arm_fir_interpolate_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_fir_interpolate_init_q31.c  
00009 *  
00010 * Description:  Q31 FIR interpolator 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 FIR_Interpolate  
00038  * @{  
00039  */ 
00040  
00041  
00042 /**  
00043  * @brief  Initialization function for the Q31 FIR interpolator.  
00044  * @param[in,out] *S        points to an instance of the Q31 FIR interpolator structure.  
00045  * @param[in]     L         upsample factor.  
00046  * @param[in]     numTaps   number of filter coefficients in the filter.  
00047  * @param[in]     *pCoeffs  points to the filter coefficient buffer.  
00048  * @param[in]     *pState   points to the state buffer.  
00049  * @param[in]     blockSize number of input samples to process per call.  
00050  * @return        The function returns ARM_MATH_SUCCESS if initialization was successful or ARM_MATH_LENGTH_ERROR if  
00051  * the filter length <code>numTaps</code> is not a multiple of the interpolation factor <code>L</code>.  
00052  *  
00053  * <b>Description:</b>  
00054  * \par  
00055  * <code>pCoeffs</code> points to the array of filter coefficients stored in time reversed order:  
00056  * <pre>  
00057  *    {b[numTaps-1], b[numTaps-2], b[numTaps-2], ..., b[1], b[0]}  
00058  * </pre>  
00059  * The length of the filter <code>numTaps</code> must be a multiple of the interpolation factor <code>L</code>.  
00060  * \par  
00061  * <code>pState</code> points to the array of state variables.  
00062  * <code>pState</code> is of length <code>(numTaps/L)+blockSize-1</code> words  
00063  * where <code>blockSize</code> is the number of input samples processed by each call to <code>arm_fir_interpolate_q31()</code>.  
00064  */ 
00065  
00066 arm_status arm_fir_interpolate_init_q31( 
00067   arm_fir_interpolate_instance_q31 * S, 
00068   uint8_t L, 
00069   uint16_t numTaps, 
00070   q31_t * pCoeffs, 
00071   q31_t * pState, 
00072   uint32_t blockSize) 
00073 { 
00074   arm_status status; 
00075  
00076   /* The filter length must be a multiple of the interpolation factor */ 
00077   if((numTaps % L) != 0u) 
00078   { 
00079     /* Set status as ARM_MATH_LENGTH_ERROR */ 
00080     status = ARM_MATH_LENGTH_ERROR; 
00081   } 
00082   else 
00083   { 
00084  
00085     /* Assign coefficient pointer */ 
00086     S->pCoeffs = pCoeffs; 
00087  
00088     /* Assign Interpolation factor */ 
00089     S->L = L; 
00090  
00091     /* Assign polyPhaseLength */ 
00092     S->phaseLength = numTaps / L; 
00093  
00094     /* Clear state buffer and size of buffer is always phaseLength + blockSize - 1 */ 
00095     memset(pState, 0, 
00096            (blockSize + ((uint32_t) S->phaseLength - 1u)) * sizeof(q31_t)); 
00097  
00098     /* Assign state pointer */ 
00099     S->pState = pState; 
00100  
00101     status = ARM_MATH_SUCCESS; 
00102   } 
00103  
00104   return (status); 
00105  
00106 } 
00107  
00108  /**  
00109   * @} end of FIR_Interpolate group  
00110   */