| 提交 | 用户 | age | ||
| bfc108 | 1 | /* ---------------------------------------------------------------------- |
| Q | 2 | * Copyright (C) 2010-2014 ARM Limited. All rights reserved. |
| 3 | * | |
| 4 | * $Date: 19. March 2015 | |
| 5 | * $Revision: V.1.4.5 | |
| 6 | * | |
| 7 | * Project: CMSIS DSP Library | |
| 8 | * Title: arm_rms_f32.c | |
| 9 | * | |
| 10 | * Description: Root mean square value of an array of F32 type | |
| 11 | * | |
| 12 | * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 | |
| 13 | * | |
| 14 | * Redistribution and use in source and binary forms, with or without | |
| 15 | * modification, are permitted provided that the following conditions | |
| 16 | * are met: | |
| 17 | * - Redistributions of source code must retain the above copyright | |
| 18 | * notice, this list of conditions and the following disclaimer. | |
| 19 | * - Redistributions in binary form must reproduce the above copyright | |
| 20 | * notice, this list of conditions and the following disclaimer in | |
| 21 | * the documentation and/or other materials provided with the | |
| 22 | * distribution. | |
| 23 | * - Neither the name of ARM LIMITED nor the names of its contributors | |
| 24 | * may be used to endorse or promote products derived from this | |
| 25 | * software without specific prior written permission. | |
| 26 | * | |
| 27 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
| 28 | * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
| 29 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS | |
| 30 | * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE | |
| 31 | * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, | |
| 32 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, | |
| 33 | * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; | |
| 34 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER | |
| 35 | * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
| 36 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN | |
| 37 | * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE | |
| 38 | * POSSIBILITY OF SUCH DAMAGE. | |
| 39 | * ---------------------------------------------------------------------------- */ | |
| 40 | ||
| 41 | #include "arm_math.h" | |
| 42 | ||
| 43 | /** | |
| 44 | * @ingroup groupStats | |
| 45 | */ | |
| 46 | ||
| 47 | /** | |
| 48 | * @defgroup RMS Root mean square (RMS) | |
| 49 | * | |
| 50 | * | |
| 51 | * Calculates the Root Mean Sqaure of the elements in the input vector. | |
| 52 | * The underlying algorithm is used: | |
| 53 | * | |
| 54 | * <pre> | |
| 55 | * Result = sqrt(((pSrc[0] * pSrc[0] + pSrc[1] * pSrc[1] + ... + pSrc[blockSize-1] * pSrc[blockSize-1]) / blockSize)); | |
| 56 | * </pre> | |
| 57 | * | |
| 58 | * There are separate functions for floating point, Q31, and Q15 data types. | |
| 59 | */ | |
| 60 | ||
| 61 | /** | |
| 62 | * @addtogroup RMS | |
| 63 | * @{ | |
| 64 | */ | |
| 65 | ||
| 66 | ||
| 67 | /** | |
| 68 | * @brief Root Mean Square of the elements of a floating-point vector. | |
| 69 | * @param[in] *pSrc points to the input vector | |
| 70 | * @param[in] blockSize length of the input vector | |
| 71 | * @param[out] *pResult rms value returned here | |
| 72 | * @return none. | |
| 73 | * | |
| 74 | */ | |
| 75 | ||
| 76 | void arm_rms_f32( | |
| 77 | float32_t * pSrc, | |
| 78 | uint32_t blockSize, | |
| 79 | float32_t * pResult) | |
| 80 | { | |
| 81 | float32_t sum = 0.0f; /* Accumulator */ | |
| 82 | float32_t in; /* Tempoprary variable to store input value */ | |
| 83 | uint32_t blkCnt; /* loop counter */ | |
| 84 | ||
| 85 | #ifndef ARM_MATH_CM0_FAMILY | |
| 86 | ||
| 87 | /* Run the below code for Cortex-M4 and Cortex-M3 */ | |
| 88 | ||
| 89 | /* loop Unrolling */ | |
| 90 | blkCnt = blockSize >> 2u; | |
| 91 | ||
| 92 | /* First part of the processing with loop unrolling. Compute 4 outputs at a time. | |
| 93 | ** a second loop below computes the remaining 1 to 3 samples. */ | |
| 94 | while(blkCnt > 0u) | |
| 95 | { | |
| 96 | /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */ | |
| 97 | /* Compute sum of the squares and then store the result in a temporary variable, sum */ | |
| 98 | in = *pSrc++; | |
| 99 | sum += in * in; | |
| 100 | in = *pSrc++; | |
| 101 | sum += in * in; | |
| 102 | in = *pSrc++; | |
| 103 | sum += in * in; | |
| 104 | in = *pSrc++; | |
| 105 | sum += in * in; | |
| 106 | ||
| 107 | /* Decrement the loop counter */ | |
| 108 | blkCnt--; | |
| 109 | } | |
| 110 | ||
| 111 | /* If the blockSize is not a multiple of 4, compute any remaining output samples here. | |
| 112 | ** No loop unrolling is used. */ | |
| 113 | blkCnt = blockSize % 0x4u; | |
| 114 | ||
| 115 | #else | |
| 116 | ||
| 117 | /* Run the below code for Cortex-M0 */ | |
| 118 | ||
| 119 | /* Loop over blockSize number of values */ | |
| 120 | blkCnt = blockSize; | |
| 121 | ||
| 122 | #endif /* #ifndef ARM_MATH_CM0_FAMILY */ | |
| 123 | ||
| 124 | while(blkCnt > 0u) | |
| 125 | { | |
| 126 | /* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */ | |
| 127 | /* Compute sum of the squares and then store the results in a temporary variable, sum */ | |
| 128 | in = *pSrc++; | |
| 129 | sum += in * in; | |
| 130 | ||
| 131 | /* Decrement the loop counter */ | |
| 132 | blkCnt--; | |
| 133 | } | |
| 134 | ||
| 135 | /* Compute Rms and store the result in the destination */ | |
| 136 | arm_sqrt_f32(sum / (float32_t) blockSize, pResult); | |
| 137 | } | |
| 138 | ||
| 139 | /** | |
| 140 | * @} end of RMS group | |
| 141 | */ | |
