1*2c64e9cbSAndy Shevchenko /*
2*2c64e9cbSAndy Shevchenko * Copyright (c) 2011 Broadcom Corporation
3*2c64e9cbSAndy Shevchenko *
4*2c64e9cbSAndy Shevchenko * Permission to use, copy, modify, and/or distribute this software for any
5*2c64e9cbSAndy Shevchenko * purpose with or without fee is hereby granted, provided that the above
6*2c64e9cbSAndy Shevchenko * copyright notice and this permission notice appear in all copies.
7*2c64e9cbSAndy Shevchenko *
8*2c64e9cbSAndy Shevchenko * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9*2c64e9cbSAndy Shevchenko * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10*2c64e9cbSAndy Shevchenko * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
11*2c64e9cbSAndy Shevchenko * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12*2c64e9cbSAndy Shevchenko * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
13*2c64e9cbSAndy Shevchenko * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
14*2c64e9cbSAndy Shevchenko * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15*2c64e9cbSAndy Shevchenko */
16*2c64e9cbSAndy Shevchenko #include <linux/module.h>
17*2c64e9cbSAndy Shevchenko #include <linux/cordic.h>
18*2c64e9cbSAndy Shevchenko
19*2c64e9cbSAndy Shevchenko static const s32 arctan_table[] = {
20*2c64e9cbSAndy Shevchenko 2949120,
21*2c64e9cbSAndy Shevchenko 1740967,
22*2c64e9cbSAndy Shevchenko 919879,
23*2c64e9cbSAndy Shevchenko 466945,
24*2c64e9cbSAndy Shevchenko 234379,
25*2c64e9cbSAndy Shevchenko 117304,
26*2c64e9cbSAndy Shevchenko 58666,
27*2c64e9cbSAndy Shevchenko 29335,
28*2c64e9cbSAndy Shevchenko 14668,
29*2c64e9cbSAndy Shevchenko 7334,
30*2c64e9cbSAndy Shevchenko 3667,
31*2c64e9cbSAndy Shevchenko 1833,
32*2c64e9cbSAndy Shevchenko 917,
33*2c64e9cbSAndy Shevchenko 458,
34*2c64e9cbSAndy Shevchenko 229,
35*2c64e9cbSAndy Shevchenko 115,
36*2c64e9cbSAndy Shevchenko 57,
37*2c64e9cbSAndy Shevchenko 29
38*2c64e9cbSAndy Shevchenko };
39*2c64e9cbSAndy Shevchenko
40*2c64e9cbSAndy Shevchenko /*
41*2c64e9cbSAndy Shevchenko * cordic_calc_iq() - calculates the i/q coordinate for given angle
42*2c64e9cbSAndy Shevchenko *
43*2c64e9cbSAndy Shevchenko * theta: angle in degrees for which i/q coordinate is to be calculated
44*2c64e9cbSAndy Shevchenko * coord: function output parameter holding the i/q coordinate
45*2c64e9cbSAndy Shevchenko */
cordic_calc_iq(s32 theta)46*2c64e9cbSAndy Shevchenko struct cordic_iq cordic_calc_iq(s32 theta)
47*2c64e9cbSAndy Shevchenko {
48*2c64e9cbSAndy Shevchenko struct cordic_iq coord;
49*2c64e9cbSAndy Shevchenko s32 angle, valtmp;
50*2c64e9cbSAndy Shevchenko unsigned iter;
51*2c64e9cbSAndy Shevchenko int signx = 1;
52*2c64e9cbSAndy Shevchenko int signtheta;
53*2c64e9cbSAndy Shevchenko
54*2c64e9cbSAndy Shevchenko coord.i = CORDIC_ANGLE_GEN;
55*2c64e9cbSAndy Shevchenko coord.q = 0;
56*2c64e9cbSAndy Shevchenko angle = 0;
57*2c64e9cbSAndy Shevchenko
58*2c64e9cbSAndy Shevchenko theta = CORDIC_FIXED(theta);
59*2c64e9cbSAndy Shevchenko signtheta = (theta < 0) ? -1 : 1;
60*2c64e9cbSAndy Shevchenko theta = ((theta + CORDIC_FIXED(180) * signtheta) % CORDIC_FIXED(360)) -
61*2c64e9cbSAndy Shevchenko CORDIC_FIXED(180) * signtheta;
62*2c64e9cbSAndy Shevchenko
63*2c64e9cbSAndy Shevchenko if (CORDIC_FLOAT(theta) > 90) {
64*2c64e9cbSAndy Shevchenko theta -= CORDIC_FIXED(180);
65*2c64e9cbSAndy Shevchenko signx = -1;
66*2c64e9cbSAndy Shevchenko } else if (CORDIC_FLOAT(theta) < -90) {
67*2c64e9cbSAndy Shevchenko theta += CORDIC_FIXED(180);
68*2c64e9cbSAndy Shevchenko signx = -1;
69*2c64e9cbSAndy Shevchenko }
70*2c64e9cbSAndy Shevchenko
71*2c64e9cbSAndy Shevchenko for (iter = 0; iter < CORDIC_NUM_ITER; iter++) {
72*2c64e9cbSAndy Shevchenko if (theta > angle) {
73*2c64e9cbSAndy Shevchenko valtmp = coord.i - (coord.q >> iter);
74*2c64e9cbSAndy Shevchenko coord.q += (coord.i >> iter);
75*2c64e9cbSAndy Shevchenko angle += arctan_table[iter];
76*2c64e9cbSAndy Shevchenko } else {
77*2c64e9cbSAndy Shevchenko valtmp = coord.i + (coord.q >> iter);
78*2c64e9cbSAndy Shevchenko coord.q -= (coord.i >> iter);
79*2c64e9cbSAndy Shevchenko angle -= arctan_table[iter];
80*2c64e9cbSAndy Shevchenko }
81*2c64e9cbSAndy Shevchenko coord.i = valtmp;
82*2c64e9cbSAndy Shevchenko }
83*2c64e9cbSAndy Shevchenko
84*2c64e9cbSAndy Shevchenko coord.i *= signx;
85*2c64e9cbSAndy Shevchenko coord.q *= signx;
86*2c64e9cbSAndy Shevchenko return coord;
87*2c64e9cbSAndy Shevchenko }
88*2c64e9cbSAndy Shevchenko EXPORT_SYMBOL(cordic_calc_iq);
89*2c64e9cbSAndy Shevchenko
90*2c64e9cbSAndy Shevchenko MODULE_DESCRIPTION("CORDIC algorithm");
91*2c64e9cbSAndy Shevchenko MODULE_AUTHOR("Broadcom Corporation");
92*2c64e9cbSAndy Shevchenko MODULE_LICENSE("Dual BSD/GPL");
93