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 It has been superceded by \ref arm_rfft_fast_init_f32 and will be removed in the future.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