/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * 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.
 */

#ifndef _FENV_H_
#define _FENV_H_

#include <sys/cdefs.h>
#include <sys/_types.h>
#include <ieeefp.h>

#ifndef __fenv_static
#define __fenv_static   static
#endif

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

#ifdef __i386__
/*
 * 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;
#else /* __amd64__ */
typedef struct {
        struct {
                __uint32_t      __control;
                __uint32_t      __status;
                __uint32_t      __tag;
                char            __other[16];
        } __x87;
        __uint32_t              __mxcsr;
} fenv_t;
#endif /* __i386__ */

__BEGIN_DECLS

/* Default floating-point environment */
extern const fenv_t     __fe_dfl_env;
#define FE_DFL_ENV      (&__fe_dfl_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 __fwait()               __asm __volatile("fwait")

int fegetenv(fenv_t *__envp);
int feholdexcept(fenv_t *__envp);
int fesetexceptflag(const fexcept_t *__flagp, int __excepts);
int feraiseexcept(int __excepts);
int feupdateenv(const fenv_t *__envp);

__fenv_static inline int
__fegetround_int(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);
}

#if __BSD_VISIBLE

int feenableexcept(int __mask);
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 */

int feclearexcept(int);
int fegetexceptflag(fexcept_t *, int);
int fetestexcept(int);
int fesetround(int);
int fegetround(void);
int fesetenv(const fenv_t *);

#define feclearexcept(a)        __feclearexcept_int(a)
#define fegetexceptflag(e, a)   __fegetexceptflag_int(e, a)
#define fetestexcept(a)         __fetestexcept_int(a)
#define fesetround(a)           __fesetround_int(a)
#define fegetround()            __fegetround_int()
#define fesetenv(a)             __fesetenv_int(a)

#ifdef __i386__

/* 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 __has_sse;
int __test_sse(void);
#ifdef __SSE__
#define __HAS_SSE()     1
#else
#define __HAS_SSE()     (__has_sse == __SSE_YES ||                      \
                         (__has_sse == __SSE_UNK && __test_sse()))
#endif

#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)

__fenv_static inline int
__feclearexcept_int(int __excepts)
{
        fenv_t __env;
        __uint32_t __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);
}

__fenv_static inline int
__fegetexceptflag_int(fexcept_t *__flagp, int __excepts)
{
        __uint32_t __mxcsr;
        __uint16_t __status;

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

__fenv_static inline int
__fetestexcept_int(int __excepts)
{
        __uint32_t __mxcsr;
        __uint16_t __status;

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

__fenv_static inline int
__fesetround_int(int __round)
{
        __uint32_t __mxcsr;
        __uint16_t __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);
}

__fenv_static inline int
__fesetenv_int(const fenv_t *__envp)
{
        fenv_t __env = *__envp;
        __uint32_t __mxcsr;

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

#else /* __amd64__ */

__fenv_static inline int
__feclearexcept_int(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_int(fexcept_t *__flagp, int __excepts)
{
        __uint32_t __mxcsr;
        __uint16_t __status;

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

__fenv_static inline int
__fetestexcept_int(int __excepts)
{
        __uint32_t __mxcsr;
        __uint16_t __status;

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

__fenv_static inline int
__fesetround_int(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);
}

__fenv_static inline int
__fesetenv_int(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);
}

#endif /* __i386__ */

__END_DECLS

#endif  /* !_FENV_H_ */