1/* origin: FreeBSD /usr/src/lib/msun/src/e_asinl.c */
2/*
3 * ====================================================
4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
5 *
6 * Developed at SunSoft, a Sun Microsystems, Inc. business.
7 * Permission to use, copy, modify, and distribute this
8 * software is freely granted, provided that this notice
9 * is preserved.
10 * ====================================================
11 */
12/*
13 * See comments in asin.c.
14 * Converted to long double by David Schultz <das@FreeBSD.ORG>.
15 */
16
17#include "libm.h"
18
19#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
20long double asinl(long double x)
21{
22 return asin(x);
23}
24#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
25#include "__invtrigl.h"
26#if LDBL_MANT_DIG == 64
27#define CLOSETO1(u) (u.i.m>>56 >= 0xf7)
28#define CLEARBOTTOM(u) (u.i.m &= -1ULL << 32)
29#elif LDBL_MANT_DIG == 113
30#define CLOSETO1(u) (u.i.top >= 0xee00)
31#define CLEARBOTTOM(u) (u.i.lo = 0)
32#endif
33
34long double asinl(long double x)
35{
36 union ldshape u = {x};
37 long double z, r, s;
38 uint16_t e = u.i.se & 0x7fff;
39 int sign = u.i.se >> 15;
40
41 if (e >= 0x3fff) { /* |x| >= 1 or nan */
42 /* asin(+-1)=+-pi/2 with inexact */
43 if (x == 1 || x == -1)
44 return x*pio2_hi + 0x1p-120f;
45 return 0/(x-x);
46 }
47 if (e < 0x3fff - 1) { /* |x| < 0.5 */
48 if (e < 0x3fff - (LDBL_MANT_DIG+1)/2) {
49 /* return x with inexact if x!=0 */
50 FORCE_EVAL(x + 0x1p120f);
51 return x;
52 }
53 return x + x*__invtrigl_R(x*x);
54 }
55 /* 1 > |x| >= 0.5 */
56 z = (1.0 - fabsl(x))*0.5;
57 s = sqrtl(z);
58 r = __invtrigl_R(z);
59 if (CLOSETO1(u)) {
60 x = pio2_hi - (2*(s+s*r)-pio2_lo);
61 } else {
62 long double f, c;
63 u.f = s;
64 CLEARBOTTOM(u);
65 f = u.f;
66 c = (z - f*f)/(s + f);
67 x = 0.5*pio2_hi-(2*s*r - (pio2_lo-2*c) - (0.5*pio2_hi-2*f));
68 }
69 return sign ? -x : x;
70}
71#endif