arm_lms_init_q15.c

00001 /*-----------------------------------------------------------------------------    
00002 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
00003 *    
00004 * $Date:        19. March 2015
00005 * $Revision:    V.1.4.5
00006 *    
00007 * Project:      CMSIS DSP Library    
00008 * Title:        arm_lms_init_q15.c    
00009 *    
00010 * Description:  Q15 LMS filter initialization function.    
00011 *    
00012 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
00013 *  
00014 * Redistribution and use in source and binary forms, with or without 
00015 * modification, are permitted provided that the following conditions
00016 * are met:
00017 *   - Redistributions of source code must retain the above copyright
00018 *     notice, this list of conditions and the following disclaimer.
00019 *   - Redistributions in binary form must reproduce the above copyright
00020 *     notice, this list of conditions and the following disclaimer in
00021 *     the documentation and/or other materials provided with the 
00022 *     distribution.
00023 *   - Neither the name of ARM LIMITED nor the names of its contributors
00024 *     may be used to endorse or promote products derived from this
00025 *     software without specific prior written permission.
00026 *
00027 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
00028 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
00029 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
00030 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
00031 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
00032 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
00033 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
00034 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
00035 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
00036 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
00037 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
00038 * POSSIBILITY OF SUCH DAMAGE.   
00039 * ---------------------------------------------------------------------------*/
00040 
00041 #include "arm_math.h"
00042 
00043 /**    
00044  * @ingroup groupFilters    
00045  */
00046 
00047 /**    
00048  * @addtogroup LMS    
00049  * @{    
00050  */
00051 
00052 /**    
00053 * @brief Initialization function for the Q15 LMS filter.    
00054 * @param[in] *S points to an instance of the Q15 LMS filter structure.    
00055 * @param[in] numTaps  number of filter coefficients.    
00056 * @param[in] *pCoeffs points to the coefficient buffer.    
00057 * @param[in] *pState points to the state buffer.    
00058 * @param[in] mu step size that controls filter coefficient updates.    
00059 * @param[in] blockSize number of samples to process.    
00060 * @param[in] postShift bit shift applied to coefficients.    
00061 * @return    none.    
00062 *    
00063 * \par Description:    
00064 * <code>pCoeffs</code> points to the array of filter coefficients stored in time reversed order:    
00065 * <pre>    
00066 *    {b[numTaps-1], b[numTaps-2], b[N-2], ..., b[1], b[0]}    
00067 * </pre>    
00068 * The initial filter coefficients serve as a starting point for the adaptive filter.    
00069 * <code>pState</code> points to the array of state variables and size of array is    
00070 * <code>numTaps+blockSize-1</code> samples, where <code>blockSize</code> is the number of    
00071 * input samples processed by each call to <code>arm_lms_q15()</code>.    
00072 */
00073 
00074 void arm_lms_init_q15(
00075   arm_lms_instance_q15 * S,
00076   uint16_t numTaps,
00077   q15_t * pCoeffs,
00078   q15_t * pState,
00079   q15_t mu,
00080   uint32_t blockSize,
00081   uint32_t postShift)
00082 {
00083   /* Assign filter taps */
00084   S->numTaps = numTaps;
00085 
00086   /* Assign coefficient pointer */
00087   S->pCoeffs = pCoeffs;
00088 
00089   /* Clear state buffer and size is always blockSize + numTaps - 1 */
00090   memset(pState, 0, (numTaps + (blockSize - 1u)) * sizeof(q15_t));
00091 
00092   /* Assign state pointer */
00093   S->pState = pState;
00094 
00095   /* Assign Step size value */
00096   S->mu = mu;
00097 
00098   /* Assign postShift value to be applied */
00099   S->postShift = postShift;
00100 
00101 }
00102 
00103 /**    
00104  * @} end of LMS group    
00105  */