1 /*-
2 * Copyright (c) 2016 Adrian Chadd <adrian@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer,
10 * without modification.
11 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
12 * similar to the "NO WARRANTY" disclaimer below ("Disclaimer") and any
13 * redistribution must be conditioned upon including a substantially
14 * similar Disclaimer requirement for further binary redistribution.
15 *
16 * NO WARRANTY
17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19 * LIMITED TO, THE IMPLIED WARRANTIES OF NONINFRINGEMENT, MERCHANTIBILITY
20 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
21 * THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY,
22 * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
23 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
24 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
25 * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
26 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
27 * THE POSSIBILITY OF SUCH DAMAGES.
28 */
29 #ifndef __IF_BWN_CORDIC_H__
30 #define __IF_BWN_CORDIC_H__
31
32 /*
33 * These functions are used by the PHY code.
34 */
35
36 /* Complex number using 2 32-bit signed integers */
37 struct bwn_c32 {
38 int32_t i;
39 int32_t q;
40 };
41
42 #define CORDIC_CONVERT(value) (((value) >= 0) ? \
43 ((((value) >> 15) + 1) >> 1) : \
44 -((((-(value)) >> 15) + 1) >> 1))
45
46 static const uint32_t bwn_arctg[] = {
47 2949120, 1740967, 919879, 466945, 234379, 117304, 58666, 29335, 14668,
48 7334, 3667, 1833, 917, 458, 229, 115, 57, 29,
49 };
50
51 /* http://bcm-v4.sipsolutions.net/802.11/PHY/Cordic */
52 static inline struct bwn_c32
bwn_cordic(int theta)53 bwn_cordic(int theta)
54 {
55 uint8_t i;
56 int32_t tmp;
57 int8_t signx = 1;
58 uint32_t angle = 0;
59 struct bwn_c32 ret = { .i = 39797, .q = 0, };
60
61 while (theta > (180 << 16))
62 theta -= (360 << 16);
63 while (theta < -(180 << 16))
64 theta += (360 << 16);
65
66 if (theta > (90 << 16)) {
67 theta -= (180 << 16);
68 signx = -1;
69 } else if (theta < -(90 << 16)) {
70 theta += (180 << 16);
71 signx = -1;
72 }
73
74 for (i = 0; i <= 17; i++) {
75 if (theta > angle) {
76 tmp = ret.i - (ret.q >> i);
77 ret.q += ret.i >> i;
78 ret.i = tmp;
79 angle += bwn_arctg[i];
80 } else {
81 tmp = ret.i + (ret.q >> i);
82 ret.q -= ret.i >> i;
83 ret.i = tmp;
84 angle -= bwn_arctg[i];
85 }
86 }
87
88 ret.i *= signx;
89 ret.q *= signx;
90
91 return ret;
92 }
93
94 #endif /* __IF_BWN_CORDIC_H__ */
95