John Garlitos / Mbed OS EVAL-CN0540-ARDZ

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Dependencies:   platform_drivers LTC26X6 AD77681

CMSIS-DSP_Lib/Source/StatisticsFunctions/arm_std_f32.c@1:9dd7c64b4a64, 2021-12-06 (annotated)

Committer:
jngarlitos
Date:
Mon Dec 06 05:22:28 2021 +0000
Revision:
1:9dd7c64b4a64
EVAL-CN0540-ARDZ mbed example program Initial Commit

Who changed what in which revision?

UserRevisionLine numberNew contents of line
jngarlitos 1:9dd7c64b4a64 1 /* ----------------------------------------------------------------------
jngarlitos 1:9dd7c64b4a64 2 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.
jngarlitos 1:9dd7c64b4a64 3 *
jngarlitos 1:9dd7c64b4a64 4 * $Date: 19. March 2015
jngarlitos 1:9dd7c64b4a64 5 * $Revision: V.1.4.5
jngarlitos 1:9dd7c64b4a64 6 *
jngarlitos 1:9dd7c64b4a64 7 * Project: CMSIS DSP Library
jngarlitos 1:9dd7c64b4a64 8 * Title: arm_std_f32.c
jngarlitos 1:9dd7c64b4a64 9 *
jngarlitos 1:9dd7c64b4a64 10 * Description: Standard deviation of the elements of a floating-point vector.
jngarlitos 1:9dd7c64b4a64 11 *
jngarlitos 1:9dd7c64b4a64 12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
jngarlitos 1:9dd7c64b4a64 13 *
jngarlitos 1:9dd7c64b4a64 14 * Redistribution and use in source and binary forms, with or without
jngarlitos 1:9dd7c64b4a64 15 * modification, are permitted provided that the following conditions
jngarlitos 1:9dd7c64b4a64 16 * are met:
jngarlitos 1:9dd7c64b4a64 17 * - Redistributions of source code must retain the above copyright
jngarlitos 1:9dd7c64b4a64 18 * notice, this list of conditions and the following disclaimer.
jngarlitos 1:9dd7c64b4a64 19 * - Redistributions in binary form must reproduce the above copyright
jngarlitos 1:9dd7c64b4a64 20 * notice, this list of conditions and the following disclaimer in
jngarlitos 1:9dd7c64b4a64 21 * the documentation and/or other materials provided with the
jngarlitos 1:9dd7c64b4a64 22 * distribution.
jngarlitos 1:9dd7c64b4a64 23 * - Neither the name of ARM LIMITED nor the names of its contributors
jngarlitos 1:9dd7c64b4a64 24 * may be used to endorse or promote products derived from this
jngarlitos 1:9dd7c64b4a64 25 * software without specific prior written permission.
jngarlitos 1:9dd7c64b4a64 26 *
jngarlitos 1:9dd7c64b4a64 27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
jngarlitos 1:9dd7c64b4a64 28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
jngarlitos 1:9dd7c64b4a64 29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
jngarlitos 1:9dd7c64b4a64 30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
jngarlitos 1:9dd7c64b4a64 31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
jngarlitos 1:9dd7c64b4a64 32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
jngarlitos 1:9dd7c64b4a64 33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
jngarlitos 1:9dd7c64b4a64 34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
jngarlitos 1:9dd7c64b4a64 35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
jngarlitos 1:9dd7c64b4a64 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
jngarlitos 1:9dd7c64b4a64 37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
jngarlitos 1:9dd7c64b4a64 38 * POSSIBILITY OF SUCH DAMAGE.
jngarlitos 1:9dd7c64b4a64 39 * ---------------------------------------------------------------------------- */
jngarlitos 1:9dd7c64b4a64 40
jngarlitos 1:9dd7c64b4a64 41 #include "arm_math.h"
jngarlitos 1:9dd7c64b4a64 42
jngarlitos 1:9dd7c64b4a64 43 /**
jngarlitos 1:9dd7c64b4a64 44 * @ingroup groupStats
jngarlitos 1:9dd7c64b4a64 45 */
jngarlitos 1:9dd7c64b4a64 46
jngarlitos 1:9dd7c64b4a64 47 /**
jngarlitos 1:9dd7c64b4a64 48 * @defgroup STD Standard deviation
jngarlitos 1:9dd7c64b4a64 49 *
jngarlitos 1:9dd7c64b4a64 50 * Calculates the standard deviation of the elements in the input vector.
