The CMSIS DSP 5 library
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functions/FilteringFunctions/arm_fir_decimate_init_q31.c
- Committer:
- xorjoep
- Date:
- 2018-06-21
- Revision:
- 3:4098b9d3d571
- Parent:
- 1:24714b45cd1b
File content as of revision 3:4098b9d3d571:
/* ---------------------------------------------------------------------- * Project: CMSIS DSP Library * Title: arm_fir_decimate_init_q31.c * Description: Initialization function for Q31 FIR Decimation filter * * $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_decimate * @{ */ /** * @brief Initialization function for the Q31 FIR decimator. * @param[in,out] *S points to an instance of the Q31 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 per call. * @return The function returns ARM_MATH_SUCCESS if initialization was successful or ARM_MATH_LENGTH_ERROR if * <code>blockSize</code> is not a multiple of <code>M</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[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 passed to <code>arm_fir_decimate_q31()</code>. * <code>M</code> is the decimation factor. */ arm_status arm_fir_decimate_init_q31( arm_fir_decimate_instance_q31 * S, uint16_t numTaps, uint8_t M, q31_t * pCoeffs, q31_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 - 1)) * sizeof(q31_t)); /* Assign state pointer */ S->pState = pState; /* Assign Decimation factor */ S->M = M; status = ARM_MATH_SUCCESS; } return (status); } /** * @} end of FIR_decimate group */