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| 2 | mjames | 1 | /* ---------------------------------------------------------------------- |
| 2 | * Copyright (C) 2010-2014 ARM Limited. All rights reserved. |
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| 3 | * |
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| 4 | * $Date: 19. March 2015 |
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| 5 | * $Revision: V.1.4.5 |
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| 6 | * |
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| 7 | * Project: CMSIS DSP Library |
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| 8 | * Title: arm_rms_f32.c |
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| 9 | * |
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| 10 | * Description: Root mean square value of an array of F32 type |
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| 11 | * |
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| 12 | * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 |
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| 13 | * |
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| 14 | * Redistribution and use in source and binary forms, with or without |
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| 15 | * modification, are permitted provided that the following conditions |
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| 16 | * are met: |
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| 17 | * - Redistributions of source code must retain the above copyright |
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| 18 | * notice, this list of conditions and the following disclaimer. |
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| 19 | * - Redistributions in binary form must reproduce the above copyright |
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| 20 | * notice, this list of conditions and the following disclaimer in |
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| 21 | * the documentation and/or other materials provided with the |
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| 22 | * distribution. |
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| 23 | * - Neither the name of ARM LIMITED nor the names of its contributors |
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| 24 | * may be used to endorse or promote products derived from this |
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| 25 | * software without specific prior written permission. |
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| 26 | * |
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| 27 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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| 28 | * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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| 29 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
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| 30 | * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
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| 31 | * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
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| 32 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
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| 33 | * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
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| 34 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
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| 35 | * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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| 36 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN |
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| 37 | * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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| 38 | * POSSIBILITY OF SUCH DAMAGE. |
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| 39 | * ---------------------------------------------------------------------------- */ |
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| 40 | |||
| 41 | #include "arm_math.h" |
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| 42 | |||
| 43 | /** |
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| 44 | * @ingroup groupStats |
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| 45 | */ |
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| 46 | |||
| 47 | /** |
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| 48 | * @defgroup RMS Root mean square (RMS) |
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| 49 | * |
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| 50 | * |
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| 51 | * Calculates the Root Mean Sqaure of the elements in the input vector. |
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| 52 | * The underlying algorithm is used: |
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| 53 | * |
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| 54 | * <pre> |
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| 55 | * Result = sqrt(((pSrc[0] * pSrc[0] + pSrc[1] * pSrc[1] + ... + pSrc[blockSize-1] * pSrc[blockSize-1]) / blockSize)); |
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| 56 | * </pre> |
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| 57 | * |
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| 58 | * There are separate functions for floating point, Q31, and Q15 data types. |
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| 59 | */ |
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| 60 | |||
| 61 | /** |
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| 62 | * @addtogroup RMS |
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| 63 | * @{ |
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| 64 | */ |
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| 65 | |||
| 66 | |||
| 67 | /** |
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| 68 | * @brief Root Mean Square of the elements of a floating-point vector. |
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| 69 | * @param[in] *pSrc points to the input vector |
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| 70 | * @param[in] blockSize length of the input vector |
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| 71 | * @param[out] *pResult rms value returned here |
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| 72 | * @return none. |
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| 73 | * |
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| 74 | */ |
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| 75 | |||
| 76 | void arm_rms_f32( |
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| 77 | float32_t * pSrc, |
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| 78 | uint32_t blockSize, |
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| 79 | float32_t * pResult) |
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| 80 | { |
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| 81 | float32_t sum = 0.0f; /* Accumulator */ |
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| 82 | float32_t in; /* Tempoprary variable to store input value */ |
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| 83 | uint32_t blkCnt; /* loop counter */ |
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| 84 | |||
| 85 | #ifndef ARM_MATH_CM0_FAMILY |
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| 86 | |||
| 87 | /* Run the below code for Cortex-M4 and Cortex-M3 */ |
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| 88 | |||
| 89 | /* loop Unrolling */ |
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| 90 | blkCnt = blockSize >> 2u; |
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| 91 | |||
| 92 | /* First part of the processing with loop unrolling. Compute 4 outputs at a time. |
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| 93 | ** a second loop below computes the remaining 1 to 3 samples. */ |
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| 94 | while(blkCnt > 0u) |
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| 95 | { |
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| 96 | /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */ |
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| 97 | /* Compute sum of the squares and then store the result in a temporary variable, sum */ |
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| 98 | in = *pSrc++; |
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| 99 | sum += in * in; |
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| 100 | in = *pSrc++; |
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| 101 | sum += in * in; |
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| 102 | in = *pSrc++; |
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| 103 | sum += in * in; |
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| 104 | in = *pSrc++; |
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| 105 | sum += in * in; |
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| 106 | |||
| 107 | /* Decrement the loop counter */ |
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| 108 | blkCnt--; |
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| 109 | } |
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| 110 | |||
| 111 | /* If the blockSize is not a multiple of 4, compute any remaining output samples here. |
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| 112 | ** No loop unrolling is used. */ |
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| 113 | blkCnt = blockSize % 0x4u; |
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| 114 | |||
| 115 | #else |
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| 116 | |||
| 117 | /* Run the below code for Cortex-M0 */ |
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| 118 | |||
| 119 | /* Loop over blockSize number of values */ |
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| 120 | blkCnt = blockSize; |
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| 121 | |||
| 122 | #endif /* #ifndef ARM_MATH_CM0_FAMILY */ |
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| 123 | |||
| 124 | while(blkCnt > 0u) |
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| 125 | { |
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| 126 | /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */ |
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| 127 | /* Compute sum of the squares and then store the results in a temporary variable, sum */ |
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| 128 | in = *pSrc++; |
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| 129 | sum += in * in; |
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| 130 | |||
| 131 | /* Decrement the loop counter */ |
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| 132 | blkCnt--; |
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| 133 | } |
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| 134 | |||
| 135 | /* Compute Rms and store the result in the destination */ |
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| 136 | arm_sqrt_f32(sum / (float32_t) blockSize, pResult); |
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| 137 | } |
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| 138 | |||
| 139 | /** |
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| 140 | * @} end of RMS group |
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| 141 | */ |