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The CMSIS DSP 5 library

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functions/ControllerFunctions/arm_sin_cos_f32.c@1:24714b45cd1b, 2018-06-20 (annotated)

Committer:
xorjoep
Date:
Wed Jun 20 11:21:31 2018 +0000
Revision:
1:24714b45cd1b
The newest version of the CMSIS library

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xorjoep 1:24714b45cd1b 1 /* ----------------------------------------------------------------------
xorjoep 1:24714b45cd1b 2 * Project: CMSIS DSP Library
xorjoep 1:24714b45cd1b 3 * Title: arm_sin_cos_f32.c
xorjoep 1:24714b45cd1b 4 * Description: Sine and Cosine calculation for floating-point values
xorjoep 1:24714b45cd1b 5 *
xorjoep 1:24714b45cd1b 6 * $Date: 27. January 2017
xorjoep 1:24714b45cd1b 7 * $Revision: V.1.5.1
xorjoep 1:24714b45cd1b 8 *
xorjoep 1:24714b45cd1b 9 * Target Processor: Cortex-M cores
xorjoep 1:24714b45cd1b 10 * -------------------------------------------------------------------- */
xorjoep 1:24714b45cd1b 11 /*
xorjoep 1:24714b45cd1b 12 * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
xorjoep 1:24714b45cd1b 13 *
xorjoep 1:24714b45cd1b 14 * SPDX-License-Identifier: Apache-2.0
xorjoep 1:24714b45cd1b 15 *
xorjoep 1:24714b45cd1b 16 * Licensed under the Apache License, Version 2.0 (the License); you may
xorjoep 1:24714b45cd1b 17 * not use this file except in compliance with the License.
xorjoep 1:24714b45cd1b 18 * You may obtain a copy of the License at
xorjoep 1:24714b45cd1b 19 *
xorjoep 1:24714b45cd1b 20 * www.apache.org/licenses/LICENSE-2.0
xorjoep 1:24714b45cd1b 21 *
xorjoep 1:24714b45cd1b 22 * Unless required by applicable law or agreed to in writing, software
xorjoep 1:24714b45cd1b 23 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
xorjoep 1:24714b45cd1b 24 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
xorjoep 1:24714b45cd1b 25 * See the License for the specific language governing permissions and
xorjoep 1:24714b45cd1b 26 * limitations under the License.
xorjoep 1:24714b45cd1b 27 */
xorjoep 1:24714b45cd1b 28
xorjoep 1:24714b45cd1b 29 #include "arm_math.h"
xorjoep 1:24714b45cd1b 30 #include "arm_common_tables.h"
xorjoep 1:24714b45cd1b 31
xorjoep 1:24714b45cd1b 32 /**
xorjoep 1:24714b45cd1b 33 * @ingroup groupController
xorjoep 1:24714b45cd1b 34 */
xorjoep 1:24714b45cd1b 35
xorjoep 1:24714b45cd1b 36 /**
xorjoep 1:24714b45cd1b 37 * @defgroup SinCos Sine Cosine
xorjoep 1:24714b45cd1b 38 *
xorjoep 1:24714b45cd1b 39 * Computes the trigonometric sine and cosine values using a combination of table lookup
xorjoep 1:24714b45cd1b 40 * and linear interpolation.
xorjoep 1:24714b45cd1b 41 * There are separate functions for Q31 and floating-point data types.
xorjoep 1:24714b45cd1b 42 * The input to the floating-point version is in degrees while the
xorjoep 1:24714b45cd1b 43 * fixed-point Q31 have a scaled input with the range
xorjoep 1:24714b45cd1b 44 * [-1 0.9999] mapping to [-180 +180] degrees.
xorjoep 1:24714b45cd1b 45 *
xorjoep 1:24714b45cd1b 46 * The floating point function also allows values that are out of the usual range. When this happens, the function will
xorjoep 1:24714b45cd1b 47 * take extra time to adjust the input value to the range of [-180 180].
