97 lines
2.8 KiB
C
97 lines
2.8 KiB
C
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/*-
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* Copyright (c) 2016 Adrian Chadd <adrian@FreeBSD.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer,
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* without modification.
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* 2. Redistributions in binary form must reproduce at minimum a disclaimer
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* similar to the "NO WARRANTY" disclaimer below ("Disclaimer") and any
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* redistribution must be conditioned upon including a substantially
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* similar Disclaimer requirement for further binary redistribution.
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*
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* NO WARRANTY
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF NONINFRINGEMENT, MERCHANTIBILITY
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* AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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* THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY,
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* OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
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* IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
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* THE POSSIBILITY OF SUCH DAMAGES.
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*
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* $FreeBSD$
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*/
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#ifndef __IF_BWN_CORDIC_H__
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#define __IF_BWN_CORDIC_H__
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/*
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* These functions are used by the PHY code.
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*/
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/* Complex number using 2 32-bit signed integers */
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struct bwn_c32 {
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int32_t i;
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int32_t q;
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};
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#define CORDIC_CONVERT(value) (((value) >= 0) ? \
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((((value) >> 15) + 1) >> 1) : \
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-((((-(value)) >> 15) + 1) >> 1))
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static const uint32_t bwn_arctg[] = {
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2949120, 1740967, 919879, 466945, 234379, 117304, 58666, 29335, 14668,
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7334, 3667, 1833, 917, 458, 229, 115, 57, 29,
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};
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/* http://bcm-v4.sipsolutions.net/802.11/PHY/Cordic */
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static inline struct bwn_c32
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bwn_cordic(int theta)
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{
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uint8_t i;
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int32_t tmp;
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int8_t signx = 1;
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uint32_t angle = 0;
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struct bwn_c32 ret = { .i = 39797, .q = 0, };
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while (theta > (180 << 16))
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theta -= (360 << 16);
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while (theta < -(180 << 16))
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theta += (360 << 16);
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if (theta > (90 << 16)) {
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theta -= (180 << 16);
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signx = -1;
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} else if (theta < -(90 << 16)) {
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theta += (180 << 16);
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signx = -1;
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}
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for (i = 0; i <= 17; i++) {
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if (theta > angle) {
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tmp = ret.i - (ret.q >> i);
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ret.q += ret.i >> i;
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ret.i = tmp;
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angle += bwn_arctg[i];
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} else {
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tmp = ret.i + (ret.q >> i);
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ret.q -= ret.i >> i;
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ret.i = tmp;
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angle -= bwn_arctg[i];
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}
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}
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ret.i *= signx;
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ret.q *= signx;
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return ret;
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}
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#endif /* __IF_BWN_CORDIC_H__ */
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