John Garlitos / Mbed OS EVAL-CN0540-ARDZ

Important changes to repositories hosted on mbed.com

Mbed hosted mercurial repositories are deprecated and are due to be permanently deleted in July 2026.

To keep a copy of this software download the repository Zip archive or clone locally using Mercurial.

It is also possible to export all your personal repositories from the account settings page.

Dependencies:   platform_drivers LTC26X6 AD77681

CMSIS-DSP_Lib/Source/StatisticsFunctions/arm_std_q31.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_q31.c
jngarlitos 1:9dd7c64b4a64 9 *
jngarlitos 1:9dd7c64b4a64 10 * Description: Standard deviation of an array of Q31 type.
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 * @addtogroup STD
jngarlitos 1:9dd7c64b4a64 49 * @{
jngarlitos 1:9dd7c64b4a64 50 */
jngarlitos 1:9dd7c64b4a64 51
jngarlitos 1:9dd7c64b4a64 52
jngarlitos 1:9dd7c64b4a64 53 /**
jngarlitos 1:9dd7c64b4a64 54 * @brief Standard deviation of the elements of a Q31 vector.
jngarlitos 1:9dd7c64b4a64 55 * @param[in] *pSrc points to the input vector
jngarlitos 1:9dd7c64b4a64 56 * @param[in] blockSize length of the input vector
jngarlitos 1:9dd7c64b4a64 57 * @param[out] *pResult standard deviation value returned here
jngarlitos 1:9dd7c64b4a64 58 * @return none.
jngarlitos 1:9dd7c64b4a64 59 * @details
jngarlitos 1:9dd7c64b4a64 60 * <b>Scaling and Overflow Behavior:</b>
jngarlitos 1:9dd7c64b4a64 61 *
jngarlitos 1:9dd7c64b4a64 62 *\par
jngarlitos 1:9dd7c64b4a64 63 * The function is implemented using an internal 64-bit accumulator.
jngarlitos 1:9dd7c64b4a64 64 * The input is represented in 1.31 format, which is then downshifted by 8 bits
jngarlitos 1:9dd7c64b4a64 65 * which yields 1.23, and intermediate multiplication yields a 2.46 format.
jngarlitos 1:9dd7c64b4a64 66 * The accumulator maintains full precision of the intermediate multiplication results,
jngarlitos 1:9dd7c64b4a64 67 * but provides only a 16 guard bits.
jngarlitos 1:9dd7c64b4a64 68 * There is no saturation on intermediate additions.
jngarlitos 1:9dd7c64b4a64 69 * If the accumulator overflows it wraps around and distorts the result.
jngarlitos 1:9dd7c64b4a64 70 * In order to avoid overflows completely the input signal must be scaled down by
jngarlitos 1:9dd7c64b4a64 71 * log2(blockSize)-8 bits, as a total of blockSize additions are performed internally.
jngarlitos 1:9dd7c64b4a64 72 * After division, internal variables should be Q18.46
jngarlitos 1:9dd7c64b4a64 73 * Finally, the 18.46 accumulator is right shifted by 15 bits to yield a 1.31 format value.
jngarlitos 1:9dd7c64b4a64 74 *
jngarlitos 1:9dd7c64b4a64 75 */
jngarlitos 1:9dd7c64b4a64 76
jngarlitos 1:9dd7c64b4a64 77
jngarlitos 1:9dd7c64b4a64 78 void arm_std_q31(
jngarlitos 1:9dd7c64b4a64 79 q31_t * pSrc,
jngarlitos 1:9dd7c64b4a64 80 uint32_t blockSize,
jngarlitos 1:9dd7c64b4a64 81 q31_t * pResult)
jngarlitos 1:9dd7c64b4a64 82 {
