arm_cfft_radix4_init_q15.c

00001 /* ----------------------------------------------------------------------
00002  * Project:      CMSIS DSP Library
00003  * Title:        arm_cfft_radix4_init_q15.c
00004  * Description:  Radix-4 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 /**
00044 * @brief Initialization function for the Q15 CFFT/CIFFT.
00045 * @deprecated Do not use this function.  It has been superseded by \ref arm_cfft_q15 and will be removed
00046 * @param[in,out] *S             points to an instance of the Q15 CFFT/CIFFT structure.
00047 * @param[in]     fftLen         length of the FFT.
00048 * @param[in]     ifftFlag       flag that selects forward (ifftFlag=0) or inverse (ifftFlag=1) transform.
00049 * @param[in]     bitReverseFlag flag that enables (bitReverseFlag=1) or disables (bitReverseFlag=0) bit reversal of output.
00050 * @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.
00051 *
00052 * \par Description:
00053 * \par
00054 * The parameter <code>ifftFlag</code> controls whether a forward or inverse transform is computed.
00055 * Set(=1) ifftFlag for calculation of CIFFT otherwise  CFFT is calculated
00056 * \par
00057 * The parameter <code>bitReverseFlag</code> controls whether output is in normal order or bit reversed order.
00058 * Set(=1) bitReverseFlag for output to be in normal order otherwise output is in bit reversed order.
00059 * \par
00060 * The parameter <code>fftLen</code> Specifies length of CFFT/CIFFT process. Supported FFT Lengths are 16, 64, 256, 1024.
00061 * \par
00062 * This Function also initializes Twiddle factor table pointer and Bit reversal table pointer.
00063 */
00064 
00065 arm_status arm_cfft_radix4_init_q15(
00066   arm_cfft_radix4_instance_q15 * S,
00067   uint16_t fftLen,
00068   uint8_t ifftFlag,
00069   uint8_t bitReverseFlag)
00070 {
00071   /*  Initialise the default arm status */
00072   arm_status status = ARM_MATH_SUCCESS;
00073   /*  Initialise the FFT length */
00074   S->fftLen = fftLen;
00075   /*  Initialise the Twiddle coefficient pointer */
00076   S->pTwiddle = (q15_t *) twiddleCoef_4096_q15 ;
00077   /*  Initialise the Flag for selection of CFFT or CIFFT */
00078   S->ifftFlag = ifftFlag;
00079   /*  Initialise the Flag for calculation Bit reversal or not */
00080   S->bitReverseFlag = bitReverseFlag;
00081 
00082   /*  Initializations of structure parameters depending on the FFT length */
00083   switch (S->fftLen)
00084   {
00085   case 4096U:
00086     /*  Initializations of structure parameters for 4096 point FFT */
00087 
00088     /*  Initialise the twiddle coef modifier value */
00089     S->twidCoefModifier = 1U;
00090     /*  Initialise the bit reversal table modifier */
00091     S->bitRevFactor = 1U;
00092     /*  Initialise the bit reversal table pointer */
00093     S->pBitRevTable = (uint16_t *) armBitRevTable ;
00094 
00095     break;
00096 
00097   case 1024U:
00098     /*  Initializations of structure parameters for 1024 point FFT */
00099     S->twidCoefModifier = 4U;
00100     S->bitRevFactor = 4U;
00101     S->pBitRevTable = (uint16_t *) & armBitRevTable [3];
00102 
00103     break;
00104 
00105   case 256U:
00106     /*  Initializations of structure parameters for 256 point FFT */
00107     S->twidCoefModifier = 16U;
00108     S->bitRevFactor = 16U;
00109     S->pBitRevTable = (uint16_t *) & armBitRevTable [15];
00110 
00111     break;
00112 
00113   case 64U:
00114     /*  Initializations of structure parameters for 64 point FFT */
00115     S->twidCoefModifier = 64U;
00116     S->bitRevFactor = 64U;
00117     S->pBitRevTable = (uint16_t *) & armBitRevTable [63];
00118 
00119     break;
00120 
00121   case 16U:
00122     /*  Initializations of structure parameters for 16 point FFT */
00123     S->twidCoefModifier = 256U;
00124     S->bitRevFactor = 256U;
00125     S->pBitRevTable = (uint16_t *) & armBitRevTable [255];
00126 
00127     break;
00128 
00129   default:
00130     /*  Reporting argument error if fftSize is not valid value */
00131     status = ARM_MATH_ARGUMENT_ERROR;
00132     break;
00133   }
00134 
00135   return (status);
00136 }
00137 
00138 /**
00139  * @} end of ComplexFFT group
00140  */
00141