/* ----------------------------------------------------------------------
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* Project: CMSIS DSP Library
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* Title: arm_cfft_init_f32.c
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* Description: Split Radix Decimation in Frequency CFFT Floating point processing 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 RealFFT
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* @{
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*/
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/**
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* @brief Initialization function for the floating-point real FFT.
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* @param[in,out] *S points to an arm_rfft_fast_instance_f32 structure.
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* @param[in] fftLen length of the Real Sequence.
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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>fftLen</code> Specifies length of RFFT/CIFFT process. Supported FFT Lengths are 32, 64, 128, 256, 512, 1024, 2048, 4096.
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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_rfft_fast_init_f32(
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arm_rfft_fast_instance_f32 * S,
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uint16_t fftLen)
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{
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arm_cfft_instance_f32 * Sint;
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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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Sint = &(S->Sint);
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Sint->fftLen = fftLen/2;
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S->fftLenRFFT = fftLen;
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/* Initializations of structure parameters depending on the FFT length */
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switch (Sint->fftLen)
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{
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case 2048U:
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/* Initializations of structure parameters for 2048 point FFT */
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/* Initialise the bit reversal table length */
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Sint->bitRevLength = ARMBITREVINDEXTABLE_2048_TABLE_LENGTH;
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/* Initialise the bit reversal table pointer */
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Sint->pBitRevTable = (uint16_t *)armBitRevIndexTable2048;
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/* Initialise the Twiddle coefficient pointers */
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Sint->pTwiddle = (float32_t *) twiddleCoef_2048;
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S->pTwiddleRFFT = (float32_t *) twiddleCoef_rfft_4096;
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break;
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case 1024U:
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Sint->bitRevLength = ARMBITREVINDEXTABLE_1024_TABLE_LENGTH;
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Sint->pBitRevTable = (uint16_t *)armBitRevIndexTable1024;
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Sint->pTwiddle = (float32_t *) twiddleCoef_1024;
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S->pTwiddleRFFT = (float32_t *) twiddleCoef_rfft_2048;
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break;
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case 512U:
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Sint->bitRevLength = ARMBITREVINDEXTABLE_512_TABLE_LENGTH;
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Sint->pBitRevTable = (uint16_t *)armBitRevIndexTable512;
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Sint->pTwiddle = (float32_t *) twiddleCoef_512;
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S->pTwiddleRFFT = (float32_t *) twiddleCoef_rfft_1024;
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break;
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case 256U:
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Sint->bitRevLength = ARMBITREVINDEXTABLE_256_TABLE_LENGTH;
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Sint->pBitRevTable = (uint16_t *)armBitRevIndexTable256;
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Sint->pTwiddle = (float32_t *) twiddleCoef_256;
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S->pTwiddleRFFT = (float32_t *) twiddleCoef_rfft_512;
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break;
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case 128U:
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Sint->bitRevLength = ARMBITREVINDEXTABLE_128_TABLE_LENGTH;
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Sint->pBitRevTable = (uint16_t *)armBitRevIndexTable128;
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Sint->pTwiddle = (float32_t *) twiddleCoef_128;
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S->pTwiddleRFFT = (float32_t *) twiddleCoef_rfft_256;
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break;
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case 64U:
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Sint->bitRevLength = ARMBITREVINDEXTABLE_64_TABLE_LENGTH;
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Sint->pBitRevTable = (uint16_t *)armBitRevIndexTable64;
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Sint->pTwiddle = (float32_t *) twiddleCoef_64;
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S->pTwiddleRFFT = (float32_t *) twiddleCoef_rfft_128;
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break;
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case 32U:
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Sint->bitRevLength = ARMBITREVINDEXTABLE_32_TABLE_LENGTH;
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Sint->pBitRevTable = (uint16_t *)armBitRevIndexTable32;
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Sint->pTwiddle = (float32_t *) twiddleCoef_32;
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S->pTwiddleRFFT = (float32_t *) twiddleCoef_rfft_64;
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break;
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case 16U:
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Sint->bitRevLength = ARMBITREVINDEXTABLE_16_TABLE_LENGTH;
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Sint->pBitRevTable = (uint16_t *)armBitRevIndexTable16;
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Sint->pTwiddle = (float32_t *) twiddleCoef_16;
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S->pTwiddleRFFT = (float32_t *) twiddleCoef_rfft_32;
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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 RealFFT group
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*/
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