| 1 | /* ----------------------------------------------------------------------
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| 2 | * Project: CMSIS DSP Library
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| 3 | * Title: arm_lms_init_q15.c
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| 4 | * Description: Q15 LMS filter initialization function
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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 |
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| 29 | #include "arm_math.h"
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| 30 |
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| 31 | /**
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| 32 | * @ingroup groupFilters
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| 33 | */
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| 34 |
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| 35 | /**
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| 36 | * @addtogroup LMS
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| 37 | * @{
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| 38 | */
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| 39 |
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| 40 | /**
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| 41 | * @brief Initialization function for the Q15 LMS filter.
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| 42 | * @param[in] *S points to an instance of the Q15 LMS filter structure.
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| 43 | * @param[in] numTaps number of filter coefficients.
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| 44 | * @param[in] *pCoeffs points to the coefficient buffer.
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| 45 | * @param[in] *pState points to the state buffer.
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| 46 | * @param[in] mu step size that controls filter coefficient updates.
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| 47 | * @param[in] blockSize number of samples to process.
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| 48 | * @param[in] postShift bit shift applied to coefficients.
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| 49 | * @return none.
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| 50 | *
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| 51 | * \par Description:
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| 52 | * <code>pCoeffs</code> points to the array of filter coefficients stored in time reversed order:
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| 53 | * <pre>
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| 54 | * {b[numTaps-1], b[numTaps-2], b[N-2], ..., b[1], b[0]}
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| 55 | * </pre>
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| 56 | * The initial filter coefficients serve as a starting point for the adaptive filter.
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| 57 | * <code>pState</code> points to the array of state variables and size of array is
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| 58 | * <code>numTaps+blockSize-1</code> samples, where <code>blockSize</code> is the number of
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| 59 | * input samples processed by each call to <code>arm_lms_q15()</code>.
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| 60 | */
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| 61 |
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| 62 | void arm_lms_init_q15(
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| 63 | arm_lms_instance_q15 * S,
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| 64 | uint16_t numTaps,
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| 65 | q15_t * pCoeffs,
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| 66 | q15_t * pState,
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| 67 | q15_t mu,
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| 68 | uint32_t blockSize,
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| 69 | uint32_t postShift)
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| 70 | {
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| 71 | /* Assign filter taps */
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| 72 | S->numTaps = numTaps;
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| 73 |
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| 74 | /* Assign coefficient pointer */
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| 75 | S->pCoeffs = pCoeffs;
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| 76 |
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| 77 | /* Clear state buffer and size is always blockSize + numTaps - 1 */
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| 78 | memset(pState, 0, (numTaps + (blockSize - 1U)) * sizeof(q15_t));
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| 79 |
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| 80 | /* Assign state pointer */
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| 81 | S->pState = pState;
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| 82 |
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| 83 | /* Assign Step size value */
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| 84 | S->mu = mu;
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| 85 |
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| 86 | /* Assign postShift value to be applied */
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| 87 | S->postShift = postShift;
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| 88 |
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| 89 | }
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| 90 |
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| 91 | /**
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| 92 | * @} end of LMS group
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| 93 | */
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