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lib: cordic: add library module providing cordic angle calculation

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The brcm80211 driver in the staging tree has a cordic function to
determine cosine and sine for a given angle. Feedback received from
John Linville suggested that these kind of functions should be made
available to others as a library function in the kernel tree. The
b43 driver also has a cordic angle calculation implemented.

Cc: linux-kernel@vger.kernel.org
Cc: linux-wireless@vger.kernel.org
Cc: "John W. Linville" <linville@tuxdriver.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Dan Carpenter <error27@gmail.com>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: Larry Finger <Larry.Finger@lwfinger.net>
Reviewed-by: Roland Vossen <rvossen@broadcom.com>
Reviewed-by: Henry Ptasinski <henryp@broadcom.com>
Reviewed-by: Franky (Zhenhui) Lin <frankyl@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Arend van Spriel 2011-05-31 11:22:16 +02:00 • committed by John W. Linville
parent 7150962d63
commit 10f8113ecb
4 changed files with 158 additions and 0 deletions
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48
include/linux/cordic.h Normal file
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/*
* Copyright (c) 2011 Broadcom Corporation
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#ifndef __CORDIC_H_
#define __CORDIC_H_
#include <linux/types.h>
/**
* struct cordic_iq - i/q coordinate.
*
* @i: real part of coordinate (in phase).
* @q: imaginary part of coordinate (quadrature).
*/
struct cordic_iq {
s32 i;
s32 q;
};
/**
* cordic_calc_iq() - calculates the i/q coordinate for given angle.
*
* @theta: angle in degrees for which i/q coordinate is to be calculated.
* @coord: function output parameter holding the i/q coordinate.
*
* The function calculates the i/q coordinate for a given angle using
* cordic algorithm. The coordinate consists of a real (i) and an
* imaginary (q) part. The real part is essentially the cosine of the
* angle and the imaginary part is the sine of the angle. The returned
* values are scaled by 2^16 for precision. The range for theta is
* for -180 degrees to +180 degrees. Passed values outside this range are
* converted before doing the actual calculation.
*/
struct cordic_iq cordic_calc_iq(s32 theta);
#endif /* __CORDIC_H_ */