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 */
37struct 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
46static 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 */
52static inline struct bwn_c32
53bwn_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