jngarlitos 1:9dd7c64b4a64 83 q63_t sum = 0; /* Accumulator */
jngarlitos 1:9dd7c64b4a64 84 q63_t meanOfSquares, squareOfMean; /* square of mean and mean of square */
jngarlitos 1:9dd7c64b4a64 85 q31_t in; /* input value */
jngarlitos 1:9dd7c64b4a64 86 uint32_t blkCnt; /* loop counter */
jngarlitos 1:9dd7c64b4a64 87 q63_t sumOfSquares = 0; /* Accumulator */
jngarlitos 1:9dd7c64b4a64 88
jngarlitos 1:9dd7c64b4a64 89 if(blockSize == 1)
jngarlitos 1:9dd7c64b4a64 90 {
jngarlitos 1:9dd7c64b4a64 91 *pResult = 0;
jngarlitos 1:9dd7c64b4a64 92 return;
jngarlitos 1:9dd7c64b4a64 93 }
jngarlitos 1:9dd7c64b4a64 94
jngarlitos 1:9dd7c64b4a64 95 #ifndef ARM_MATH_CM0_FAMILY
jngarlitos 1:9dd7c64b4a64 96
jngarlitos 1:9dd7c64b4a64 97 /* Run the below code for Cortex-M4 and Cortex-M3 */
jngarlitos 1:9dd7c64b4a64 98
jngarlitos 1:9dd7c64b4a64 99 /*loop Unrolling */
jngarlitos 1:9dd7c64b4a64 100 blkCnt = blockSize >> 2u;
jngarlitos 1:9dd7c64b4a64 101
jngarlitos 1:9dd7c64b4a64 102 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
jngarlitos 1:9dd7c64b4a64 103 ** a second loop below computes the remaining 1 to 3 samples. */
jngarlitos 1:9dd7c64b4a64 104 while(blkCnt > 0u)
jngarlitos 1:9dd7c64b4a64 105 {
jngarlitos 1:9dd7c64b4a64 106 /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
jngarlitos 1:9dd7c64b4a64 107 /* Compute Sum of squares of the input samples
jngarlitos 1:9dd7c64b4a64 108 * and then store the result in a temporary variable, sum. */
jngarlitos 1:9dd7c64b4a64 109 in = *pSrc++ >> 8;
jngarlitos 1:9dd7c64b4a64 110 sum += in;
jngarlitos 1:9dd7c64b4a64 111 sumOfSquares += ((q63_t) (in) * (in));
jngarlitos 1:9dd7c64b4a64 112 in = *pSrc++ >> 8;
jngarlitos 1:9dd7c64b4a64 113 sum += in;
jngarlitos 1:9dd7c64b4a64 114 sumOfSquares += ((q63_t) (in) * (in));
jngarlitos 1:9dd7c64b4a64 115 in = *pSrc++ >> 8;
jngarlitos 1:9dd7c64b4a64 116 sum += in;
jngarlitos 1:9dd7c64b4a64 117 sumOfSquares += ((q63_t) (in) * (in));
jngarlitos 1:9dd7c64b4a64 118 in = *pSrc++ >> 8;
jngarlitos 1:9dd7c64b4a64 119 sum += in;
jngarlitos 1:9dd7c64b4a64 120 sumOfSquares += ((q63_t) (in) * (in));
jngarlitos 1:9dd7c64b4a64 121
jngarlitos 1:9dd7c64b4a64 122 /* Decrement the loop counter */
jngarlitos 1:9dd7c64b4a64 123 blkCnt--;
jngarlitos 1:9dd7c64b4a64 124 }
jngarlitos 1:9dd7c64b4a64 125
jngarlitos 1:9dd7c64b4a64 126 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
jngarlitos 1:9dd7c64b4a64 127 ** No loop unrolling is used. */
jngarlitos 1:9dd7c64b4a64 128 blkCnt = blockSize % 0x4u;
jngarlitos 1:9dd7c64b4a64 129
jngarlitos 1:9dd7c64b4a64 130 while(blkCnt > 0u)
jngarlitos 1:9dd7c64b4a64 131 {
jngarlitos 1:9dd7c64b4a64 132 /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
jngarlitos 1:9dd7c64b4a64 133 /* Compute Sum of squares of the input samples
jngarlitos 1:9dd7c64b4a64 134 * and then store the result in a temporary variable, sum. */
