The CMSIS DSP 5 library
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functions/StatisticsFunctions/arm_var_f32.c@1:24714b45cd1b, 2018-06-20 (annotated)
- Committer:
- xorjoep
- Date:
- Wed Jun 20 11:21:31 2018 +0000
- Revision:
- 1:24714b45cd1b
The newest version of the CMSIS library
Who changed what in which revision?
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xorjoep | 1:24714b45cd1b | 1 | /* ---------------------------------------------------------------------- |
xorjoep | 1:24714b45cd1b | 2 | * Project: CMSIS DSP Library |
xorjoep | 1:24714b45cd1b | 3 | * Title: arm_var_f32.c |
xorjoep | 1:24714b45cd1b | 4 | * Description: Variance of the elements of a floating-point vector |
xorjoep | 1:24714b45cd1b | 5 | * |
xorjoep | 1:24714b45cd1b | 6 | * $Date: 27. January 2017 |
xorjoep | 1:24714b45cd1b | 7 | * $Revision: V.1.5.1 |
xorjoep | 1:24714b45cd1b | 8 | * |
xorjoep | 1:24714b45cd1b | 9 | * Target Processor: Cortex-M cores |
xorjoep | 1:24714b45cd1b | 10 | * -------------------------------------------------------------------- */ |
xorjoep | 1:24714b45cd1b | 11 | /* |
xorjoep | 1:24714b45cd1b | 12 | * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved. |
xorjoep | 1:24714b45cd1b | 13 | * |
xorjoep | 1:24714b45cd1b | 14 | * SPDX-License-Identifier: Apache-2.0 |
xorjoep | 1:24714b45cd1b | 15 | * |
xorjoep | 1:24714b45cd1b | 16 | * Licensed under the Apache License, Version 2.0 (the License); you may |
xorjoep | 1:24714b45cd1b | 17 | * not use this file except in compliance with the License. |
xorjoep | 1:24714b45cd1b | 18 | * You may obtain a copy of the License at |
xorjoep | 1:24714b45cd1b | 19 | * |
xorjoep | 1:24714b45cd1b | 20 | * www.apache.org/licenses/LICENSE-2.0 |
xorjoep | 1:24714b45cd1b | 21 | * |
xorjoep | 1:24714b45cd1b | 22 | * Unless required by applicable law or agreed to in writing, software |
xorjoep | 1:24714b45cd1b | 23 | * distributed under the License is distributed on an AS IS BASIS, WITHOUT |
xorjoep | 1:24714b45cd1b | 24 | * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
xorjoep | 1:24714b45cd1b | 25 | * See the License for the specific language governing permissions and |
xorjoep | 1:24714b45cd1b | 26 | * limitations under the License. |
xorjoep | 1:24714b45cd1b | 27 | */ |
xorjoep | 1:24714b45cd1b | 28 | |
xorjoep | 1:24714b45cd1b | 29 | #include "arm_math.h" |
xorjoep | 1:24714b45cd1b | 30 | |
xorjoep | 1:24714b45cd1b | 31 | /** |
xorjoep | 1:24714b45cd1b | 32 | * @ingroup groupStats |
xorjoep | 1:24714b45cd1b | 33 | */ |
xorjoep | 1:24714b45cd1b | 34 | |
xorjoep | 1:24714b45cd1b | 35 | /** |
xorjoep | 1:24714b45cd1b | 36 | * @defgroup variance Variance |
xorjoep | 1:24714b45cd1b | 37 | * |
xorjoep | 1:24714b45cd1b | 38 | * Calculates the variance of the elements in the input vector. |
xorjoep | 1:24714b45cd1b | 39 | * The underlying algorithm used is the direct method sometimes referred to as the two-pass method: |
xorjoep | 1:24714b45cd1b | 40 | * |
xorjoep | 1:24714b45cd1b | 41 | * <pre> |
xorjoep | 1:24714b45cd1b | 42 | * Result = sum(element - meanOfElements)^2) / numElement - 1 |
xorjoep | 1:24714b45cd1b | 43 | * |
xorjoep | 1:24714b45cd1b | 44 | * where, meanOfElements = ( pSrc[0] * pSrc[0] + pSrc[1] * pSrc[1] + ... + pSrc[blockSize-1] ) / blockSize |
xorjoep | 1:24714b45cd1b | 45 | * |
xorjoep | 1:24714b45cd1b | 46 | * </pre> |
xorjoep | 1:24714b45cd1b | 47 | * |
xorjoep | 1:24714b45cd1b | 48 | * There are separate functions for floating point, Q31, and Q15 data types. |
xorjoep | 1:24714b45cd1b | 49 | */ |