jngarlitos 1:9dd7c64b4a64 51 * The underlying algorithm is used:
jngarlitos 1:9dd7c64b4a64 52 *
jngarlitos 1:9dd7c64b4a64 53 * <pre>
jngarlitos 1:9dd7c64b4a64 54 * Result = sqrt((sumOfSquares - sum<sup>2</sup> / blockSize) / (blockSize - 1))
jngarlitos 1:9dd7c64b4a64 55 *
jngarlitos 1:9dd7c64b4a64 56 * where, sumOfSquares = pSrc[0] * pSrc[0] + pSrc[1] * pSrc[1] + ... + pSrc[blockSize-1] * pSrc[blockSize-1]
jngarlitos 1:9dd7c64b4a64 57 *
jngarlitos 1:9dd7c64b4a64 58 * sum = pSrc[0] + pSrc[1] + pSrc[2] + ... + pSrc[blockSize-1]
jngarlitos 1:9dd7c64b4a64 59 * </pre>
jngarlitos 1:9dd7c64b4a64 60 *
jngarlitos 1:9dd7c64b4a64 61 * There are separate functions for floating point, Q31, and Q15 data types.
jngarlitos 1:9dd7c64b4a64 62 */
jngarlitos 1:9dd7c64b4a64 63
jngarlitos 1:9dd7c64b4a64 64 /**
jngarlitos 1:9dd7c64b4a64 65 * @addtogroup STD
jngarlitos 1:9dd7c64b4a64 66 * @{
jngarlitos 1:9dd7c64b4a64 67 */
jngarlitos 1:9dd7c64b4a64 68
jngarlitos 1:9dd7c64b4a64 69
jngarlitos 1:9dd7c64b4a64 70 /**
jngarlitos 1:9dd7c64b4a64 71 * @brief Standard deviation of the elements of a floating-point vector.
jngarlitos 1:9dd7c64b4a64 72 * @param[in] *pSrc points to the input vector
jngarlitos 1:9dd7c64b4a64 73 * @param[in] blockSize length of the input vector
jngarlitos 1:9dd7c64b4a64 74 * @param[out] *pResult standard deviation value returned here
jngarlitos 1:9dd7c64b4a64 75 * @return none.
jngarlitos 1:9dd7c64b4a64 76 *
jngarlitos 1:9dd7c64b4a64 77 */
jngarlitos 1:9dd7c64b4a64 78
jngarlitos 1:9dd7c64b4a64 79
jngarlitos 1:9dd7c64b4a64 80 void arm_std_f32(
jngarlitos 1:9dd7c64b4a64 81 float32_t * pSrc,
jngarlitos 1:9dd7c64b4a64 82 uint32_t blockSize,
jngarlitos 1:9dd7c64b4a64 83 float32_t * pResult)
jngarlitos 1:9dd7c64b4a64 84 {
jngarlitos 1:9dd7c64b4a64 85 float32_t sum = 0.0f; /* Temporary result storage */
jngarlitos 1:9dd7c64b4a64 86 float32_t sumOfSquares = 0.0f; /* Sum of squares */
jngarlitos 1:9dd7c64b4a64 87 float32_t in; /* input value */
jngarlitos 1:9dd7c64b4a64 88 uint32_t blkCnt; /* loop counter */
jngarlitos 1:9dd7c64b4a64 89
jngarlitos 1:9dd7c64b4a64 90 #ifndef ARM_MATH_CM0_FAMILY
jngarlitos 1:9dd7c64b4a64 91
jngarlitos 1:9dd7c64b4a64 92 /* Run the below code for Cortex-M4 and Cortex-M3 */
jngarlitos 1:9dd7c64b4a64 93
jngarlitos 1:9dd7c64b4a64 94 float32_t meanOfSquares, mean, squareOfMean;
jngarlitos 1:9dd7c64b4a64 95
jngarlitos 1:9dd7c64b4a64 96 if(blockSize == 1)
jngarlitos 1:9dd7c64b4a64 97 {
jngarlitos 1:9dd7c64b4a64 98 *pResult = 0;
jngarlitos 1:9dd7c64b4a64 99 return;
jngarlitos 1:9dd7c64b4a64 100 }
jngarlitos 1:9dd7c64b4a64 101
jngarlitos 1:9dd7c64b4a64 102 /*loop Unrolling */
jngarlitos 1:9dd7c64b4a64 103 blkCnt = blockSize >> 2u;
jngarlitos 1:9dd7c64b4a64 104
jngarlitos 1:9dd7c64b4a64 105 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
