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/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_fir_interpolate_init_q31.c
* Description: Q31 FIR interpolator initialization function
*
* $Date: 27. January 2017
* $Revision: V.1.5.1
*
* Target Processor: Cortex-M cores
* -------------------------------------------------------------------- */
/*
* Copyright (C) 2010-2017 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 Q31 FIR interpolator.
* @param[in,out] *S points to an instance of the Q31 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 The function returns ARM_MATH_SUCCESS if initialization was successful or ARM_MATH_LENGTH_ERROR if
* the filter length <code>numTaps</code> is not a multiple of the interpolation factor <code>L</code>.
*
* <b>Description:</b>
* \par
* <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>
* 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_q31()</code>.
*/
arm_status arm_fir_interpolate_init_q31(
arm_fir_interpolate_instance_q31 * S,
uint8_t L,
uint16_t numTaps,
q31_t * pCoeffs,
q31_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(q31_t));
/* Assign state pointer */
S->pState = pState;
status = ARM_MATH_SUCCESS;
}
return (status);
}
/**
* @} end of FIR_Interpolate group
*/
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