The CMSIS DSP 5 library
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functions/StatisticsFunctions/arm_mean_q7.c@3:4098b9d3d571, 2018-06-21 (annotated)
- Committer:
- xorjoep
- Date:
- Thu Jun 21 11:56:27 2018 +0000
- Revision:
- 3:4098b9d3d571
- Parent:
- 1:24714b45cd1b
headers is a folder not a library
Who changed what in which revision?
User | Revision | Line number | New contents of line |
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xorjoep | 1:24714b45cd1b | 1 | /* ---------------------------------------------------------------------- |
xorjoep | 1:24714b45cd1b | 2 | * Project: CMSIS DSP Library |
xorjoep | 1:24714b45cd1b | 3 | * Title: arm_mean_q7.c |
xorjoep | 1:24714b45cd1b | 4 | * Description: Mean value of a Q7 vector |
xorjoep | 1:24714b45cd1b | 5 | * |
xorjoep | 1:24714b45cd1b | 6 | * $Date: 27. January 2017 |
xorjoep | 1:24714b45cd1b | 7 | * $Revision: V.1.5.1 |
xorjoep | 1:24714b45cd1b | 8 | * |
xorjoep | 1:24714b45cd1b | 9 | * Target Processor: Cortex-M cores |
xorjoep | 1:24714b45cd1b | 10 | * -------------------------------------------------------------------- */ |
xorjoep | 1:24714b45cd1b | 11 | /* |
xorjoep | 1:24714b45cd1b | 12 | * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved. |
xorjoep | 1:24714b45cd1b | 13 | * |
xorjoep | 1:24714b45cd1b | 14 | * SPDX-License-Identifier: Apache-2.0 |
xorjoep | 1:24714b45cd1b | 15 | * |
xorjoep | 1:24714b45cd1b | 16 | * Licensed under the Apache License, Version 2.0 (the License); you may |
xorjoep | 1:24714b45cd1b | 17 | * not use this file except in compliance with the License. |
xorjoep | 1:24714b45cd1b | 18 | * You may obtain a copy of the License at |
xorjoep | 1:24714b45cd1b | 19 | * |
xorjoep | 1:24714b45cd1b | 20 | * www.apache.org/licenses/LICENSE-2.0 |
xorjoep | 1:24714b45cd1b | 21 | * |
xorjoep | 1:24714b45cd1b | 22 | * Unless required by applicable law or agreed to in writing, software |
xorjoep | 1:24714b45cd1b | 23 | * distributed under the License is distributed on an AS IS BASIS, WITHOUT |
xorjoep | 1:24714b45cd1b | 24 | * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
xorjoep | 1:24714b45cd1b | 25 | * See the License for the specific language governing permissions and |
xorjoep | 1:24714b45cd1b | 26 | * limitations under the License. |
xorjoep | 1:24714b45cd1b | 27 | */ |
xorjoep | 1:24714b45cd1b | 28 | |
xorjoep | 1:24714b45cd1b | 29 | #include "arm_math.h" |
xorjoep | 1:24714b45cd1b | 30 | |
xorjoep | 1:24714b45cd1b | 31 | /** |
xorjoep | 1:24714b45cd1b | 32 | * @ingroup groupStats |
xorjoep | 1:24714b45cd1b | 33 | */ |
xorjoep | 1:24714b45cd1b | 34 | |
xorjoep | 1:24714b45cd1b | 35 | /** |
xorjoep | 1:24714b45cd1b | 36 | * @addtogroup mean |
xorjoep | 1:24714b45cd1b | 37 | * @{ |
xorjoep | 1:24714b45cd1b | 38 | */ |
xorjoep | 1:24714b45cd1b | 39 | |
xorjoep | 1:24714b45cd1b | 40 | |
xorjoep | 1:24714b45cd1b | 41 | /** |
xorjoep | 1:24714b45cd1b | 42 | * @brief Mean value of a Q7 vector. |
xorjoep | 1:24714b45cd1b | 43 | * @param[in] *pSrc points to the input vector |
xorjoep | 1:24714b45cd1b | 44 | * @param[in] blockSize length of the input vector |
xorjoep | 1:24714b45cd1b | 45 | * @param[out] *pResult mean value returned here |
xorjoep | 1:24714b45cd1b | 46 | * @return none. |
xorjoep | 1:24714b45cd1b | 47 | * |
xorjoep | 1:24714b45cd1b | 48 | * @details |
xorjoep | 1:24714b45cd1b | 49 | * <b>Scaling and Overflow Behavior:</b> |
xorjoep | 1:24714b45cd1b | 50 | * \par |
xorjoep | 1:24714b45cd1b | 51 | * The function is implemented using a 32-bit internal accumulator. |
xorjoep | 1:24714b45cd1b | 52 | * The input is represented in 1.7 format and is accumulated in a 32-bit |
xorjoep | 1:24714b45cd1b | 53 | * accumulator in 25.7 format. |
