| /* ---------------------------------------------------------------------- |
| * Project: CMSIS DSP Library |
| * Title: arm_fir_interpolate_init_q15.c |
| * Description: Q15 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 Q15 FIR interpolator. |
| @param[in,out] S points to an instance of the Q15 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> |
| 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_q15()</code>. |
| */ |
| |
| arm_status arm_fir_interpolate_init_q15( |
| arm_fir_interpolate_instance_q15 * S, |
| uint8_t L, |
| uint16_t numTaps, |
| const q15_t * pCoeffs, |
| q15_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(q15_t)); |
| |
| /* Assign state pointer */ |
| S->pState = pState; |
| |
| status = ARM_MATH_SUCCESS; |
| } |
| |
| return (status); |
| } |
| |
| /** |
| @} end of FIR_Interpolate group |
| */ |