arm_cfft_radix2_init_f32.c

00001 /* ----------------------------------------------------------------------
00002  * Project:      CMSIS DSP Library
00003  * Title:        arm_cfft_radix2_init_f32.c
00004  * Description:  Radix-2 Decimation in Frequency Floating-point CFFT & CIFFT Initialization function
00005  *
00006  * $Date:        27. January 2017
00007  * $Revision:    V.1.5.1
00008  *
00009  * Target Processor: Cortex-M cores
00010  * -------------------------------------------------------------------- */
00011 /*
00012  * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
00013  *
00014  * SPDX-License-Identifier: Apache-2.0
00015  *
00016  * Licensed under the Apache License, Version 2.0 (the License); you may
00017  * not use this file except in compliance with the License.
00018  * You may obtain a copy of the License at
00019  *
00020  * www.apache.org/licenses/LICENSE-2.0
00021  *
00022  * Unless required by applicable law or agreed to in writing, software
00023  * distributed under the License is distributed on an AS IS BASIS, WITHOUT
00024  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00025  * See the License for the specific language governing permissions and
00026  * limitations under the License.
00027  */
00028 
00029 #include "arm_math.h"
00030 #include "arm_common_tables.h"
00031 
00032 /**
00033  * @ingroup groupTransforms
00034  */
00035 
00036 /**
00037  * @addtogroup ComplexFFT
00038  * @{
00039  */
00040 
00041 /**
00042 * @brief  Initialization function for the floating-point CFFT/CIFFT.
00043 * @deprecated Do not use this function.  It has been superseded by \ref arm_cfft_f32 and will be removed
00044 * in the future.
00045 * @param[in,out] *S             points to an instance of the floating-point CFFT/CIFFT structure.
00046 * @param[in]     fftLen         length of the FFT.
00047 * @param[in]     ifftFlag       flag that selects forward (ifftFlag=0) or inverse (ifftFlag=1) transform.
00048 * @param[in]     bitReverseFlag flag that enables (bitReverseFlag=1) or disables (bitReverseFlag=0) bit reversal of output.
00049 * @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.
00050 *
00051 * \par Description:
00052 * \par
00053 * The parameter <code>ifftFlag</code> controls whether a forward or inverse transform is computed.
00054 * Set(=1) ifftFlag for calculation of CIFFT otherwise  CFFT is calculated
00055 * \par
00056 * The parameter <code>bitReverseFlag</code> controls whether output is in normal order or bit reversed order.
00057 * Set(=1) bitReverseFlag for output to be in normal order otherwise output is in bit reversed order.
00058 * \par
00059 * The parameter <code>fftLen</code> Specifies length of CFFT/CIFFT process. Supported FFT Lengths are 16, 64, 256, 1024.
00060 * \par
00061 * This Function also initializes Twiddle factor table pointer and Bit reversal table pointer.
00062 */
00063 arm_status arm_cfft_radix2_init_f32(
00064   arm_cfft_radix2_instance_f32 * S,
00065   uint16_t fftLen,
00066   uint8_t ifftFlag,
00067   uint8_t bitReverseFlag)
00068 {
00069   /*  Initialise the default arm status */
00070   arm_status status = ARM_MATH_SUCCESS;
00071 
00072   /*  Initialise the FFT length */
00073   S->fftLen = fftLen;
00074 
00075   /*  Initialise the Twiddle coefficient pointer */
00076   S->pTwiddle = (float32_t *) twiddleCoef;
00077 
00078   /*  Initialise the Flag for selection of CFFT or CIFFT */
00079   S->ifftFlag = ifftFlag;
00080 
00081   /*  Initialise the Flag for calculation Bit reversal or not */
00082   S->bitReverseFlag = bitReverseFlag;
00083 
00084   /*  Initializations of structure parameters depending on the FFT length */
00085   switch (S->fftLen)
00086   {
00087 
00088   case 4096U:
