107 lines
3.4 KiB
C
107 lines
3.4 KiB
C
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/* ----------------------------------------------------------------------
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* Project: CMSIS DSP Library
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* Title: arm_fir_interpolate_init_q15.c
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* Description: Q15 FIR interpolator initialization function
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*
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* $Date: 18. March 2019
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* $Revision: V1.6.0
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*
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* Target Processor: Cortex-M cores
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* -------------------------------------------------------------------- */
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/*
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* Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved.
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the License); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an AS IS BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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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_Interpolate
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@{
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*/
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/**
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@brief Initialization function for the Q15 FIR interpolator.
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@param[in,out] S points to an instance of the Q15 FIR interpolator structure
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@param[in] L upsample factor
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@param[in] numTaps number of filter coefficients in the filter
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@param[in] pCoeffs points to the filter coefficient buffer
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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 execution status
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- \ref ARM_MATH_SUCCESS : Operation successful
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- \ref ARM_MATH_ARGUMENT_ERROR : filter length <code>numTaps</code> is not a multiple of the interpolation factor <code>L</code>
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@par Details
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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[numTaps-2], ..., b[1], b[0]}
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</pre>
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The length of the filter <code>numTaps</code> must be a multiple of the interpolation factor <code>L</code>.
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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/L)+blockSize-1</code> words
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where <code>blockSize</code> is the number of input samples processed by each call to <code>arm_fir_interpolate_q15()</code>.
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*/
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arm_status arm_fir_interpolate_init_q15(
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arm_fir_interpolate_instance_q15 * S,
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uint8_t L,
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uint16_t numTaps,
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const q15_t * pCoeffs,
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q15_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 filter length must be a multiple of the interpolation factor */
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if ((numTaps % L) != 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 coefficient pointer */
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S->pCoeffs = pCoeffs;
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/* Assign Interpolation factor */
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S->L = L;
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/* Assign polyPhaseLength */
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S->phaseLength = numTaps / L;
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/* Clear state buffer and size of buffer is always phaseLength + blockSize - 1 */
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memset(pState, 0, (blockSize + ((uint32_t) S->phaseLength - 1U)) * sizeof(q15_t));
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/* Assign state pointer */
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S->pState = pState;
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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_Interpolate group
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*/
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