arm_cfft_radix2_init_f32.c

00001 /* ----------------------------------------------------------------------   
00002 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.   
00003 *   
00004 * $Date:        17. January 2013  
00005 * $Revision:    V1.4.1  
00006 *   
00007 * Project:      CMSIS DSP Library   
00008 * Title:        arm_cfft_radix4_init_f32.c   
00009 *   
00010 * Description:  Radix-4 Decimation in Frequency Floating-point CFFT & CIFFT Initialization function   
00011 *   
00012 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
00013 *  
00014 * Redistribution and use in source and binary forms, with or without 
00015 * modification, are permitted provided that the following conditions
00016 * are met:
00017 *   - Redistributions of source code must retain the above copyright
00018 *     notice, this list of conditions and the following disclaimer.
00019 *   - Redistributions in binary form must reproduce the above copyright
00020 *     notice, this list of conditions and the following disclaimer in
00021 *     the documentation and/or other materials provided with the 
00022 *     distribution.
00023 *   - Neither the name of ARM LIMITED nor the names of its contributors
00024 *     may be used to endorse or promote products derived from this
00025 *     software without specific prior written permission.
00026 *
00027 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
00028 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
00029 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
00030 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
00031 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
00032 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
00033 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
00034 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
00035 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
00036 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
00037 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
00038 * POSSIBILITY OF SUCH DAMAGE.  
00039 * -------------------------------------------------------------------- */
00040 
00041 
00042 #include "arm_math.h"
00043 #include "arm_common_tables.h"
00044 
00045 /**   
00046  * @ingroup groupTransforms   
00047  */
00048 
00049 /**   
00050  * @addtogroup ComplexFFT   
00051  * @{   
00052  */
00053 
00054 /**   
00055 * @brief  Initialization function for the floating-point CFFT/CIFFT.  
00056 * @deprecated Do not use this function.  It has been superceded by \ref arm_cfft_f32 and will be removed
00057 * in the future.
00058 * @param[in,out] *S             points to an instance of the floating-point CFFT/CIFFT structure.  
00059 * @param[in]     fftLen         length of the FFT.  
00060 * @param[in]     ifftFlag       flag that selects forward (ifftFlag=0) or inverse (ifftFlag=1) transform.  
00061 * @param[in]     bitReverseFlag flag that enables (bitReverseFlag=1) or disables (bitReverseFlag=0) bit reversal of output.  
00062 * @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.  
00063 *   
00064 * \par Description:  
00065 * \par   
00066 * The parameter <code>ifftFlag</code> controls whether a forward or inverse transform is computed.   
00067 * Set(=1) ifftFlag for calculation of CIFFT otherwise  CFFT is calculated  
00068 * \par   
00069 * The parameter <code>bitReverseFlag</code> controls whether output is in normal order or bit reversed order.   
00070 * Set(=1) bitReverseFlag for output to be in normal order otherwise output is in bit reversed order.   
00071 * \par   
00072 * The parameter <code>fftLen</code> Specifies length of CFFT/CIFFT process. Supported FFT Lengths are 16, 64, 256, 1024.   
00073 * \par   
00074 * This Function also initializes Twiddle factor table pointer and Bit reversal table pointer.   
