CMSIS DSP library
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cmsis_dsp/StatisticsFunctions/arm_std_q31.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_std_q31.c |
emilmont | 1:fdd22bb7aa52 | 9 | * |
emilmont | 2:da51fb522205 | 10 | * Description: Standard deviation of an array of Q31 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 STD |
emilmont | 1:fdd22bb7aa52 | 49 | * @{ |
emilmont | 1:fdd22bb7aa52 | 50 | */ |
emilmont | 1:fdd22bb7aa52 | 51 | |
emilmont | 1:fdd22bb7aa52 | 52 | |
emilmont | 1:fdd22bb7aa52 | 53 | /** |
emilmont | 1:fdd22bb7aa52 | 54 | * @brief Standard deviation of the elements of a Q31 vector. |
emilmont | 1:fdd22bb7aa52 | 55 | * @param[in] *pSrc points to the input vector |
emilmont | 1:fdd22bb7aa52 | 56 | * @param[in] blockSize length of the input vector |
emilmont | 1:fdd22bb7aa52 | 57 | * @param[out] *pResult standard deviation value returned here |
emilmont | 1:fdd22bb7aa52 | 58 | * @return none. |
emilmont | 1:fdd22bb7aa52 | 59 | * @details |
emilmont | 1:fdd22bb7aa52 | 60 | * <b>Scaling and Overflow Behavior:</b> |
emilmont | 1:fdd22bb7aa52 | 61 | * |
emilmont | 1:fdd22bb7aa52 | 62 | *\par |
mbed_official | 5:3762170b6d4d | 63 | * The function is implemented using an internal 64-bit accumulator. |
mbed_official | 5:3762170b6d4d | 64 | * The input is represented in 1.31 format, which is then downshifted by 8 bits |
mbed_official | 5:3762170b6d4d | 65 | * which yields 1.23, and intermediate multiplication yields a 2.46 format. |
mbed_official | 5:3762170b6d4d | 66 | * The accumulator maintains full precision of the intermediate multiplication results, |
mbed_official | 5:3762170b6d4d | 67 | * but provides only a 16 guard bits. |
mbed_official | 5:3762170b6d4d | 68 | * There is no saturation on intermediate additions. |
mbed_official | 5:3762170b6d4d | 69 | * If the accumulator overflows it wraps around and distorts the result. |
mbed_official | 5:3762170b6d4d | 70 | * In order to avoid overflows completely the input signal must be scaled down by |
mbed_official | 5:3762170b6d4d | 71 | * log2(blockSize)-8 bits, as a total of blockSize additions are performed internally. |
mbed_official | 5:3762170b6d4d | 72 | * After division, internal variables should be Q18.46 |
mbed_official | 5:3762170b6d4d | 73 | * Finally, the 18.46 accumulator is right shifted by 15 bits to yield a 1.31 format value. |
emilmont | 1:fdd22bb7aa52 | 74 | * |
emilmont | 1:fdd22bb7aa52 | 75 | */ |
emilmont | 1:fdd22bb7aa52 | 76 | |
emilmont | 1:fdd22bb7aa52 | 77 | |
emilmont | 1:fdd22bb7aa52 | 78 | void arm_std_q31( |
emilmont | 1:fdd22bb7aa52 | 79 | q31_t * pSrc, |
emilmont | 1:fdd22bb7aa52 | 80 | uint32_t blockSize, |
emilmont | 1:fdd22bb7aa52 | 81 | q31_t * pResult) |
emilmont | 1:fdd22bb7aa52 | 82 | { |
emilmont | 1:fdd22bb7aa52 | 83 | q63_t sum = 0; /* Accumulator */ |
