/* ----------------------------------------------------------------------
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* Project: CMSIS DSP Library
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* Title: arm_cfft_radix2_init_q15.c
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* Description: Radix-2 Decimation in Frequency Q15 FFT & IFFT initialization function
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*
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* $Date: 27. January 2017
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* $Revision: V.1.5.1
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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) 2010-2017 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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#include "arm_common_tables.h"
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/**
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* @ingroup groupTransforms
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*/
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/**
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* @addtogroup ComplexFFT
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* @{
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*/
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/**
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* @brief Initialization function for the Q15 CFFT/CIFFT.
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* @deprecated Do not use this function. It has been superseded by \ref arm_cfft_q15 and will be removed
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* @param[in,out] *S points to an instance of the Q15 CFFT/CIFFT structure.
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* @param[in] fftLen length of the FFT.
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* @param[in] ifftFlag flag that selects forward (ifftFlag=0) or inverse (ifftFlag=1) transform.
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* @param[in] bitReverseFlag flag that enables (bitReverseFlag=1) or disables (bitReverseFlag=0) bit reversal of output.
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* @return The function returns ARM_MATH_SUCCESS if initialization is successful or ARM_MATH_ARGUMENT_ERROR if <code>fftLen</code> is not a supported value.
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*
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* \par Description:
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* \par
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* The parameter <code>ifftFlag</code> controls whether a forward or inverse transform is computed.
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* Set(=1) ifftFlag for calculation of CIFFT otherwise CFFT is calculated
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* \par
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* The parameter <code>bitReverseFlag</code> controls whether output is in normal order or bit reversed order.
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* Set(=1) bitReverseFlag for output to be in normal order otherwise output is in bit reversed order.
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* \par
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* The parameter <code>fftLen</code> Specifies length of CFFT/CIFFT process. Supported FFT Lengths are 16, 64, 256, 1024.
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* \par
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* This Function also initializes Twiddle factor table pointer and Bit reversal table pointer.
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*/
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arm_status arm_cfft_radix2_init_q15(
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arm_cfft_radix2_instance_q15 * S,
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uint16_t fftLen,
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uint8_t ifftFlag,
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uint8_t bitReverseFlag)
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{
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/* Initialise the default arm status */
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arm_status status = ARM_MATH_SUCCESS;
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/* Initialise the FFT length */
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S->fftLen = fftLen;
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/* Initialise the Twiddle coefficient pointer */
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S->pTwiddle = (q15_t *) twiddleCoef_4096_q15;
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/* Initialise the Flag for selection of CFFT or CIFFT */
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S->ifftFlag = ifftFlag;
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/* Initialise the Flag for calculation Bit reversal or not */
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S->bitReverseFlag = bitReverseFlag;
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/* Initializations of structure parameters depending on the FFT length */
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switch (S->fftLen)
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{
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case 4096U:
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/* Initializations of structure parameters for 4096 point FFT */
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/* Initialise the twiddle coef modifier value */
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S->twidCoefModifier = 1U;
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/* Initialise the bit reversal table modifier */
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S->bitRevFactor = 1U;
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/* Initialise the bit reversal table pointer */
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S->pBitRevTable = (uint16_t *) armBitRevTable;
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break;
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case 2048U:
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/* Initializations of structure parameters for 2048 point FFT */
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/* Initialise the twiddle coef modifier value */
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S->twidCoefModifier = 2U;
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/* Initialise the bit reversal table modifier */
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S->bitRevFactor = 2U;
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/* Initialise the bit reversal table pointer */
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S->pBitRevTable = (uint16_t *) & armBitRevTable[1];
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break;
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case 1024U:
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/* Initializations of structure parameters for 1024 point FFT */
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S->twidCoefModifier = 4U;
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S->bitRevFactor = 4U;
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S->pBitRevTable = (uint16_t *) & armBitRevTable[3];
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break;
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case 512U:
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/* Initializations of structure parameters for 512 point FFT */
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S->twidCoefModifier = 8U;
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S->bitRevFactor = 8U;
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S->pBitRevTable = (uint16_t *) & armBitRevTable[7];
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break;
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case 256U:
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/* Initializations of structure parameters for 256 point FFT */
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S->twidCoefModifier = 16U;
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S->bitRevFactor = 16U;
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S->pBitRevTable = (uint16_t *) & armBitRevTable[15];
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break;
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case 128U:
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/* Initializations of structure parameters for 128 point FFT */
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S->twidCoefModifier = 32U;
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S->bitRevFactor = 32U;
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S->pBitRevTable = (uint16_t *) & armBitRevTable[31];
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break;
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case 64U:
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/* Initializations of structure parameters for 64 point FFT */
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S->twidCoefModifier = 64U;
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S->bitRevFactor = 64U;
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S->pBitRevTable = (uint16_t *) & armBitRevTable[63];
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break;
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case 32U:
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/* Initializations of structure parameters for 32 point FFT */
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S->twidCoefModifier = 128U;
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S->bitRevFactor = 128U;
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S->pBitRevTable = (uint16_t *) & armBitRevTable[127];
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break;
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case 16U:
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/* Initializations of structure parameters for 16 point FFT */
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S->twidCoefModifier = 256U;
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S->bitRevFactor = 256U;
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S->pBitRevTable = (uint16_t *) & armBitRevTable[255];
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break;
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default:
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/* Reporting argument error if fftSize is not valid value */
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status = ARM_MATH_ARGUMENT_ERROR;
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break;
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}
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return (status);
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}
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/**
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* @} end of ComplexFFT group
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*/
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