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The CMSIS DSP 5 library

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functions/FilteringFunctions/arm_fir_interpolate_init_q15.c@3:4098b9d3d571, 2018-06-21 (annotated)

Committer:
xorjoep
Date:
Thu Jun 21 11:56:27 2018 +0000
Revision:
3:4098b9d3d571
Parent:
1:24714b45cd1b 
headers is a folder not a library

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xorjoep 1:24714b45cd1b 1 /* ----------------------------------------------------------------------
xorjoep 1:24714b45cd1b 2 * Project: CMSIS DSP Library
xorjoep 1:24714b45cd1b 3 * Title: arm_fir_interpolate_init_q15.c
xorjoep 1:24714b45cd1b 4 * Description: Q15 FIR interpolator initialization function
xorjoep 1:24714b45cd1b 5 *
xorjoep 1:24714b45cd1b 6 * $Date: 27. January 2017
xorjoep 1:24714b45cd1b 7 * $Revision: V.1.5.1
xorjoep 1:24714b45cd1b 8 *
xorjoep 1:24714b45cd1b 9 * Target Processor: Cortex-M cores
xorjoep 1:24714b45cd1b 10 * -------------------------------------------------------------------- */
xorjoep 1:24714b45cd1b 11 /*
xorjoep 1:24714b45cd1b 12 * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
xorjoep 1:24714b45cd1b 13 *
xorjoep 1:24714b45cd1b 14 * SPDX-License-Identifier: Apache-2.0
xorjoep 1:24714b45cd1b 15 *
xorjoep 1:24714b45cd1b 16 * Licensed under the Apache License, Version 2.0 (the License); you may
xorjoep 1:24714b45cd1b 17 * not use this file except in compliance with the License.
xorjoep 1:24714b45cd1b 18 * You may obtain a copy of the License at
xorjoep 1:24714b45cd1b 19 *
xorjoep 1:24714b45cd1b 20 * www.apache.org/licenses/LICENSE-2.0
xorjoep 1:24714b45cd1b 21 *
xorjoep 1:24714b45cd1b 22 * Unless required by applicable law or agreed to in writing, software
xorjoep 1:24714b45cd1b 23 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
xorjoep 1:24714b45cd1b 24 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
xorjoep 1:24714b45cd1b 25 * See the License for the specific language governing permissions and
xorjoep 1:24714b45cd1b 26 * limitations under the License.
xorjoep 1:24714b45cd1b 27 */
xorjoep 1:24714b45cd1b 28
xorjoep 1:24714b45cd1b 29 #include "arm_math.h"
xorjoep 1:24714b45cd1b 30
xorjoep 1:24714b45cd1b 31 /**
xorjoep 1:24714b45cd1b 32 * @ingroup groupFilters
xorjoep 1:24714b45cd1b 33 */
xorjoep 1:24714b45cd1b 34
xorjoep 1:24714b45cd1b 35 /**
xorjoep 1:24714b45cd1b 36 * @addtogroup FIR_Interpolate
xorjoep 1:24714b45cd1b 37 * @{
xorjoep 1:24714b45cd1b 38 */
xorjoep 1:24714b45cd1b 39
xorjoep 1:24714b45cd1b 40 /**
xorjoep 1:24714b45cd1b 41 * @brief Initialization function for the Q15 FIR interpolator.
xorjoep 1:24714b45cd1b 42 * @param[in,out] *S points to an instance of the Q15 FIR interpolator structure.
xorjoep 1:24714b45cd1b 43 * @param[in] L upsample factor.
xorjoep 1:24714b45cd1b 44 * @param[in] numTaps number of filter coefficients in the filter.
xorjoep 1:24714b45cd1b 45 * @param[in] *pCoeffs points to the filter coefficient buffer.
xorjoep 1:24714b45cd1b 46 * @param[in] *pState points to the state buffer.
xorjoep 1:24714b45cd1b 47 * @param[in] blockSize number of input samples to process per call.
