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/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_sin_cos_q31.c
* Description: Cosine & Sine calculation for Q31 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
*/
/**
@addtogroup SinCos
@{
*/
/**
@brief Q31 sin_cos function.
@param[in] theta scaled input value in degrees
@param[out] pSinVal points to processed sine output
@param[out] pCosVal points to processed cosine output
@return none
The Q31 input value is in the range [-1 0.999999] and is mapped to a degree value in the range [-180 179].
*/
void arm_sin_cos_q31(
q31_t theta,
q31_t * pSinVal,
q31_t * pCosVal)
{
q31_t fract; /* Temporary input, output variables */
uint16_t indexS, indexC; /* Index variable */
q31_t f1, f2, d1, d2; /* Two nearest output values */
q31_t Dn, Df;
q63_t temp;
/* Calculate the nearest index */
indexS = (uint32_t)theta >> CONTROLLER_Q31_SHIFT;
indexC = (indexS + 128) & 0x1ff;
/* Calculation of fractional value */
fract = (theta - (indexS << CONTROLLER_Q31_SHIFT)) << 8;
/* Read two nearest values of input value from the cos & sin tables */
f1 = sinTable_q31[indexC ];
f2 = sinTable_q31[indexC+1];
d1 = -sinTable_q31[indexS ];
d2 = -sinTable_q31[indexS+1];
Dn = 0x1921FB5; /* 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 * ((q63_t)d1 + d2);
temp = temp - ((q63_t)Df << 32);
temp = (q63_t)fract * (temp >> 31);
temp = temp + ((3 * (q63_t)Df << 31) - (d2 + ((q63_t)d1 << 1)) * Dn);
temp = (q63_t)fract * (temp >> 31);
temp = temp + (q63_t)d1 * Dn;
temp = (q63_t)fract * (temp >> 31);
/* Calculation of cosine value */
*pCosVal = clip_q63_to_q31((temp >> 31) + (q63_t)f1);
/* Read two nearest values of input value from the cos & sin tables */
f1 = sinTable_q31[indexS ];
f2 = sinTable_q31[indexS+1];
d1 = sinTable_q31[indexC ];
d2 = sinTable_q31[indexC+1];
Df = f2 - f1; // delta between the values of the functions
temp = Dn * ((q63_t)d1 + d2);
temp = temp - ((q63_t)Df << 32);
temp = (q63_t)fract * (temp >> 31);
temp = temp + ((3 * (q63_t)Df << 31) - (d2 + ((q63_t)d1 << 1)) * Dn);
temp = (q63_t)fract * (temp >> 31);
temp = temp + (q63_t)d1 * Dn;
temp = (q63_t)fract * (temp >> 31);
/* Calculation of sine value */
*pSinVal = clip_q63_to_q31((temp >> 31) + (q63_t)f1);
}
/**
@} end of SinCos group
*/
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