text: /* ----------------------------------------------------------------------
   * Project:      CMSIS DSP Library
   * Title:        arm_rms_f32.c
   * Description:  Root mean square value of an array of F32 type
   *
   * $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 groupStats
   */
  
  /**
   * @defgroup RMS Root mean square (RMS)
   *
   *
   * Calculates the Root Mean Sqaure of the elements in the input vector.
   * The underlying algorithm is used:
   *
   * <pre>
   * 	Result = sqrt(((pSrc[0] * pSrc[0] + pSrc[1] * pSrc[1] + ... + pSrc[blockSize-1] * pSrc[blockSize-1]) / blockSize));
   * </pre>
   *
   * There are separate functions for floating point, Q31, and Q15 data types.
   */
  
  /**
   * @addtogroup RMS
   * @{
   */
  
  
  /**
   * @brief Root Mean Square of the elements of a floating-point vector.
   * @param[in]       *pSrc points to the input vector
   * @param[in]       blockSize length of the input vector
   * @param[out]      *pResult rms value returned here
   * @return none.
   *
   */
  
  void arm_rms_f32(
    const float32_t * pSrc,
    uint32_t blockSize,
    float32_t * pResult)
  {
    float32_t sum = 0.0f;                          /* Accumulator */
    float32_t in;                                  /* Tempoprary variable to store input value */
    uint32_t blkCnt;                               /* loop counter */
  
  #if defined (ARM_MATH_DSP)
    /* Run the below code for Cortex-M4 and Cortex-M3 */
  
    /* loop Unrolling */
    blkCnt = blockSize >> 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 = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */
      /* Compute sum of the squares and then store the result in a temporary variable, sum  */
      in = *pSrc++;
      sum += in * in;
      in = *pSrc++;
      sum += in * in;
      in = *pSrc++;
      sum += in * in;
      in = *pSrc++;
      sum += in * in;
  
      /* Decrement the loop counter */
      blkCnt--;
    }
  
    /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
     ** No loop unrolling is used. */
    blkCnt = blockSize % 0x4U;
  
  #else
    /* Run the below code for Cortex-M0 */
  
    /* Loop over blockSize number of values */
    blkCnt = blockSize;
  
  #endif /* #if defined (ARM_MATH_DSP) */
  
    while (blkCnt > 0U)
    {
      /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */
      /* Compute sum of the squares and then store the results in a temporary variable, sum  */
      in = *pSrc++;
      sum += in * in;
  
      /* Decrement the loop counter */
      blkCnt--;
    }
  
    /* Compute Rms and store the result in the destination */
    arm_sqrt_f32(sum / (float32_t) blockSize, pResult);
  }
  
  /**
   * @} end of RMS group
   */
  