github.com/afumu/libc@v0.0.6/musl/src/math/tanhl.c (about)

     1  #include "libm.h"
     2  
     3  #if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
     4  long double tanhl(long double x)
     5  {
     6  	return tanh(x);
     7  }
     8  #elif LDBL_MANT_DIG == 64 && LDBL_MAX_EXP == 16384
     9  long double tanhl(long double x)
    10  {
    11  	union ldshape u = {x};
    12  	unsigned ex = u.i.se & 0x7fff;
    13  	unsigned sign = u.i.se & 0x8000;
    14  	uint32_t w;
    15  	long double t;
    16  
    17  	/* x = |x| */
    18  	u.i.se = ex;
    19  	x = u.f;
    20  	w = u.i.m >> 32;
    21  
    22  	if (ex > 0x3ffe || (ex == 0x3ffe && w > 0x8c9f53d5)) {
    23  		/* |x| > log(3)/2 ~= 0.5493 or nan */
    24  		if (ex >= 0x3fff+5) {
    25  			/* |x| >= 32 */
    26  			t = 1 + 0/(x + 0x1p-120f);
    27  		} else {
    28  			t = expm1l(2*x);
    29  			t = 1 - 2/(t+2);
    30  		}
    31  	} else if (ex > 0x3ffd || (ex == 0x3ffd && w > 0x82c577d4)) {
    32  		/* |x| > log(5/3)/2 ~= 0.2554 */
    33  		t = expm1l(2*x);
    34  		t = t/(t+2);
    35  	} else {
    36  		/* |x| is small */
    37  		t = expm1l(-2*x);
    38  		t = -t/(t+2);
    39  	}
    40  	return sign ? -t : t;
    41  }
    42  #elif LDBL_MANT_DIG == 113 && LDBL_MAX_EXP == 16384
    43  // TODO: broken implementation to make things compile
    44  long double tanhl(long double x)
    45  {
    46  	return tanh(x);
    47  }
    48  #endif