tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/TransformFunctions/arm_cfft_radix2_init_q31.c

   1 /* ----------------------------------------------------------------------
   2 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
   3 *
   4 * $Date:        17. January 2013
   5 * $Revision:    V1.4.1
   6 *
   7 * Project:          CMSIS DSP Library
   8 * Title:            arm_cfft_radix2_init_q31.c
   9 *
  10 * Description:  Radix-2 Decimation in Frequency Fixed-point CFFT & CIFFT Initialization function
  11 *
  12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
  13 *
  14 * Redistribution and use in source and binary forms, with or without
  15 * modification, are permitted provided that the following conditions
  16 * are met:
  17 *   - Redistributions of source code must retain the above copyright
  18 *     notice, this list of conditions and the following disclaimer.
  19 *   - Redistributions in binary form must reproduce the above copyright
  20 *     notice, this list of conditions and the following disclaimer in
  21 *     the documentation and/or other materials provided with the
  22 *     distribution.
  23 *   - Neither the name of ARM LIMITED nor the names of its contributors
  24 *     may be used to endorse or promote products derived from this
  25 *     software without specific prior written permission.
  26 *
  27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  38 * POSSIBILITY OF SUCH DAMAGE.
  39 * -------------------------------------------------------------------- */
  40
  41
  42 #include "arm_math.h"
  43 #include "arm_common_tables.h"
  44
  45 /**
  46  * @ingroup groupTransforms
  47  */
  48
  49 /**
  50  * @addtogroup ComplexFFT
  51  * @{
  52  */
  53
  54
  55 /**
  56 *
  57 * @brief  Initialization function for the Q31 CFFT/CIFFT.
  58 * @param[in,out] *S             points to an instance of the Q31 CFFT/CIFFT structure.
  59 * @param[in]     fftLen         length of the FFT.
  60 * @param[in]     ifftFlag       flag that selects forward (ifftFlag=0) or inverse (ifftFlag=1) transform.
  61 * @param[in]     bitReverseFlag flag that enables (bitReverseFlag=1) or disables (bitReverseFlag=0) bit reversal of output.
  62 * @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.
  63 *
  64 * \par Description:
  65 * \par
  66 * The parameter <code>ifftFlag</code> controls whether a forward or inverse transform is computed.
  67 * Set(=1) ifftFlag for calculation of CIFFT otherwise  CFFT is calculated
  68 * \par
  69 * The parameter <code>bitReverseFlag</code> controls whether output is in normal order or bit reversed order.
  70 * Set(=1) bitReverseFlag for output to be in normal order otherwise output is in bit reversed order.
  71 * \par
  72 * The parameter <code>fftLen</code>     Specifies length of CFFT/CIFFT process. Supported FFT Lengths are 16, 64, 256, 1024.
  73 * \par
  74 * This Function also initializes Twiddle factor table pointer and Bit reversal table pointer.
  75 */
  76
  77 arm_status arm_cfft_radix2_init_q31(
  78   arm_cfft_radix2_instance_q31 * S,
  79   uint16_t fftLen,
  80   uint8_t ifftFlag,
  81   uint8_t bitReverseFlag)
  82 {
  83   /*  Initialise the default arm status */
  84   arm_status status = ARM_MATH_SUCCESS;
  85
  86   /*  Initialise the FFT length */
  87   S->fftLen = fftLen;
  88
  89   /*  Initialise the Twiddle coefficient pointer */
  90   S->pTwiddle = (q31_t *) twiddleCoefQ31;
  91   /*  Initialise the Flag for selection of CFFT or CIFFT */
  92   S->ifftFlag = ifftFlag;
  93   /*  Initialise the Flag for calculation Bit reversal or not */
  94   S->bitReverseFlag = bitReverseFlag;
  95
  96   /*  Initializations of Instance structure depending on the FFT length */
  97   switch (S->fftLen)
  98   {
  99     /*  Initializations of structure parameters for 4096 point FFT */
 100   case 4096u:
 101     /*  Initialise the twiddle coef modifier value */
 102     S->twidCoefModifier = 1u;
 103     /*  Initialise the bit reversal table modifier */
 104     S->bitRevFactor = 1u;
 105     /*  Initialise the bit reversal table pointer */
 106     S->pBitRevTable = (uint16_t *) armBitRevTable;
 107     break;
 108
 109     /*  Initializations of structure parameters for 2048 point FFT */
 110   case 2048u:
 111     /*  Initialise the twiddle coef modifier value */
 112     S->twidCoefModifier = 2u;
 113     /*  Initialise the bit reversal table modifier */
 114     S->bitRevFactor = 2u;
 115     /*  Initialise the bit reversal table pointer */
 116     S->pBitRevTable = (uint16_t *) & armBitRevTable[1];
 117     break;
 118
 119     /*  Initializations of structure parameters for 1024 point FFT */
 120   case 1024u:
 121     /*  Initialise the twiddle coef modifier value */
 122     S->twidCoefModifier = 4u;
 123     /*  Initialise the bit reversal table modifier */
 124     S->bitRevFactor = 4u;
 125     /*  Initialise the bit reversal table pointer */
 126     S->pBitRevTable = (uint16_t *) & armBitRevTable[3];
 127     break;
 128
 129     /*  Initializations of structure parameters for 512 point FFT */
 130   case 512u:
 131     /*  Initialise the twiddle coef modifier value */
 132     S->twidCoefModifier = 8u;
 133     /*  Initialise the bit reversal table modifier */
 134     S->bitRevFactor = 8u;
 135     /*  Initialise the bit reversal table pointer */
 136     S->pBitRevTable = (uint16_t *) & armBitRevTable[7];
 137     break;
 138
 139   case 256u:
 140     /*  Initializations of structure parameters for 256 point FFT */
 141     S->twidCoefModifier = 16u;
 142     S->bitRevFactor = 16u;
 143     S->pBitRevTable = (uint16_t *) & armBitRevTable[15];
 144     break;
 145
 146   case 128u:
 147     /*  Initializations of structure parameters for 128 point FFT */
 148     S->twidCoefModifier = 32u;
 149     S->bitRevFactor = 32u;
 150     S->pBitRevTable = (uint16_t *) & armBitRevTable[31];
 151     break;
 152
 153   case 64u:
 154     /*  Initializations of structure parameters for 64 point FFT */
 155     S->twidCoefModifier = 64u;
 156     S->bitRevFactor = 64u;
 157     S->pBitRevTable = (uint16_t *) & armBitRevTable[63];
 158     break;
 159
 160   case 32u:
 161     /*  Initializations of structure parameters for 32 point FFT */
 162     S->twidCoefModifier = 128u;
 163     S->bitRevFactor = 128u;
 164     S->pBitRevTable = (uint16_t *) & armBitRevTable[127];
 165     break;
 166
 167   case 16u:
 168     /*  Initializations of structure parameters for 16 point FFT */
 169     S->twidCoefModifier = 256u;
 170     S->bitRevFactor = 256u;
 171     S->pBitRevTable = (uint16_t *) & armBitRevTable[255];
 172     break;
 173
 174
 175   default:
 176     /*  Reporting argument error if fftSize is not valid value */
 177     status = ARM_MATH_ARGUMENT_ERROR;
 178     break;
 179   }
 180
 181   return (status);
 182 }
 183
 184 /**
 185  * @} end of ComplexFFT group
 186  */