CMSIS DSP library
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cmsis_dsp/StatisticsFunctions/arm_var_q15.c@5:3762170b6d4d, 2015-11-20 (annotated)
- Committer:
- mbed_official
- Date:
- Fri Nov 20 08:45:18 2015 +0000
- Revision:
- 5:3762170b6d4d
- Parent:
- 3:7a284390b0ce
Synchronized with git revision 2eb940b9a73af188d3004a2575fdfbb05febe62b
Full URL: https://github.com/mbedmicro/mbed/commit/2eb940b9a73af188d3004a2575fdfbb05febe62b/
Added option to build rpc library. closes #1426
Who changed what in which revision?
User | Revision | Line number | New contents of line |
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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 | */ |