MESA Project 2 / Harmonic_analyzer

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cmsis_dsp/StatisticsFunctions/arm_var_q15.c@6:1c28ca64ca38, 2019-10-28 (annotated)

Committer:
nmaududi
Date:
Mon Oct 28 01:06:40 2019 +0000
Revision:
6:1c28ca64ca38
Parent:
5:3762170b6d4d 
intial;

Who changed what in which revision?

UserRevisionLine numberNew contents of line
emilmont 1:fdd22bb7aa52 1 /* ----------------------------------------------------------------------
mbed_official 5:3762170b6d4d 2 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.
emilmont 1:fdd22bb7aa52 3 *
mbed_official 5:3762170b6d4d 4 * $Date: 19. March 2015
mbed_official 5:3762170b6d4d 5 * $Revision: V.1.4.5
emilmont 1:fdd22bb7aa52 6 *
emilmont 2:da51fb522205 7 * Project: CMSIS DSP Library
emilmont 2:da51fb522205 8 * Title: arm_var_q15.c
emilmont 1:fdd22bb7aa52 9 *
emilmont 2:da51fb522205 10 * Description: Variance of an array of Q15 type.
emilmont 1:fdd22bb7aa52 11 *
emilmont 1:fdd22bb7aa52 12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
emilmont 1:fdd22bb7aa52 13 *
mbed_official 3:7a284390b0ce 14 * Redistribution and use in source and binary forms, with or without
mbed_official 3:7a284390b0ce 15 * modification, are permitted provided that the following conditions
mbed_official 3:7a284390b0ce 16 * are met:
mbed_official 3:7a284390b0ce 17 * - Redistributions of source code must retain the above copyright
mbed_official 3:7a284390b0ce 18 * notice, this list of conditions and the following disclaimer.
mbed_official 3:7a284390b0ce 19 * - Redistributions in binary form must reproduce the above copyright
mbed_official 3:7a284390b0ce 20 * notice, this list of conditions and the following disclaimer in
mbed_official 3:7a284390b0ce 21 * the documentation and/or other materials provided with the
mbed_official 3:7a284390b0ce 22 * distribution.
mbed_official 3:7a284390b0ce 23 * - Neither the name of ARM LIMITED nor the names of its contributors
mbed_official 3:7a284390b0ce 24 * may be used to endorse or promote products derived from this
mbed_official 3:7a284390b0ce 25 * software without specific prior written permission.
mbed_official 3:7a284390b0ce 26 *
mbed_official 3:7a284390b0ce 27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
mbed_official 3:7a284390b0ce 28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
mbed_official 3:7a284390b0ce 29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
mbed_official 3:7a284390b0ce 30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
mbed_official 3:7a284390b0ce 31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
mbed_official 3:7a284390b0ce 32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
mbed_official 3:7a284390b0ce 33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
mbed_official 3:7a284390b0ce 34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
mbed_official 3:7a284390b0ce 35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
mbed_official 3:7a284390b0ce 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
mbed_official 3:7a284390b0ce 37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
mbed_official 3:7a284390b0ce 38 * POSSIBILITY OF SUCH DAMAGE.
emilmont 1:fdd22bb7aa52 39 * -------------------------------------------------------------------- */
emilmont 1:fdd22bb7aa52 40
emilmont 1:fdd22bb7aa52 41 #include "arm_math.h"
emilmont 1:fdd22bb7aa52 42
emilmont 1:fdd22bb7aa52 43 /**
emilmont 1:fdd22bb7aa52 44 * @ingroup groupStats
emilmont 1:fdd22bb7aa52 45 */
emilmont 1:fdd22bb7aa52 46
emilmont 1:fdd22bb7aa52 47 /**
emilmont 1:fdd22bb7aa52 48 * @addtogroup variance
emilmont 1:fdd22bb7aa52 49 * @{
emilmont 1:fdd22bb7aa52 50 */
emilmont 1:fdd22bb7aa52 51
emilmont 1:fdd22bb7aa52 52 /**
emilmont 1:fdd22bb7aa52 53 * @brief Variance of the elements of a Q15 vector.
emilmont 1:fdd22bb7aa52 54 * @param[in] *pSrc points to the input vector
emilmont 1:fdd22bb7aa52 55 * @param[in] blockSize length of the input vector
emilmont 1:fdd22bb7aa52 56 * @param[out] *pResult variance value returned here
emilmont 1:fdd22bb7aa52 57 * @return none.
emilmont 1:fdd22bb7aa52 58 *
emilmont 1:fdd22bb7aa52 59 * @details
emilmont 1:fdd22bb7aa52 60 * <b>Scaling and Overflow Behavior:</b>
emilmont 1:fdd22bb7aa52 61 *
emilmont 1:fdd22bb7aa52 62 * \par
emilmont 1:fdd22bb7aa52 63 * The function is implemented using a 64-bit internal accumulator.
emilmont 1:fdd22bb7aa52 64 * The input is represented in 1.15 format.