jngarlitos 1:9dd7c64b4a64 106 ** a second loop below computes the remaining 1 to 3 samples. */
jngarlitos 1:9dd7c64b4a64 107 while(blkCnt > 0u)
jngarlitos 1:9dd7c64b4a64 108 {
jngarlitos 1:9dd7c64b4a64 109 /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
jngarlitos 1:9dd7c64b4a64 110 /* Compute Sum of squares of the input samples
jngarlitos 1:9dd7c64b4a64 111 * and then store the result in a temporary variable, sum. */
jngarlitos 1:9dd7c64b4a64 112 in = *pSrc++;
jngarlitos 1:9dd7c64b4a64 113 sum += in;
jngarlitos 1:9dd7c64b4a64 114 sumOfSquares += in * in;
jngarlitos 1:9dd7c64b4a64 115 in = *pSrc++;
jngarlitos 1:9dd7c64b4a64 116 sum += in;
jngarlitos 1:9dd7c64b4a64 117 sumOfSquares += in * in;
jngarlitos 1:9dd7c64b4a64 118 in = *pSrc++;
jngarlitos 1:9dd7c64b4a64 119 sum += in;
jngarlitos 1:9dd7c64b4a64 120 sumOfSquares += in * in;
jngarlitos 1:9dd7c64b4a64 121 in = *pSrc++;
jngarlitos 1:9dd7c64b4a64 122 sum += in;
jngarlitos 1:9dd7c64b4a64 123 sumOfSquares += in * in;
jngarlitos 1:9dd7c64b4a64 124
jngarlitos 1:9dd7c64b4a64 125 /* Decrement the loop counter */
jngarlitos 1:9dd7c64b4a64 126 blkCnt--;
jngarlitos 1:9dd7c64b4a64 127 }
jngarlitos 1:9dd7c64b4a64 128
jngarlitos 1:9dd7c64b4a64 129 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
jngarlitos 1:9dd7c64b4a64 130 ** No loop unrolling is used. */
jngarlitos 1:9dd7c64b4a64 131 blkCnt = blockSize % 0x4u;
jngarlitos 1:9dd7c64b4a64 132
jngarlitos 1:9dd7c64b4a64 133 while(blkCnt > 0u)
jngarlitos 1:9dd7c64b4a64 134 {
jngarlitos 1:9dd7c64b4a64 135 /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
jngarlitos 1:9dd7c64b4a64 136 /* Compute Sum of squares of the input samples
jngarlitos 1:9dd7c64b4a64 137 * and then store the result in a temporary variable, sum. */
jngarlitos 1:9dd7c64b4a64 138 in = *pSrc++;
jngarlitos 1:9dd7c64b4a64 139 sum += in;
jngarlitos 1:9dd7c64b4a64 140 sumOfSquares += in * in;
jngarlitos 1:9dd7c64b4a64 141
jngarlitos 1:9dd7c64b4a64 142 /* Decrement the loop counter */
jngarlitos 1:9dd7c64b4a64 143 blkCnt--;
jngarlitos 1:9dd7c64b4a64 144 }
jngarlitos 1:9dd7c64b4a64 145
jngarlitos 1:9dd7c64b4a64 146 /* Compute Mean of squares of the input samples
jngarlitos 1:9dd7c64b4a64 147 * and then store the result in a temporary variable, meanOfSquares. */
jngarlitos 1:9dd7c64b4a64 148 meanOfSquares = sumOfSquares / ((float32_t) blockSize - 1.0f);
jngarlitos 1:9dd7c64b4a64 149
jngarlitos 1:9dd7c64b4a64 150 /* Compute mean of all input values */
jngarlitos 1:9dd7c64b4a64 151 mean = sum / (float32_t) blockSize;
jngarlitos 1:9dd7c64b4a64 152
jngarlitos 1:9dd7c64b4a64 153 /* Compute square of mean */
jngarlitos 1:9dd7c64b4a64 154 squareOfMean = (mean * mean) * (((float32_t) blockSize) /
jngarlitos 1:9dd7c64b4a64 155 ((float32_t) blockSize - 1.0f));
