tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/StatisticsFunctions/arm_mean_f32.c

   1 /* ----------------------------------------------------------------------
   2 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
   3 *
   4 * $Date:        17. January 2013
   5 * $Revision:    V1.4.1
   6 *
   7 * Project:          CMSIS DSP Library
   8 * Title:                arm_mean_f32.c
   9 *
  10 * Description:  Mean value of a floating-point vector.
  11 *
  12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
  13 *
  14 * Redistribution and use in source and binary forms, with or without
  15 * modification, are permitted provided that the following conditions
  16 * are met:
  17 *   - Redistributions of source code must retain the above copyright
  18 *     notice, this list of conditions and the following disclaimer.
  19 *   - Redistributions in binary form must reproduce the above copyright
  20 *     notice, this list of conditions and the following disclaimer in
  21 *     the documentation and/or other materials provided with the
  22 *     distribution.
  23 *   - Neither the name of ARM LIMITED nor the names of its contributors
  24 *     may be used to endorse or promote products derived from this
  25 *     software without specific prior written permission.
  26 *
  27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  38 * POSSIBILITY OF SUCH DAMAGE.
  39 * ---------------------------------------------------------------------------- */
  40
  41 #include "arm_math.h"
  42
  43 /**
  44  * @ingroup groupStats
  45  */
  46
  47 /**
  48  * @defgroup mean Mean
  49  *
  50  * Calculates the mean of the input vector. Mean is defined as the average of the elements in the vector.
  51  * The underlying algorithm is used:
  52  *
  53  * <pre>
  54  *      Result = (pSrc[0] + pSrc[1] + pSrc[2] + ... + pSrc[blockSize-1]) / blockSize;
  55  * </pre>
  56  *
  57  * There are separate functions for floating-point, Q31, Q15, and Q7 data types.
  58  */
  59
  60 /**
  61  * @addtogroup mean
  62  * @{
  63  */
  64
  65
  66 /**
  67  * @brief Mean value of a floating-point vector.
  68  * @param[in]       *pSrc points to the input vector
  69  * @param[in]       blockSize length of the input vector
  70  * @param[out]      *pResult mean value returned here
  71  * @return none.
  72  */
  73
  74
  75 void arm_mean_f32(
  76   float32_t * pSrc,
  77   uint32_t blockSize,
  78   float32_t * pResult)
  79 {
  80   float32_t sum = 0.0f;                          /* Temporary result storage */
  81   uint32_t blkCnt;                               /* loop counter */
  82
  83 #ifndef ARM_MATH_CM0_FAMILY
  84
  85   /* Run the below code for Cortex-M4 and Cortex-M3 */
  86   float32_t in1, in2, in3, in4;
  87
  88   /*loop Unrolling */
  89   blkCnt = blockSize >> 2u;
  90
  91   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  92    ** a second loop below computes the remaining 1 to 3 samples. */
  93   while(blkCnt > 0u)
  94   {
  95     /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */
  96     in1 = *pSrc++;
  97     in2 = *pSrc++;
  98     in3 = *pSrc++;
  99     in4 = *pSrc++;
 100
 101     sum += in1;
 102     sum += in2;
 103     sum += in3;
 104     sum += in4;
 105
 106     /* Decrement the loop counter */
 107     blkCnt--;
 108   }
 109
 110   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
 111    ** No loop unrolling is used. */
 112   blkCnt = blockSize % 0x4u;
 113
 114 #else
 115
 116   /* Run the below code for Cortex-M0 */
 117
 118   /* Loop over blockSize number of values */
 119   blkCnt = blockSize;
 120
 121 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
 122
 123   while(blkCnt > 0u)
 124   {
 125     /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */
 126     sum += *pSrc++;
 127
 128     /* Decrement the loop counter */
 129     blkCnt--;
 130   }
 131
 132   /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) / blockSize  */
 133   /* Store the result to the destination */
 134   *pResult = sum / (float32_t) blockSize;
 135 }
 136
 137 /**
 138  * @} end of mean group
 139  */