1 /* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_lms_norm_init_q31.c
4 * Description: Q31 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 #include "arm_common_tables.h"
31
32 /**
33 @addtogroup LMS_NORM
34 @{
35 */
36
37 /**
38 @brief Initialization function for Q31 normalized LMS filter.
39 @param[in] S points to an instance of the Q31 normalized LMS filter structure.
40 @param[in] numTaps number of filter coefficients.
41 @param[in] pCoeffs points to coefficient buffer.
42 @param[in] pState points to state buffer.
43 @param[in] mu step size that controls filter coefficient updates.
44 @param[in] blockSize number of samples to process.
45 @param[in] postShift bit shift applied to coefficients.
46
47 @par Details
48 <code>pCoeffs</code> points to the array of filter coefficients stored in time reversed order:
49 <pre>
50 {b[numTaps-1], b[numTaps-2], b[N-2], ..., b[1], b[0]}
51 </pre>
52 The initial filter coefficients serve as a starting point for the adaptive filter.
53 <code>pState</code> points to an array of length <code>numTaps+blockSize-1</code> samples,
54 where <code>blockSize</code> is the number of input samples processed by each call to <code>arm_lms_norm_q31()</code>.
55 */
56
arm_lms_norm_init_q31(arm_lms_norm_instance_q31 * S,uint16_t numTaps,q31_t * pCoeffs,q31_t * pState,q31_t mu,uint32_t blockSize,uint8_t postShift)57 void arm_lms_norm_init_q31(
58 arm_lms_norm_instance_q31 * S,
59 uint16_t numTaps,
60 q31_t * pCoeffs,
61 q31_t * pState,
62 q31_t mu,
63 uint32_t blockSize,
64 uint8_t postShift)
65 {
66 /* Assign filter taps */
67 S->numTaps = numTaps;
68
69 /* Assign coefficient pointer */
70 S->pCoeffs = pCoeffs;
71
72 /* Clear state buffer and size is always blockSize + numTaps - 1 */
73 memset(pState, 0, (numTaps + (blockSize - 1U)) * sizeof(q31_t));
74
75 /* Assign post Shift value applied to coefficients */
76 S->postShift = postShift;
77
78 /* Assign state pointer */
79 S->pState = pState;
80
81 /* Assign Step size value */
82 S->mu = mu;
83
84 /* Initialize reciprocal pointer table */
85 S->recipTable = (q31_t *) armRecipTableQ31;
86
87 /* Initialise Energy to zero */
88 S->energy = 0;
89
90 /* Initialise x0 to zero */
91 S->x0 = 0;
92 }
93
94 /**
95 @} end of LMS_NORM group
96 */
97
