1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21/*
22 * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
23 */
24/*
25 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
26 * Use is subject to license terms.
27 */
28
29#pragma weak __catanf = catanf
30
31#include "libm.h"
32#include "complex_wrapper.h"
33
34#if defined(__i386) && !defined(__amd64)
35extern int __swapRP(int);
36#endif
37
38static const float
39	pi_2 = 1.570796326794896558e+00F,
40	zero = 0.0F,
41	half = 0.5F,
42	two = 2.0F,
43	one = 1.0F;
44
45fcomplex
46catanf(fcomplex z) {
47	fcomplex	ans;
48	float		x, y, ax, ay, t;
49	double		dx, dy, dt;
50	int		hx, hy, ix, iy;
51
52	x = F_RE(z);
53	y = F_IM(z);
54	ax = fabsf(x);
55	ay = fabsf(y);
56	hx = THE_WORD(x);
57	hy = THE_WORD(y);
58	ix = hx & 0x7fffffff;
59	iy = hy & 0x7fffffff;
60
61	if (ix >= 0x7f800000) {		/* x is inf or NaN */
62		if (ix == 0x7f800000) {
63			F_RE(ans) = pi_2;
64			F_IM(ans) = zero;
65		} else {
66			F_RE(ans) = x * x;
67			if (iy == 0 || iy == 0x7f800000)
68				F_IM(ans) = zero;
69			else
70				F_IM(ans) = (fabsf(y) - ay) / (fabsf(y) - ay);
71		}
72	} else if (iy >= 0x7f800000) {	/* y is inf or NaN */
73		if (iy == 0x7f800000) {
74			F_RE(ans) = pi_2;
75			F_IM(ans) = zero;
76		} else {
77			F_RE(ans) = (fabsf(x) - ax) / (fabsf(x) - ax);
78			F_IM(ans) = y * y;
79		}
80	} else if (ix == 0) {
81		/* INDENT OFF */
82		/*
83		 * x = 0
84		 *      1                            1
85		 * A = --- * atan2(2x, 1-x*x-y*y) = --- atan2(0,1-|y|)
86		 *      2                            2
87		 *
88		 *     1     [ (y+1)*(y+1) ]   1          2      1         2y
89		 * B = - log [ ----------- ] = - log (1+ ---) or - log(1+ ----)
90		 *     4     [ (y-1)*(y-1) ]   2         y-1     2         1-y
91		 */
92		/* INDENT ON */
93		t = one - ay;
94		if (iy == 0x3f800000) {
95			/* y=1: catan(0,1)=(0,+inf) with 1/0 signal */
96			F_IM(ans) = ay / ax;
97			F_RE(ans) = zero;
98		} else if (iy > 0x3f800000) {	/* y>1 */
99			F_IM(ans) = half * log1pf(two / (-t));
100			F_RE(ans) = pi_2;
101		} else {		/* y<1 */
102			F_IM(ans) = half * log1pf((ay + ay) / t);
103			F_RE(ans) = zero;
104		}
105	} else {
106		/* INDENT OFF */
107		/*
108		 * use double precision x,y
109		 *      1
110		 * A = --- * atan2(2x, 1-x*x-y*y)
111		 *      2
112		 *
113		 *     1     [ x*x+(y+1)*(y+1) ]   1               4y
114		 * B = - log [ --------------- ] = - log (1+ -----------------)
115		 *     4     [ x*x+(y-1)*(y-1) ]   4         x*x + (y-1)*(y-1)
116		 */
117		/* INDENT ON */
118#if defined(__i386) && !defined(__amd64)
119		int	rp = __swapRP(fp_extended);
120#endif
121		dx = (double)ax;
122		dy = (double)ay;
123		F_RE(ans) = (float)(0.5 * atan2(dx + dx,
124		    1.0 - dx * dx - dy * dy));
125		dt = dy - 1.0;
126		F_IM(ans) = (float)(0.25 * log1p(4.0 * dy /
127		    (dx * dx + dt * dt)));
128#if defined(__i386) && !defined(__amd64)
129		if (rp != fp_extended)
130			(void) __swapRP(rp);
131#endif
132	}
133	if (hx < 0)
134		F_RE(ans) = -F_RE(ans);
135	if (hy < 0)
136		F_IM(ans) = -F_IM(ans);
137	return (ans);
138}
139