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/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_cfft_init_f32.c
* Description: Split Radix Decimation in Frequency CFFT Floating point processing function
*
* $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"
#include "arm_common_tables.h"
/**
* @ingroup groupTransforms
*/
/**
* @addtogroup RealFFT
* @{
*/
/**
* @brief Initialization function for the floating-point real FFT.
* @param[in,out] *S points to an arm_rfft_fast_instance_f32 structure.
* @param[in] fftLen length of the Real Sequence.
* @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.
*
* \par Description:
* \par
* The parameter <code>fftLen</code> Specifies length of RFFT/CIFFT process. Supported FFT Lengths are 32, 64, 128, 256, 512, 1024, 2048, 4096.
* \par
* This Function also initializes Twiddle factor table pointer and Bit reversal table pointer.
*/
arm_status arm_rfft_fast_init_f32(
arm_rfft_fast_instance_f32 * S,
uint16_t fftLen)
{
arm_cfft_instance_f32 * Sint;
/* Initialise the default arm status */
arm_status status = ARM_MATH_SUCCESS;
/* Initialise the FFT length */
Sint = &(S->Sint);
Sint->fftLen = fftLen/2;
S->fftLenRFFT = fftLen;
/* Initializations of structure parameters depending on the FFT length */
switch (Sint->fftLen)
{
case 2048U:
/* Initializations of structure parameters for 2048 point FFT */
/* Initialise the bit reversal table length */
Sint->bitRevLength = ARMBITREVINDEXTABLE_2048_TABLE_LENGTH;
/* Initialise the bit reversal table pointer */
Sint->pBitRevTable = (uint16_t *)armBitRevIndexTable2048;
/* Initialise the Twiddle coefficient pointers */
Sint->pTwiddle = (float32_t *) twiddleCoef_2048;
S->pTwiddleRFFT = (float32_t *) twiddleCoef_rfft_4096;
break;
case 1024U:
Sint->bitRevLength = ARMBITREVINDEXTABLE_1024_TABLE_LENGTH;
Sint->pBitRevTable = (uint16_t *)armBitRevIndexTable1024;
Sint->pTwiddle = (float32_t *) twiddleCoef_1024;
S->pTwiddleRFFT = (float32_t *) twiddleCoef_rfft_2048;
break;
case 512U:
Sint->bitRevLength = ARMBITREVINDEXTABLE_512_TABLE_LENGTH;
Sint->pBitRevTable = (uint16_t *)armBitRevIndexTable512;
Sint->pTwiddle = (float32_t *) twiddleCoef_512;
S->pTwiddleRFFT = (float32_t *) twiddleCoef_rfft_1024;
break;
case 256U:
Sint->bitRevLength = ARMBITREVINDEXTABLE_256_TABLE_LENGTH;
Sint->pBitRevTable = (uint16_t *)armBitRevIndexTable256;
Sint->pTwiddle = (float32_t *) twiddleCoef_256;
S->pTwiddleRFFT = (float32_t *) twiddleCoef_rfft_512;
break;
case 128U:
Sint->bitRevLength = ARMBITREVINDEXTABLE_128_TABLE_LENGTH;
Sint->pBitRevTable = (uint16_t *)armBitRevIndexTable128;
Sint->pTwiddle = (float32_t *) twiddleCoef_128;
S->pTwiddleRFFT = (float32_t *) twiddleCoef_rfft_256;
break;
case 64U:
Sint->bitRevLength = ARMBITREVINDEXTABLE_64_TABLE_LENGTH;
Sint->pBitRevTable = (uint16_t *)armBitRevIndexTable64;
Sint->pTwiddle = (float32_t *) twiddleCoef_64;
S->pTwiddleRFFT = (float32_t *) twiddleCoef_rfft_128;
break;
case 32U:
Sint->bitRevLength = ARMBITREVINDEXTABLE_32_TABLE_LENGTH;
Sint->pBitRevTable = (uint16_t *)armBitRevIndexTable32;
Sint->pTwiddle = (float32_t *) twiddleCoef_32;
S->pTwiddleRFFT = (float32_t *) twiddleCoef_rfft_64;
break;
case 16U:
Sint->bitRevLength = ARMBITREVINDEXTABLE_16_TABLE_LENGTH;
Sint->pBitRevTable = (uint16_t *)armBitRevIndexTable16;
Sint->pTwiddle = (float32_t *) twiddleCoef_16;
S->pTwiddleRFFT = (float32_t *) twiddleCoef_rfft_32;
break;
default:
/* Reporting argument error if fftSize is not valid value */
status = ARM_MATH_ARGUMENT_ERROR;
break;
}
return (status);
}
/**
* @} end of RealFFT group
*/
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