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/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_rfft_init_q15.c
* Description: RFFT & RIFFT Q15 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"
#include "arm_const_structs.h"
/**
@addtogroup RealFFT
@{
*/
/**
@brief Initialization function for the Q15 RFFT/RIFFT.
@param[in,out] S points to an instance of the Q15 RFFT/RIFFT 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 Details
The parameter <code>fftLenReal</code> specifies length of RFFT/RIFFT Process.
Supported FFT Lengths are 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192.
@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_q15(
arm_rfft_instance_q15 * S,
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 Twiddle coefficientA pointer */
S->pTwiddleAReal = (q15_t *) realCoefAQ15;
/* Initialize the Twiddle coefficientB pointer */
S->pTwiddleBReal = (q15_t *) realCoefBQ15;
/* 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;
/* Initialization of coef modifier depending on the FFT length */
switch (S->fftLenReal)
{
#if !defined(ARM_DSP_CONFIG_TABLES) || defined(ARM_ALL_FFT_TABLES) || (defined(ARM_TABLE_TWIDDLECOEF_Q15_4096) && defined(ARM_TABLE_BITREVIDX_FXT_4096))
case 8192U:
S->twidCoefRModifier = 1U;
S->pCfft = &arm_cfft_sR_q15_len4096;
break;
#endif
#if !defined(ARM_DSP_CONFIG_TABLES) || defined(ARM_ALL_FFT_TABLES) || (defined(ARM_TABLE_TWIDDLECOEF_Q15_2048) && defined(ARM_TABLE_BITREVIDX_FXT_2048))
case 4096U:
S->twidCoefRModifier = 2U;
S->pCfft = &arm_cfft_sR_q15_len2048;
break;
#endif
#if !defined(ARM_DSP_CONFIG_TABLES) || defined(ARM_ALL_FFT_TABLES) || (defined(ARM_TABLE_TWIDDLECOEF_Q15_1024) && defined(ARM_TABLE_BITREVIDX_FXT_1024))
case 2048U:
S->twidCoefRModifier = 4U;
S->pCfft = &arm_cfft_sR_q15_len1024;
break;
#endif
#if !defined(ARM_DSP_CONFIG_TABLES) || defined(ARM_ALL_FFT_TABLES) || (defined(ARM_TABLE_TWIDDLECOEF_Q15_512) && defined(ARM_TABLE_BITREVIDX_FXT_512))
case 1024U:
S->twidCoefRModifier = 8U;
S->pCfft = &arm_cfft_sR_q15_len512;
break;
#endif
#if !defined(ARM_DSP_CONFIG_TABLES) || defined(ARM_ALL_FFT_TABLES) || (defined(ARM_TABLE_TWIDDLECOEF_Q15_256) && defined(ARM_TABLE_BITREVIDX_FXT_256))
case 512U:
S->twidCoefRModifier = 16U;
S->pCfft = &arm_cfft_sR_q15_len256;
break;
#endif
#if !defined(ARM_DSP_CONFIG_TABLES) || defined(ARM_ALL_FFT_TABLES) || (defined(ARM_TABLE_TWIDDLECOEF_Q15_128) && defined(ARM_TABLE_BITREVIDX_FXT_128))
case 256U:
S->twidCoefRModifier = 32U;
S->pCfft = &arm_cfft_sR_q15_len128;
break;
#endif
#if !defined(ARM_DSP_CONFIG_TABLES) || defined(ARM_ALL_FFT_TABLES) || (defined(ARM_TABLE_TWIDDLECOEF_Q15_64) && defined(ARM_TABLE_BITREVIDX_FXT_64))
case 128U:
S->twidCoefRModifier = 64U;
S->pCfft = &arm_cfft_sR_q15_len64;
break;
#endif
#if !defined(ARM_DSP_CONFIG_TABLES) || defined(ARM_ALL_FFT_TABLES) || (defined(ARM_TABLE_TWIDDLECOEF_Q15_32) && defined(ARM_TABLE_BITREVIDX_FXT_32))
case 64U:
S->twidCoefRModifier = 128U;
S->pCfft = &arm_cfft_sR_q15_len32;
break;
#endif
#if !defined(ARM_DSP_CONFIG_TABLES) || defined(ARM_ALL_FFT_TABLES) || (defined(ARM_TABLE_TWIDDLECOEF_Q15_16) && defined(ARM_TABLE_BITREVIDX_FXT_16))
case 32U:
S->twidCoefRModifier = 256U;
S->pCfft = &arm_cfft_sR_q15_len16;
break;
#endif
default:
/* Reporting argument error if rfftSize is not valid value */
status = ARM_MATH_ARGUMENT_ERROR;
break;
}
/* return the status of RFFT Init function */
return (status);
}
/**
@} end of RealFFT group
*/
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