xorjoep 1:24714b45cd1b 48 *
xorjoep 1:24714b45cd1b 49 * The result is accurate to 5 digits after the decimal point.
xorjoep 1:24714b45cd1b 50 *
xorjoep 1:24714b45cd1b 51 * The implementation is based on table lookup using 360 values together with linear interpolation.
xorjoep 1:24714b45cd1b 52 * The steps used are:
xorjoep 1:24714b45cd1b 53 * -# Calculation of the nearest integer table index.
xorjoep 1:24714b45cd1b 54 * -# Compute the fractional portion (fract) of the input.
xorjoep 1:24714b45cd1b 55 * -# Fetch the value corresponding to \c index from sine table to \c y0 and also value from \c index+1 to \c y1.
xorjoep 1:24714b45cd1b 56 * -# Sine value is computed as <code> *psinVal = y0 + (fract * (y1 - y0))</code>.
xorjoep 1:24714b45cd1b 57 * -# Fetch the value corresponding to \c index from cosine table to \c y0 and also value from \c index+1 to \c y1.
xorjoep 1:24714b45cd1b 58 * -# Cosine value is computed as <code> *pcosVal = y0 + (fract * (y1 - y0))</code>.
xorjoep 1:24714b45cd1b 59 */
xorjoep 1:24714b45cd1b 60
xorjoep 1:24714b45cd1b 61 /**
xorjoep 1:24714b45cd1b 62 * @addtogroup SinCos
xorjoep 1:24714b45cd1b 63 * @{
xorjoep 1:24714b45cd1b 64 */
xorjoep 1:24714b45cd1b 65
xorjoep 1:24714b45cd1b 66 /**
xorjoep 1:24714b45cd1b 67 * @brief Floating-point sin_cos function.
xorjoep 1:24714b45cd1b 68 * @param[in] theta input value in degrees
xorjoep 1:24714b45cd1b 69 * @param[out] *pSinVal points to the processed sine output.
xorjoep 1:24714b45cd1b 70 * @param[out] *pCosVal points to the processed cos output.
xorjoep 1:24714b45cd1b 71 * @return none.
xorjoep 1:24714b45cd1b 72 */
xorjoep 1:24714b45cd1b 73
xorjoep 1:24714b45cd1b 74 void arm_sin_cos_f32(
xorjoep 1:24714b45cd1b 75 float32_t theta,
xorjoep 1:24714b45cd1b 76 float32_t * pSinVal,
xorjoep 1:24714b45cd1b 77 float32_t * pCosVal)
xorjoep 1:24714b45cd1b 78 {
xorjoep 1:24714b45cd1b 79 float32_t fract, in; /* Temporary variables for input, output */
xorjoep 1:24714b45cd1b 80 uint16_t indexS, indexC; /* Index variable */
xorjoep 1:24714b45cd1b 81 float32_t f1, f2, d1, d2; /* Two nearest output values */
xorjoep 1:24714b45cd1b 82 float32_t findex, Dn, Df, temp;
xorjoep 1:24714b45cd1b 83
xorjoep 1:24714b45cd1b 84 /* input x is in degrees */
xorjoep 1:24714b45cd1b 85 /* Scale the input, divide input by 360, for cosine add 0.25 (pi/2) to read sine table */
xorjoep 1:24714b45cd1b 86 in = theta * 0.00277777777778f;
xorjoep 1:24714b45cd1b 87
xorjoep 1:24714b45cd1b 88 if (in < 0.0f)
xorjoep 1:24714b45cd1b 89 {
xorjoep 1:24714b45cd1b 90 in = -in;
xorjoep 1:24714b45cd1b 91 }
xorjoep 1:24714b45cd1b 92
xorjoep 1:24714b45cd1b 93 in = in - (int32_t)in;
xorjoep 1:24714b45cd1b 94
