| 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 |
|
| 19 | static 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 |
|
| 46 | struct 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 | }
|
| 88 | EXPORT_SYMBOL(cordic_calc_iq);
|
| 89 |
|
| 90 | MODULE_DESCRIPTION("CORDIC algorithm");
|
| 91 | MODULE_AUTHOR("Broadcom Corporation");
|
| 92 | MODULE_LICENSE("Dual BSD/GPL");
|