cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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cordic.c (2277B)

      1/*
      2 * Copyright (c) 2011 Broadcom Corporation
      3 *
      4 * Permission to use, copy, modify, and/or distribute this software for any
      5 * purpose with or without fee is hereby granted, provided that the above
      6 * copyright notice and this permission notice appear in all copies.
      7 *
      8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
      9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
     10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
     11 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
     12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
     13 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
     14 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
     15 */
     16#include <linux/module.h>
     17#include <linux/cordic.h>
     18
     19static const s32 arctan_table[] = {
     20	2949120,
     21	1740967,
     22	919879,
     23	466945,
     24	234379,
     25	117304,
     26	58666,
     27	29335,
     28	14668,
     29	7334,
     30	3667,
     31	1833,
     32	917,
     33	458,
     34	229,
     35	115,
     36	57,
     37	29
     38};
     39
     40/*
     41 * cordic_calc_iq() - calculates the i/q coordinate for given angle
     42 *
     43 * theta: angle in degrees for which i/q coordinate is to be calculated
     44 * coord: function output parameter holding the i/q coordinate
     45 */
     46struct cordic_iq cordic_calc_iq(s32 theta)
     47{
     48	struct cordic_iq coord;
     49	s32 angle, valtmp;
     50	unsigned iter;
     51	int signx = 1;
     52	int signtheta;
     53
     54	coord.i = CORDIC_ANGLE_GEN;
     55	coord.q = 0;
     56	angle = 0;
     57
     58	theta = CORDIC_FIXED(theta);
     59	signtheta = (theta < 0) ? -1 : 1;
     60	theta = ((theta + CORDIC_FIXED(180) * signtheta) % CORDIC_FIXED(360)) -
     61		CORDIC_FIXED(180) * signtheta;
     62
     63	if (CORDIC_FLOAT(theta) > 90) {
     64		theta -= CORDIC_FIXED(180);
     65		signx = -1;
     66	} else if (CORDIC_FLOAT(theta) < -90) {
     67		theta += CORDIC_FIXED(180);
     68		signx = -1;
     69	}
     70
     71	for (iter = 0; iter < CORDIC_NUM_ITER; iter++) {
     72		if (theta > angle) {
     73			valtmp = coord.i - (coord.q >> iter);
     74			coord.q += (coord.i >> iter);
     75			angle += arctan_table[iter];
     76		} else {
     77			valtmp = coord.i + (coord.q >> iter);
     78			coord.q -= (coord.i >> iter);
     79			angle -= arctan_table[iter];
     80		}
     81		coord.i = valtmp;
     82	}
     83
     84	coord.i *= signx;
     85	coord.q *= signx;
     86	return coord;
     87}
     88EXPORT_SYMBOL(cordic_calc_iq);
     89
     90MODULE_DESCRIPTION("CORDIC algorithm");
     91MODULE_AUTHOR("Broadcom Corporation");
     92MODULE_LICENSE("Dual BSD/GPL");