xorjoep | 1:24714b45cd1b | 50 | |
xorjoep | 1:24714b45cd1b | 51 | /** |
xorjoep | 1:24714b45cd1b | 52 | * @addtogroup variance |
xorjoep | 1:24714b45cd1b | 53 | * @{ |
xorjoep | 1:24714b45cd1b | 54 | */ |
xorjoep | 1:24714b45cd1b | 55 | |
xorjoep | 1:24714b45cd1b | 56 | |
xorjoep | 1:24714b45cd1b | 57 | /** |
xorjoep | 1:24714b45cd1b | 58 | * @brief Variance of the elements of a floating-point vector. |
xorjoep | 1:24714b45cd1b | 59 | * @param[in] *pSrc points to the input vector |
xorjoep | 1:24714b45cd1b | 60 | * @param[in] blockSize length of the input vector |
xorjoep | 1:24714b45cd1b | 61 | * @param[out] *pResult variance value returned here |
xorjoep | 1:24714b45cd1b | 62 | * @return none. |
xorjoep | 1:24714b45cd1b | 63 | */ |
xorjoep | 1:24714b45cd1b | 64 | |
xorjoep | 1:24714b45cd1b | 65 | void arm_var_f32( |
xorjoep | 1:24714b45cd1b | 66 | float32_t * pSrc, |
xorjoep | 1:24714b45cd1b | 67 | uint32_t blockSize, |
xorjoep | 1:24714b45cd1b | 68 | float32_t * pResult) |
xorjoep | 1:24714b45cd1b | 69 | { |
xorjoep | 1:24714b45cd1b | 70 | float32_t fMean, fValue; |
xorjoep | 1:24714b45cd1b | 71 | uint32_t blkCnt; /* loop counter */ |
xorjoep | 1:24714b45cd1b | 72 | float32_t * pInput = pSrc; |
xorjoep | 1:24714b45cd1b | 73 | float32_t sum = 0.0f; |
xorjoep | 1:24714b45cd1b | 74 | float32_t fSum = 0.0f; |
xorjoep | 1:24714b45cd1b | 75 | #if defined(ARM_MATH_DSP) |
xorjoep | 1:24714b45cd1b | 76 | float32_t in1, in2, in3, in4; |
xorjoep | 1:24714b45cd1b | 77 | #endif |
xorjoep | 1:24714b45cd1b | 78 | |
xorjoep | 1:24714b45cd1b | 79 | if (blockSize <= 1U) |
xorjoep | 1:24714b45cd1b | 80 | { |
xorjoep | 1:24714b45cd1b | 81 | *pResult = 0; |
xorjoep | 1:24714b45cd1b | 82 | return; |
xorjoep | 1:24714b45cd1b | 83 | } |
xorjoep | 1:24714b45cd1b | 84 | |
xorjoep | 1:24714b45cd1b | 85 | #if defined(ARM_MATH_DSP) |
xorjoep | 1:24714b45cd1b | 86 | /* Run the below code for Cortex-M4 and Cortex-M7 */ |
xorjoep | 1:24714b45cd1b | 87 | |
xorjoep | 1:24714b45cd1b | 88 | /*loop Unrolling */ |
xorjoep | 1:24714b45cd1b | 89 | blkCnt = blockSize >> 2U; |
xorjoep | 1:24714b45cd1b | 90 | |
xorjoep | 1:24714b45cd1b | 91 | /* First part of the processing with loop unrolling. Compute 4 outputs at a time. |
xorjoep | 1:24714b45cd1b | 92 | ** a second loop below computes the remaining 1 to 3 samples. */ |
xorjoep | 1:24714b45cd1b | 93 | while (blkCnt > 0U) |
xorjoep | 1:24714b45cd1b | 94 | { |
xorjoep | 1:24714b45cd1b | 95 | /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */ |
xorjoep | 1:24714b45cd1b | 96 | in1 = *pInput++; |
xorjoep | 1:24714b45cd1b | 97 | in2 = *pInput++; |
xorjoep | 1:24714b45cd1b | 98 | in3 = *pInput++; |
xorjoep | 1:24714b45cd1b | 99 | in4 = *pInput++; |
xorjoep | 1:24714b45cd1b | 100 | |
xorjoep | 1:24714b45cd1b | 101 | sum += in1; |
xorjoep | 1:24714b45cd1b | 102 | sum += in2; |
xorjoep | 1:24714b45cd1b | 103 | sum += in3; |
xorjoep | 1:24714b45cd1b | 104 | sum += in4; |
xorjoep | 1:24714b45cd1b | 105 | |
xorjoep | 1:24714b45cd1b | 106 | /* Decrement the loop counter */ |
xorjoep | 1:24714b45cd1b | 107 | blkCnt--; |
xorjoep | 1:24714b45cd1b | 108 | } |
xorjoep | 1:24714b45cd1b | 109 | |
xorjoep | 1:24714b45cd1b | 110 | /* If the blockSize is not a multiple of 4, compute any remaining output samples here. |
xorjoep | 1:24714b45cd1b | 111 | ** No loop unrolling is used. */ |
xorjoep | 1:24714b45cd1b | 112 | blkCnt = blockSize % 0x4U; |
xorjoep | 1:24714b45cd1b | 113 | |
xorjoep | 1:24714b45cd1b | 114 | #else |
xorjoep | 1:24714b45cd1b | 115 | /* Run the below code for Cortex-M0 or Cortex-M3 */ |
