arm_fir_interpolate_init_f32.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_f32.c  
00009 *  
00010 * Description:  Floating-point 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  * @brief  Initialization function for the floating-point FIR interpolator.  
00043  * @param[in,out] *S        points to an instance of the floating-point FIR interpolator structure.  
00044  * @param[in]     L         upsample factor.  
00045  * @param[in]     numTaps   number of filter coefficients in the filter.  
00046  * @param[in]     *pCoeffs  points to the filter coefficient buffer.  
00047  * @param[in]     *pState   points to the state buffer.  
00048  * @param[in]     blockSize number of input samples to process per call.  
00049  * @return        The function returns ARM_MATH_SUCCESS if initialization was successful or ARM_MATH_LENGTH_ERROR if  
00050  * the filter length <code>numTaps</code> is not a multiple of the interpolation factor <code>L</code>.  
00051  *  
00052  * <b>Description:</b>  
00053  * \par  
00054  * <code>pCoeffs</code> points to the array of filter coefficients stored in time reversed order:  
00055  * <pre>  
00056  *    {b[numTaps-1], b[numTaps-2], b[numTaps-2], ..., b[1], b[0]}  
00057  * </pre>  
00058  * The length of the filter <code>numTaps</code> must be a multiple of the interpolation factor <code>L</code>.  
00059  * \par  
00060  * <code>pState</code> points to the array of state variables.  
00061  * <code>pState</code> is of length <code>(numTaps/L)+blockSize-1</code> words  
00062  * where <code>blockSize</code> is the number of input samples processed by each call to <code>arm_fir_interpolate_f32()</code>.  
00063  */ 
00064  
00065 arm_status arm_fir_interpolate_init_f32( 
00066   arm_fir_interpolate_instance_f32 * S, 
00067   uint8_t L, 
00068   uint16_t numTaps, 
00069   float32_t * pCoeffs, 
00070   float32_t * pState, 
00071   uint32_t blockSize) 
00072 { 
00073   arm_status status; 
00074  
00075   /* The filter length must be a multiple of the interpolation factor */ 
00076   if((numTaps % L) != 0u) 
00077   { 
00078     /* Set status as ARM_MATH_LENGTH_ERROR */ 
00079     status = ARM_MATH_LENGTH_ERROR; 
00080   } 
00081   else 
00082   { 
00083  
00084     /* Assign coefficient pointer */ 
00085     S->pCoeffs = pCoeffs; 
00086  
00087     /* Assign Interpolation factor */ 
00088     S->L = L; 
00089  
00090     /* Assign polyPhaseLength */ 
00091     S->phaseLength = numTaps / L; 
00092  
00093     /* Clear state buffer and size of state array is always phaseLength + blockSize - 1 */ 
00094     memset(pState, 0, 
00095            (blockSize + 
00096             ((uint32_t) S->phaseLength - 1u)) * sizeof(float32_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   */