xorjoep 1:24714b45cd1b 95 /* Calculation of index of the table */
xorjoep 1:24714b45cd1b 96 findex = (float32_t) FAST_MATH_TABLE_SIZE * in;
xorjoep 1:24714b45cd1b 97 indexS = ((uint16_t)findex) & 0x1ff;
xorjoep 1:24714b45cd1b 98 indexC = (indexS + (FAST_MATH_TABLE_SIZE / 4)) & 0x1ff;
xorjoep 1:24714b45cd1b 99
xorjoep 1:24714b45cd1b 100 /* fractional value calculation */
xorjoep 1:24714b45cd1b 101 fract = findex - (float32_t) indexS;
xorjoep 1:24714b45cd1b 102
xorjoep 1:24714b45cd1b 103 /* Read two nearest values of input value from the cos & sin tables */
xorjoep 1:24714b45cd1b 104 f1 = sinTable_f32[indexC+0];
xorjoep 1:24714b45cd1b 105 f2 = sinTable_f32[indexC+1];
xorjoep 1:24714b45cd1b 106 d1 = -sinTable_f32[indexS+0];
xorjoep 1:24714b45cd1b 107 d2 = -sinTable_f32[indexS+1];
xorjoep 1:24714b45cd1b 108
xorjoep 1:24714b45cd1b 109 temp = (1.0f - fract) * f1 + fract * f2;
xorjoep 1:24714b45cd1b 110
xorjoep 1:24714b45cd1b 111 Dn = 0.0122718463030f; // delta between the two points (fixed), in this case 2*pi/FAST_MATH_TABLE_SIZE
xorjoep 1:24714b45cd1b 112 Df = f2 - f1; // delta between the values of the functions
xorjoep 1:24714b45cd1b 113
xorjoep 1:24714b45cd1b 114 temp = Dn *(d1 + d2) - 2 * Df;
xorjoep 1:24714b45cd1b 115 temp = fract * temp + (3 * Df - (d2 + 2 * d1) * Dn);
xorjoep 1:24714b45cd1b 116 temp = fract * temp + d1 * Dn;
xorjoep 1:24714b45cd1b 117
xorjoep 1:24714b45cd1b 118 /* Calculation of cosine value */
xorjoep 1:24714b45cd1b 119 *pCosVal = fract * temp + f1;
xorjoep 1:24714b45cd1b 120
xorjoep 1:24714b45cd1b 121 /* Read two nearest values of input value from the cos & sin tables */
xorjoep 1:24714b45cd1b 122 f1 = sinTable_f32[indexS+0];
xorjoep 1:24714b45cd1b 123 f2 = sinTable_f32[indexS+1];
xorjoep 1:24714b45cd1b 124 d1 = sinTable_f32[indexC+0];
xorjoep 1:24714b45cd1b 125 d2 = sinTable_f32[indexC+1];
xorjoep 1:24714b45cd1b 126
xorjoep 1:24714b45cd1b 127 temp = (1.0f - fract) * f1 + fract * f2;
xorjoep 1:24714b45cd1b 128
xorjoep 1:24714b45cd1b 129 Df = f2 - f1; // delta between the values of the functions
xorjoep 1:24714b45cd1b 130 temp = Dn*(d1 + d2) - 2*Df;
xorjoep 1:24714b45cd1b 131 temp = fract*temp + (3*Df - (d2 + 2*d1)*Dn);
xorjoep 1:24714b45cd1b 132 temp = fract*temp + d1*Dn;
xorjoep 1:24714b45cd1b 133
xorjoep 1:24714b45cd1b 134 /* Calculation of sine value */
xorjoep 1:24714b45cd1b 135 *pSinVal = fract*temp + f1;
xorjoep 1:24714b45cd1b 136
xorjoep 1:24714b45cd1b 137 if (theta < 0.0f)
xorjoep 1:24714b45cd1b 138 {
xorjoep 1:24714b45cd1b 139 *pSinVal = -*pSinVal;
xorjoep 1:24714b45cd1b 140 }
xorjoep 1:24714b45cd1b 141 }
xorjoep 1:24714b45cd1b 142 /**
xorjoep 1:24714b45cd1b 143 * @} end of SinCos group
xorjoep 1:24714b45cd1b 144 */