jngarlitos 1:9dd7c64b4a64 135 in = *pSrc++ >> 8;
jngarlitos 1:9dd7c64b4a64 136 sum += in;
jngarlitos 1:9dd7c64b4a64 137 sumOfSquares += ((q63_t) (in) * (in));
jngarlitos 1:9dd7c64b4a64 138
jngarlitos 1:9dd7c64b4a64 139 /* Decrement the loop counter */
jngarlitos 1:9dd7c64b4a64 140 blkCnt--;
jngarlitos 1:9dd7c64b4a64 141 }
jngarlitos 1:9dd7c64b4a64 142
jngarlitos 1:9dd7c64b4a64 143 /* Compute Mean of squares of the input samples
jngarlitos 1:9dd7c64b4a64 144 * and then store the result in a temporary variable, meanOfSquares. */
jngarlitos 1:9dd7c64b4a64 145 meanOfSquares = sumOfSquares / (q63_t)(blockSize - 1);
jngarlitos 1:9dd7c64b4a64 146
jngarlitos 1:9dd7c64b4a64 147 #else
jngarlitos 1:9dd7c64b4a64 148
jngarlitos 1:9dd7c64b4a64 149 /* Run the below code for Cortex-M0 */
jngarlitos 1:9dd7c64b4a64 150
jngarlitos 1:9dd7c64b4a64 151 /* Loop over blockSize number of values */
jngarlitos 1:9dd7c64b4a64 152 blkCnt = blockSize;
jngarlitos 1:9dd7c64b4a64 153
jngarlitos 1:9dd7c64b4a64 154 while(blkCnt > 0u)
jngarlitos 1:9dd7c64b4a64 155 {
jngarlitos 1:9dd7c64b4a64 156 /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
jngarlitos 1:9dd7c64b4a64 157 /* Compute Sum of squares of the input samples
jngarlitos 1:9dd7c64b4a64 158 * and then store the result in a temporary variable, sumOfSquares. */
jngarlitos 1:9dd7c64b4a64 159 in = *pSrc++ >> 8;
jngarlitos 1:9dd7c64b4a64 160 sumOfSquares += ((q63_t) (in) * (in));
jngarlitos 1:9dd7c64b4a64 161
jngarlitos 1:9dd7c64b4a64 162 /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */
jngarlitos 1:9dd7c64b4a64 163 /* Compute sum of all input values and then store the result in a temporary variable, sum. */
jngarlitos 1:9dd7c64b4a64 164 sum += in;
jngarlitos 1:9dd7c64b4a64 165
jngarlitos 1:9dd7c64b4a64 166 /* Decrement the loop counter */
jngarlitos 1:9dd7c64b4a64 167 blkCnt--;
jngarlitos 1:9dd7c64b4a64 168 }
jngarlitos 1:9dd7c64b4a64 169
jngarlitos 1:9dd7c64b4a64 170 /* Compute Mean of squares of the input samples
jngarlitos 1:9dd7c64b4a64 171 * and then store the result in a temporary variable, meanOfSquares. */
jngarlitos 1:9dd7c64b4a64 172 meanOfSquares = sumOfSquares / (q63_t)(blockSize - 1);
jngarlitos 1:9dd7c64b4a64 173
jngarlitos 1:9dd7c64b4a64 174 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
jngarlitos 1:9dd7c64b4a64 175
jngarlitos 1:9dd7c64b4a64 176 /* Compute square of mean */
jngarlitos 1:9dd7c64b4a64 177 squareOfMean = sum * sum / (q63_t)(blockSize * (blockSize - 1u));
jngarlitos 1:9dd7c64b4a64 178
jngarlitos 1:9dd7c64b4a64 179 /* Compute standard deviation and then store the result to the destination */
jngarlitos 1:9dd7c64b4a64 180 arm_sqrt_q31((meanOfSquares - squareOfMean) >> 15, pResult);
jngarlitos 1:9dd7c64b4a64 181
jngarlitos 1:9dd7c64b4a64 182 }
jngarlitos 1:9dd7c64b4a64 183
jngarlitos 1:9dd7c64b4a64 184 /**
jngarlitos 1:9dd7c64b4a64 185 * @} end of STD group
jngarlitos 1:9dd7c64b4a64 186 */