1 /* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_lms_init_q15.c
4 * Description: Q15 LMS filter initialization function
5 *
6 * $Date: 23 April 2021
7 * $Revision: V1.9.0
8 *
9 * Target Processor: Cortex-M and Cortex-A cores
10 * -------------------------------------------------------------------- */
11 /*
12 * Copyright (C) 2010-2021 ARM Limited or its affiliates. All rights reserved.
13 *
14 * SPDX-License-Identifier: Apache-2.0
15 *
16 * Licensed under the Apache License, Version 2.0 (the License); you may
17 * not use this file except in compliance with the License.
18 * You may obtain a copy of the License at
19 *
20 * www.apache.org/licenses/LICENSE-2.0
21 *
22 * Unless required by applicable law or agreed to in writing, software
23 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
24 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
25 * See the License for the specific language governing permissions and
26 * limitations under the License.
27 */
28
29 #include "dsp/filtering_functions.h"
30
31 /**
32 @ingroup groupFilters
33 */
34
35 /**
36 @addtogroup LMS
37 @{
38 */
39
40 /**
41 @brief Initialization function for the Q15 LMS filter.
42 @param[in] S points to an instance of the Q15 LMS filter structure.
43 @param[in] numTaps number of filter coefficients.
44 @param[in] pCoeffs points to coefficient buffer.
45 @param[in] pState points to state buffer.
46 @param[in] mu step size that controls filter coefficient updates.
47 @param[in] blockSize number of samples to process.
48 @param[in] postShift bit shift applied to coefficients.
49 @return none
50
51 @par Details
52 <code>pCoeffs</code> points to the array of filter coefficients stored in time reversed order:
53 <pre>
54 {b[numTaps-1], b[numTaps-2], b[N-2], ..., b[1], b[0]}
55 </pre>
56 The initial filter coefficients serve as a starting point for the adaptive filter.
57 <code>pState</code> points to the array of state variables and size of array is
58 <code>numTaps+blockSize-1</code> samples, where <code>blockSize</code> is the number of
59 input samples processed by each call to <code>arm_lms_q15()</code>.
60 */
61
arm_lms_init_q15(arm_lms_instance_q15 * S,uint16_t numTaps,q15_t * pCoeffs,q15_t * pState,q15_t mu,uint32_t blockSize,uint32_t postShift)62 void arm_lms_init_q15(
63 arm_lms_instance_q15 * S,
64 uint16_t numTaps,
65 q15_t * pCoeffs,
66 q15_t * pState,
67 q15_t mu,
68 uint32_t blockSize,
69 uint32_t postShift)
70 {
71 /* Assign filter taps */
72 S->numTaps = numTaps;
73
74 /* Assign coefficient pointer */
75 S->pCoeffs = pCoeffs;
76
77 /* Clear state buffer and size is always blockSize + numTaps - 1 */
78 memset(pState, 0, (numTaps + (blockSize - 1U)) * sizeof(q15_t));
79
80 /* Assign state pointer */
81 S->pState = pState;
82
83 /* Assign Step size value */
84 S->mu = mu;
85
86 /* Assign postShift value to be applied */
87 S->postShift = postShift;
88 }
89
90 /**
91 @} end of LMS group
92 */
93
