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/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_cfft_radix4_init_q31.c
* Description: Radix-4 Decimation in Frequency Q31 FFT & IFFT initialization 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"
/**
@ingroup groupTransforms
*/
/**
@addtogroup ComplexFFT
@{
*/
/**
@brief Initialization function for the Q31 CFFT/CIFFT.
@deprecated Do not use this function. It has been superseded by \ref arm_cfft_q31 and will be removed in the future.
@param[in,out] S points to an instance of the Q31 CFFT/CIFFT structure.
@param[in] fftLen length of the FFT.
@param[in] ifftFlag 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>fftLen</code> is not a supported length
@par Details
The parameter <code>ifftFlag</code> controls whether a forward or inverse transform is computed.
Set(=1) ifftFlag for calculation of CIFFT otherwise CFFT 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
The parameter <code>fftLen</code> Specifies length of CFFT/CIFFT process. Supported FFT Lengths are 16, 64, 256, 1024.
@par
This Function also initializes Twiddle factor table pointer and Bit reversal table pointer.
*/
arm_status arm_cfft_radix4_init_q31(
arm_cfft_radix4_instance_q31 * S,
uint16_t fftLen,
uint8_t ifftFlag,
uint8_t bitReverseFlag)
{
/* Initialise the default arm status */
arm_status status = ARM_MATH_SUCCESS;
/* Initialise the FFT length */
S->fftLen = fftLen;
/* Initialise the Twiddle coefficient pointer */
S->pTwiddle = (q31_t *) twiddleCoef_4096_q31;
/* Initialise the Flag for selection of CFFT or CIFFT */
S->ifftFlag = ifftFlag;
/* Initialise the Flag for calculation Bit reversal or not */
S->bitReverseFlag = bitReverseFlag;
/* Initializations of Instance structure depending on the FFT length */
switch (S->fftLen)
{
/* Initializations of structure parameters for 4096 point FFT */
case 4096U:
/* Initialise the twiddle coef modifier value */
S->twidCoefModifier = 1U;
/* Initialise the bit reversal table modifier */
S->bitRevFactor = 1U;
/* Initialise the bit reversal table pointer */
S->pBitRevTable = (uint16_t *) armBitRevTable;
break;
/* Initializations of structure parameters for 1024 point FFT */
case 1024U:
/* Initialise the twiddle coef modifier value */
S->twidCoefModifier = 4U;
/* Initialise the bit reversal table modifier */
S->bitRevFactor = 4U;
/* Initialise the bit reversal table pointer */
S->pBitRevTable = (uint16_t *) & armBitRevTable[3];
break;
case 256U:
/* Initializations of structure parameters for 256 point FFT */
S->twidCoefModifier = 16U;
S->bitRevFactor = 16U;
S->pBitRevTable = (uint16_t *) & armBitRevTable[15];
break;
case 64U:
/* Initializations of structure parameters for 64 point FFT */
S->twidCoefModifier = 64U;
S->bitRevFactor = 64U;
S->pBitRevTable = (uint16_t *) & armBitRevTable[63];
break;
case 16U:
/* Initializations of structure parameters for 16 point FFT */
S->twidCoefModifier = 256U;
S->bitRevFactor = 256U;
S->pBitRevTable = (uint16_t *) & armBitRevTable[255];
break;
default:
/* Reporting argument error if fftSize is not valid value */
status = ARM_MATH_ARGUMENT_ERROR;
break;
}
return (status);
}
/**
@} end of ComplexFFT group
*/
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