cordic.rar_The Given

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