| /* ---------------------------------------------------------------------- |
| * Project: CMSIS DSP Library |
| * Title: arm_cfft_radix4_init_q15.c |
| * Description: Radix-4 Decimation in Frequency Q15 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 Q15 CFFT/CIFFT. |
| @deprecated Do not use this function. It has been superseded by \ref arm_cfft_q15 and will be removed in the future. |
| @param[in,out] S points to an instance of the Q15 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_q15( |
| arm_cfft_radix4_instance_q15 * 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 = (q15_t *) twiddleCoef_4096_q15; |
| /* 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 structure parameters depending on the FFT length */ |
| switch (S->fftLen) |
| { |
| case 4096U: |
| /* Initializations of structure parameters for 4096 point FFT */ |
| |
| /* 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; |
| |
| case 1024U: |
| /* Initializations of structure parameters for 1024 point FFT */ |
| S->twidCoefModifier = 4U; |
| S->bitRevFactor = 4U; |
| 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 |
| */ |