openlibm_fenv_amd64.h

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/*-
 * 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/amd64/fenv.h,v 1.8 2011/10/10 15:43:09 das Exp $
 */
 
#ifndef _FENV_H_
#define _FENV_H_
 
#include "openlibm_defs.h"
#include "../inc/cdefs-compat.h"
#include "../inc/types-compat.h"
 
#ifndef __fenv_static
#define __fenv_static   static
#endif
 
typedef struct {
    struct {
        uint32_t    __control;
        uint32_t    __status;
        uint32_t    __tag;
        char        __other[16];
    } __x87;
    uint32_t        __mxcsr;
} fenv_t;
 
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
 
__BEGIN_DECLS
 
/* 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 __fldenvx(__env)    __asm __volatile("fldenv %0" : : "m" (__env)  \
                : "st", "st(1)", "st(2)", "st(3)", "st(4)",   \
                "st(5)", "st(6)", "st(7)")
#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)))
 
__fenv_static __attribute__((always_inline)) inline int
feclearexcept(int __excepts)
{
    fenv_t __env;
 
    if (__excepts == FE_ALL_EXCEPT) {
        __fnclex();
    } else {
        __fnstenv(&__env.__x87);
        __env.__x87.__status &= ~__excepts;
        __fldenv(__env.__x87);
    }
    __stmxcsr(&__env.__mxcsr);
    __env.__mxcsr &= ~__excepts;
    __ldmxcsr(__env.__mxcsr);
    return (0);
}
 
__fenv_static inline int
fegetexceptflag(fexcept_t *__flagp, int __excepts)
{
    uint32_t __mxcsr;
    uint16_t __status;
 
    __stmxcsr(&__mxcsr);
    __fnstsw(&__status);
    *__flagp = (__mxcsr | __status) & __excepts;
    return (0);
}
 
OLM_DLLEXPORT int fesetexceptflag(const fexcept_t *__flagp, int __excepts);
OLM_DLLEXPORT int feraiseexcept(int __excepts);
 
__fenv_static __attribute__((always_inline)) inline int
fetestexcept(int __excepts)
{
    uint32_t __mxcsr;
    uint16_t __status;
 
    __stmxcsr(&__mxcsr);
    __fnstsw(&__status);
    return ((__status | __mxcsr) & __excepts);
}
 
__fenv_static inline int
fegetround(void)
{
    uint16_t __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);
}
 
__fenv_static inline int
fesetround(int __round)
{
    uint32_t __mxcsr;
    uint16_t __control;
 
    if (__round & ~_ROUND_MASK)
        return (-1);
 
    __fnstcw(&__control);
    __control &= ~_ROUND_MASK;
    __control |= __round;
    __fldcw(__control);
 
    __stmxcsr(&__mxcsr);
    __mxcsr &= ~(_ROUND_MASK << _SSE_ROUND_SHIFT);
    __mxcsr |= __round << _SSE_ROUND_SHIFT;
    __ldmxcsr(__mxcsr);
 
    return (0);
}
 
OLM_DLLEXPORT int fegetenv(fenv_t *__envp);
OLM_DLLEXPORT int feholdexcept(fenv_t *__envp);
 
__fenv_static inline int
fesetenv(const fenv_t *__envp)
{
 
    /*
     * XXX Using fldenvx() instead of fldenv() tells the compiler that this
     * instruction clobbers the i387 register stack.  This happens because
     * we restore the tag word from the saved environment.  Normally, this
     * would happen anyway and we wouldn't care, because the ABI allows
     * function calls to clobber the i387 regs.  However, fesetenv() is
     * inlined, so we need to be more careful.
     */
    __fldenvx(__envp->__x87);
    __ldmxcsr(__envp->__mxcsr);
    return (0);
}
 
OLM_DLLEXPORT int feupdateenv(const fenv_t *__envp);
 
#if __BSD_VISIBLE
 
OLM_DLLEXPORT int feenableexcept(int __mask);
OLM_DLLEXPORT int fedisableexcept(int __mask);
 
/* We currently provide no external definition of fegetexcept(). */
static inline int
fegetexcept(void)
{
    uint16_t __control;
 
    /*
     * We assume that the masks for the x87 and the SSE unit are
     * the same.
     */
    __fnstcw(&__control);
    return (~__control & FE_ALL_EXCEPT);
}
 
#endif /* __BSD_VISIBLE */
 
__END_DECLS
 
#endif  /* !_FENV_H_ */