text: /* ----------------------------------------------------------------------
   * Project:      CMSIS DSP Library
   * Title:        arm_cmplx_mag_q31.c
   * Description:  Q31 complex magnitude
   *
   * $Date:        28. February 2019
   * $Revision:    V.1.5.5
   *
   * 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"
  
  /**
    @ingroup groupCmplxMath
   */
  
  /**
    @addtogroup cmplx_mag
    @{
   */
  
  /**
    @brief         Q31 complex magnitude.
    @param[in]     pSrc        points to input vector
    @param[out]    pDst        points to output vector
    @param[in]     numSamples  number of samples in each vector
    @return        none
  
    @par           Scaling and Overflow Behavior
                     The function implements 1.31 by 1.31 multiplications and finally output is converted into 2.30 format.
                     Input down scaling is not required.
   */
  
  void arm_cmplx_mag_q31(
    const q31_t * pSrc,
          q31_t * pDst,
          uint32_t numSamples)
  {
          uint32_t blkCnt;                               /* Loop counter */
          q31_t real, imag;                              /* Temporary input variables */
          q31_t acc0, acc1;                              /* Accumulators */
  
  #if defined (ARM_MATH_LOOPUNROLL)
  
    /* Loop unrolling: Compute 4 outputs at a time */
    blkCnt = numSamples >> 2U;
  
    while (blkCnt > 0U)
    {
      /* C[0] = sqrt(A[0] * A[0] + A[1] * A[1]) */
  
      real = *pSrc++;
      imag = *pSrc++;
      acc0 = (q31_t) (((q63_t) real * real) >> 33);
      acc1 = (q31_t) (((q63_t) imag * imag) >> 33);
  
      /* store result in 2.30 format in destination buffer. */
      arm_sqrt_q31(acc0 + acc1, pDst++);
  
      real = *pSrc++;
      imag = *pSrc++;
      acc0 = (q31_t) (((q63_t) real * real) >> 33);
      acc1 = (q31_t) (((q63_t) imag * imag) >> 33);
      arm_sqrt_q31(acc0 + acc1, pDst++);
  
      real = *pSrc++;
      imag = *pSrc++;
      acc0 = (q31_t) (((q63_t) real * real) >> 33);
      acc1 = (q31_t) (((q63_t) imag * imag) >> 33);
      arm_sqrt_q31(acc0 + acc1, pDst++);
  
      real = *pSrc++;
      imag = *pSrc++;
      acc0 = (q31_t) (((q63_t) real * real) >> 33);
      acc1 = (q31_t) (((q63_t) imag * imag) >> 33);
      arm_sqrt_q31(acc0 + acc1, pDst++);
  
      /* 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) */
  
    while (blkCnt > 0U)
    {
      /* C[0] = sqrt(A[0] * A[0] + A[1] * A[1]) */
  
      real = *pSrc++;
      imag = *pSrc++;
      acc0 = (q31_t) (((q63_t) real * real) >> 33);
      acc1 = (q31_t) (((q63_t) imag * imag) >> 33);
  
      /* store result in 2.30 format in destination buffer. */
      arm_sqrt_q31(acc0 + acc1, pDst++);
  
      /* Decrement loop counter */
      blkCnt--;
    }
  
  }
  
  /**
    @} end of cmplx_mag group
   */
  