lib/main/CMSIS/DSP/Source/StatisticsFunctions/arm_mean_f32.c

   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  */