00089     /*  Initializations of structure parameters for 4096 point FFT */
00090 
00091     /*  Initialise the twiddle coef modifier value */
00092     S->twidCoefModifier = 1U;
00093     /*  Initialise the bit reversal table modifier */
00094     S->bitRevFactor = 1U;
00095     /*  Initialise the bit reversal table pointer */
00096     S->pBitRevTable = (uint16_t *) armBitRevTable ;
00097     /*  Initialise the 1/fftLen Value */
00098     S->onebyfftLen = 0.000244140625;
00099     break;
00100 
00101   case 2048U:
00102     /*  Initializations of structure parameters for 2048 point FFT */
00103 
00104     /*  Initialise the twiddle coef modifier value */
00105     S->twidCoefModifier = 2U;
00106     /*  Initialise the bit reversal table modifier */
00107     S->bitRevFactor = 2U;
00108     /*  Initialise the bit reversal table pointer */
00109     S->pBitRevTable = (uint16_t *) & armBitRevTable [1];
00110     /*  Initialise the 1/fftLen Value */
00111     S->onebyfftLen = 0.00048828125;
00112     break;
00113 
00114   case 1024U:
00115     /*  Initializations of structure parameters for 1024 point FFT */
00116 
00117     /*  Initialise the twiddle coef modifier value */
00118     S->twidCoefModifier = 4U;
00119     /*  Initialise the bit reversal table modifier */
00120     S->bitRevFactor = 4U;
00121     /*  Initialise the bit reversal table pointer */
00122     S->pBitRevTable = (uint16_t *) & armBitRevTable [3];
00123     /*  Initialise the 1/fftLen Value */
00124     S->onebyfftLen = 0.0009765625f;
00125     break;
00126 
00127   case 512U:
00128     /*  Initializations of structure parameters for 512 point FFT */
00129 
00130     /*  Initialise the twiddle coef modifier value */
00131     S->twidCoefModifier = 8U;
00132     /*  Initialise the bit reversal table modifier */
00133     S->bitRevFactor = 8U;
00134     /*  Initialise the bit reversal table pointer */
00135     S->pBitRevTable = (uint16_t *) & armBitRevTable [7];
00136     /*  Initialise the 1/fftLen Value */
00137     S->onebyfftLen = 0.001953125;
00138     break;
00139 
00140   case 256U:
00141     /*  Initializations of structure parameters for 256 point FFT */
00142     S->twidCoefModifier = 16U;
00143     S->bitRevFactor = 16U;
00144     S->pBitRevTable = (uint16_t *) & armBitRevTable [15];
00145     S->onebyfftLen = 0.00390625f;
00146     break;
00147 
00148   case 128U:
00149     /*  Initializations of structure parameters for 128 point FFT */
00150     S->twidCoefModifier = 32U;
00151     S->bitRevFactor = 32U;
00152     S->pBitRevTable = (uint16_t *) & armBitRevTable [31];
00153     S->onebyfftLen = 0.0078125;
00154     break;
00155 
00156   case 64U:
00157     /*  Initializations of structure parameters for 64 point FFT */
00158     S->twidCoefModifier = 64U;
00159     S->bitRevFactor = 64U;
00160     S->pBitRevTable = (uint16_t *) & armBitRevTable [63];
00161     S->onebyfftLen = 0.015625f;
00162     break;
00163 
00164   case 32U:
00165     /*  Initializations of structure parameters for 64 point FFT */
00166     S->twidCoefModifier = 128U;
00167     S->bitRevFactor = 128U;
00168     S->pBitRevTable = (uint16_t *) & armBitRevTable [127];
00169     S->onebyfftLen = 0.03125;
00170     break;
00171 
00172   case 16U:
00173     /*  Initializations of structure parameters for 16 point FFT */
00174     S->twidCoefModifier = 256U;
00175     S->bitRevFactor = 256U;
00176     S->pBitRevTable = (uint16_t *) & armBitRevTable [255];
00177     S->onebyfftLen = 0.0625f;
00178     break;
00179 
00180 
00181   default:
00182     /*  Reporting argument error if fftSize is not valid value */
00183     status = ARM_MATH_ARGUMENT_ERROR;
00184     break;
00185   }
00186 
00187   return (status);
00188 }
00189 
00190 /**
00191  * @} end of ComplexFFT group
00192  */
00193