The CMSIS DSP 5 library
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functions/TransformFunctions/arm_cfft_radix4_init_f32.c
- Committer:
- xorjoep
- Date:
- 2018-06-21
- Revision:
- 3:4098b9d3d571
- Parent:
- 1:24714b45cd1b
File content as of revision 3:4098b9d3d571:
/* ---------------------------------------------------------------------- * Project: CMSIS DSP Library * Title: arm_cfft_radix4_init_f32.c * Description: Radix-4 Decimation in Frequency Floating-point CFFT & CIFFT Initialization function * * $Date: 27. January 2017 * $Revision: V.1.5.1 * * Target Processor: Cortex-M cores * -------------------------------------------------------------------- */ /* * Copyright (C) 2010-2017 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 floating-point CFFT/CIFFT. * @deprecated Do not use this function. It has been superceded by \ref arm_cfft_f32 and will be removed * in the future. * @param[in,out] *S points to an instance of the floating-point CFFT/CIFFT structure. * @param[in] fftLen length of the FFT. * @param[in] ifftFlag flag that selects forward (ifftFlag=0) or inverse (ifftFlag=1) transform. * @param[in] bitReverseFlag flag that enables (bitReverseFlag=1) or disables (bitReverseFlag=0) bit reversal of output. * @return The function returns ARM_MATH_SUCCESS if initialization is successful or ARM_MATH_ARGUMENT_ERROR if <code>fftLen</code> is not a supported value. * * \par Description: * \par * 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_f32( arm_cfft_radix4_instance_f32 * 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 = (float32_t *) twiddleCoef; /* 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; /* Initialise the 1/fftLen Value */ S->onebyfftLen = 0.000244140625; break; case 1024U: /* Initializations of structure parameters for 1024 point FFT */ /* 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]; /* Initialise the 1/fftLen Value */ S->onebyfftLen = 0.0009765625f; break; case 256U: /* Initializations of structure parameters for 256 point FFT */ S->twidCoefModifier = 16U; S->bitRevFactor = 16U; S->pBitRevTable = (uint16_t *) & armBitRevTable[15]; S->onebyfftLen = 0.00390625f; break; case 64U: /* Initializations of structure parameters for 64 point FFT */ S->twidCoefModifier = 64U; S->bitRevFactor = 64U; S->pBitRevTable = (uint16_t *) & armBitRevTable[63]; S->onebyfftLen = 0.015625f; break; case 16U: /* Initializations of structure parameters for 16 point FFT */ S->twidCoefModifier = 256U; S->bitRevFactor = 256U; S->pBitRevTable = (uint16_t *) & armBitRevTable[255]; S->onebyfftLen = 0.0625f; break; default: /* Reporting argument error if fftSize is not valid value */ status = ARM_MATH_ARGUMENT_ERROR; break; } return (status); } /** * @} end of ComplexFFT group */