118 rader
4.1 KiB
C
118 rader
4.1 KiB
C
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/* ----------------------------------------------------------------------
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* Copyright (C) 2010-2013 ARM Limited. All rights reserved.
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*
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* $Date: 17. January 2013
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* $Revision: V1.4.1
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*
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* Project: CMSIS DSP Library
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* Title: arm_fir_decimate_init_q31.c
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*
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* Description: Initialization function for Q31 FIR Decimation filter.
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*
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* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* - Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* - Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* - Neither the name of ARM LIMITED nor the names of its contributors
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* may be used to endorse or promote products derived from this
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* software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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* ------------------------------------------------------------------- */
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#include "arm_math.h"
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/**
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* @ingroup groupFilters
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*/
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/**
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* @addtogroup FIR_decimate
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* @{
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*/
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/**
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* @brief Initialization function for the Q31 FIR decimator.
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* @param[in,out] *S points to an instance of the Q31 FIR decimator structure.
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* @param[in] numTaps number of coefficients in the filter.
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* @param[in] M decimation factor.
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* @param[in] *pCoeffs points to the filter coefficients.
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* @param[in] *pState points to the state buffer.
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* @param[in] blockSize number of input samples to process per call.
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* @return The function returns ARM_MATH_SUCCESS if initialization was successful or ARM_MATH_LENGTH_ERROR if
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* <code>blockSize</code> is not a multiple of <code>M</code>.
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*
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* <b>Description:</b>
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* \par
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* <code>pCoeffs</code> points to the array of filter coefficients stored in time reversed order:
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* <pre>
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* {b[numTaps-1], b[numTaps-2], b[N-2], ..., b[1], b[0]}
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* </pre>
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* \par
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* <code>pState</code> points to the array of state variables.
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* <code>pState</code> is of length <code>numTaps+blockSize-1</code> words where <code>blockSize</code> is the number of input samples passed to <code>arm_fir_decimate_q31()</code>.
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* <code>M</code> is the decimation factor.
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*/
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arm_status arm_fir_decimate_init_q31(
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arm_fir_decimate_instance_q31 * S,
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uint16_t numTaps,
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uint8_t M,
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q31_t * pCoeffs,
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q31_t * pState,
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uint32_t blockSize)
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{
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arm_status status;
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/* The size of the input block must be a multiple of the decimation factor */
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if((blockSize % M) != 0u)
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{
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/* Set status as ARM_MATH_LENGTH_ERROR */
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status = ARM_MATH_LENGTH_ERROR;
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}
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else
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{
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/* Assign filter taps */
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S->numTaps = numTaps;
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/* Assign coefficient pointer */
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S->pCoeffs = pCoeffs;
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/* Clear the state buffer. The size is always (blockSize + numTaps - 1) */
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memset(pState, 0, (numTaps + (blockSize - 1)) * sizeof(q31_t));
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/* Assign state pointer */
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S->pState = pState;
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/* Assign Decimation factor */
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S->M = M;
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status = ARM_MATH_SUCCESS;
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}
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return (status);
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}
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/**
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* @} end of FIR_decimate group
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*/
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