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  1. /* ----------------------------------------------------------------------
  2.  * Project:      CMSIS DSP Library
  3.  * Title:        arm_cmplx_conj_f32.c
  4.  * Description:  Floating-point complex conjugate
  5.  *
  6.  * $Date:        27. January 2017
  7.  * $Revision:    V.1.5.1
  8.  *
  9.  * Target Processor: Cortex-M cores
  10.  * -------------------------------------------------------------------- */
  11. /*
  12.  * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
  13.  *
  14.  * SPDX-License-Identifier: Apache-2.0
  15.  *
  16.  * Licensed under the Apache License, Version 2.0 (the License); you may
  17.  * not use this file except in compliance with the License.
  18.  * You may obtain a copy of the License at
  19.  *
  20.  * www.apache.org/licenses/LICENSE-2.0
  21.  *
  22.  * Unless required by applicable law or agreed to in writing, software
  23.  * distributed under the License is distributed on an AS IS BASIS, WITHOUT
  24.  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  25.  * See the License for the specific language governing permissions and
  26.  * limitations under the License.
  27.  */
  28.  
  29. #include "arm_math.h"
  30.  
  31. /**
  32.  * @ingroup groupCmplxMath
  33.  */
  34.  
  35. /**
  36.  * @defgroup cmplx_conj Complex Conjugate
  37.  *
  38.  * Conjugates the elements of a complex data vector.
  39.  *
  40.  * The <code>pSrc</code> points to the source data and
  41.  * <code>pDst</code> points to the where the result should be written.
  42.  * <code>numSamples</code> specifies the number of complex samples
  43.  * and the data in each array is stored in an interleaved fashion
  44.  * (real, imag, real, imag, ...).
  45.  * Each array has a total of <code>2*numSamples</code> values.
  46.  * The underlying algorithm is used:
  47.  *
  48.  * <pre>
  49.  * for(n=0; n<numSamples; n++) {
  50.  *     pDst[(2*n)+0)] = pSrc[(2*n)+0];     // real part
  51.  *     pDst[(2*n)+1)] = -pSrc[(2*n)+1];    // imag part
  52.  * }
  53.  * </pre>
  54.  *
  55.  * There are separate functions for floating-point, Q15, and Q31 data types.
  56.  */
  57.  
  58. /**
  59.  * @addtogroup cmplx_conj
  60.  * @{
  61.  */
  62.  
  63. /**
  64.  * @brief  Floating-point complex conjugate.
  65.  * @param  *pSrc points to the input vector
  66.  * @param  *pDst points to the output vector
  67.  * @param  numSamples number of complex samples in each vector
  68.  * @return none.
  69.  */
  70.  
  71. void arm_cmplx_conj_f32(
  72.   float32_t * pSrc,
  73.   float32_t * pDst,
  74.   uint32_t numSamples)
  75. {
  76.   uint32_t blkCnt;                               /* loop counter */
  77.  
  78. #if defined (ARM_MATH_DSP)
  79.  
  80.   /* Run the below code for Cortex-M4 and Cortex-M3 */
  81.   float32_t inR1, inR2, inR3, inR4;
  82.   float32_t inI1, inI2, inI3, inI4;
  83.  
  84.   /*loop Unrolling */
  85.   blkCnt = numSamples >> 2U;
  86.  
  87.   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  88.    ** a second loop below computes the remaining 1 to 3 samples. */
  89.   while (blkCnt > 0U)
  90.   {
  91.     /* C[0]+jC[1] = A[0]+ j (-1) A[1] */
  92.     /* Calculate Complex Conjugate and then store the results in the destination buffer. */
  93.     /* read real input samples */
  94.     inR1 = pSrc[0];
  95.     /* store real samples to destination */
  96.     pDst[0] = inR1;
  97.     inR2 = pSrc[2];
  98.     pDst[2] = inR2;
  99.     inR3 = pSrc[4];
  100.     pDst[4] = inR3;
  101.     inR4 = pSrc[6];
  102.     pDst[6] = inR4;
  103.  
  104.     /* read imaginary input samples */
  105.     inI1 = pSrc[1];
  106.     inI2 = pSrc[3];
  107.  
  108.     /* conjugate input */
  109.     inI1 = -inI1;
  110.  
  111.     /* read imaginary input samples */
  112.     inI3 = pSrc[5];
  113.  
  114.     /* conjugate input */
  115.     inI2 = -inI2;
  116.  
  117.     /* read imaginary input samples */
  118.     inI4 = pSrc[7];
  119.  
  120.     /* conjugate input */
  121.     inI3 = -inI3;
  122.  
  123.     /* store imaginary samples to destination */
  124.     pDst[1] = inI1;
  125.     pDst[3] = inI2;
  126.  
  127.     /* conjugate input */
  128.     inI4 = -inI4;
  129.  
  130.     /* store imaginary samples to destination */
  131.     pDst[5] = inI3;
  132.  
  133.     /* increment source pointer by 8 to process next sampels */
  134.     pSrc += 8U;
  135.  
  136.     /* store imaginary sample to destination */
  137.     pDst[7] = inI4;
  138.  
  139.     /* increment destination pointer by 8 to store next samples */
  140.     pDst += 8U;
  141.  
  142.     /* Decrement the loop counter */
  143.     blkCnt--;
  144.   }
  145.  
  146.   /* If the numSamples is not a multiple of 4, compute any remaining output samples here.
  147.    ** No loop unrolling is used. */
  148.   blkCnt = numSamples % 0x4U;
  149.  
  150. #else
  151.  
  152.   /* Run the below code for Cortex-M0 */
  153.   blkCnt = numSamples;
  154.  
  155. #endif /* #if defined (ARM_MATH_DSP) */
  156.  
  157.   while (blkCnt > 0U)
  158.   {
  159.     /* realOut + j (imagOut) = realIn + j (-1) imagIn */
  160.     /* Calculate Complex Conjugate and then store the results in the destination buffer. */
  161.     *pDst++ = *pSrc++;
  162.     *pDst++ = -*pSrc++;
  163.  
  164.     /* Decrement the loop counter */
  165.     blkCnt--;
  166.   }
  167. }
  168.  
  169. /**
  170.  * @} end of cmplx_conj group
  171.  */
  172.