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  1. /* ----------------------------------------------------------------------
  2.  * Project:      CMSIS DSP Library
  3.  * Title:        arm_mean_f32.c
  4.  * Description:  Mean value of a floating-point vector
  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 groupStats
  33.  */
  34.  
  35. /**
  36.  * @defgroup mean Mean
  37.  *
  38.  * Calculates the mean of the input vector. Mean is defined as the average of the elements in the vector.
  39.  * The underlying algorithm is used:
  40.  *
  41.  * <pre>
  42.  *      Result = (pSrc[0] + pSrc[1] + pSrc[2] + ... + pSrc[blockSize-1]) / blockSize;
  43.  * </pre>
  44.  *
  45.  * There are separate functions for floating-point, Q31, Q15, and Q7 data types.
  46.  */
  47.  
  48. /**
  49.  * @addtogroup mean
  50.  * @{
  51.  */
  52.  
  53.  
  54. /**
  55.  * @brief Mean value of a floating-point vector.
  56.  * @param[in]       *pSrc points to the input vector
  57.  * @param[in]       blockSize length of the input vector
  58.  * @param[out]      *pResult mean value returned here
  59.  * @return none.
  60.  */
  61.  
  62. void arm_mean_f32(
  63.   float32_t * pSrc,
  64.   uint32_t blockSize,
  65.   float32_t * pResult)
  66. {
  67.   float32_t sum = 0.0f;                          /* Temporary result storage */
  68.   uint32_t blkCnt;                               /* loop counter */
  69.  
  70. #if defined (ARM_MATH_DSP)
  71.   /* Run the below code for Cortex-M4 and Cortex-M3 */
  72.  
  73.   float32_t in1, in2, in3, in4;
  74.  
  75.   /*loop Unrolling */
  76.   blkCnt = blockSize >> 2U;
  77.  
  78.   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  79.    ** a second loop below computes the remaining 1 to 3 samples. */
  80.   while (blkCnt > 0U)
  81.   {
  82.     /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */
  83.     in1 = *pSrc++;
  84.     in2 = *pSrc++;
  85.     in3 = *pSrc++;
  86.     in4 = *pSrc++;
  87.  
  88.     sum += in1;
  89.     sum += in2;
  90.     sum += in3;
  91.     sum += in4;
  92.  
  93.     /* Decrement the loop counter */
  94.     blkCnt--;
  95.   }
  96.  
  97.   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
  98.    ** No loop unrolling is used. */
  99.   blkCnt = blockSize % 0x4U;
  100.  
  101. #else
  102.   /* Run the below code for Cortex-M0 */
  103.  
  104.   /* Loop over blockSize number of values */
  105.   blkCnt = blockSize;
  106.  
  107. #endif /* #if defined (ARM_MATH_DSP) */
  108.  
  109.   while (blkCnt > 0U)
  110.   {
  111.     /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */
  112.     sum += *pSrc++;
  113.  
  114.     /* Decrement the loop counter */
  115.     blkCnt--;
  116.   }
  117.  
  118.   /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) / blockSize  */
  119.   /* Store the result to the destination */
  120.   *pResult = sum / (float32_t) blockSize;
  121. }
  122.  
  123. /**
  124.  * @} end of mean group
  125.  */
  126.