/*-
 * 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.
 *
 * $FreeBSD$
 */

#ifndef _FENV_H_
#define _FENV_H_

#include <stdint.h>
#include <sys/cdefs.h>
#include <sys/types.h>

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)))

static __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);
}

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);
}

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

static __inline int
fetestexcept(int __excepts)
{
        uint32_t __mxcsr;
        uint16_t __status;

        __stmxcsr(&__mxcsr);
        __fnstsw(&__status);
        return ((__status | __mxcsr) & __excepts);
}

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);
}

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);
}

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

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);
}

int feupdateenv(const fenv_t *__envp);

#ifdef _DEFAULT_SOURCE

int feenableexcept(int __mask);
int fedisableexcept(int __mask);

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 /* _DEFAULT_SOURCE */

__END_DECLS

#endif  /* !_FENV_H_ */