arm_lms_init_q31.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_init_q31.c  
00009 *  
00010 * Description:  Q31 LMS filter 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  
00032 /**  
00033  * @ingroup groupFilters  
00034  */ 
00035  
00036 /**  
00037  * @addtogroup LMS  
00038  * @{  
00039  */ 
00040  
00041   /**  
00042    * @brief Initialization function for Q31 LMS filter.  
00043    * @param[in] *S points to an instance of the Q31 LMS filter structure.  
00044    * @param[in] numTaps  number of filter coefficients.  
00045    * @param[in] *pCoeffs points to coefficient buffer.  
00046    * @param[in] *pState points to state buffer.  
00047    * @param[in] mu step size that controls filter coefficient updates.  
00048    * @param[in] blockSize number of samples to process.  
00049    * @param[in] postShift bit shift applied to coefficients.  
00050    * @return none.  
00051  *  
00052  * \par Description:  
00053  * <code>pCoeffs</code> points to the array of filter coefficients stored in time reversed order:  
00054  * <pre>  
00055  *    {b[numTaps-1], b[numTaps-2], b[N-2], ..., b[1], b[0]}  
00056  * </pre>  
00057  * The initial filter coefficients serve as a starting point for the adaptive filter.  
00058  * <code>pState</code> points to an array of length <code>numTaps+blockSize-1</code>samples,  
00059  * where <code>blockSize</code> is the number of input samples processed by each call to  
00060  * <code>arm_lms_q31()</code>.  
00061  */ 
00062  
00063 void arm_lms_init_q31( 
00064   arm_lms_instance_q31 * S, 
00065   uint16_t numTaps, 
00066   q31_t * pCoeffs, 
00067   q31_t * pState, 
00068   q31_t mu, 
00069   uint32_t blockSize, 
00070   uint32_t postShift) 
00071 { 
00072   /* Assign filter taps */ 
00073   S->numTaps = numTaps; 
00074  
00075   /* Assign coefficient pointer */ 
00076   S->pCoeffs = pCoeffs; 
00077  
00078   /* Clear state buffer and size is always blockSize + numTaps - 1 */ 
00079   memset(pState, 0, ((uint32_t) numTaps + (blockSize - 1u)) * sizeof(q31_t)); 
00080  
00081   /* Assign state pointer */ 
00082   S->pState = pState; 
00083  
00084   /* Assign Step size value */ 
00085   S->mu = mu; 
00086  
00087   /* Assign postShift value to be applied */ 
00088   S->postShift = postShift; 
00089  
00090 } 
00091  
00092 /**  
00093  * @} end of LMS group  
00094  */