mxcsr;

    __mxcsr = __get_mxcsr(__env);
    __set_mxcsr(__env, 0xffffffff);
    __fldenv(__env);
    if (__HAS_SSE())
        __ldmxcsr(__mxcsr);
    return (0);
}

int RT_NOCRT(feupdateenv)(const fenv_t *__envp);
int RT_NOCRT(feenableexcept)(int __mask);
int RT_NOCRT(fedisableexcept)(int __mask);

DECLINLINE(int)
fegetexcept(void)
{
    int __control;

    /*
     * We assume that the masks for the x87 and the SSE unit are
     * the same.
     */
    __fnstcw(&__control);
    return (~__control & FE_ALL_EXCEPT);
}

RT_C_DECLS_END

#ifndef RT_WIHTOUT_NOCRT_WRAPPERS
# define __has_sse RT_NOCRT(__has_sse)
# define __test_sse RT_NOCRT(__test_sse)
# define __test_sse RT_NOCRT(__test_sse)
# define fesetexceptflag RT_NOCRT(fesetexceptflag)
# define feraiseexcept RT_NOCRT(feraiseexcept)
# define fegetenv RT_NOCRT(fegetenv)
# define feholdexcept RT_NOCRT(feholdexcept)
# define feupdateenv RT_NOCRT(feupdateenv)
# define feenableexcept RT_NOCRT(feenableexcept)
# define fedisableexcept RT_NOCRT(fedisableexcept)
#endif

#endif  /* !__iprt_nocrt_x86_fenv_h__ */


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