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/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_fir_decimate_init_q15.c
* Description: Initialization function for the Q15 FIR Decimator
*
* $Date: 18. March 2019
* $Revision: V1.6.0
*
* Target Processor: Cortex-M cores
* -------------------------------------------------------------------- */
/*
* Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved.
*
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the License); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an AS IS BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "arm_math.h"
/**
@ingroup groupFilters
*/
/**
@addtogroup FIR_decimate
@{
*/
/**
@brief Initialization function for the Q15 FIR decimator.
@param[in,out] S points to an instance of the Q15 FIR decimator structure
@param[in] numTaps number of coefficients in the filter
@param[in] M decimation factor
@param[in] pCoeffs points to the filter coefficients
@param[in] pState points to the state buffer
@param[in] blockSize number of input samples to process
@return execution status
- \ref ARM_MATH_SUCCESS : Operation successful
- \ref ARM_MATH_LENGTH_ERROR : <code>blockSize</code> is not a multiple of <code>M</code>
@par Details
<code>pCoeffs</code> points to the array of filter coefficients stored in time reversed order:
<pre>
{b[numTaps-1], b[numTaps-2], b[N-2], ..., b[1], b[0]}
</pre>
@par
<code>pState</code> points to the array of state variables.
<code>pState</code> is of length <code>numTaps+blockSize-1</code> words where <code>blockSize</code> is the number of input samples
to the call <code>arm_fir_decimate_q15()</code>.
<code>M</code> is the decimation factor.
*/
arm_status arm_fir_decimate_init_q15(
arm_fir_decimate_instance_q15 * S,
uint16_t numTaps,
uint8_t M,
const q15_t * pCoeffs,
q15_t * pState,
uint32_t blockSize)
{
arm_status status;
/* The size of the input block must be a multiple of the decimation factor */
if ((blockSize % M) != 0U)
{
/* Set status as ARM_MATH_LENGTH_ERROR */
status = ARM_MATH_LENGTH_ERROR;
}
else
{
/* Assign filter taps */
S->numTaps = numTaps;
/* Assign coefficient pointer */
S->pCoeffs = pCoeffs;
/* Clear the state buffer. The size is always (blockSize + numTaps - 1) */
memset(pState, 0, (numTaps + (blockSize - 1U)) * sizeof(q15_t));
/* Assign state pointer */
S->pState = pState;
/* Assign Decimation Factor */
S->M = M;
status = ARM_MATH_SUCCESS;
}
return (status);
}
/**
@} end of FIR_decimate group
*/
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