00075 */
00076 arm_status arm_cfft_radix2_init_f32(
00077   arm_cfft_radix2_instance_f32 * S,
00078   uint16_t fftLen,
00079   uint8_t ifftFlag,
00080   uint8_t bitReverseFlag)
00081 {
00082   /*  Initialise the default arm status */
00083   arm_status status = ARM_MATH_SUCCESS;
00084 
00085   /*  Initialise the FFT length */
00086   S->fftLen = fftLen;
00087 
00088   /*  Initialise the Twiddle coefficient pointer */
00089   S->pTwiddle = (float32_t *) twiddleCoef;
00090 
00091   /*  Initialise the Flag for selection of CFFT or CIFFT */
00092   S->ifftFlag = ifftFlag;
00093 
00094   /*  Initialise the Flag for calculation Bit reversal or not */
00095   S->bitReverseFlag = bitReverseFlag;
00096 
00097   /*  Initializations of structure parameters depending on the FFT length */
00098   switch (S->fftLen)
00099   {
00100 
00101   case 4096u:
00102     /*  Initializations of structure parameters for 4096 point FFT */
00103 
00104     /*  Initialise the twiddle coef modifier value */
00105     S->twidCoefModifier = 1u;
00106     /*  Initialise the bit reversal table modifier */
00107     S->bitRevFactor = 1u;
00108     /*  Initialise the bit reversal table pointer */
00109     S->pBitRevTable = (uint16_t *) armBitRevTable ;
00110     /*  Initialise the 1/fftLen Value */
00111     S->onebyfftLen = 0.000244140625;
00112     break;
00113 
00114   case 2048u:
00115     /*  Initializations of structure parameters for 2048 point FFT */
00116 
00117     /*  Initialise the twiddle coef modifier value */
00118     S->twidCoefModifier = 2u;
00119     /*  Initialise the bit reversal table modifier */
00120     S->bitRevFactor = 2u;
00121     /*  Initialise the bit reversal table pointer */
00122     S->pBitRevTable = (uint16_t *) & armBitRevTable [1];
00123     /*  Initialise the 1/fftLen Value */
00124     S->onebyfftLen = 0.00048828125;
00125     break;
00126 
00127   case 1024u:
00128     /*  Initializations of structure parameters for 1024 point FFT */
00129 
00130     /*  Initialise the twiddle coef modifier value */
00131     S->twidCoefModifier = 4u;
00132     /*  Initialise the bit reversal table modifier */
00133     S->bitRevFactor = 4u;
00134     /*  Initialise the bit reversal table pointer */
00135     S->pBitRevTable = (uint16_t *) & armBitRevTable [3];
00136     /*  Initialise the 1/fftLen Value */
00137     S->onebyfftLen = 0.0009765625f;
00138     break;
00139 
00140   case 512u:
00141     /*  Initializations of structure parameters for 512 point FFT */
00142 
00143     /*  Initialise the twiddle coef modifier value */
00144     S->twidCoefModifier = 8u;
00145     /*  Initialise the bit reversal table modifier */
00146     S->bitRevFactor = 8u;
00147     /*  Initialise the bit reversal table pointer */
00148     S->pBitRevTable = (uint16_t *) & armBitRevTable [7];
00149     /*  Initialise the 1/fftLen Value */
00150     S->onebyfftLen = 0.001953125;
00151     break;
00152 
00153   case 256u:
00154     /*  Initializations of structure parameters for 256 point FFT */
00155     S->twidCoefModifier = 16u;
00156     S->bitRevFactor = 16u;
00157     S->pBitRevTable = (uint16_t *) & armBitRevTable [15];
00158     S->onebyfftLen = 0.00390625f;
00159     break;
00160 
00161   case 128u:
00162     /*  Initializations of structure parameters for 128 point FFT */
00163     S->twidCoefModifier = 32u;
00164     S->bitRevFactor = 32u;
00165     S->pBitRevTable = (uint16_t *) & armBitRevTable [31];
00166     S->onebyfftLen = 0.0078125;
00167     break;
00168 
00169   case 64u:
00170     /*  Initializations of structure parameters for 64 point FFT */
00171     S->twidCoefModifier = 64u;
00172     S->bitRevFactor = 64u;
00173     S->pBitRevTable = (uint16_t *) & armBitRevTable [63];
00174     S->onebyfftLen = 0.015625f;
00175     break;
00176 
00177   case 32u:
00178     /*  Initializations of structure parameters for 64 point FFT */
00179     S->twidCoefModifier = 128u;
00180     S->bitRevFactor = 128u;
00181     S->pBitRevTable = (uint16_t *) & armBitRevTable [127];
00182     S->onebyfftLen = 0.03125;
00183     break;
00184 
00185   case 16u:
00186     /*  Initializations of structure parameters for 16 point FFT */
00187     S->twidCoefModifier = 256u;
00188     S->bitRevFactor = 256u;
00189     S->pBitRevTable = (uint16_t *) & armBitRevTable [255];
00190     S->onebyfftLen = 0.0625f;
00191     break;
00192 
00193 
00194   default:
00195     /*  Reporting argument error if fftSize is not valid value */
00196     status = ARM_MATH_ARGUMENT_ERROR;
00197     break;
00198   }
00199 
00200   return (status);
00201 }
00202 
00203 /**   
00204  * @} end of ComplexFFT group   
00205  */