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92 lines
2.2 KiB
92 lines
2.2 KiB
/* |
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* Copyright (c) 2011 Broadcom Corporation |
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* |
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* Permission to use, copy, modify, and/or distribute this software for any |
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* purpose with or without fee is hereby granted, provided that the above |
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* copyright notice and this permission notice appear in all copies. |
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* |
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES |
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY |
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* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION |
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* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN |
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* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
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*/ |
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#include <linux/module.h> |
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#include <linux/cordic.h> |
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static const s32 arctan_table[] = { |
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2949120, |
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1740967, |
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919879, |
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466945, |
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234379, |
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117304, |
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58666, |
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29335, |
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14668, |
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7334, |
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3667, |
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1833, |
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917, |
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458, |
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229, |
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115, |
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57, |
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29 |
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}; |
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/* |
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* cordic_calc_iq() - calculates the i/q coordinate for given angle |
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* |
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* theta: angle in degrees for which i/q coordinate is to be calculated |
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* coord: function output parameter holding the i/q coordinate |
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*/ |
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struct cordic_iq cordic_calc_iq(s32 theta) |
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{ |
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struct cordic_iq coord; |
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s32 angle, valtmp; |
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unsigned iter; |
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int signx = 1; |
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int signtheta; |
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coord.i = CORDIC_ANGLE_GEN; |
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coord.q = 0; |
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angle = 0; |
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theta = CORDIC_FIXED(theta); |
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signtheta = (theta < 0) ? -1 : 1; |
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theta = ((theta + CORDIC_FIXED(180) * signtheta) % CORDIC_FIXED(360)) - |
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CORDIC_FIXED(180) * signtheta; |
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if (CORDIC_FLOAT(theta) > 90) { |
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theta -= CORDIC_FIXED(180); |
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signx = -1; |
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} else if (CORDIC_FLOAT(theta) < -90) { |
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theta += CORDIC_FIXED(180); |
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signx = -1; |
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} |
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for (iter = 0; iter < CORDIC_NUM_ITER; iter++) { |
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if (theta > angle) { |
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valtmp = coord.i - (coord.q >> iter); |
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coord.q += (coord.i >> iter); |
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angle += arctan_table[iter]; |
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} else { |
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valtmp = coord.i + (coord.q >> iter); |
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coord.q -= (coord.i >> iter); |
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angle -= arctan_table[iter]; |
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} |
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coord.i = valtmp; |
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} |
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coord.i *= signx; |
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coord.q *= signx; |
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return coord; |
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} |
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EXPORT_SYMBOL(cordic_calc_iq); |
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MODULE_DESCRIPTION("CORDIC algorithm"); |
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MODULE_AUTHOR("Broadcom Corporation"); |
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MODULE_LICENSE("Dual BSD/GPL");
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