jngarlitos 1:9dd7c64b4a64 156
jngarlitos 1:9dd7c64b4a64 157 /* Compute standard deviation and then store the result to the destination */
jngarlitos 1:9dd7c64b4a64 158 arm_sqrt_f32((meanOfSquares - squareOfMean), pResult);
jngarlitos 1:9dd7c64b4a64 159
jngarlitos 1:9dd7c64b4a64 160 #else
jngarlitos 1:9dd7c64b4a64 161
jngarlitos 1:9dd7c64b4a64 162 /* Run the below code for Cortex-M0 */
jngarlitos 1:9dd7c64b4a64 163
jngarlitos 1:9dd7c64b4a64 164 float32_t squareOfSum; /* Square of Sum */
jngarlitos 1:9dd7c64b4a64 165 float32_t var; /* Temporary varaince storage */
jngarlitos 1:9dd7c64b4a64 166
jngarlitos 1:9dd7c64b4a64 167 if(blockSize == 1)
jngarlitos 1:9dd7c64b4a64 168 {
jngarlitos 1:9dd7c64b4a64 169 *pResult = 0;
jngarlitos 1:9dd7c64b4a64 170 return;
jngarlitos 1:9dd7c64b4a64 171 }
jngarlitos 1:9dd7c64b4a64 172
jngarlitos 1:9dd7c64b4a64 173 /* Loop over blockSize number of values */
jngarlitos 1:9dd7c64b4a64 174 blkCnt = blockSize;
jngarlitos 1:9dd7c64b4a64 175
jngarlitos 1:9dd7c64b4a64 176 while(blkCnt > 0u)
jngarlitos 1:9dd7c64b4a64 177 {
jngarlitos 1:9dd7c64b4a64 178 /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
jngarlitos 1:9dd7c64b4a64 179 /* Compute Sum of squares of the input samples
jngarlitos 1:9dd7c64b4a64 180 * and then store the result in a temporary variable, sumOfSquares. */
jngarlitos 1:9dd7c64b4a64 181 in = *pSrc++;
jngarlitos 1:9dd7c64b4a64 182 sumOfSquares += in * in;
jngarlitos 1:9dd7c64b4a64 183
jngarlitos 1:9dd7c64b4a64 184 /* C = (A[0] + A[1] + ... + A[blockSize-1]) */
jngarlitos 1:9dd7c64b4a64 185 /* Compute Sum of the input samples
jngarlitos 1:9dd7c64b4a64 186 * and then store the result in a temporary variable, sum. */
jngarlitos 1:9dd7c64b4a64 187 sum += in;
jngarlitos 1:9dd7c64b4a64 188
jngarlitos 1:9dd7c64b4a64 189 /* Decrement the loop counter */
jngarlitos 1:9dd7c64b4a64 190 blkCnt--;
jngarlitos 1:9dd7c64b4a64 191 }
jngarlitos 1:9dd7c64b4a64 192
jngarlitos 1:9dd7c64b4a64 193 /* Compute the square of sum */
jngarlitos 1:9dd7c64b4a64 194 squareOfSum = ((sum * sum) / (float32_t) blockSize);
jngarlitos 1:9dd7c64b4a64 195
jngarlitos 1:9dd7c64b4a64 196 /* Compute the variance */
jngarlitos 1:9dd7c64b4a64 197 var = ((sumOfSquares - squareOfSum) / (float32_t) (blockSize - 1.0f));
jngarlitos 1:9dd7c64b4a64 198
jngarlitos 1:9dd7c64b4a64 199 /* Compute standard deviation and then store the result to the destination */
jngarlitos 1:9dd7c64b4a64 200 arm_sqrt_f32(var, pResult);
jngarlitos 1:9dd7c64b4a64 201
jngarlitos 1:9dd7c64b4a64 202 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
jngarlitos 1:9dd7c64b4a64 203
jngarlitos 1:9dd7c64b4a64 204 }
jngarlitos 1:9dd7c64b4a64 205
jngarlitos 1:9dd7c64b4a64 206 /**
jngarlitos 1:9dd7c64b4a64 207 * @} end of STD group
jngarlitos 1:9dd7c64b4a64 208 */