xorjoep | 1:24714b45cd1b | 116 | |
xorjoep | 1:24714b45cd1b | 117 | /* Loop over blockSize number of values */ |
xorjoep | 1:24714b45cd1b | 118 | blkCnt = blockSize; |
xorjoep | 1:24714b45cd1b | 119 | |
xorjoep | 1:24714b45cd1b | 120 | #endif |
xorjoep | 1:24714b45cd1b | 121 | |
xorjoep | 1:24714b45cd1b | 122 | while (blkCnt > 0U) |
xorjoep | 1:24714b45cd1b | 123 | { |
xorjoep | 1:24714b45cd1b | 124 | /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */ |
xorjoep | 1:24714b45cd1b | 125 | sum += *pInput++; |
xorjoep | 1:24714b45cd1b | 126 | |
xorjoep | 1:24714b45cd1b | 127 | /* Decrement the loop counter */ |
xorjoep | 1:24714b45cd1b | 128 | blkCnt--; |
xorjoep | 1:24714b45cd1b | 129 | } |
xorjoep | 1:24714b45cd1b | 130 | |
xorjoep | 1:24714b45cd1b | 131 | /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) / blockSize */ |
xorjoep | 1:24714b45cd1b | 132 | fMean = sum / (float32_t) blockSize; |
xorjoep | 1:24714b45cd1b | 133 | |
xorjoep | 1:24714b45cd1b | 134 | pInput = pSrc; |
xorjoep | 1:24714b45cd1b | 135 | |
xorjoep | 1:24714b45cd1b | 136 | #if defined(ARM_MATH_DSP) |
xorjoep | 1:24714b45cd1b | 137 | |
xorjoep | 1:24714b45cd1b | 138 | /*loop Unrolling */ |
xorjoep | 1:24714b45cd1b | 139 | blkCnt = blockSize >> 2U; |
xorjoep | 1:24714b45cd1b | 140 | |
xorjoep | 1:24714b45cd1b | 141 | /* First part of the processing with loop unrolling. Compute 4 outputs at a time. |
xorjoep | 1:24714b45cd1b | 142 | ** a second loop below computes the remaining 1 to 3 samples. */ |
xorjoep | 1:24714b45cd1b | 143 | while (blkCnt > 0U) |
xorjoep | 1:24714b45cd1b | 144 | { |
xorjoep | 1:24714b45cd1b | 145 | fValue = *pInput++ - fMean; |
xorjoep | 1:24714b45cd1b | 146 | fSum += fValue * fValue; |
xorjoep | 1:24714b45cd1b | 147 | fValue = *pInput++ - fMean; |
xorjoep | 1:24714b45cd1b | 148 | fSum += fValue * fValue; |
xorjoep | 1:24714b45cd1b | 149 | fValue = *pInput++ - fMean; |
xorjoep | 1:24714b45cd1b | 150 | fSum += fValue * fValue; |
xorjoep | 1:24714b45cd1b | 151 | fValue = *pInput++ - fMean; |
xorjoep | 1:24714b45cd1b | 152 | fSum += fValue * fValue; |
xorjoep | 1:24714b45cd1b | 153 | |
xorjoep | 1:24714b45cd1b | 154 | /* Decrement the loop counter */ |
xorjoep | 1:24714b45cd1b | 155 | blkCnt--; |
xorjoep | 1:24714b45cd1b | 156 | } |
xorjoep | 1:24714b45cd1b | 157 | |
xorjoep | 1:24714b45cd1b | 158 | blkCnt = blockSize % 0x4U; |
xorjoep | 1:24714b45cd1b | 159 | #else |
xorjoep | 1:24714b45cd1b | 160 | /* Run the below code for Cortex-M0 or Cortex-M3 */ |
xorjoep | 1:24714b45cd1b | 161 | |
xorjoep | 1:24714b45cd1b | 162 | /* Loop over blockSize number of values */ |
xorjoep | 1:24714b45cd1b | 163 | blkCnt = blockSize; |
xorjoep | 1:24714b45cd1b | 164 | #endif |
xorjoep | 1:24714b45cd1b | 165 | |
xorjoep | 1:24714b45cd1b | 166 | while (blkCnt > 0U) |
xorjoep | 1:24714b45cd1b | 167 | { |
xorjoep | 1:24714b45cd1b | 168 | fValue = *pInput++ - fMean; |
xorjoep | 1:24714b45cd1b | 169 | fSum += fValue * fValue; |
xorjoep | 1:24714b45cd1b | 170 | |
xorjoep | 1:24714b45cd1b | 171 | /* Decrement the loop counter */ |
xorjoep | 1:24714b45cd1b | 172 | blkCnt--; |
xorjoep | 1:24714b45cd1b | 173 | } |
xorjoep | 1:24714b45cd1b | 174 | |
xorjoep | 1:24714b45cd1b | 175 | /* Variance */ |
xorjoep | 1:24714b45cd1b | 176 | *pResult = fSum / (float32_t)(blockSize - 1.0f); |
xorjoep | 1:24714b45cd1b | 177 | } |
xorjoep | 1:24714b45cd1b | 178 | |
xorjoep | 1:24714b45cd1b | 179 | /** |
xorjoep | 1:24714b45cd1b | 180 | * @} end of variance group |
xorjoep | 1:24714b45cd1b | 181 | */ |