text: #include "edge-impulse-sdk/dsp/config.hpp"
  #if EIDSP_LOAD_CMSIS_DSP_SOURCES
  /* ----------------------------------------------------------------------
   * Project:      CMSIS DSP Library
   * Title:        arm_cmplx_conj_f32.c
   * Description:  Floating-point complex conjugate
   *
   * $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 "edge-impulse-sdk/CMSIS/DSP/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 destination data 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)  ] =  pSrc[(2*n)  ];    // 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[in]     pSrc        points to the input vector
    @param[out]    pDst        points to the output vector
    @param[in]     numSamples  number of samples in each vector
    @return        none
   */
  
  #if defined(ARM_MATH_MVEF) && !defined(ARM_MATH_AUTOVECTORIZE)
  
  void arm_cmplx_conj_f32(
      const float32_t * pSrc,
      float32_t * pDst,
      uint32_t numSamples)
  {
      static const float32_t cmplx_conj_sign[4] = { 1.0f, -1.0f, 1.0f, -1.0f };
      uint32_t blockSize = numSamples * CMPLX_DIM;   /* loop counters */
      uint32_t blkCnt;
      f32x4_t vecSrc;
      f32x4_t vecSign;
  
      /*
       * load sign vector
       */
      vecSign = *(f32x4_t *) cmplx_conj_sign;
  
      /* Compute 4 real samples at a time */
      blkCnt = blockSize >> 2U;
  
      while (blkCnt > 0U)
      {
          vecSrc = vld1q(pSrc);
          vst1q(pDst,vmulq(vecSrc, vecSign));
          /*
           * Decrement the blkCnt loop counter
           * Advance vector source and destination pointers
           */
          pSrc += 4;
          pDst += 4;
          blkCnt--;
      }
  
       /* Tail */
      blkCnt = (blockSize & 0x3) >> 1;
  
      while (blkCnt > 0U)
      {
        /* C[0] + jC[1] = A[0]+ j(-1)A[1] */
    
        /* Calculate Complex Conjugate and store result in destination buffer. */
        *pDst++ =  *pSrc++;
        *pDst++ = -*pSrc++;
    
        /* Decrement loop counter */
        blkCnt--;
      }
  
  }
  
  #else
  void arm_cmplx_conj_f32(
    const float32_t * pSrc,
          float32_t * pDst,
          uint32_t numSamples)
  {
          uint32_t blkCnt;                               /* Loop counter */
  
  #if defined(ARM_MATH_NEON) && !defined(ARM_MATH_AUTOVECTORIZE)
     float32x4_t zero;
     float32x4x2_t vec;
  
     zero = vdupq_n_f32(0.0f);
  
     /* Compute 4 outputs at a time */
     blkCnt = numSamples >> 2U;
  
     while (blkCnt > 0U)
     {
       /* C[0]+jC[1] = A[0]+(-1)*jA[1] */
       /* Calculate Complex Conjugate and then store the results in the destination buffer. */
       vec = vld2q_f32(pSrc);
       vec.val[1] = vsubq_f32(zero,vec.val[1]);
       vst2q_f32(pDst,vec);
  
       /* Increment pointers */
       pSrc += 8;
       pDst += 8;
          
       /* Decrement the loop counter */
       blkCnt--;
     }
  
     /* Tail */
     blkCnt = numSamples & 0x3;
  
  #else
  #if defined (ARM_MATH_LOOPUNROLL) && !defined(ARM_MATH_AUTOVECTORIZE)
  
    /* Loop unrolling: Compute 4 outputs at a time */
    blkCnt = numSamples >> 2U;
  
    while (blkCnt > 0U)
    {
      /* C[0] + jC[1] = A[0]+ j(-1)A[1] */
  
      /* Calculate Complex Conjugate and store result in destination buffer. */
      *pDst++ =  *pSrc++;
      *pDst++ = -*pSrc++;
  
      *pDst++ =  *pSrc++;
      *pDst++ = -*pSrc++;
  
      *pDst++ =  *pSrc++;
      *pDst++ = -*pSrc++;
  
      *pDst++ =  *pSrc++;
      *pDst++ = -*pSrc++;
  
      /* Decrement loop counter */
      blkCnt--;
    }
  
    /* Loop unrolling: Compute remaining outputs */
    blkCnt = numSamples % 0x4U;
  
  #else
  
    /* Initialize blkCnt with number of samples */
    blkCnt = numSamples;
  
  #endif /* #if defined (ARM_MATH_LOOPUNROLL) */
  #endif /* #if defined (ARM_MATH_NEON) */
  
    while (blkCnt > 0U)
    {
      /* C[0] + jC[1] = A[0]+ j(-1)A[1] */
  
      /* Calculate Complex Conjugate and store result in destination buffer. */
      *pDst++ =  *pSrc++;
      *pDst++ = -*pSrc++;
  
      /* Decrement loop counter */
      blkCnt--;
    }
  
  }
  #endif /* defined(ARM_MATH_MVEF) && !defined(ARM_MATH_AUTOVECTORIZE) */
  
  /**
    @} end of cmplx_conj group
   */
  
  #endif // EIDSP_LOAD_CMSIS_DSP_SOURCES
  