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  1. /* ----------------------------------------------------------------------    
  2. * Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
  3. *    
  4. * $Date:        19. March 2015
  5. * $Revision:    V.1.4.5  
  6. *    
  7. * Project:          CMSIS DSP Library    
  8. * Title:            arm_rfft_init_f32.c    
  9. *    
  10. * Description:  RFFT & RIFFT Floating point initialisation 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.  
  44. /**    
  45.  * @ingroup groupTransforms    
  46.  */
  47.  
  48. /**    
  49.  * @addtogroup RealFFT    
  50.  * @{    
  51.  */
  52.  
  53. /**    
  54. * \par    
  55. * Generation of realCoefA array:    
  56. * \par    
  57. *       n = 4096    
  58. * <pre>for (i = 0; i < n; i++)    
  59. *  {    
  60. *    pATable[2 * i] = 0.5 * (1.0 - sin (2 * PI / (double) (2 * n) * (double) i));    
  61. *    pATable[2 * i + 1] = 0.5 * (-1.0 * cos (2 * PI / (double) (2 * n) * (double) i));    
  62. *  } </pre>    
  63. *//**    
  64. * \par  
  65. * Generation of realCoefB array:    
  66. * \par  
  67. * n = 4096    
  68. * <pre>for (i = 0; i < n; i++)    
  69. * {    
  70. *    pBTable[2 * i] = 0.5 * (1.0 + sin (2 * PI / (double) (2 * n) * (double) i));    
  71. *    pBTable[2 * i + 1] = 0.5 * (1.0 * cos (2 * PI / (double) (2 * n) * (double) i));    
  72. *  } </pre>    
  73. *    
  74. *//**    
  75. * @brief  Initialization function for the floating-point RFFT/RIFFT.  
  76. * @deprecated Do not use this function.  It has been superceded by \ref arm_rfft_fast_init_f32 and will be removed
  77. * in the future.
  78. * @param[in,out] *S             points to an instance of the floating-point RFFT/RIFFT structure.  
  79. * @param[in,out] *S_CFFT        points to an instance of the floating-point CFFT/CIFFT structure.  
  80. * @param[in]     fftLenReal     length of the FFT.  
  81. * @param[in]     ifftFlagR      flag that selects forward (ifftFlagR=0) or inverse (ifftFlagR=1) transform.  
  82. * @param[in]     bitReverseFlag flag that enables (bitReverseFlag=1) or disables (bitReverseFlag=0) bit reversal of output.  
  83. * @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.  
  84. *    
  85. * \par Description:  
  86. * \par  
  87. * The parameter <code>fftLenReal</code> Specifies length of RFFT/RIFFT Process. Supported FFT Lengths are 128, 512, 2048.    
  88. * \par    
  89. * The parameter <code>ifftFlagR</code> controls whether a forward or inverse transform is computed.    
  90. * Set(=1) ifftFlagR to calculate RIFFT, otherwise RFFT is calculated.    
  91. * \par    
  92. * The parameter <code>bitReverseFlag</code> controls whether output is in normal order or bit reversed order.    
  93. * Set(=1) bitReverseFlag for output to be in normal order otherwise output is in bit reversed order.  
  94. * \par    
  95. * This function also initializes Twiddle factor table.    
  96. */
  97.  
  98. arm_status arm_rfft_init_f32(
  99.   arm_rfft_instance_f32 * S,
  100.   arm_cfft_radix4_instance_f32 * S_CFFT,
  101.   uint32_t fftLenReal,
  102.   uint32_t ifftFlagR,
  103.   uint32_t bitReverseFlag)
  104. {
  105.  
  106.   /*  Initialise the default arm status */
  107.   arm_status status = ARM_MATH_SUCCESS;
  108.  
  109.   /*  Initialize the Real FFT length */
  110.   S->fftLenReal = (uint16_t) fftLenReal;
  111.  
  112.   /*  Initialize the Complex FFT length */
  113.   S->fftLenBy2 = (uint16_t) fftLenReal / 2u;
  114.  
  115.   /*  Initialize the Twiddle coefficientA pointer */
  116.   S->pTwiddleAReal = (float32_t *) realCoefA;
  117.  
  118.   /*  Initialize the Twiddle coefficientB pointer */
  119.   S->pTwiddleBReal = (float32_t *) realCoefB;
  120.  
  121.   /*  Initialize the Flag for selection of RFFT or RIFFT */
  122.   S->ifftFlagR = (uint8_t) ifftFlagR;
  123.  
  124.   /*  Initialize the Flag for calculation Bit reversal or not */
  125.   S->bitReverseFlagR = (uint8_t) bitReverseFlag;
  126.  
  127.   /*  Initializations of structure parameters depending on the FFT length */
  128.   switch (S->fftLenReal)
  129.   {
  130.     /* Init table modifier value */
  131.   case 8192u:
  132.     S->twidCoefRModifier = 1u;
  133.     break;
  134.   case 2048u:
  135.     S->twidCoefRModifier = 4u;
  136.     break;
  137.   case 512u:
  138.     S->twidCoefRModifier = 16u;
  139.     break;
  140.   case 128u:
  141.     S->twidCoefRModifier = 64u;
  142.     break;
  143.   default:
  144.     /*  Reporting argument error if rfftSize is not valid value */
  145.     status = ARM_MATH_ARGUMENT_ERROR;
  146.     break;
  147.   }
  148.  
  149.   /* Init Complex FFT Instance */
  150.   S->pCfft = S_CFFT;
  151.  
  152.   if(S->ifftFlagR)
  153.   {
  154.     /* Initializes the CIFFT Module for fftLenreal/2 length */
  155.     arm_cfft_radix4_init_f32(S->pCfft, S->fftLenBy2, 1u, 0u);
  156.   }
  157.   else
  158.   {
  159.     /* Initializes the CFFT Module for fftLenreal/2 length */
  160.     arm_cfft_radix4_init_f32(S->pCfft, S->fftLenBy2, 0u, 0u);
  161.   }
  162.  
  163.   /* return the status of RFFT Init function */
  164.   return (status);
  165.  
  166. }
  167.  
  168.   /**    
  169.    * @} end of RealFFT group    
  170.    */
  171.