adtools/clib2

/*
 * $Id: math_tanh.c,v 1.5 2006-01-08 12:04:24 obarthel Exp $
 *
 * :ts=4
 *
 * Portable ISO 'C' (1994) runtime library for the Amiga computer
 * Copyright (c) 2002-2015 by Olaf Barthel <obarthel (at) gmx.net>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Neither the name of Olaf Barthel nor the names of contributors
 *     may be used to endorse or promote products derived from this
 *     software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
 *
 *
 * PowerPC math library based in part on work by Sun Microsystems
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunPro, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice
 * is preserved.
 */

#ifndef _MATH_HEADERS_H
#include "math_headers.h"
#endif /* _MATH_HEADERS_H */

/****************************************************************************/

#if defined(FLOATING_POINT_SUPPORT)

/****************************************************************************/

#if defined(IEEE_FLOATING_POINT_SUPPORT)

/****************************************************************************/

#if defined(__GNUC__)

/****************************************************************************/

#if defined(SMALL_DATA)
#define A4(x) "a4@(" #x ":W)"
#elif defined(SMALL_DATA32)
#define A4(x) "a4@(" #x ":L)"
#else
#define A4(x) #x
#endif /* SMALL_DATA */

/****************************************************************************/

extern double __tanh(double x);

/****************************************************************************/

asm("

    .text
    .even

    .globl    _MathIeeeDoubTransBase
    .globl    ___tanh

___tanh:

    movel    a6,sp@-
    movel    "A4(_MathIeeeDoubTransBase)",a6
    moveml    sp@(8),d0/d1
    jsr        a6@(-72:W)
    movel    sp@+,a6
    rts

");

/****************************************************************************/

#else

/****************************************************************************/

INLINE STATIC const double
__tanh(double x)
{
    double result;

    result = IEEEDPTanh(x);

    return(result);
}

/****************************************************************************/

#endif /* __GNUC__ */

/****************************************************************************/

#endif /* IEEE_FLOATING_POINT_SUPPORT */

/****************************************************************************/

#if defined(M68881_FLOATING_POINT_SUPPORT)

INLINE STATIC const double
__tanh(double x)
{
    double result;

    __asm ("ftanh%.x %1,%0"
           : "=f" (result)
           : "f" (x));

    return(result);
}

#endif /* M68881_FLOATING_POINT_SUPPORT */

/****************************************************************************/

#if defined(PPC_FLOATING_POINT_SUPPORT)

static const double one=1.0, two=2.0, tiny = 1.0e-300;

INLINE STATIC double
__tanh(double x)
{
    double t,z;
    int jx,ix;

    /* High word of |x|. */
    GET_HIGH_WORD(jx,x);
    ix = jx&0x7fffffff;

    /* x is INF or NaN */
    if(ix>=0x7ff00000) { 
        if (jx>=0) return one/x+one;    /* tanh(+-inf)=+-1 */
        else       return one/x-one;    /* tanh(NaN) = NaN */
    }

    /* |x| < 22 */
    if (ix < 0x40360000) {        /* |x|<22 */
        if (ix<0x3c800000)         /* |x|<2**-55 */
        return x*(one+x);        /* tanh(small) = small */
        if (ix>=0x3ff00000) {    /* |x|>=1  */
        t = __expm1(two*fabs(x));
        z = one - two/(t+two);
        } else {
            t = __expm1(-two*fabs(x));
            z= -t/(t+two);
        }
    /* |x| > 22, return +-1 */
    } else {
        z = one - tiny;        /* raised inexact flag */
    }
    return (jx>=0)? z: -z;
}

#endif /* PPC_FLOATING_POINT_SUPPORT */

/****************************************************************************/

double
tanh(double x)
{
    double result;

    result = __tanh(x);

    return(result);
}

/****************************************************************************/

#endif /* FLOATING_POINT_SUPPORT */