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1 /* ----------------------------------------------------------------------
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2 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.
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3 *
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4 * $Date: 19. March 2015
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5 * $Revision: V.1.4.5
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6 *
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7 * Project: CMSIS DSP Library
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8 * Title: arm_mean_f32.c
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9 *
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10 * Description: Mean value of a floating-point vector.
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11 *
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12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
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13 *
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14 * Redistribution and use in source and binary forms, with or without
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15 * modification, are permitted provided that the following conditions
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16 * are met:
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17 * - Redistributions of source code must retain the above copyright
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18 * notice, this list of conditions and the following disclaimer.
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19 * - Redistributions in binary form must reproduce the above copyright
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20 * notice, this list of conditions and the following disclaimer in
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21 * the documentation and/or other materials provided with the
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22 * distribution.
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23 * - Neither the name of ARM LIMITED nor the names of its contributors
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24 * may be used to endorse or promote products derived from this
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25 * software without specific prior written permission.
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26 *
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27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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38 * POSSIBILITY OF SUCH DAMAGE.
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39 * ---------------------------------------------------------------------------- */
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40
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41 #include "arm_math.h"
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42
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43 /**
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44 * @ingroup groupStats
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45 */
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46
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47 /**
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48 * @defgroup mean Mean
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49 *
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50 * Calculates the mean of the input vector. Mean is defined as the average of the elements in the vector.
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51 * The underlying algorithm is used:
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52 *
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53 * <pre>
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54 * Result = (pSrc[0] + pSrc[1] + pSrc[2] + ... + pSrc[blockSize-1]) / blockSize;
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55 * </pre>
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56 *
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57 * There are separate functions for floating-point, Q31, Q15, and Q7 data types.
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58 */
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59
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60 /**
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61 * @addtogroup mean
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62 * @{
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63 */
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64
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65
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66 /**
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67 * @brief Mean value of a floating-point vector.
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68 * @param[in] *pSrc points to the input vector
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69 * @param[in] blockSize length of the input vector
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70 * @param[out] *pResult mean value returned here
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71 * @return none.
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72 */
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73
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74
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75 void arm_mean_f32(
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76 float32_t * pSrc,
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77 uint32_t blockSize,
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78 float32_t * pResult)
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79 {
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80 float32_t sum = 0.0f; /* Temporary result storage */
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81 uint32_t blkCnt; /* loop counter */
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82
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83 #ifndef ARM_MATH_CM0_FAMILY
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84
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85 /* Run the below code for Cortex-M4 and Cortex-M3 */
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86 float32_t in1, in2, in3, in4;
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87
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88 /*loop Unrolling */
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89 blkCnt = blockSize >> 2u;
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90
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91 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
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92 ** a second loop below computes the remaining 1 to 3 samples. */
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93 while(blkCnt > 0u)
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94 {
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95 /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */
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96 in1 = *pSrc++;
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97 in2 = *pSrc++;
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98 in3 = *pSrc++;
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99 in4 = *pSrc++;
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100
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101 sum += in1;
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102 sum += in2;
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103 sum += in3;
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104 sum += in4;
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105
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106 /* Decrement the loop counter */
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107 blkCnt--;
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108 }
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109
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110 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
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111 ** No loop unrolling is used. */
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112 blkCnt = blockSize % 0x4u;
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113
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114 #else
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115
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116 /* Run the below code for Cortex-M0 */
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117
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118 /* Loop over blockSize number of values */
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119 blkCnt = blockSize;
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120
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121 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
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122
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123 while(blkCnt > 0u)
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124 {
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125 /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */
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126 sum += *pSrc++;
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127
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128 /* Decrement the loop counter */
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129 blkCnt--;
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130 }
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131
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132 /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) / blockSize */
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133 /* Store the result to the destination */
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134 *pResult = sum / (float32_t) blockSize;
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135 }
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136
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137 /**
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138 * @} end of mean group
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139 */
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