1/*
2 * Copyright (c) 2011 Broadcom Corporation
3 *
4 * Permission to use, copy, modify, and/or distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
7 *
8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
11 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
13 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
14 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15 */
16#include <linux/module.h>
17#include <linux/cordic.h>
18
19static const s32 arctan_table[] = {
20	2949120,
21	1740967,
22	919879,
23	466945,
24	234379,
25	117304,
26	58666,
27	29335,
28	14668,
29	7334,
30	3667,
31	1833,
32	917,
33	458,
34	229,
35	115,
36	57,
37	29
38};
39
40/*
41 * cordic_calc_iq() - calculates the i/q coordinate for given angle
42 *
43 * theta: angle in degrees for which i/q coordinate is to be calculated
44 * coord: function output parameter holding the i/q coordinate
45 */
46struct cordic_iq cordic_calc_iq(s32 theta)
47{
48	struct cordic_iq coord;
49	s32 angle, valtmp;
50	unsigned iter;
51	int signx = 1;
52	int signtheta;
53
54	coord.i = CORDIC_ANGLE_GEN;
55	coord.q = 0;
56	angle = 0;
57
58	theta = CORDIC_FIXED(theta);
59	signtheta = (theta < 0) ? -1 : 1;
60	theta = ((theta + CORDIC_FIXED(180) * signtheta) % CORDIC_FIXED(360)) -
61		CORDIC_FIXED(180) * signtheta;
62
63	if (CORDIC_FLOAT(theta) > 90) {
64		theta -= CORDIC_FIXED(180);
65		signx = -1;
66	} else if (CORDIC_FLOAT(theta) < -90) {
67		theta += CORDIC_FIXED(180);
68		signx = -1;
69	}
70
71	for (iter = 0; iter < CORDIC_NUM_ITER; iter++) {
72		if (theta > angle) {
73			valtmp = coord.i - (coord.q >> iter);
74			coord.q += (coord.i >> iter);
75			angle += arctan_table[iter];
76		} else {
77			valtmp = coord.i + (coord.q >> iter);
78			coord.q -= (coord.i >> iter);
79			angle -= arctan_table[iter];
80		}
81		coord.i = valtmp;
82	}
83
84	coord.i *= signx;
85	coord.q *= signx;
86	return coord;
87}
88EXPORT_SYMBOL(cordic_calc_iq);
89
90MODULE_DESCRIPTION("CORDIC algorithm");
91MODULE_AUTHOR("Broadcom Corporation");
92MODULE_LICENSE("Dual BSD/GPL");
93