/* s_tanhf.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 "math.h"
#include "math_private.h"

static const volatile float tiny = 1.0e-30;
static const float one=1.0, two=2.0, huge = 1.0e30;

float
tanhf(float x)
{
        float t,z;
        int32_t jx,ix;

        GET_FLOAT_WORD(jx,x);
        ix = jx&0x7fffffff;

    /* x is INF or NaN */
        if(ix>=0x7f800000) {
            if (jx>=0) return one/x+one;    /* tanh(+-inf)=+-1 */
            else       return one/x-one;    /* tanh(NaN) = NaN */
        }

    /* |x| < 9 */
        if (ix < 0x41100000) {          /* |x|<9 */
            if (ix<0x39800000) {        /* |x|<2**-12 */
                if(huge+x>one) return x; /* tanh(tiny) = tiny with inexact */
            }
            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| >= 9, return +-1 */
        } else {
            z = one - tiny;             /* raise inexact flag */
        }
        return (jx>=0)? z: -z;
}