Subversion Repositories openrisc_2011-10-31

/* sf_tanh.c -- float version of s_tanh.c.

 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.

 */

/*

 * ====================================================

 * 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.

 * ====================================================

 */

#include "fdlibm.h"

#ifdef __STDC__

static const float one=1.0, two=2.0, tiny = 1.0e-30;

#else

static float one=1.0, two=2.0, tiny = 1.0e-30;

#endif

#ifdef __STDC__

        float tanhf(float x)

#else

        float tanhf(x)

        float x;

#endif

{

        float t,z;

        __int32_t jx,ix;

        GET_FLOAT_WORD(jx,x);

        ix = jx&0x7fffffff;

    /* x is INF or NaN */

        if(!FLT_UWORD_IS_FINITE(ix)) {

            if (jx>=0) return one/x+one;    /* tanh(+-inf)=+-1 */

            else       return one/x-one;    /* tanh(NaN) = NaN */

        }

    /* |x| < 22 */

        if (ix < 0x41b00000) {          /* |x|<22 */

            if (ix<0x24000000)          /* |x|<2**-55 */

                return x*(one+x);       /* tanh(small) = small */

            if (ix>=0x3f800000) {       /* |x|>=1  */

                t = expm1f(two*fabsf(x));

                z = one - two/(t+two);

            } else {

                t = expm1f(-two*fabsf(x));

                z= -t/(t+two);

            }

    /* |x| > 22, return +-1 */

        } else {

            z = one - tiny;             /* raised inexact flag */

        }

        return (jx>=0)? z: -z;

}

#ifdef _DOUBLE_IS_32BITS

#ifdef __STDC__

        double tanh(double x)

#else

        double tanh(x)

        double x;

#endif

{

        return (double) tanhf((float) x);

}

#endif /* defined(_DOUBLE_IS_32BITS) */