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/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_cmplx_conj_f32.c
* Description: Floating-point complex conjugate
*
* $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"
/**
* @ingroup groupCmplxMath
*/
/**
* @defgroup cmplx_conj Complex Conjugate
*
* Conjugates the elements of a complex data vector.
*
* The <code>pSrc</code> points to the source data and
* <code>pDst</code> points to the where the result should be written.
* <code>numSamples</code> specifies the number of complex samples
* and the data in each array is stored in an interleaved fashion
* (real, imag, real, imag, ...).
* Each array has a total of <code>2*numSamples</code> values.
* The underlying algorithm is used:
*
* <pre>
* for(n=0; n<numSamples; n++) {
* pDst[(2*n)+0)] = pSrc[(2*n)+0]; // real part
* pDst[(2*n)+1)] = -pSrc[(2*n)+1]; // imag part
* }
* </pre>
*
* There are separate functions for floating-point, Q15, and Q31 data types.
*/
/**
* @addtogroup cmplx_conj
* @{
*/
/**
* @brief Floating-point complex conjugate.
* @param *pSrc points to the input vector
* @param *pDst points to the output vector
* @param numSamples number of complex samples in each vector
* @return none.
*/
void arm_cmplx_conj_f32(
float32_t * pSrc,
float32_t * pDst,
uint32_t numSamples)
{
uint32_t blkCnt; /* loop counter */
#if defined (ARM_MATH_DSP)
/* Run the below code for Cortex-M4 and Cortex-M3 */
float32_t inR1, inR2, inR3, inR4;
float32_t inI1, inI2, inI3, inI4;
/*loop Unrolling */
blkCnt = numSamples >> 2U;
/* First part of the processing with loop unrolling. Compute 4 outputs at a time.
** a second loop below computes the remaining 1 to 3 samples. */
while (blkCnt > 0U)
{
/* C[0]+jC[1] = A[0]+ j (-1) A[1] */
/* Calculate Complex Conjugate and then store the results in the destination buffer. */
/* read real input samples */
inR1 = pSrc[0];
/* store real samples to destination */
pDst[0] = inR1;
inR2 = pSrc[2];
pDst[2] = inR2;
inR3 = pSrc[4];
pDst[4] = inR3;
inR4 = pSrc[6];
pDst[6] = inR4;
/* read imaginary input samples */
inI1 = pSrc[1];
inI2 = pSrc[3];
/* conjugate input */
inI1 = -inI1;
/* read imaginary input samples */
inI3 = pSrc[5];
/* conjugate input */
inI2 = -inI2;
/* read imaginary input samples */
inI4 = pSrc[7];
/* conjugate input */
inI3 = -inI3;
/* store imaginary samples to destination */
pDst[1] = inI1;
pDst[3] = inI2;
/* conjugate input */
inI4 = -inI4;
/* store imaginary samples to destination */
pDst[5] = inI3;
/* increment source pointer by 8 to process next sampels */
pSrc += 8U;
/* store imaginary sample to destination */
pDst[7] = inI4;
/* increment destination pointer by 8 to store next samples */
pDst += 8U;
/* Decrement the loop counter */
blkCnt--;
}
/* If the numSamples is not a multiple of 4, compute any remaining output samples here.
** No loop unrolling is used. */
blkCnt = numSamples % 0x4U;
#else
/* Run the below code for Cortex-M0 */
blkCnt = numSamples;
#endif /* #if defined (ARM_MATH_DSP) */
while (blkCnt > 0U)
{
/* realOut + j (imagOut) = realIn + j (-1) imagIn */
/* Calculate Complex Conjugate and then store the results in the destination buffer. */
*pDst++ = *pSrc++;
*pDst++ = -*pSrc++;
/* Decrement the loop counter */
blkCnt--;
}
}
/**
* @} end of cmplx_conj group
*/
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