arm_fir_interpolate_init_q15.c

00001 /*-----------------------------------------------------------------------------    
00002 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.    
00003 *    
00004 * $Date:        17. January 2013
00005 * $Revision:    V1.4.1
00006 *    
00007 * Project:      CMSIS DSP Library    
00008 * Title:        arm_fir_interpolate_init_q15.c    
00009 *    
00010 * Description:  Q15 FIR interpolator 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 FIR_Interpolate    
00049  * @{    
00050  */
00051 
00052 /**    
00053  * @brief  Initialization function for the Q15 FIR interpolator.    
00054  * @param[in,out] *S        points to an instance of the Q15 FIR interpolator structure.    
00055  * @param[in]     L         upsample factor.    
00056  * @param[in]     numTaps   number of filter coefficients in the filter.    
00057  * @param[in]     *pCoeffs  points to the filter coefficient buffer.    
00058  * @param[in]     *pState   points to the state buffer.    
00059  * @param[in]     blockSize number of input samples to process per call.    
00060  * @return        The function returns ARM_MATH_SUCCESS if initialization was successful or ARM_MATH_LENGTH_ERROR if    
00061  * the filter length <code>numTaps</code> is not a multiple of the interpolation factor <code>L</code>.    
00062  *    
00063  * <b>Description:</b>    
00064  * \par    
00065  * <code>pCoeffs</code> points to the array of filter coefficients stored in time reversed order:    
00066  * <pre>    
00067  *    {b[numTaps-1], b[numTaps-2], b[numTaps-2], ..., b[1], b[0]}    
00068  * </pre>    
00069  * The length of the filter <code>numTaps</code> must be a multiple of the interpolation factor <code>L</code>.    
00070  * \par    
00071  * <code>pState</code> points to the array of state variables.    
00072  * <code>pState</code> is of length <code>(numTaps/L)+blockSize-1</code> words    
00073  * where <code>blockSize</code> is the number of input samples processed by each call to <code>arm_fir_interpolate_q15()</code>.    
00074  */
00075 
00076 arm_status arm_fir_interpolate_init_q15(
00077   arm_fir_interpolate_instance_q15 * S,
00078   uint8_t L,
00079   uint16_t numTaps,
00080   q15_t * pCoeffs,
00081   q15_t * pState,
00082   uint32_t blockSize)
00083 {
00084   arm_status status;
00085 
00086   /* The filter length must be a multiple of the interpolation factor */
00087   if((numTaps % L) != 0u)
00088   {
00089     /* Set status as ARM_MATH_LENGTH_ERROR */
00090     status = ARM_MATH_LENGTH_ERROR;
00091   }
00092   else
00093   {
00094 
00095     /* Assign coefficient pointer */
00096     S->pCoeffs = pCoeffs;
00097 
00098     /* Assign Interpolation factor */
00099     S->L = L;
00100 
00101     /* Assign polyPhaseLength */
00102     S->phaseLength = numTaps / L;
00103 
00104     /* Clear state buffer and size of buffer is always phaseLength + blockSize - 1 */
00105     memset(pState, 0,
00106            (blockSize + ((uint32_t) S->phaseLength - 1u)) * sizeof(q15_t));
00107 
00108     /* Assign state pointer */
00109     S->pState = pState;
00110 
00111     status = ARM_MATH_SUCCESS;
00112   }
00113 
00114   return (status);
00115 
00116 }
00117 
00118  /**    
00119   * @} end of FIR_Interpolate group    
00120   */