1#include "libm.h"
 2
 3#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
 4long double acoshl(long double x)
 5{
 6	return acosh(x);
 7}
 8#elif LDBL_MANT_DIG == 64 && LDBL_MAX_EXP == 16384
 9/* acosh(x) = log(x + sqrt(x*x-1)) */
10long double acoshl(long double x)
11{
12	union ldshape u = {x};
13	int e = u.i.se;
14
15	if (e < 0x3fff + 1)
16		/* 0 <= x < 2, invalid if x < 1 */
17		return log1pl(x-1 + sqrtl((x-1)*(x-1)+2*(x-1)));
18	if (e < 0x3fff + 32)
19		/* 2 <= x < 0x1p32 */
20		return logl(2*x - 1/(x+sqrtl(x*x-1)));
21	if (e & 0x8000)
22		/* x < 0 or x = -0, invalid */
23		return (x - x) / (x - x);
24	/* 0x1p32 <= x or nan */
25	return logl(x) + 0.693147180559945309417232121458176568L;
26}
27#elif LDBL_MANT_DIG == 113 && LDBL_MAX_EXP == 16384
28// TODO: broken implementation to make things compile
29long double acoshl(long double x)
30{
31	return acosh(x);
32}
33#endif