emilmont 1:fdd22bb7aa52 65 * Intermediate multiplication yields a 2.30 format, and this
emilmont 1:fdd22bb7aa52 66 * result is added without saturation to a 64-bit accumulator in 34.30 format.
emilmont 1:fdd22bb7aa52 67 * With 33 guard bits in the accumulator, there is no risk of overflow, and the
emilmont 1:fdd22bb7aa52 68 * full precision of the intermediate multiplication is preserved.
emilmont 1:fdd22bb7aa52 69 * Finally, the 34.30 result is truncated to 34.15 format by discarding the lower
emilmont 1:fdd22bb7aa52 70 * 15 bits, and then saturated to yield a result in 1.15 format.
emilmont 1:fdd22bb7aa52 71 *
emilmont 1:fdd22bb7aa52 72 */
emilmont 1:fdd22bb7aa52 73
emilmont 1:fdd22bb7aa52 74
emilmont 1:fdd22bb7aa52 75 void arm_var_q15(
emilmont 1:fdd22bb7aa52 76 q15_t * pSrc,
emilmont 1:fdd22bb7aa52 77 uint32_t blockSize,
mbed_official 5:3762170b6d4d 78 q15_t * pResult)
emilmont 1:fdd22bb7aa52 79 {
mbed_official 5:3762170b6d4d 80
emilmont 1:fdd22bb7aa52 81 q31_t sum = 0; /* Accumulator */
mbed_official 5:3762170b6d4d 82 q31_t meanOfSquares, squareOfMean; /* square of mean and mean of square */
emilmont 1:fdd22bb7aa52 83 uint32_t blkCnt; /* loop counter */
emilmont 1:fdd22bb7aa52 84 q63_t sumOfSquares = 0; /* Accumulator */
mbed_official 5:3762170b6d4d 85
mbed_official 3:7a284390b0ce 86 #ifndef ARM_MATH_CM0_FAMILY
emilmont 1:fdd22bb7aa52 87
emilmont 1:fdd22bb7aa52 88 /* Run the below code for Cortex-M4 and Cortex-M3 */
emilmont 1:fdd22bb7aa52 89
mbed_official 5:3762170b6d4d 90 q31_t in; /* input value */
mbed_official 5:3762170b6d4d 91 q15_t in1; /* input value */
mbed_official 5:3762170b6d4d 92
mbed_official 5:3762170b6d4d 93 if(blockSize == 1)
mbed_official 5:3762170b6d4d 94 {
mbed_official 5:3762170b6d4d 95 *pResult = 0;
mbed_official 5:3762170b6d4d 96 return;
mbed_official 5:3762170b6d4d 97 }
emilmont 1:fdd22bb7aa52 98
emilmont 1:fdd22bb7aa52 99 /*loop Unrolling */
emilmont 1:fdd22bb7aa52 100 blkCnt = blockSize >> 2u;
emilmont 1:fdd22bb7aa52 101
emilmont 1:fdd22bb7aa52 102 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
emilmont 1:fdd22bb7aa52 103 ** a second loop below computes the remaining 1 to 3 samples. */
emilmont 1:fdd22bb7aa52 104 while(blkCnt > 0u)
emilmont 1:fdd22bb7aa52 105 {
emilmont 1:fdd22bb7aa52 106 /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
emilmont 1:fdd22bb7aa52 107 /* Compute Sum of squares of the input samples
emilmont 1:fdd22bb7aa52 108 * and then store the result in a temporary variable, sum. */
emilmont 1:fdd22bb7aa52 109 in = *__SIMD32(pSrc)++;
emilmont 1:fdd22bb7aa52 110 sum += ((in << 16) >> 16);
emilmont 1:fdd22bb7aa52 111 sum += (in >> 16);
emilmont 1:fdd22bb7aa52 112 sumOfSquares = __SMLALD(in, in, sumOfSquares);
emilmont 1:fdd22bb7aa52 113 in = *__SIMD32(pSrc)++;
emilmont 1:fdd22bb7aa52 114 sum += ((in << 16) >> 16);
emilmont 1:fdd22bb7aa52 115 sum += (in >> 16);
emilmont 1:fdd22bb7aa52 116 sumOfSquares = __SMLALD(in, in, sumOfSquares);
emilmont 1:fdd22bb7aa52 117
emilmont 1:fdd22bb7aa52 118 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 119 blkCnt--;
emilmont 1:fdd22bb7aa52 120 }
emilmont 1:fdd22bb7aa52 121
emilmont 1:fdd22bb7aa52 122 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
emilmont 1:fdd22bb7aa52 123 ** No loop unrolling is used. */
emilmont 1:fdd22bb7aa52 124 blkCnt = blockSize % 0x4u;
emilmont 1:fdd22bb7aa52 125
emilmont 1:fdd22bb7aa52 126 while(blkCnt > 0u)
emilmont 1:fdd22bb7aa52 127 {
emilmont 1:fdd22bb7aa52 128 /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
emilmont 1:fdd22bb7aa52 129 /* Compute Sum of squares of the input samples