mbed_official | 5:3762170b6d4d | 84 | q63_t meanOfSquares, squareOfMean; /* square of mean and mean of square */ |
emilmont | 1:fdd22bb7aa52 | 85 | q31_t in; /* input value */ |
emilmont | 1:fdd22bb7aa52 | 86 | uint32_t blkCnt; /* loop counter */ |
emilmont | 1:fdd22bb7aa52 | 87 | q63_t sumOfSquares = 0; /* Accumulator */ |
emilmont | 1:fdd22bb7aa52 | 88 | |
mbed_official | 5:3762170b6d4d | 89 | if(blockSize == 1) |
mbed_official | 5:3762170b6d4d | 90 | { |
mbed_official | 5:3762170b6d4d | 91 | *pResult = 0; |
mbed_official | 5:3762170b6d4d | 92 | return; |
mbed_official | 5:3762170b6d4d | 93 | } |
mbed_official | 5:3762170b6d4d | 94 | |
mbed_official | 3:7a284390b0ce | 95 | #ifndef ARM_MATH_CM0_FAMILY |
emilmont | 1:fdd22bb7aa52 | 96 | |
emilmont | 1:fdd22bb7aa52 | 97 | /* Run the below code for Cortex-M4 and Cortex-M3 */ |
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. */ |
mbed_official | 5:3762170b6d4d | 109 | in = *pSrc++ >> 8; |
emilmont | 1:fdd22bb7aa52 | 110 | sum += in; |
emilmont | 1:fdd22bb7aa52 | 111 | sumOfSquares += ((q63_t) (in) * (in)); |
mbed_official | 5:3762170b6d4d | 112 | in = *pSrc++ >> 8; |
emilmont | 1:fdd22bb7aa52 | 113 | sum += in; |
emilmont | 1:fdd22bb7aa52 | 114 | sumOfSquares += ((q63_t) (in) * (in)); |
mbed_official | 5:3762170b6d4d | 115 | in = *pSrc++ >> 8; |
emilmont | 1:fdd22bb7aa52 | 116 | sum += in; |
emilmont | 1:fdd22bb7aa52 | 117 | sumOfSquares += ((q63_t) (in) * (in)); |
mbed_official | 5:3762170b6d4d | 118 | in = *pSrc++ >> 8; |
emilmont | 1:fdd22bb7aa52 | 119 | sum += in; |
emilmont | 1:fdd22bb7aa52 | 120 | sumOfSquares += ((q63_t) (in) * (in)); |
emilmont | 1:fdd22bb7aa52 | 121 | |
emilmont | 1:fdd22bb7aa52 | 122 | /* Decrement the loop counter */ |
emilmont | 1:fdd22bb7aa52 | 123 | blkCnt--; |
emilmont | 1:fdd22bb7aa52 | 124 | } |
emilmont | 1:fdd22bb7aa52 | 125 | |
emilmont | 1:fdd22bb7aa52 | 126 | /* If the blockSize is not a multiple of 4, compute any remaining output samples here. |
emilmont | 1:fdd22bb7aa52 | 127 | ** No loop unrolling is used. */ |
emilmont | 1:fdd22bb7aa52 | 128 | blkCnt = blockSize % 0x4u; |
emilmont | 1:fdd22bb7aa52 | 129 | |
emilmont | 1:fdd22bb7aa52 | 130 | while(blkCnt > 0u) |
emilmont | 1:fdd22bb7aa52 | 131 | { |
emilmont | 1:fdd22bb7aa52 | 132 | /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */ |
emilmont | 1:fdd22bb7aa52 | 133 | /* Compute Sum of squares of the input samples |
emilmont | 1:fdd22bb7aa52 | 134 | * and then store the result in a temporary variable, sum. */ |
mbed_official | 5:3762170b6d4d | 135 | in = *pSrc++ >> 8; |
emilmont | 1:fdd22bb7aa52 | 136 | sum += in; |
emilmont | 1:fdd22bb7aa52 | 137 | sumOfSquares += ((q63_t) (in) * (in)); |
emilmont | 1:fdd22bb7aa52 | 138 | |
emilmont | 1:fdd22bb7aa52 | 139 | /* Decrement the loop counter */ |
emilmont | 1:fdd22bb7aa52 | 140 | blkCnt--; |
emilmont | 1:fdd22bb7aa52 | 141 | } |
