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/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_fir_interpolate_init_f32.c
* Description: Floating-point FIR interpolator initialization function
*
* $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_Interpolate
@{
*/
/**
@brief Initialization function for the floating-point FIR interpolator.
@param[in,out] S points to an instance of the floating-point FIR interpolator structure
@param[in] L upsample factor
@param[in] numTaps number of filter coefficients in the filter
@param[in] pCoeffs points to the filter coefficient buffer
@param[in] pState points to the state buffer
@param[in] blockSize number of input samples to process per call
@return execution status
- \ref ARM_MATH_SUCCESS : Operation successful
- \ref ARM_MATH_ARGUMENT_ERROR : filter length <code>numTaps</code> is not a multiple of the interpolation factor <code>L</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[numTaps-2], ..., b[1], b[0]}
</pre>
@par
The length of the filter <code>numTaps</code> must be a multiple of the interpolation factor <code>L</code>.
@par
<code>pState</code> points to the array of state variables.
<code>pState</code> is of length <code>(numTaps/L)+blockSize-1</code> words
where <code>blockSize</code> is the number of input samples processed by each call to <code>arm_fir_interpolate_f32()</code>.
*/
arm_status arm_fir_interpolate_init_f32(
arm_fir_interpolate_instance_f32 * S,
uint8_t L,
uint16_t numTaps,
const float32_t * pCoeffs,
float32_t * pState,
uint32_t blockSize)
{
arm_status status;
/* The filter length must be a multiple of the interpolation factor */
if ((numTaps % L) != 0U)
{
/* Set status as ARM_MATH_LENGTH_ERROR */
status = ARM_MATH_LENGTH_ERROR;
}
else
{
/* Assign coefficient pointer */
S->pCoeffs = pCoeffs;
/* Assign Interpolation factor */
S->L = L;
/* Assign polyPhaseLength */
S->phaseLength = numTaps / L;
/* Clear state buffer and size of buffer is always phaseLength + blockSize - 1 */
memset(pState, 0, (blockSize + ((uint32_t) S->phaseLength - 1U)) * sizeof(float32_t));
/* Assign state pointer */
S->pState = pState;
status = ARM_MATH_SUCCESS;
}
return (status);
}
/**
@} end of FIR_Interpolate group
*/
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