text: /* ----------------------------------------------------------------------
   * Project:      CMSIS DSP Library
   * Title:        arm_lms_norm_init_q31.c
   * Description:  Q31 NLMS filter initialization function
   *
   * $Date:        18. March 2019
   * $Revision:    V1.6.0
   *
   * Target Processor: Cortex-M cores
   * -------------------------------------------------------------------- */
  /*
   * Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved.
   *
   * SPDX-License-Identifier: Apache-2.0
   *
   * Licensed under the Apache License, Version 2.0 (the License); you may
   * not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   * www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an AS IS BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  #include "edge-impulse-sdk/CMSIS/DSP/Include/arm_math.h"
  #include "edge-impulse-sdk/CMSIS/DSP/Include/arm_common_tables.h"
  
  /**
    @addtogroup LMS_NORM
    @{
   */
  
  /**
    @brief         Initialization function for Q31 normalized LMS filter.
    @param[in]     S         points to an instance of the Q31 normalized LMS filter structure.
    @param[in]     numTaps   number of filter coefficients.
    @param[in]     pCoeffs   points to coefficient buffer.
    @param[in]     pState    points to state buffer.
    @param[in]     mu        step size that controls filter coefficient updates.
    @param[in]     blockSize number of samples to process.
    @param[in]     postShift bit shift applied to coefficients.
    @return        none
  
    @par           Details
                     <code>pCoeffs</code> points to the array of filter coefficients stored in time reversed order:
    <pre>
       {b[numTaps-1], b[numTaps-2], b[N-2], ..., b[1], b[0]}
    </pre>
                     The initial filter coefficients serve as a starting point for the adaptive filter.
                     <code>pState</code> points to an array of length <code>numTaps+blockSize-1</code> samples,
                     where <code>blockSize</code> is the number of input samples processed by each call to <code>arm_lms_norm_q31()</code>.
   */
  
  void 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)
  {
    /* Assign filter taps */
    S->numTaps = numTaps;
  
    /* Assign coefficient pointer */
    S->pCoeffs = pCoeffs;
  
    /* Clear state buffer and size is always blockSize + numTaps - 1 */
    memset(pState, 0, (numTaps + (blockSize - 1U)) * sizeof(q31_t));
  
    /* Assign post Shift value applied to coefficients */
    S->postShift = postShift;
  
    /* Assign state pointer */
    S->pState = pState;
  
    /* Assign Step size value */
    S->mu = mu;
  
    /* Initialize reciprocal pointer table */
    S->recipTable = (q31_t *) armRecipTableQ31;
  
    /* Initialise Energy to zero */
    S->energy = 0;
  
    /* Initialise x0 to zero */
    S->x0 = 0;
  }
  
  /**
    @} end of LMS_NORM group
   */
  