emilmont | 1:fdd22bb7aa52 | 142 | |
emilmont | 1:fdd22bb7aa52 | 143 | /* Compute Mean of squares of the input samples |
emilmont | 1:fdd22bb7aa52 | 144 | * and then store the result in a temporary variable, meanOfSquares. */ |
mbed_official | 5:3762170b6d4d | 145 | meanOfSquares = sumOfSquares / (q63_t)(blockSize - 1); |
emilmont | 1:fdd22bb7aa52 | 146 | |
emilmont | 1:fdd22bb7aa52 | 147 | #else |
emilmont | 1:fdd22bb7aa52 | 148 | |
emilmont | 1:fdd22bb7aa52 | 149 | /* Run the below code for Cortex-M0 */ |
emilmont | 1:fdd22bb7aa52 | 150 | |
emilmont | 1:fdd22bb7aa52 | 151 | /* Loop over blockSize number of values */ |
emilmont | 1:fdd22bb7aa52 | 152 | blkCnt = blockSize; |
emilmont | 1:fdd22bb7aa52 | 153 | |
emilmont | 1:fdd22bb7aa52 | 154 | while(blkCnt > 0u) |
emilmont | 1:fdd22bb7aa52 | 155 | { |
emilmont | 1:fdd22bb7aa52 | 156 | /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */ |
emilmont | 1:fdd22bb7aa52 | 157 | /* Compute Sum of squares of the input samples |
emilmont | 1:fdd22bb7aa52 | 158 | * and then store the result in a temporary variable, sumOfSquares. */ |
mbed_official | 5:3762170b6d4d | 159 | in = *pSrc++ >> 8; |
emilmont | 1:fdd22bb7aa52 | 160 | sumOfSquares += ((q63_t) (in) * (in)); |
emilmont | 1:fdd22bb7aa52 | 161 | |
emilmont | 1:fdd22bb7aa52 | 162 | /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */ |
emilmont | 1:fdd22bb7aa52 | 163 | /* Compute sum of all input values and then store the result in a temporary variable, sum. */ |
emilmont | 1:fdd22bb7aa52 | 164 | sum += in; |
emilmont | 1:fdd22bb7aa52 | 165 | |
emilmont | 1:fdd22bb7aa52 | 166 | /* Decrement the loop counter */ |
emilmont | 1:fdd22bb7aa52 | 167 | blkCnt--; |
emilmont | 1:fdd22bb7aa52 | 168 | } |
emilmont | 1:fdd22bb7aa52 | 169 | |
emilmont | 1:fdd22bb7aa52 | 170 | /* Compute Mean of squares of the input samples |
emilmont | 1:fdd22bb7aa52 | 171 | * and then store the result in a temporary variable, meanOfSquares. */ |
mbed_official | 5:3762170b6d4d | 172 | meanOfSquares = sumOfSquares / (q63_t)(blockSize - 1); |
emilmont | 1:fdd22bb7aa52 | 173 | |
mbed_official | 3:7a284390b0ce | 174 | #endif /* #ifndef ARM_MATH_CM0_FAMILY */ |
emilmont | 1:fdd22bb7aa52 | 175 | |
emilmont | 1:fdd22bb7aa52 | 176 | /* Compute square of mean */ |
mbed_official | 5:3762170b6d4d | 177 | squareOfMean = sum * sum / (q63_t)(blockSize * (blockSize - 1u)); |
emilmont | 1:fdd22bb7aa52 | 178 | |
emilmont | 1:fdd22bb7aa52 | 179 | /* Compute standard deviation and then store the result to the destination */ |
mbed_official | 5:3762170b6d4d | 180 | arm_sqrt_q31((meanOfSquares - squareOfMean) >> 15, pResult); |
emilmont | 1:fdd22bb7aa52 | 181 | |
emilmont | 1:fdd22bb7aa52 | 182 | } |
emilmont | 1:fdd22bb7aa52 | 183 | |
emilmont | 1:fdd22bb7aa52 | 184 | /** |
emilmont | 1:fdd22bb7aa52 | 185 | * @} end of STD group |
emilmont | 1:fdd22bb7aa52 | 186 | */ |