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| Rev | Author | Line No. | Line |
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| 2 | mjames | 1 | /* ---------------------------------------------------------------------- |
| 2 | * Project: CMSIS DSP Library |
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| 3 | * Title: arm_rms_f32.c |
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| 4 | * Description: Root mean square value of an array of F32 type |
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| 5 | * |
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| 6 | * $Date: 27. January 2017 |
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| 7 | * $Revision: V.1.5.1 |
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| 8 | * |
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| 9 | * Target Processor: Cortex-M cores |
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| 10 | * -------------------------------------------------------------------- */ |
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| 11 | /* |
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| 12 | * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved. |
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| 13 | * |
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| 14 | * SPDX-License-Identifier: Apache-2.0 |
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| 15 | * |
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| 16 | * Licensed under the Apache License, Version 2.0 (the License); you may |
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| 17 | * not use this file except in compliance with the License. |
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| 18 | * You may obtain a copy of the License at |
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| 19 | * |
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| 20 | * www.apache.org/licenses/LICENSE-2.0 |
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| 21 | * |
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| 22 | * Unless required by applicable law or agreed to in writing, software |
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| 23 | * distributed under the License is distributed on an AS IS BASIS, WITHOUT |
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| 24 | * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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| 25 | * See the License for the specific language governing permissions and |
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| 26 | * limitations under the License. |
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| 27 | */ |
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| 28 | |||
| 29 | #include "arm_math.h" |
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| 30 | |||
| 31 | /** |
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| 32 | * @ingroup groupStats |
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| 33 | */ |
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| 34 | |||
| 35 | /** |
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| 36 | * @defgroup RMS Root mean square (RMS) |
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| 37 | * |
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| 38 | * |
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| 39 | * Calculates the Root Mean Sqaure of the elements in the input vector. |
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| 40 | * The underlying algorithm is used: |
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| 41 | * |
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| 42 | * <pre> |
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| 43 | * Result = sqrt(((pSrc[0] * pSrc[0] + pSrc[1] * pSrc[1] + ... + pSrc[blockSize-1] * pSrc[blockSize-1]) / blockSize)); |
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| 44 | * </pre> |
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| 45 | * |
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| 46 | * There are separate functions for floating point, Q31, and Q15 data types. |
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| 47 | */ |
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| 48 | |||
| 49 | /** |
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| 50 | * @addtogroup RMS |
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| 51 | * @{ |
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| 52 | */ |
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| 53 | |||
| 54 | |||
| 55 | /** |
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| 56 | * @brief Root Mean Square of the elements of a floating-point vector. |
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| 57 | * @param[in] *pSrc points to the input vector |
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| 58 | * @param[in] blockSize length of the input vector |
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| 59 | * @param[out] *pResult rms value returned here |
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| 60 | * @return none. |
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| 61 | * |
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| 62 | */ |
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| 63 | |||
| 64 | void arm_rms_f32( |
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| 65 | float32_t * pSrc, |
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| 66 | uint32_t blockSize, |
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| 67 | float32_t * pResult) |
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| 68 | { |
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| 69 | float32_t sum = 0.0f; /* Accumulator */ |
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| 70 | float32_t in; /* Tempoprary variable to store input value */ |
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| 71 | uint32_t blkCnt; /* loop counter */ |
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| 72 | |||
| 73 | #if defined (ARM_MATH_DSP) |
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| 74 | /* Run the below code for Cortex-M4 and Cortex-M3 */ |
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| 75 | |||
| 76 | /* loop Unrolling */ |
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| 77 | blkCnt = blockSize >> 2U; |
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| 78 | |||
| 79 | /* First part of the processing with loop unrolling. Compute 4 outputs at a time. |
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| 80 | ** a second loop below computes the remaining 1 to 3 samples. */ |
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| 81 | while (blkCnt > 0U) |
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| 82 | { |
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| 83 | /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */ |
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| 84 | /* Compute sum of the squares and then store the result in a temporary variable, sum */ |
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| 85 | in = *pSrc++; |
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| 86 | sum += in * in; |
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| 87 | in = *pSrc++; |
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| 88 | sum += in * in; |
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| 89 | in = *pSrc++; |
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| 90 | sum += in * in; |
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| 91 | in = *pSrc++; |
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| 92 | sum += in * in; |
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| 93 | |||
| 94 | /* Decrement the loop counter */ |
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| 95 | blkCnt--; |
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| 96 | } |
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| 97 | |||
| 98 | /* If the blockSize is not a multiple of 4, compute any remaining output samples here. |
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| 99 | ** No loop unrolling is used. */ |
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| 100 | blkCnt = blockSize % 0x4U; |
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| 101 | |||
| 102 | #else |
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| 103 | /* Run the below code for Cortex-M0 */ |
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| 104 | |||
| 105 | /* Loop over blockSize number of values */ |
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| 106 | blkCnt = blockSize; |
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| 107 | |||
| 108 | #endif /* #if defined (ARM_MATH_DSP) */ |
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| 109 | |||
| 110 | while (blkCnt > 0U) |
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| 111 | { |
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| 112 | /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */ |
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| 113 | /* Compute sum of the squares and then store the results in a temporary variable, sum */ |
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| 114 | in = *pSrc++; |
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| 115 | sum += in * in; |
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| 116 | |||
| 117 | /* Decrement the loop counter */ |
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| 118 | blkCnt--; |
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| 119 | } |
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| 120 | |||
| 121 | /* Compute Rms and store the result in the destination */ |
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| 122 | arm_sqrt_f32(sum / (float32_t) blockSize, pResult); |
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| 123 | } |
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| 124 | |||
| 125 | /** |
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| 126 | * @} end of RMS group |
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| 127 | */ |