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1 /* ----------------------------------------------------------------------
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2 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.
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3 *
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4 * $Date: 19. March 2015
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5 * $Revision: V.1.4.5
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6 *
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7 * Project: CMSIS DSP Library
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8 * Title: arm_sin_q15.c
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9 *
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10 * Description: Fast sine calculation for Q15 values.
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11 *
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12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
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13 *
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14 * Redistribution and use in source and binary forms, with or without
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15 * modification, are permitted provided that the following conditions
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16 * are met:
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17 * - Redistributions of source code must retain the above copyright
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18 * notice, this list of conditions and the following disclaimer.
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19 * - Redistributions in binary form must reproduce the above copyright
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20 * notice, this list of conditions and the following disclaimer in
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21 * the documentation and/or other materials provided with the
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22 * distribution.
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23 * - Neither the name of ARM LIMITED nor the names of its contributors
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24 * may be used to endorse or promote products derived from this
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25 * software without specific prior written permission.
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26 *
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27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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38 * POSSIBILITY OF SUCH DAMAGE.
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39 * -------------------------------------------------------------------- */
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40
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41 #include "arm_math.h"
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42 #include "arm_common_tables.h"
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43
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44 /**
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45 * @ingroup groupFastMath
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46 */
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47
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48 /**
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49 * @addtogroup sin
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50 * @{
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51 */
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52
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53 /**
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54 * @brief Fast approximation to the trigonometric sine function for Q15 data.
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55 * @param[in] x Scaled input value in radians.
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56 * @return sin(x).
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57 *
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58 * The Q15 input value is in the range [0 +0.9999] and is mapped to a radian value in the range [0 2*pi).
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59 */
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60
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61 q15_t arm_sin_q15(
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62 q15_t x)
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63 {
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64 q15_t sinVal; /* Temporary variables for input, output */
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65 int32_t index; /* Index variables */
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66 q15_t a, b; /* Four nearest output values */
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67 q15_t fract; /* Temporary values for fractional values */
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68
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69 /* Calculate the nearest index */
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70 index = (uint32_t)x >> FAST_MATH_Q15_SHIFT;
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71
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72 /* Calculation of fractional value */
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73 fract = (x - (index << FAST_MATH_Q15_SHIFT)) << 9;
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74
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75 /* Read two nearest values of input value from the sin table */
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76 a = sinTable_q15[index];
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77 b = sinTable_q15[index+1];
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78
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79 /* Linear interpolation process */
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80 sinVal = (q31_t)(0x8000-fract)*a >> 16;
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81 sinVal = (q15_t)((((q31_t)sinVal << 16) + ((q31_t)fract*b)) >> 16);
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82
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83 return sinVal << 1;
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84 }
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85
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86 /**
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87 * @} end of sin group
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88 */
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