xorjoep | 1:24714b45cd1b | 54 | * There is no risk of internal overflow with this approach, and the |
xorjoep | 1:24714b45cd1b | 55 | * full precision of intermediate result is preserved. |
xorjoep | 1:24714b45cd1b | 56 | * Finally, the accumulator is truncated to yield a result of 1.7 format. |
xorjoep | 1:24714b45cd1b | 57 | * |
xorjoep | 1:24714b45cd1b | 58 | */ |
xorjoep | 1:24714b45cd1b | 59 | |
xorjoep | 1:24714b45cd1b | 60 | void arm_mean_q7( |
xorjoep | 1:24714b45cd1b | 61 | q7_t * pSrc, |
xorjoep | 1:24714b45cd1b | 62 | uint32_t blockSize, |
xorjoep | 1:24714b45cd1b | 63 | q7_t * pResult) |
xorjoep | 1:24714b45cd1b | 64 | { |
xorjoep | 1:24714b45cd1b | 65 | q31_t sum = 0; /* Temporary result storage */ |
xorjoep | 1:24714b45cd1b | 66 | uint32_t blkCnt; /* loop counter */ |
xorjoep | 1:24714b45cd1b | 67 | |
xorjoep | 1:24714b45cd1b | 68 | #if defined (ARM_MATH_DSP) |
xorjoep | 1:24714b45cd1b | 69 | /* Run the below code for Cortex-M4 and Cortex-M3 */ |
xorjoep | 1:24714b45cd1b | 70 | |
xorjoep | 1:24714b45cd1b | 71 | q31_t in; |
xorjoep | 1:24714b45cd1b | 72 | |
xorjoep | 1:24714b45cd1b | 73 | /*loop Unrolling */ |
xorjoep | 1:24714b45cd1b | 74 | blkCnt = blockSize >> 2U; |
xorjoep | 1:24714b45cd1b | 75 | |
xorjoep | 1:24714b45cd1b | 76 | /* First part of the processing with loop unrolling. Compute 4 outputs at a time. |
xorjoep | 1:24714b45cd1b | 77 | ** a second loop below computes the remaining 1 to 3 samples. */ |
xorjoep | 1:24714b45cd1b | 78 | while (blkCnt > 0U) |
xorjoep | 1:24714b45cd1b | 79 | { |
xorjoep | 1:24714b45cd1b | 80 | /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */ |
xorjoep | 1:24714b45cd1b | 81 | in = *__SIMD32(pSrc)++; |
xorjoep | 1:24714b45cd1b | 82 | |
xorjoep | 1:24714b45cd1b | 83 | sum += ((in << 24U) >> 24U); |
xorjoep | 1:24714b45cd1b | 84 | sum += ((in << 16U) >> 24U); |
xorjoep | 1:24714b45cd1b | 85 | sum += ((in << 8U) >> 24U); |
xorjoep | 1:24714b45cd1b | 86 | sum += (in >> 24U); |
xorjoep | 1:24714b45cd1b | 87 | |
xorjoep | 1:24714b45cd1b | 88 | /* Decrement the loop counter */ |
xorjoep | 1:24714b45cd1b | 89 | blkCnt--; |
xorjoep | 1:24714b45cd1b | 90 | } |
xorjoep | 1:24714b45cd1b | 91 | |
xorjoep | 1:24714b45cd1b | 92 | /* If the blockSize is not a multiple of 4, compute any remaining output samples here. |
xorjoep | 1:24714b45cd1b | 93 | ** No loop unrolling is used. */ |
xorjoep | 1:24714b45cd1b | 94 | blkCnt = blockSize % 0x4U; |
xorjoep | 1:24714b45cd1b | 95 | |
xorjoep | 1:24714b45cd1b | 96 | #else |
xorjoep | 1:24714b45cd1b | 97 | /* Run the below code for Cortex-M0 */ |
xorjoep | 1:24714b45cd1b | 98 | |
xorjoep | 1:24714b45cd1b | 99 | /* Loop over blockSize number of values */ |
xorjoep | 1:24714b45cd1b | 100 | blkCnt = blockSize; |
xorjoep | 1:24714b45cd1b | 101 | |
xorjoep | 1:24714b45cd1b | 102 | #endif /* #if defined (ARM_MATH_DSP) */ |
xorjoep | 1:24714b45cd1b | 103 | |
xorjoep | 1:24714b45cd1b | 104 | while (blkCnt > 0U) |
xorjoep | 1:24714b45cd1b | 105 | { |
xorjoep | 1:24714b45cd1b | 106 | /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) */ |
xorjoep | 1:24714b45cd1b | 107 | sum += *pSrc++; |
xorjoep | 1:24714b45cd1b | 108 | |
xorjoep | 1:24714b45cd1b | 109 | /* Decrement the loop counter */ |
xorjoep | 1:24714b45cd1b | 110 | blkCnt--; |
xorjoep | 1:24714b45cd1b | 111 | } |
xorjoep | 1:24714b45cd1b | 112 | |
xorjoep | 1:24714b45cd1b | 113 | /* C = (A[0] + A[1] + A[2] + ... + A[blockSize-1]) / blockSize */ |
xorjoep | 1:24714b45cd1b | 114 | /* Store the result to the destination */ |
xorjoep | 1:24714b45cd1b | 115 | *pResult = (q7_t) (sum / (int32_t) blockSize); |
xorjoep | 1:24714b45cd1b | 116 | } |
xorjoep | 1:24714b45cd1b | 117 | |
xorjoep | 1:24714b45cd1b | 118 | /** |
xorjoep | 1:24714b45cd1b | 119 | * @} end of mean group |
xorjoep | 1:24714b45cd1b | 120 | */ |