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  1. /* ----------------------------------------------------------------------
  2.  * Project:      CMSIS DSP Library
  3.  * Title:        arm_cfft_radix2_init_q15.c
  4.  * Description:  Radix-2 Decimation in Frequency Q15 FFT & IFFT initialization 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. #include "arm_common_tables.h"
  31.  
  32. /**
  33.  * @ingroup groupTransforms
  34.  */
  35.  
  36.  
  37. /**
  38.  * @addtogroup ComplexFFT
  39.  * @{
  40.  */
  41.  
  42. /**
  43. * @brief Initialization function for the Q15 CFFT/CIFFT.
  44. * @deprecated Do not use this function.  It has been superseded by \ref arm_cfft_q15 and will be removed
  45. * @param[in,out] *S             points to an instance of the Q15 CFFT/CIFFT structure.
  46. * @param[in]     fftLen         length of the FFT.
  47. * @param[in]     ifftFlag       flag that selects forward (ifftFlag=0) or inverse (ifftFlag=1) transform.
  48. * @param[in]     bitReverseFlag flag that enables (bitReverseFlag=1) or disables (bitReverseFlag=0) bit reversal of output.
  49. * @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.
  50. *
  51. * \par Description:
  52. * \par
  53. * The parameter <code>ifftFlag</code> controls whether a forward or inverse transform is computed.
  54. * Set(=1) ifftFlag for calculation of CIFFT otherwise  CFFT is calculated
  55. * \par
  56. * The parameter <code>bitReverseFlag</code> controls whether output is in normal order or bit reversed order.
  57. * Set(=1) bitReverseFlag for output to be in normal order otherwise output is in bit reversed order.
  58. * \par
  59. * The parameter <code>fftLen</code>     Specifies length of CFFT/CIFFT process. Supported FFT Lengths are 16, 64, 256, 1024.
  60. * \par
  61. * This Function also initializes Twiddle factor table pointer and Bit reversal table pointer.
  62. */
  63.  
  64. arm_status arm_cfft_radix2_init_q15(
  65.   arm_cfft_radix2_instance_q15 * S,
  66.   uint16_t fftLen,
  67.   uint8_t ifftFlag,
  68.   uint8_t bitReverseFlag)
  69. {
  70.   /*  Initialise the default arm status */
  71.   arm_status status = ARM_MATH_SUCCESS;
  72.  
  73.   /*  Initialise the FFT length */
  74.   S->fftLen = fftLen;
  75.  
  76.   /*  Initialise the Twiddle coefficient pointer */
  77.   S->pTwiddle = (q15_t *) twiddleCoef_4096_q15;
  78.   /*  Initialise the Flag for selection of CFFT or CIFFT */
  79.   S->ifftFlag = ifftFlag;
  80.   /*  Initialise the Flag for calculation Bit reversal or not */
  81.   S->bitReverseFlag = bitReverseFlag;
  82.  
  83.   /*  Initializations of structure parameters depending on the FFT length */
  84.   switch (S->fftLen)
  85.   {
  86.   case 4096U:
  87.     /*  Initializations of structure parameters for 4096 point FFT */
  88.  
  89.     /*  Initialise the twiddle coef modifier value */
  90.     S->twidCoefModifier = 1U;
  91.     /*  Initialise the bit reversal table modifier */
  92.     S->bitRevFactor = 1U;
  93.     /*  Initialise the bit reversal table pointer */
  94.     S->pBitRevTable = (uint16_t *) armBitRevTable;
  95.  
  96.     break;
  97.  
  98.   case 2048U:
  99.     /*  Initializations of structure parameters for 2048 point FFT */
  100.  
  101.     /*  Initialise the twiddle coef modifier value */
  102.     S->twidCoefModifier = 2U;
  103.     /*  Initialise the bit reversal table modifier */
  104.     S->bitRevFactor = 2U;
  105.     /*  Initialise the bit reversal table pointer */
  106.     S->pBitRevTable = (uint16_t *) & armBitRevTable[1];
  107.  
  108.     break;
  109.  
  110.   case 1024U:
  111.     /*  Initializations of structure parameters for 1024 point FFT */
  112.     S->twidCoefModifier = 4U;
  113.     S->bitRevFactor = 4U;
  114.     S->pBitRevTable = (uint16_t *) & armBitRevTable[3];
  115.  
  116.     break;
  117.  
  118.   case 512U:
  119.     /*  Initializations of structure parameters for 512 point FFT */
  120.     S->twidCoefModifier = 8U;
  121.     S->bitRevFactor = 8U;
  122.     S->pBitRevTable = (uint16_t *) & armBitRevTable[7];
  123.  
  124.     break;
  125.  
  126.   case 256U:
  127.     /*  Initializations of structure parameters for 256 point FFT */
  128.     S->twidCoefModifier = 16U;
  129.     S->bitRevFactor = 16U;
  130.     S->pBitRevTable = (uint16_t *) & armBitRevTable[15];
  131.  
  132.     break;
  133.  
  134.   case 128U:
  135.     /*  Initializations of structure parameters for 128 point FFT */
  136.     S->twidCoefModifier = 32U;
  137.     S->bitRevFactor = 32U;
  138.     S->pBitRevTable = (uint16_t *) & armBitRevTable[31];
  139.  
  140.     break;
  141.  
  142.   case 64U:
  143.     /*  Initializations of structure parameters for 64 point FFT */
  144.     S->twidCoefModifier = 64U;
  145.     S->bitRevFactor = 64U;
  146.     S->pBitRevTable = (uint16_t *) & armBitRevTable[63];
  147.  
  148.     break;
  149.  
  150.   case 32U:
  151.     /*  Initializations of structure parameters for 32 point FFT */
  152.     S->twidCoefModifier = 128U;
  153.     S->bitRevFactor = 128U;
  154.     S->pBitRevTable = (uint16_t *) & armBitRevTable[127];
  155.  
  156.     break;
  157.  
  158.   case 16U:
  159.     /*  Initializations of structure parameters for 16 point FFT */
  160.     S->twidCoefModifier = 256U;
  161.     S->bitRevFactor = 256U;
  162.     S->pBitRevTable = (uint16_t *) & armBitRevTable[255];
  163.  
  164.     break;
  165.  
  166.   default:
  167.     /*  Reporting argument error if fftSize is not valid value */
  168.     status = ARM_MATH_ARGUMENT_ERROR;
  169.     break;
  170.   }
  171.  
  172.   return (status);
  173. }
  174.  
  175. /**
  176.  * @} end of ComplexFFT group
  177.  */
  178.