1 /* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_lms_init_q31.c
4 * Description: Q31 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 Q31 LMS filter.
42 @param[in] S points to an instance of the Q31 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
50 @par Details
51 <code>pCoeffs</code> points to the array of filter coefficients stored in time reversed order:
52 <pre>
53 {b[numTaps-1], b[numTaps-2], b[N-2], ..., b[1], b[0]}
54 </pre>
55 The initial filter coefficients serve as a starting point for the adaptive filter.
56 <code>pState</code> points to an array of length <code>numTaps+blockSize-1</code> samples,
57 where <code>blockSize</code> is the number of input samples processed by each call to
58 <code>arm_lms_q31()</code>.
59 */
60
arm_lms_init_q31(arm_lms_instance_q31 * S,uint16_t numTaps,q31_t * pCoeffs,q31_t * pState,q31_t mu,uint32_t blockSize,uint32_t postShift)61 void arm_lms_init_q31(
62 arm_lms_instance_q31 * S,
63 uint16_t numTaps,
64 q31_t * pCoeffs,
65 q31_t * pState,
66 q31_t mu,
67 uint32_t blockSize,
68 uint32_t postShift)
69 {
70 /* Assign filter taps */
71 S->numTaps = numTaps;
72
73 /* Assign coefficient pointer */
74 S->pCoeffs = pCoeffs;
75
76 /* Clear state buffer and size is always blockSize + numTaps - 1 */
77 memset(pState, 0, (numTaps + (blockSize - 1U)) * sizeof(q31_t));
78
79 /* Assign state pointer */
80 S->pState = pState;
81
82 /* Assign Step size value */
83 S->mu = mu;
84
85 /* Assign postShift value to be applied */
86 S->postShift = postShift;
87 }
88
89 /**
90 @} end of LMS group
91 */
92
