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