arm_lms_norm_init_q15.c

00001 /*-----------------------------------------------------------------------------  
00002 * Copyright (C) 2010 ARM Limited. All rights reserved.  
00003 *  
00004 * $Date:        29. November 2010  
00005 * $Revision:    V1.0.3  
00006 *  
00007 * Project:      CMSIS DSP Library  
00008 * Title:        arm_lms_norm_init_q15.c  
00009 *  
00010 * Description:  Q15 NLMS initialization function.  
00011 *  
00012 * Target Processor: Cortex-M4/Cortex-M3
00013 *  
00014 * Version 1.0.3 2010/11/29 
00015 *    Re-organized the CMSIS folders and updated documentation.  
00016 *   
00017 * Version 1.0.2 2010/11/11  
00018 *    Documentation updated.   
00019 *  
00020 * Version 1.0.1 2010/10/05   
00021 *    Production release and review comments incorporated.  
00022 *  
00023 * Version 1.0.0 2010/09/20   
00024 *    Production release and review comments incorporated  
00025 *  
00026 * Version 0.0.7  2010/06/10   
00027 *    Misra-C changes done  
00028 * ---------------------------------------------------------------------------*/ 
00029  
00030 #include "arm_math.h" 
00031 #include "arm_common_tables.h" 
00032  
00033 /**  
00034  * @addtogroup LMS_NORM  
00035  * @{  
00036  */ 
00037  
00038   /**  
00039    * @brief Initialization function for Q15 normalized LMS filter.  
00040    * @param[in] *S points to an instance of the Q15 normalized LMS filter structure.  
00041    * @param[in] numTaps  number of filter coefficients.  
00042    * @param[in] *pCoeffs points to coefficient buffer.  
00043    * @param[in] *pState points to state buffer.  
00044    * @param[in] mu step size that controls filter coefficient updates.  
00045    * @param[in] blockSize number of samples to process.  
00046    * @param[in] postShift bit shift applied to coefficients.  
00047    * @return none.  
00048  *  
00049  * <b>Description:</b>  
00050  * \par  
00051  * <code>pCoeffs</code> points to the array of filter coefficients stored in time reversed order:  
00052  * <pre>  
00053  *    {b[numTaps-1], b[numTaps-2], b[N-2], ..., b[1], b[0]}  
00054  * </pre>  
00055  * The initial filter coefficients serve as a starting point for the adaptive filter.  
00056  * <code>pState</code> points to the array of state variables and size of array is  
00057  * <code>numTaps+blockSize-1</code> samples, where <code>blockSize</code> is the number of input samples processed  
00058  * by each call to <code>arm_lms_norm_q15()</code>.  
00059  */ 
00060  
00061 void arm_lms_norm_init_q15( 
00062   arm_lms_norm_instance_q15 * S, 
00063   uint16_t numTaps, 
00064   q15_t * pCoeffs, 
00065   q15_t * pState, 
00066   q15_t mu, 
00067   uint32_t blockSize, 
00068   uint8_t postShift) 
00069 { 
00070   /* Assign filter taps */ 
00071   S->numTaps = numTaps; 
00072  
00073   /* Assign coefficient pointer */ 
00074   S->pCoeffs = pCoeffs; 
00075  
00076   /* Clear state buffer and size is always blockSize + numTaps - 1 */ 
00077   memset(pState, 0, (numTaps + (blockSize - 1u)) * sizeof(q15_t)); 
00078  
00079   /* Assign post Shift value applied to coefficients */ 
00080   S->postShift = postShift; 
00081  
00082   /* Assign state pointer */ 
00083   S->pState = pState; 
00084  
00085   /* Assign Step size value */ 
00086   S->mu = mu; 
00087  
00088   /* Initialize reciprocal pointer table */ 
00089   S->recipTable = (q15_t*)armRecipTableQ15; 
00090  
00091   /* Initialise Energy to zero */ 
00092   S->energy = 0; 
00093  
00094   /* Initialise x0 to zero */ 
00095   S->x0 = 0; 
00096  
00097 } 
00098  
00099 /**  
00100  * @} end of LMS_NORM group  
00101  */