cregit-Linux how code gets into the kernel

Release 4.17 lib/cordic.c

Directory: lib
/*
 * 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.
 */
#include <linux/module.h>
#include <linux/cordic.h>


#define CORDIC_ANGLE_GEN	39797

#define CORDIC_PRECISION_SHIFT	16

#define	CORDIC_NUM_ITER		(CORDIC_PRECISION_SHIFT + 2)


#define	FIXED(X)	((s32)((X) << CORDIC_PRECISION_SHIFT))

#define	FLOAT(X)	(((X) >= 0) \
                ? ((((X) >> (CORDIC_PRECISION_SHIFT - 1)) + 1) >> 1) \
                : -((((-(X)) >> (CORDIC_PRECISION_SHIFT - 1)) + 1) >> 1))


static const s32 arctan_table[] = {
	2949120,
	1740967,
	919879,
	466945,
	234379,
	117304,
	58666,
	29335,
	14668,
	7334,
	3667,
	1833,
	917,
	458,
	229,
	115,
	57,
	29
};

/*
 * 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
 */

struct cordic_iq cordic_calc_iq(s32 theta) { struct cordic_iq coord; s32 angle, valtmp; unsigned iter; int signx = 1; int signtheta; coord.i = CORDIC_ANGLE_GEN; coord.q = 0; angle = 0; theta = FIXED(theta); signtheta = (theta < 0) ? -1 : 1; theta = ((theta + FIXED(180) * signtheta) % FIXED(360)) - FIXED(180) * signtheta; if (FLOAT(theta) > 90) { theta -= FIXED(180); signx = -1; } else if (FLOAT(theta) < -90) { theta += FIXED(180); signx = -1; } for (iter = 0; iter < CORDIC_NUM_ITER; iter++) { if (theta > angle) { valtmp = coord.i - (coord.q >> iter); coord.q += (coord.i >> iter); angle += arctan_table[iter]; } else { valtmp = coord.i + (coord.q >> iter); coord.q -= (coord.i >> iter); angle -= arctan_table[iter]; } coord.i = valtmp; } coord.i *= signx; coord.q *= signx; return coord; }

Contributors

PersonTokensPropCommitsCommitProp
Arend Van Spriel253100.00%1100.00%
Total253100.00%1100.00%

EXPORT_SYMBOL(cordic_calc_iq); MODULE_DESCRIPTION("CORDIC algorithm"); MODULE_AUTHOR("Broadcom Corporation"); MODULE_LICENSE("Dual BSD/GPL");

Overall Contributors

PersonTokensPropCommitsCommitProp
Arend Van Spriel35099.72%150.00%
Michael Witten10.28%150.00%
Total351100.00%2100.00%
Directory: lib
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