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  1. /* ----------------------------------------------------------------------
  2.  * Project:      CMSIS DSP Library
  3.  * Title:        arm_rfft_init_f32.c
  4.  * Description:  RFFT & RIFFT Floating point initialisation function
  5.  *
  6.  * $Date:        27. January 2017
  7.  * $Revision:    V.1.5.1
  8.  *
  9.  * Target Processor: Cortex-M cores
  10.  * -------------------------------------------------------------------- */
  11. /*
  12.  * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
  13.  *
  14.  * SPDX-License-Identifier: Apache-2.0
  15.  *
  16.  * Licensed under the Apache License, Version 2.0 (the License); you may
  17.  * not use this file except in compliance with the License.
  18.  * You may obtain a copy of the License at
  19.  *
  20.  * www.apache.org/licenses/LICENSE-2.0
  21.  *
  22.  * Unless required by applicable law or agreed to in writing, software
  23.  * distributed under the License is distributed on an AS IS BASIS, WITHOUT
  24.  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  25.  * See the License for the specific language governing permissions and
  26.  * limitations under the License.
  27.  */
  28.  
  29. #include "arm_math.h"
  30.  
  31. /**
  32.  * @ingroup RealFFT
  33.  */
  34.  
  35. /**
  36.  * @addtogroup RealFFT_Table Real FFT Tables
  37.  * @{
  38.  */
  39.  
  40. /**
  41. * \par
  42. * Generation of realCoefA array:
  43. * \par
  44. *       n = 4096
  45. * <pre>for (i = 0; i < n; i++)
  46. *  {
  47. *    pATable[2 * i] = 0.5 * (1.0 - sin (2 * PI / (double) (2 * n) * (double) i));
  48. *    pATable[2 * i + 1] = 0.5 * (-1.0 * cos (2 * PI / (double) (2 * n) * (double) i));
  49. *  } </pre>
  50. *//**
  51. * \par
  52. * Generation of realCoefB array:
  53. * \par
  54. * n = 4096
  55. * <pre>for (i = 0; i < n; i++)
  56. * {
  57. *    pBTable[2 * i] = 0.5 * (1.0 + sin (2 * PI / (double) (2 * n) * (double) i));
  58. *    pBTable[2 * i + 1] = 0.5 * (1.0 * cos (2 * PI / (double) (2 * n) * (double) i));
  59. *  } </pre>
  60. *
  61. *//**
  62. * @brief  Initialization function for the floating-point RFFT/RIFFT.
  63. * @deprecated Do not use this function.  It has been superceded by \ref arm_rfft_fast_init_f32 and will be removed
  64. * in the future.
  65. * @param[in,out] *S             points to an instance of the floating-point RFFT/RIFFT structure.
  66. * @param[in,out] *S_CFFT        points to an instance of the floating-point CFFT/CIFFT structure.
  67. * @param[in]     fftLenReal     length of the FFT.
  68. * @param[in]     ifftFlagR      flag that selects forward (ifftFlagR=0) or inverse (ifftFlagR=1) transform.
  69. * @param[in]     bitReverseFlag flag that enables (bitReverseFlag=1) or disables (bitReverseFlag=0) bit reversal of output.
  70. * @return        The function returns ARM_MATH_SUCCESS if initialization is successful or ARM_MATH_ARGUMENT_ERROR if <code>fftLenReal</code> is not a supported value.
  71. *
  72. * \par Description:
  73. * \par
  74. * The parameter <code>fftLenReal</code> Specifies length of RFFT/RIFFT Process. Supported FFT Lengths are 128, 512, 2048.
  75. * \par
  76. * The parameter <code>ifftFlagR</code> controls whether a forward or inverse transform is computed.
  77. * Set(=1) ifftFlagR to calculate RIFFT, otherwise RFFT is calculated.
  78. * \par
  79. * The parameter <code>bitReverseFlag</code> controls whether output is in normal order or bit reversed order.
  80. * Set(=1) bitReverseFlag for output to be in normal order otherwise output is in bit reversed order.
  81. * \par
  82. * This function also initializes Twiddle factor table.
  83. */
  84.  
  85. /**
  86. * @} end of RealFFT_Table group
  87. */
  88.  
  89. /**
  90. * @addtogroup RealFFT
  91. * @{
  92. */
  93.  
  94. arm_status arm_rfft_init_f32(
  95.   arm_rfft_instance_f32 * S,
  96.   arm_cfft_radix4_instance_f32 * S_CFFT,
  97.   uint32_t fftLenReal,
  98.   uint32_t ifftFlagR,
  99.   uint32_t bitReverseFlag)
  100. {
  101.  
  102.   /*  Initialise the default arm status */
  103.   arm_status status = ARM_MATH_SUCCESS;
  104.  
  105.   /*  Initialize the Real FFT length */
  106.   S->fftLenReal = (uint16_t) fftLenReal;
  107.  
  108.   /*  Initialize the Complex FFT length */
  109.   S->fftLenBy2 = (uint16_t) fftLenReal / 2U;
  110.  
  111.   /*  Initialize the Twiddle coefficientA pointer */
  112.   S->pTwiddleAReal = (float32_t *) realCoefA;
  113.  
  114.   /*  Initialize the Twiddle coefficientB pointer */
  115.   S->pTwiddleBReal = (float32_t *) realCoefB;
  116.  
  117.   /*  Initialize the Flag for selection of RFFT or RIFFT */
  118.   S->ifftFlagR = (uint8_t) ifftFlagR;
  119.  
  120.   /*  Initialize the Flag for calculation Bit reversal or not */
  121.   S->bitReverseFlagR = (uint8_t) bitReverseFlag;
  122.  
  123.   /*  Initializations of structure parameters depending on the FFT length */
  124.   switch (S->fftLenReal)
  125.   {
  126.     /* Init table modifier value */
  127.   case 8192U:
  128.     S->twidCoefRModifier = 1U;
  129.     break;
  130.   case 2048U:
  131.     S->twidCoefRModifier = 4U;
  132.     break;
  133.   case 512U:
  134.     S->twidCoefRModifier = 16U;
  135.     break;
  136.   case 128U:
  137.     S->twidCoefRModifier = 64U;
  138.     break;
  139.   default:
  140.     /*  Reporting argument error if rfftSize is not valid value */
  141.     status = ARM_MATH_ARGUMENT_ERROR;
  142.     break;
  143.   }
  144.  
  145.   /* Init Complex FFT Instance */
  146.   S->pCfft = S_CFFT;
  147.  
  148.   if (S->ifftFlagR)
  149.   {
  150.     /* Initializes the CIFFT Module for fftLenreal/2 length */
  151.     arm_cfft_radix4_init_f32(S->pCfft, S->fftLenBy2, 1U, 0U);
  152.   }
  153.   else
  154.   {
  155.     /* Initializes the CFFT Module for fftLenreal/2 length */
  156.     arm_cfft_radix4_init_f32(S->pCfft, S->fftLenBy2, 0U, 0U);
  157.   }
  158.  
  159.   /* return the status of RFFT Init function */
  160.   return (status);
  161.  
  162. }
  163.  
  164.   /**
  165.    * @} end of RealFFT group
  166.    */
  167.