arm_cfft_radix2_init_q31.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_radix2_init_q31.c   
00009 *   
00010 * Description:  Radix-2 Decimation in Frequency Fixed-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 /**    
00056 *    
00057 * @brief  Initialization function for the Q31 CFFT/CIFFT.   
00058 * @param[in,out] *S             points to an instance of the Q31 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 
00077 arm_status arm_cfft_radix2_init_q31(
00078   arm_cfft_radix2_instance_q31 * S,
00079   uint16_t fftLen,
00080   uint8_t ifftFlag,
00081   uint8_t bitReverseFlag)
00082 {
00083   /*  Initialise the default arm status */
00084   arm_status status = ARM_MATH_SUCCESS;
00085 
00086   /*  Initialise the FFT length */
00087   S->fftLen = fftLen;
00088 
00089   /*  Initialise the Twiddle coefficient pointer */
00090   S->pTwiddle = (q31_t *) twiddleCoefQ31 ;
00091   /*  Initialise the Flag for selection of CFFT or CIFFT */
00092   S->ifftFlag = ifftFlag;
00093   /*  Initialise the Flag for calculation Bit reversal or not */
00094   S->bitReverseFlag = bitReverseFlag;
00095 
00096   /*  Initializations of Instance structure depending on the FFT length */
00097   switch (S->fftLen)
00098   {
00099     /*  Initializations of structure parameters for 4096 point FFT */
00100   case 4096u:
00101     /*  Initialise the twiddle coef modifier value */
00102     S->twidCoefModifier = 1u;
00103     /*  Initialise the bit reversal table modifier */
00104     S->bitRevFactor = 1u;
00105     /*  Initialise the bit reversal table pointer */
00106     S->pBitRevTable = (uint16_t *) armBitRevTable ;
00107     break;
00108 
00109     /*  Initializations of structure parameters for 2048 point FFT */
00110   case 2048u:
00111     /*  Initialise the twiddle coef modifier value */
00112     S->twidCoefModifier = 2u;
00113     /*  Initialise the bit reversal table modifier */
00114     S->bitRevFactor = 2u;
00115     /*  Initialise the bit reversal table pointer */
00116     S->pBitRevTable = (uint16_t *) & armBitRevTable [1];
00117     break;
00118 
00119     /*  Initializations of structure parameters for 1024 point FFT */
00120   case 1024u:
00121     /*  Initialise the twiddle coef modifier value */
00122     S->twidCoefModifier = 4u;
00123     /*  Initialise the bit reversal table modifier */
00124     S->bitRevFactor = 4u;
00125     /*  Initialise the bit reversal table pointer */
00126     S->pBitRevTable = (uint16_t *) & armBitRevTable [3];
00127     break;
00128 
00129     /*  Initializations of structure parameters for 512 point FFT */
00130   case 512u:
00131     /*  Initialise the twiddle coef modifier value */
00132     S->twidCoefModifier = 8u;
00133     /*  Initialise the bit reversal table modifier */
00134     S->bitRevFactor = 8u;
00135     /*  Initialise the bit reversal table pointer */
00136     S->pBitRevTable = (uint16_t *) & armBitRevTable [7];
00137     break;
00138 
00139   case 256u:
00140     /*  Initializations of structure parameters for 256 point FFT */
00141     S->twidCoefModifier = 16u;
00142     S->bitRevFactor = 16u;
00143     S->pBitRevTable = (uint16_t *) & armBitRevTable [15];
00144     break;
00145 
00146   case 128u:
00147     /*  Initializations of structure parameters for 128 point FFT */
00148     S->twidCoefModifier = 32u;
00149     S->bitRevFactor = 32u;
00150     S->pBitRevTable = (uint16_t *) & armBitRevTable [31];
00151     break;
00152 
00153   case 64u:
00154     /*  Initializations of structure parameters for 64 point FFT */
00155     S->twidCoefModifier = 64u;
00156     S->bitRevFactor = 64u;
00157     S->pBitRevTable = (uint16_t *) & armBitRevTable [63];
00158     break;
00159 
00160   case 32u:
00161     /*  Initializations of structure parameters for 32 point FFT */
00162     S->twidCoefModifier = 128u;
00163     S->bitRevFactor = 128u;
00164     S->pBitRevTable = (uint16_t *) & armBitRevTable [127];
00165     break;
00166 
00167   case 16u:
00168     /*  Initializations of structure parameters for 16 point FFT */
00169     S->twidCoefModifier = 256u;
00170     S->bitRevFactor = 256u;
00171     S->pBitRevTable = (uint16_t *) & armBitRevTable [255];
00172     break;
00173 
00174 
00175   default:
00176     /*  Reporting argument error if fftSize is not valid value */
00177     status = ARM_MATH_ARGUMENT_ERROR;
00178     break;
00179   }
00180 
00181   return (status);
00182 }
00183 
00184 /**   
00185  * @} end of ComplexFFT group   
00186  */