1 /* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_lms_norm_init_f32.c
4 * Description: Floating-point NLMS 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_NORM
37 @{
38 */
39
40 /**
41 @brief Initialization function for floating-point normalized LMS filter.
42 @param[in] S points to an instance of the floating-point 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
49 @par Details
50 <code>pCoeffs</code> points to the array of filter coefficients stored in time reversed order:
51 <pre>
52 {b[numTaps-1], b[numTaps-2], b[N-2], ..., b[1], b[0]}
53 </pre>
54 The initial filter coefficients serve as a starting point for the adaptive filter.
55 <code>pState</code> points to an array of length <code>numTaps+blockSize-1</code> samples,
56 where <code>blockSize</code> is the number of input samples processed by each call to <code>arm_lms_norm_f32()</code>.
57 */
58
arm_lms_norm_init_f32(arm_lms_norm_instance_f32 * S,uint16_t numTaps,float32_t * pCoeffs,float32_t * pState,float32_t mu,uint32_t blockSize)59 ARM_DSP_ATTRIBUTE void arm_lms_norm_init_f32(
60 arm_lms_norm_instance_f32 * S,
61 uint16_t numTaps,
62 float32_t * pCoeffs,
63 float32_t * pState,
64 float32_t mu,
65 uint32_t blockSize)
66 {
67 /* Assign filter taps */
68 S->numTaps = numTaps;
69
70 /* Assign coefficient pointer */
71 S->pCoeffs = pCoeffs;
72
73 /* Clear state buffer and size is always blockSize + numTaps - 1 */
74 memset(pState, 0, (numTaps + (blockSize - 1U)) * sizeof(float32_t));
75
76 /* Assign state pointer */
77 S->pState = pState;
78
79 /* Assign Step size value */
80 S->mu = mu;
81
82 /* Initialise Energy to zero */
83 S->energy = 0.0f;
84
85 /* Initialise x0 to zero */
86 S->x0 = 0.0f;
87 }
88
89 /**
90 @} end of LMS_NORM group
91 */
92
