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| 2 | mjames | 1 | /* ---------------------------------------------------------------------- |
| 2 | * Project: CMSIS DSP Library |
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| 3 | * Title: arm_sin_cos_q31.c |
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| 4 | * Description: Cosine & Sine calculation for Q31 values |
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| 5 | * |
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| 6 | * $Date: 27. January 2017 |
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| 7 | * $Revision: V.1.5.1 |
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| 8 | * |
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| 9 | * Target Processor: Cortex-M cores |
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| 10 | * -------------------------------------------------------------------- */ |
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| 11 | /* |
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| 12 | * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved. |
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| 13 | * |
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| 14 | * SPDX-License-Identifier: Apache-2.0 |
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| 15 | * |
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| 16 | * Licensed under the Apache License, Version 2.0 (the License); you may |
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| 17 | * not use this file except in compliance with the License. |
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| 18 | * You may obtain a copy of the License at |
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| 19 | * |
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| 20 | * www.apache.org/licenses/LICENSE-2.0 |
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| 21 | * |
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| 22 | * Unless required by applicable law or agreed to in writing, software |
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| 23 | * distributed under the License is distributed on an AS IS BASIS, WITHOUT |
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| 24 | * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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| 25 | * See the License for the specific language governing permissions and |
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| 26 | * limitations under the License. |
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| 27 | */ |
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| 28 | |||
| 29 | #include "arm_math.h" |
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| 30 | #include "arm_common_tables.h" |
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| 31 | |||
| 32 | /** |
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| 33 | * @ingroup groupController |
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| 34 | */ |
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| 35 | |||
| 36 | /** |
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| 37 | * @addtogroup SinCos |
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| 38 | * @{ |
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| 39 | */ |
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| 40 | |||
| 41 | /** |
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| 42 | * @brief Q31 sin_cos function. |
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| 43 | * @param[in] theta scaled input value in degrees |
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| 44 | * @param[out] *pSinVal points to the processed sine output. |
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| 45 | * @param[out] *pCosVal points to the processed cosine output. |
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| 46 | * @return none. |
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| 47 | * |
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| 48 | * The Q31 input value is in the range [-1 0.999999] and is mapped to a degree value in the range [-180 179]. |
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| 49 | * |
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| 50 | */ |
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| 51 | |||
| 52 | void arm_sin_cos_q31( |
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| 53 | q31_t theta, |
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| 54 | q31_t * pSinVal, |
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| 55 | q31_t * pCosVal) |
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| 56 | { |
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| 57 | q31_t fract; /* Temporary variables for input, output */ |
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| 58 | uint16_t indexS, indexC; /* Index variable */ |
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| 59 | q31_t f1, f2, d1, d2; /* Two nearest output values */ |
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| 60 | q31_t Dn, Df; |
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| 61 | q63_t temp; |
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| 62 | |||
| 63 | /* Calculate the nearest index */ |
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| 64 | indexS = (uint32_t)theta >> CONTROLLER_Q31_SHIFT; |
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| 65 | indexC = (indexS + 128) & 0x1ff; |
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| 66 | |||
| 67 | /* Calculation of fractional value */ |
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| 68 | fract = (theta - (indexS << CONTROLLER_Q31_SHIFT)) << 8; |
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| 69 | |||
| 70 | /* Read two nearest values of input value from the cos & sin tables */ |
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| 71 | f1 = sinTable_q31[indexC+0]; |
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| 72 | f2 = sinTable_q31[indexC+1]; |
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| 73 | d1 = -sinTable_q31[indexS+0]; |
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| 74 | d2 = -sinTable_q31[indexS+1]; |
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| 75 | |||
| 76 | Dn = 0x1921FB5; // delta between the two points (fixed), in this case 2*pi/FAST_MATH_TABLE_SIZE |
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| 77 | Df = f2 - f1; // delta between the values of the functions |
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| 78 | temp = Dn*((q63_t)d1 + d2); |
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| 79 | temp = temp - ((q63_t)Df << 32); |
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| 80 | temp = (q63_t)fract*(temp >> 31); |
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| 81 | temp = temp + ((3*(q63_t)Df << 31) - (d2 + ((q63_t)d1 << 1))*Dn); |
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| 82 | temp = (q63_t)fract*(temp >> 31); |
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| 83 | temp = temp + (q63_t)d1*Dn; |
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| 84 | temp = (q63_t)fract*(temp >> 31); |
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| 85 | |||
| 86 | /* Calculation of cosine value */ |
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| 87 | *pCosVal = clip_q63_to_q31((temp >> 31) + (q63_t)f1); |
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| 88 | |||
| 89 | /* Read two nearest values of input value from the cos & sin tables */ |
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| 90 | f1 = sinTable_q31[indexS+0]; |
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| 91 | f2 = sinTable_q31[indexS+1]; |
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| 92 | d1 = sinTable_q31[indexC+0]; |
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| 93 | d2 = sinTable_q31[indexC+1]; |
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| 94 | |||
| 95 | Df = f2 - f1; // delta between the values of the functions |
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| 96 | temp = Dn*((q63_t)d1 + d2); |
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| 97 | temp = temp - ((q63_t)Df << 32); |
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| 98 | temp = (q63_t)fract*(temp >> 31); |
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| 99 | temp = temp + ((3*(q63_t)Df << 31) - (d2 + ((q63_t)d1 << 1))*Dn); |
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| 100 | temp = (q63_t)fract*(temp >> 31); |
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| 101 | temp = temp + (q63_t)d1*Dn; |
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| 102 | temp = (q63_t)fract*(temp >> 31); |
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| 103 | |||
| 104 | /* Calculation of sine value */ |
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| 105 | *pSinVal = clip_q63_to_q31((temp >> 31) + (q63_t)f1); |
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| 106 | } |
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| 107 | |||
| 108 | /** |
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| 109 | * @} end of SinCos group |
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| 110 | */ |