145 lines
4.8 KiB
C
145 lines
4.8 KiB
C
/* ----------------------------------------------------------------------
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* Project: CMSIS DSP Library
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* Title: arm_sin_cos_f32.c
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* Description: Sine and Cosine calculation for floating-point values
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*
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* $Date: 27. January 2017
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* $Revision: V.1.5.1
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*
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* Target Processor: Cortex-M cores
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* -------------------------------------------------------------------- */
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/*
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* Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the License); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an AS IS BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "arm_math.h"
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#include "arm_common_tables.h"
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/**
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* @ingroup groupController
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*/
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/**
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* @defgroup SinCos Sine Cosine
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*
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* Computes the trigonometric sine and cosine values using a combination of table lookup
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* and linear interpolation.
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* There are separate functions for Q31 and floating-point data types.
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* The input to the floating-point version is in degrees while the
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* fixed-point Q31 have a scaled input with the range
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* [-1 0.9999] mapping to [-180 +180] degrees.
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*
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* The floating point function also allows values that are out of the usual range. When this happens, the function will
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* take extra time to adjust the input value to the range of [-180 180].
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*
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* The result is accurate to 5 digits after the decimal point.
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*
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* The implementation is based on table lookup using 360 values together with linear interpolation.
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* The steps used are:
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* -# Calculation of the nearest integer table index.
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* -# Compute the fractional portion (fract) of the input.
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* -# Fetch the value corresponding to \c index from sine table to \c y0 and also value from \c index+1 to \c y1.
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* -# Sine value is computed as <code> *psinVal = y0 + (fract * (y1 - y0))</code>.
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* -# Fetch the value corresponding to \c index from cosine table to \c y0 and also value from \c index+1 to \c y1.
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* -# Cosine value is computed as <code> *pcosVal = y0 + (fract * (y1 - y0))</code>.
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*/
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/**
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* @addtogroup SinCos
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* @{
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*/
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/**
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* @brief Floating-point sin_cos function.
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* @param[in] theta input value in degrees
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* @param[out] *pSinVal points to the processed sine output.
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* @param[out] *pCosVal points to the processed cos output.
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* @return none.
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*/
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void arm_sin_cos_f32(
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float32_t theta,
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float32_t * pSinVal,
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float32_t * pCosVal)
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{
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float32_t fract, in; /* Temporary variables for input, output */
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uint16_t indexS, indexC; /* Index variable */
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float32_t f1, f2, d1, d2; /* Two nearest output values */
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float32_t findex, Dn, Df, temp;
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/* input x is in degrees */
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/* Scale the input, divide input by 360, for cosine add 0.25 (pi/2) to read sine table */
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in = theta * 0.00277777777778f;
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if (in < 0.0f)
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{
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in = -in;
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}
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in = in - (int32_t)in;
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/* Calculation of index of the table */
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findex = (float32_t) FAST_MATH_TABLE_SIZE * in;
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indexS = ((uint16_t)findex) & 0x1ff;
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indexC = (indexS + (FAST_MATH_TABLE_SIZE / 4)) & 0x1ff;
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/* fractional value calculation */
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fract = findex - (float32_t) indexS;
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/* Read two nearest values of input value from the cos & sin tables */
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f1 = sinTable_f32[indexC+0];
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f2 = sinTable_f32[indexC+1];
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d1 = -sinTable_f32[indexS+0];
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d2 = -sinTable_f32[indexS+1];
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temp = (1.0f - fract) * f1 + fract * f2;
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Dn = 0.0122718463030f; // delta between the two points (fixed), in this case 2*pi/FAST_MATH_TABLE_SIZE
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Df = f2 - f1; // delta between the values of the functions
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temp = Dn *(d1 + d2) - 2 * Df;
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temp = fract * temp + (3 * Df - (d2 + 2 * d1) * Dn);
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temp = fract * temp + d1 * Dn;
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/* Calculation of cosine value */
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*pCosVal = fract * temp + f1;
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/* Read two nearest values of input value from the cos & sin tables */
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f1 = sinTable_f32[indexS+0];
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f2 = sinTable_f32[indexS+1];
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d1 = sinTable_f32[indexC+0];
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d2 = sinTable_f32[indexC+1];
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temp = (1.0f - fract) * f1 + fract * f2;
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Df = f2 - f1; // delta between the values of the functions
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temp = Dn*(d1 + d2) - 2*Df;
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temp = fract*temp + (3*Df - (d2 + 2*d1)*Dn);
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temp = fract*temp + d1*Dn;
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/* Calculation of sine value */
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*pSinVal = fract*temp + f1;
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if (theta < 0.0f)
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{
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*pSinVal = -*pSinVal;
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}
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}
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/**
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* @} end of SinCos group
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*/
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