source: azure_iot_hub/trunk/musl-1.1.18/src/math/coshl.c@ 389

#include "libm.h"

#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
long double coshl(long double x)
{
        return cosh(x);
}
#elif LDBL_MANT_DIG == 64 && LDBL_MAX_EXP == 16384
long double coshl(long double x)
{
        union ldshape u = {x};
        unsigned ex = u.i.se & 0x7fff;
        uint32_t w;
        long double t;

        /* |x| */
        u.i.se = ex;
        x = u.f;
        w = u.i.m >> 32;

        /* |x| < log(2) */
        if (ex < 0x3fff-1 || (ex == 0x3fff-1 && w < 0xb17217f7)) {
                if (ex < 0x3fff-32) {
                        FORCE_EVAL(x + 0x1p120f);
                        return 1;
                }
                t = expm1l(x);
                return 1 + t*t/(2*(1+t));
        }

        /* |x| < log(LDBL_MAX) */
        if (ex < 0x3fff+13 || (ex == 0x3fff+13 && w < 0xb17217f7)) {
                t = expl(x);
                return 0.5*(t + 1/t);
        }

        /* |x| > log(LDBL_MAX) or nan */
        t = expl(0.5*x);
        return 0.5*t*t;
}
#elif LDBL_MANT_DIG == 113 && LDBL_MAX_EXP == 16384
// TODO: broken implementation to make things compile
long double coshl(long double x)
{
        return cosh(x);
}
#endif