1/* origin: FreeBSD /usr/src/lib/msun/src/e_atan2l.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/*
14 * See comments in atan2.c.
15 * Converted to long double by David Schultz <das@FreeBSD.ORG>.
16 */
17
18#include "libm.h"
19
20#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
21long double atan2l(long double y, long double x)
22{
23	return atan2(y, x);
24}
25#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
26#include "__invtrigl.h"
27
28long double atan2l(long double y, long double x)
29{
30	union ldshape ux, uy;
31	long double z;
32	int m, ex, ey;
33
34	if (isnan(x) || isnan(y))
35		return x+y;
36	if (x == 1)
37		return atanl(y);
38	ux.f = x;
39	uy.f = y;
40	ex = ux.i.se & 0x7fff;
41	ey = uy.i.se & 0x7fff;
42	m = 2*(ux.i.se>>15) | uy.i.se>>15;
43	if (y == 0) {
44		switch(m) {
45		case 0:
46		case 1: return y;           /* atan(+-0,+anything)=+-0 */
47		case 2: return  2*pio2_hi;  /* atan(+0,-anything) = pi */
48		case 3: return -2*pio2_hi;  /* atan(-0,-anything) =-pi */
49		}
50	}
51	if (x == 0)
52		return m&1 ? -pio2_hi : pio2_hi;
53	if (ex == 0x7fff) {
54		if (ey == 0x7fff) {
55			switch(m) {
56			case 0: return  pio2_hi/2;   /* atan(+INF,+INF) */
57			case 1: return -pio2_hi/2;   /* atan(-INF,+INF) */
58			case 2: return  1.5*pio2_hi; /* atan(+INF,-INF) */
59			case 3: return -1.5*pio2_hi; /* atan(-INF,-INF) */
60			}
61		} else {
62			switch(m) {
63			case 0: return  0.0;        /* atan(+...,+INF) */
64			case 1: return -0.0;        /* atan(-...,+INF) */
65			case 2: return  2*pio2_hi;  /* atan(+...,-INF) */
66			case 3: return -2*pio2_hi;  /* atan(-...,-INF) */
67			}
68		}
69	}
70	if (ex+120 < ey || ey == 0x7fff)
71		return m&1 ? -pio2_hi : pio2_hi;
72	/* z = atan(|y/x|) without spurious underflow */
73	if ((m&2) && ey+120 < ex)  /* |y/x| < 0x1p-120, x<0 */
74		z = 0.0;
75	else
76		z = atanl(fabsl(y/x));
77	switch (m) {
78	case 0: return z;               /* atan(+,+) */
79	case 1: return -z;              /* atan(-,+) */
80	case 2: return 2*pio2_hi-(z-2*pio2_lo); /* atan(+,-) */
81	default: /* case 3 */
82		return (z-2*pio2_lo)-2*pio2_hi; /* atan(-,-) */
83	}
84}
85#endif
86