text: /* ----------------------------------------------------------------------
   * Project:      CMSIS DSP Library
   * Title:        arm_lms_norm_init_q15.c
   * Description:  Q15 NLMS initialization function
   *
   * $Date:        27. January 2017
   * $Revision:    V.1.5.1
   *
   * Target Processor: Cortex-M cores
   * -------------------------------------------------------------------- */
  /*
   * Copyright (C) 2010-2017 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 "arm_math.h"
  #include "arm_common_tables.h"
  
  /**
   * @addtogroup LMS_NORM
   * @{
   */
  
    /**
     * @brief Initialization function for Q15 normalized LMS filter.
     * @param[in] *S points to an instance of the Q15 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.
   *
   * <b>Description:</b>
   * \par
   * <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 the array of state variables and size of array is
   * <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_q15()</code>.
   */
  
  void arm_lms_norm_init_q15(
    arm_lms_norm_instance_q15 * S,
    uint16_t numTaps,
    q15_t * pCoeffs,
    q15_t * pState,
    q15_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(q15_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 = (q15_t *) armRecipTableQ15;
  
    /* Initialise Energy to zero */
    S->energy = 0;
  
    /* Initialise x0 to zero */
    S->x0 = 0;
  
  }
  
  /**
   * @} end of LMS_NORM group
   */
  