emilmont 1:fdd22bb7aa52 130 * and then store the result in a temporary variable, sum. */
emilmont 1:fdd22bb7aa52 131 in1 = *pSrc++;
mbed_official 5:3762170b6d4d 132 sumOfSquares = __SMLALD(in1, in1, sumOfSquares);
emilmont 1:fdd22bb7aa52 133 sum += in1;
emilmont 1:fdd22bb7aa52 134
emilmont 1:fdd22bb7aa52 135 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 136 blkCnt--;
emilmont 1:fdd22bb7aa52 137 }
emilmont 1:fdd22bb7aa52 138
emilmont 1:fdd22bb7aa52 139 /* Compute Mean of squares of the input samples
emilmont 1:fdd22bb7aa52 140 * and then store the result in a temporary variable, meanOfSquares. */
mbed_official 5:3762170b6d4d 141 meanOfSquares = (q31_t) (sumOfSquares / (q63_t)(blockSize - 1));
emilmont 1:fdd22bb7aa52 142
mbed_official 5:3762170b6d4d 143 /* Compute square of mean */
mbed_official 5:3762170b6d4d 144 squareOfMean = (q31_t)((q63_t)sum * sum / (q63_t)(blockSize * (blockSize - 1)));
mbed_official 5:3762170b6d4d 145
mbed_official 5:3762170b6d4d 146 /* mean of the squares minus the square of the mean. */
mbed_official 5:3762170b6d4d 147 *pResult = (meanOfSquares - squareOfMean) >> 15;
emilmont 1:fdd22bb7aa52 148
emilmont 1:fdd22bb7aa52 149 #else
emilmont 1:fdd22bb7aa52 150
emilmont 1:fdd22bb7aa52 151 /* Run the below code for Cortex-M0 */
mbed_official 5:3762170b6d4d 152 q15_t in; /* input value */
emilmont 1:fdd22bb7aa52 153
mbed_official 5:3762170b6d4d 154 if(blockSize == 1)
mbed_official 5:3762170b6d4d 155 {
mbed_official 5:3762170b6d4d 156 *pResult = 0;
mbed_official 5:3762170b6d4d 157 return;
mbed_official 5:3762170b6d4d 158 }
mbed_official 5:3762170b6d4d 159
emilmont 1:fdd22bb7aa52 160 /* Loop over blockSize number of values */
emilmont 1:fdd22bb7aa52 161 blkCnt = blockSize;
emilmont 1:fdd22bb7aa52 162
emilmont 1:fdd22bb7aa52 163 while(blkCnt > 0u)
emilmont 1:fdd22bb7aa52 164 {
emilmont 1:fdd22bb7aa52 165 /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
emilmont 1:fdd22bb7aa52 166 /* Compute Sum of squares of the input samples
emilmont 1:fdd22bb7aa52 167 * and then store the result in a temporary variable, sumOfSquares. */
emilmont 1:fdd22bb7aa52 168 in = *pSrc++;
emilmont 1:fdd22bb7aa52 169 sumOfSquares += (in * in);
emilmont 1:fdd22bb7aa52 170
emilmont 1:fdd22bb7aa52 171 /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */
emilmont 1:fdd22bb7aa52 172 /* Compute sum of all input values and then store the result in a temporary variable, sum. */
emilmont 1:fdd22bb7aa52 173 sum += in;
emilmont 1:fdd22bb7aa52 174
emilmont 1:fdd22bb7aa52 175 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 176 blkCnt--;
emilmont 1:fdd22bb7aa52 177 }
emilmont 1:fdd22bb7aa52 178
emilmont 1:fdd22bb7aa52 179 /* Compute Mean of squares of the input samples
emilmont 1:fdd22bb7aa52 180 * and then store the result in a temporary variable, meanOfSquares. */
mbed_official 5:3762170b6d4d 181 meanOfSquares = (q31_t) (sumOfSquares / (q63_t)(blockSize - 1));
mbed_official 5:3762170b6d4d 182
mbed_official 5:3762170b6d4d 183 /* Compute square of mean */
mbed_official 5:3762170b6d4d 184 squareOfMean = (q31_t)((q63_t)sum * sum / (q63_t)(blockSize * (blockSize - 1)));
mbed_official 5:3762170b6d4d 185
mbed_official 5:3762170b6d4d 186 /* mean of the squares minus the square of the mean. */
mbed_official 5:3762170b6d4d 187 *pResult = (meanOfSquares - squareOfMean) >> 15;
emilmont 1:fdd22bb7aa52 188
mbed_official 3:7a284390b0ce 189 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
emilmont 1:fdd22bb7aa52 190
emilmont 1:fdd22bb7aa52 191 }
emilmont 1:fdd22bb7aa52 192
emilmont 1:fdd22bb7aa52 193 /**
emilmont 1:fdd22bb7aa52 194 * @} end of variance group
emilmont 1:fdd22bb7aa52 195 */