arm_cfft_radix2_init_q15.c

00001 /* ----------------------------------------------------------------------
00002  * Project:      CMSIS DSP Library
00003  * Title:        arm_cfft_radix2_init_q15.c
00004  * Description:  Radix-2 Decimation in Frequency Q15 FFT & IFFT 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 /**
00038  * @addtogroup ComplexFFT
00039  * @{
00040  */
00041 
00042 /**
00043 * @brief Initialization function for the Q15 CFFT/CIFFT.
00044 * @deprecated Do not use this function.  It has been superseded by \ref arm_cfft_q15 and will be removed
00045 * @param[in,out] *S             points to an instance of the Q15 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 
00064 arm_status arm_cfft_radix2_init_q15(
00065   arm_cfft_radix2_instance_q15 * S,
00066   uint16_t fftLen,
00067   uint8_t ifftFlag,
00068   uint8_t bitReverseFlag)
00069 {
00070   /*  Initialise the default arm status */
00071   arm_status status = ARM_MATH_SUCCESS;
00072 
00073   /*  Initialise the FFT length */
00074   S->fftLen = fftLen;
00075 
00076   /*  Initialise the Twiddle coefficient pointer */
00077   S->pTwiddle = (q15_t *) twiddleCoef_4096_q15 ;
00078   /*  Initialise the Flag for selection of CFFT or CIFFT */
00079   S->ifftFlag = ifftFlag;
00080   /*  Initialise the Flag for calculation Bit reversal or not */
00081   S->bitReverseFlag = bitReverseFlag;
00082 
00083   /*  Initializations of structure parameters depending on the FFT length */
00084   switch (S->fftLen)
00085   {
00086   case 4096U:
00087     /*  Initializations of structure parameters for 4096 point FFT */
00088 
00089     /*  Initialise the twiddle coef modifier value */
00090     S->twidCoefModifier = 1U;
00091     /*  Initialise the bit reversal table modifier */
00092     S->bitRevFactor = 1U;
00093     /*  Initialise the bit reversal table pointer */
00094     S->pBitRevTable = (uint16_t *) armBitRevTable ;
00095 
00096     break;
00097 
00098   case 2048U:
00099     /*  Initializations of structure parameters for 2048 point FFT */
00100 
00101     /*  Initialise the twiddle coef modifier value */
00102     S->twidCoefModifier = 2U;
00103     /*  Initialise the bit reversal table modifier */
00104     S->bitRevFactor = 2U;
00105     /*  Initialise the bit reversal table pointer */
00106     S->pBitRevTable = (uint16_t *) & armBitRevTable [1];
00107 
00108     break;
00109 
00110   case 1024U:
00111     /*  Initializations of structure parameters for 1024 point FFT */
00112     S->twidCoefModifier = 4U;
00113     S->bitRevFactor = 4U;
00114     S->pBitRevTable = (uint16_t *) & armBitRevTable [3];
00115 
00116     break;
00117 
00118   case 512U:
00119     /*  Initializations of structure parameters for 512 point FFT */
00120     S->twidCoefModifier = 8U;
00121     S->bitRevFactor = 8U;
00122     S->pBitRevTable = (uint16_t *) & armBitRevTable [7];
00123 
00124     break;
00125 
00126   case 256U:
00127     /*  Initializations of structure parameters for 256 point FFT */
00128     S->twidCoefModifier = 16U;
00129     S->bitRevFactor = 16U;
00130     S->pBitRevTable = (uint16_t *) & armBitRevTable [15];
00131 
00132     break;
00133 
00134   case 128U:
00135     /*  Initializations of structure parameters for 128 point FFT */
00136     S->twidCoefModifier = 32U;
00137     S->bitRevFactor = 32U;
00138     S->pBitRevTable = (uint16_t *) & armBitRevTable [31];
00139 
00140     break;
00141 
00142   case 64U:
00143     /*  Initializations of structure parameters for 64 point FFT */
00144     S->twidCoefModifier = 64U;
00145     S->bitRevFactor = 64U;
00146     S->pBitRevTable = (uint16_t *) & armBitRevTable [63];
00147 
00148     break;
00149 
00150   case 32U:
00151     /*  Initializations of structure parameters for 32 point FFT */
00152     S->twidCoefModifier = 128U;
00153     S->bitRevFactor = 128U;
00154     S->pBitRevTable = (uint16_t *) & armBitRevTable [127];
00155 
00156     break;
00157 
00158   case 16U:
00159     /*  Initializations of structure parameters for 16 point FFT */
00160     S->twidCoefModifier = 256U;
00161     S->bitRevFactor = 256U;
00162     S->pBitRevTable = (uint16_t *) & armBitRevTable [255];
00163 
00164     break;
00165 
00166   default:
00167     /*  Reporting argument error if fftSize is not valid value */
00168     status = ARM_MATH_ARGUMENT_ERROR;
00169     break;
00170   }
00171 
00172   return (status);
00173 }
00174 
00175 /**
00176  * @} end of ComplexFFT group
00177  */
00178