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/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_rfft_init_f32.c
* Description: RFFT & RIFFT Floating point initialisation function
*
* $Date: 18. March 2019
* $Revision: V1.6.0
*
* Target Processor: Cortex-M cores
* -------------------------------------------------------------------- */
/*
* Copyright (C) 2010-2019 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"
/**
@addtogroup RealFFT
@{
*/
/**
@brief Initialization function for the floating-point RFFT/RIFFT.
@deprecated Do not use this function. It has been superceded by \ref arm_rfft_fast_init_f32 and will be removed in the future.
@param[in,out] S points to an instance of the floating-point RFFT/RIFFT structure
@param[in,out] S_CFFT points to an instance of the floating-point CFFT/CIFFT structure
@param[in] fftLenReal length of the FFT.
@param[in] ifftFlagR flag that selects transform direction
- value = 0: forward transform
- value = 1: inverse transform
@param[in] bitReverseFlag flag that enables / disables bit reversal of output
- value = 0: disables bit reversal of output
- value = 1: enables bit reversal of output
@return execution status
- \ref ARM_MATH_SUCCESS : Operation successful
- \ref ARM_MATH_ARGUMENT_ERROR : <code>fftLenReal</code> is not a supported length
@par Description
The parameter <code>fftLenReal</code>specifies length of RFFT/RIFFT Process.
Supported FFT Lengths are 128, 512, 2048.
@par
The parameter <code>ifftFlagR</code> controls whether a forward or inverse transform is computed.
Set(=1) ifftFlagR to calculate RIFFT, otherwise RFFT is calculated.
@par
The parameter <code>bitReverseFlag</code> controls whether output is in normal order or bit reversed order.
Set(=1) bitReverseFlag for output to be in normal order otherwise output is in bit reversed order.
@par
This function also initializes Twiddle factor table.
*/
arm_status arm_rfft_init_f32(
arm_rfft_instance_f32 * S,
arm_cfft_radix4_instance_f32 * S_CFFT,
uint32_t fftLenReal,
uint32_t ifftFlagR,
uint32_t bitReverseFlag)
{
/* Initialise the default arm status */
arm_status status = ARM_MATH_SUCCESS;
/* Initialize the Real FFT length */
S->fftLenReal = (uint16_t) fftLenReal;
/* Initialize the Complex FFT length */
S->fftLenBy2 = (uint16_t) fftLenReal / 2U;
/* Initialize the Twiddle coefficientA pointer */
S->pTwiddleAReal = (float32_t *) realCoefA;
/* Initialize the Twiddle coefficientB pointer */
S->pTwiddleBReal = (float32_t *) realCoefB;
/* Initialize the Flag for selection of RFFT or RIFFT */
S->ifftFlagR = (uint8_t) ifftFlagR;
/* Initialize the Flag for calculation Bit reversal or not */
S->bitReverseFlagR = (uint8_t) bitReverseFlag;
/* Initializations of structure parameters depending on the FFT length */
switch (S->fftLenReal)
{
/* Init table modifier value */
case 8192U:
S->twidCoefRModifier = 1U;
break;
case 2048U:
S->twidCoefRModifier = 4U;
break;
case 512U:
S->twidCoefRModifier = 16U;
break;
case 128U:
S->twidCoefRModifier = 64U;
break;
default:
/* Reporting argument error if rfftSize is not valid value */
status = ARM_MATH_ARGUMENT_ERROR;
break;
}
/* Init Complex FFT Instance */
S->pCfft = S_CFFT;
if (S->ifftFlagR)
{
/* Initializes the CIFFT Module for fftLenreal/2 length */
arm_cfft_radix4_init_f32(S->pCfft, S->fftLenBy2, 1U, 0U);
}
else
{
/* Initializes the CFFT Module for fftLenreal/2 length */
arm_cfft_radix4_init_f32(S->pCfft, S->fftLenBy2, 0U, 0U);
}
/* return the status of RFFT Init function */
return (status);
}
/**
@} end of RealFFT group
*/
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