| /* ---------------------------------------------------------------------- |
| * Project: CMSIS DSP Library |
| * Title: arm_sin_cos_f32.c |
| * Description: Sine and Cosine calculation for floating-point values |
| * |
| * $Date: 18. March 2019 |
| * $Revision: V1.6.0 |
| * |
| * Target Processor: Cortex-M cores |
| * -------------------------------------------------------------------- */ |
| /* |
| * Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved. |
| * |
| * SPDX-License-Identifier: Apache-2.0 |
| * |
| * Licensed under the Apache License, Version 2.0 (the License); you may |
| * not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an AS IS BASIS, WITHOUT |
| * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include "arm_math.h" |
| #include "arm_common_tables.h" |
| |
| /** |
| @ingroup groupController |
| */ |
| |
| /** |
| @defgroup SinCos Sine Cosine |
| |
| Computes the trigonometric sine and cosine values using a combination of table lookup |
| and linear interpolation. |
| There are separate functions for Q31 and floating-point data types. |
| The input to the floating-point version is in degrees while the |
| fixed-point Q31 have a scaled input with the range |
| [-1 0.9999] mapping to [-180 +180] degrees. |
| |
| The floating point function also allows values that are out of the usual range. When this happens, the function will |
| take extra time to adjust the input value to the range of [-180 180]. |
| |
| The result is accurate to 5 digits after the decimal point. |
| |
| The implementation is based on table lookup using 360 values together with linear interpolation. |
| The steps used are: |
| -# Calculation of the nearest integer table index. |
| -# Compute the fractional portion (fract) of the input. |
| -# Fetch the value corresponding to \c index from sine table to \c y0 and also value from \c index+1 to \c y1. |
| -# Sine value is computed as <code> *psinVal = y0 + (fract * (y1 - y0))</code>. |
| -# Fetch the value corresponding to \c index from cosine table to \c y0 and also value from \c index+1 to \c y1. |
| -# Cosine value is computed as <code> *pcosVal = y0 + (fract * (y1 - y0))</code>. |
| */ |
| |
| /** |
| @addtogroup SinCos |
| @{ |
| */ |
| |
| /** |
| @brief Floating-point sin_cos function. |
| @param[in] theta input value in degrees |
| @param[out] pSinVal points to processed sine output |
| @param[out] pCosVal points to processed cosine output |
| @return none |
| */ |
| |
| void arm_sin_cos_f32( |
| float32_t theta, |
| float32_t * pSinVal, |
| float32_t * pCosVal) |
| { |
| float32_t fract, in; /* Temporary input, output variables */ |
| uint16_t indexS, indexC; /* Index variable */ |
| float32_t f1, f2, d1, d2; /* Two nearest output values */ |
| float32_t Dn, Df; |
| float32_t temp, findex; |
| |
| /* input x is in degrees */ |
| /* Scale input, divide input by 360, for cosine add 0.25 (pi/2) to read sine table */ |
| in = theta * 0.00277777777778f; |
| |
| if (in < 0.0f) |
| { |
| in = -in; |
| } |
| |
| in = in - (int32_t)in; |
| |
| /* Calculate the nearest index */ |
| findex = (float32_t)FAST_MATH_TABLE_SIZE * in; |
| indexS = ((uint16_t)findex) & 0x1ff; |
| indexC = (indexS + (FAST_MATH_TABLE_SIZE / 4)) & 0x1ff; |
| |
| /* Calculation of fractional value */ |
| fract = findex - (float32_t) indexS; |
| |
| /* Read two nearest values of input value from the cos & sin tables */ |
| f1 = sinTable_f32[indexC ]; |
| f2 = sinTable_f32[indexC+1]; |
| d1 = -sinTable_f32[indexS ]; |
| d2 = -sinTable_f32[indexS+1]; |
| |
| temp = (1.0f - fract) * f1 + fract * f2; |
| |
| Dn = 0.0122718463030f; /* delta between the two points (fixed), in this case 2*pi/FAST_MATH_TABLE_SIZE */ |
| Df = f2 - f1; /* delta between the values of the functions */ |
| |
| temp = Dn * (d1 + d2) - 2 * Df; |
| temp = fract * temp + (3 * Df - (d2 + 2 * d1) * Dn); |
| temp = fract * temp + d1 * Dn; |
| |
| /* Calculation of cosine value */ |
| *pCosVal = fract * temp + f1; |
| |
| /* Read two nearest values of input value from the cos & sin tables */ |
| f1 = sinTable_f32[indexS ]; |
| f2 = sinTable_f32[indexS+1]; |
| d1 = sinTable_f32[indexC ]; |
| d2 = sinTable_f32[indexC+1]; |
| |
| temp = (1.0f - fract) * f1 + fract * f2; |
| |
| Df = f2 - f1; // delta between the values of the functions |
| temp = Dn * (d1 + d2) - 2 * Df; |
| temp = fract * temp + (3 * Df - (d2 + 2 * d1) * Dn); |
| temp = fract * temp + d1 * Dn; |
| |
| /* Calculation of sine value */ |
| *pSinVal = fract * temp + f1; |
| |
| if (theta < 0.0f) |
| { |
| *pSinVal = -*pSinVal; |
| } |
| } |
| |
| /** |
| @} end of SinCos group |
| */ |