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/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_sin_cos_f32.c
* Description: Sine and Cosine calculation for floating-point values
*
* $Date: 27. January 2017
* $Revision: V.1.5.1
*
* Target Processor: Cortex-M cores
* -------------------------------------------------------------------- */
/*
* Copyright (C) 2010-2017 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 the processed sine output.
* @param[out] *pCosVal points to the processed cos output.
* @return none.
*/
void arm_sin_cos_f32(
float32_t theta,
float32_t * pSinVal,
float32_t * pCosVal)
{
float32_t fract, in; /* Temporary variables for input, output */
uint16_t indexS, indexC; /* Index variable */
float32_t f1, f2, d1, d2; /* Two nearest output values */
float32_t findex, Dn, Df, temp;
/* input x is in degrees */
/* Scale the 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;
/* Calculation of index of the table */
findex = (float32_t) FAST_MATH_TABLE_SIZE * in;
indexS = ((uint16_t)findex) & 0x1ff;
indexC = (indexS + (FAST_MATH_TABLE_SIZE / 4)) & 0x1ff;
/* fractional value calculation */
fract = findex - (float32_t) indexS;
/* Read two nearest values of input value from the cos & sin tables */
f1 = sinTable_f32[indexC+0];
f2 = sinTable_f32[indexC+1];
d1 = -sinTable_f32[indexS+0];
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+0];
f2 = sinTable_f32[indexS+1];
d1 = sinTable_f32[indexC+0];
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
*/
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