xorjoep 1:24714b45cd1b 48 * @return The function returns ARM_MATH_SUCCESS if initialization was successful or ARM_MATH_LENGTH_ERROR if
xorjoep 1:24714b45cd1b 49 * the filter length <code>numTaps</code> is not a multiple of the interpolation factor <code>L</code>.
xorjoep 1:24714b45cd1b 50 *
xorjoep 1:24714b45cd1b 51 * <b>Description:</b>
xorjoep 1:24714b45cd1b 52 * \par
xorjoep 1:24714b45cd1b 53 * <code>pCoeffs</code> points to the array of filter coefficients stored in time reversed order:
xorjoep 1:24714b45cd1b 54 * <pre>
xorjoep 1:24714b45cd1b 55 * {b[numTaps-1], b[numTaps-2], b[numTaps-2], ..., b[1], b[0]}
xorjoep 1:24714b45cd1b 56 * </pre>
xorjoep 1:24714b45cd1b 57 * The length of the filter <code>numTaps</code> must be a multiple of the interpolation factor <code>L</code>.
xorjoep 1:24714b45cd1b 58 * \par
xorjoep 1:24714b45cd1b 59 * <code>pState</code> points to the array of state variables.
xorjoep 1:24714b45cd1b 60 * <code>pState</code> is of length <code>(numTaps/L)+blockSize-1</code> words
xorjoep 1:24714b45cd1b 61 * where <code>blockSize</code> is the number of input samples processed by each call to <code>arm_fir_interpolate_q15()</code>.
xorjoep 1:24714b45cd1b 62 */
xorjoep 1:24714b45cd1b 63
xorjoep 1:24714b45cd1b 64 arm_status arm_fir_interpolate_init_q15(
xorjoep 1:24714b45cd1b 65 arm_fir_interpolate_instance_q15 * S,
xorjoep 1:24714b45cd1b 66 uint8_t L,
xorjoep 1:24714b45cd1b 67 uint16_t numTaps,
xorjoep 1:24714b45cd1b 68 q15_t * pCoeffs,
xorjoep 1:24714b45cd1b 69 q15_t * pState,
xorjoep 1:24714b45cd1b 70 uint32_t blockSize)
xorjoep 1:24714b45cd1b 71 {
xorjoep 1:24714b45cd1b 72 arm_status status;
xorjoep 1:24714b45cd1b 73
xorjoep 1:24714b45cd1b 74 /* The filter length must be a multiple of the interpolation factor */
xorjoep 1:24714b45cd1b 75 if ((numTaps % L) != 0U)
xorjoep 1:24714b45cd1b 76 {
xorjoep 1:24714b45cd1b 77 /* Set status as ARM_MATH_LENGTH_ERROR */
xorjoep 1:24714b45cd1b 78 status = ARM_MATH_LENGTH_ERROR;
xorjoep 1:24714b45cd1b 79 }
xorjoep 1:24714b45cd1b 80 else
xorjoep 1:24714b45cd1b 81 {
xorjoep 1:24714b45cd1b 82
xorjoep 1:24714b45cd1b 83 /* Assign coefficient pointer */
xorjoep 1:24714b45cd1b 84 S->pCoeffs = pCoeffs;
xorjoep 1:24714b45cd1b 85
xorjoep 1:24714b45cd1b 86 /* Assign Interpolation factor */
xorjoep 1:24714b45cd1b 87 S->L = L;
xorjoep 1:24714b45cd1b 88
xorjoep 1:24714b45cd1b 89 /* Assign polyPhaseLength */
xorjoep 1:24714b45cd1b 90 S->phaseLength = numTaps / L;
xorjoep 1:24714b45cd1b 91
xorjoep 1:24714b45cd1b 92 /* Clear state buffer and size of buffer is always phaseLength + blockSize - 1 */
xorjoep 1:24714b45cd1b 93 memset(pState, 0,
xorjoep 1:24714b45cd1b 94 (blockSize + ((uint32_t) S->phaseLength - 1U)) * sizeof(q15_t));
xorjoep 1:24714b45cd1b 95
xorjoep 1:24714b45cd1b 96 /* Assign state pointer */
xorjoep 1:24714b45cd1b 97 S->pState = pState;
xorjoep 1:24714b45cd1b 98
xorjoep 1:24714b45cd1b 99 status = ARM_MATH_SUCCESS;
xorjoep 1:24714b45cd1b 100 }
xorjoep 1:24714b45cd1b 101
xorjoep 1:24714b45cd1b 102 return (status);
xorjoep 1:24714b45cd1b 103
xorjoep 1:24714b45cd1b 104 }
xorjoep 1:24714b45cd1b 105
xorjoep 1:24714b45cd1b 106 /**
xorjoep 1:24714b45cd1b 107 * @} end of FIR_Interpolate group
xorjoep 1:24714b45cd1b 108 */