36fcc18d80
This is used by the PHY-N code. Obtained from: http://bcm-v4.sipsolutions.net/802.11/PHY/Cordic
97 lines
2.8 KiB
C
97 lines
2.8 KiB
C
/*-
|
|
* 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__ */
|