DSP_Lib/Source/FilteringFunctions/arm_lms_norm_init_q15.c

/*-----------------------------------------------------------------------------    
* Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
*    
* $Date:        19. March 2015
* $Revision: 	V.1.4.5
*    
* Project: 	    CMSIS DSP Library    
* Title:        arm_lms_norm_init_q15.c    
*    
* Description:  Q15 NLMS initialization function.    
*    
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*  
* Redistribution and use in source and binary forms, with or without 
* modification, are permitted provided that the following conditions
* are met:
*   - Redistributions of source code must retain the above copyright
*     notice, this list of conditions and the following disclaimer.
*   - Redistributions in binary form must reproduce the above copyright
*     notice, this list of conditions and the following disclaimer in
*     the documentation and/or other materials provided with the 
*     distribution.
*   - Neither the name of ARM LIMITED nor the names of its contributors
*     may be used to endorse or promote products derived from this
*     software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.   
* ---------------------------------------------------------------------------*/

#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    
 */