DSP/Source/FilteringFunctions/arm_iir_lattice_init_q31.c

/* ----------------------------------------------------------------------
 * Project:      CMSIS DSP Library
 * Title:        arm_iir_lattice_init_q31.c
 * Description:  Initialization function for the Q31 IIR lattice filter
 *
 * $Date:        23 April 2021
 * $Revision:    V1.9.0
 *
 * Target Processor: Cortex-M and Cortex-A cores
 * -------------------------------------------------------------------- */
/*
 * Copyright (C) 2010-2021 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 "dsp/filtering_functions.h"

/**
  @ingroup groupFilters
 */

/**
  @addtogroup IIR_Lattice
  @{
 */

/**
  @brief         Initialization function for the Q31 IIR lattice filter.
  @param[in]     S          points to an instance of the Q31 IIR lattice structure
  @param[in]     numStages  number of stages in the filter
  @param[in]     pkCoeffs   points to reflection coefficient buffer.  The array is of length numStages
  @param[in]     pvCoeffs   points to ladder coefficient buffer.  The array is of length numStages+1
  @param[in]     pState     points to state buffer.  The array is of length numStages+blockSize
  @param[in]     blockSize  number of samples to process
  @return        none
 */

void arm_iir_lattice_init_q31(
  arm_iir_lattice_instance_q31 * S,
  uint16_t numStages,
  q31_t * pkCoeffs,
  q31_t * pvCoeffs,
  q31_t * pState,
  uint32_t blockSize)
{
  /* Assign filter taps */
  S->numStages = numStages;

  /* Assign reflection coefficient pointer */
  S->pkCoeffs = pkCoeffs;

  /* Assign ladder coefficient pointer */
  S->pvCoeffs = pvCoeffs;

  /* Clear state buffer and size is always blockSize + numStages */
  memset(pState, 0, (numStages + blockSize) * sizeof(q31_t));

  /* Assign state pointer */
  S->pState = pState;
}

/**
  @} end of IIR_Lattice group
 */