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CMSIS DSP library

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cmsis_dsp/TransformFunctions/arm_cfft_radix2_init_q31.c@2:da51fb522205, 2013-05-30 (annotated)

Committer:
emilmont
Date:
Thu May 30 17:10:11 2013 +0100
Revision:
2:da51fb522205
Parent:
1:fdd22bb7aa52
Child:
3:7a284390b0ce
Keep "cmsis-dsp" module in synch with its source

Who changed what in which revision?

UserRevisionLine numberNew contents of line
emilmont 1:fdd22bb7aa52 1 /* ----------------------------------------------------------------------
emilmont 1:fdd22bb7aa52 2 * Copyright (C) 2010 ARM Limited. All rights reserved.
emilmont 1:fdd22bb7aa52 3 *
emilmont 1:fdd22bb7aa52 4 * $Date: 15. February 2012
emilmont 2:da51fb522205 5 * $Revision: V1.1.0
emilmont 1:fdd22bb7aa52 6 *
emilmont 2:da51fb522205 7 * Project: CMSIS DSP Library
emilmont 2:da51fb522205 8 * Title: arm_cfft_radix2_init_q31.c
emilmont 1:fdd22bb7aa52 9 *
emilmont 2:da51fb522205 10 * Description: Radix-2 Decimation in Frequency Fixed-point CFFT & CIFFT Initialization function
emilmont 1:fdd22bb7aa52 11 *
emilmont 1:fdd22bb7aa52 12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
emilmont 1:fdd22bb7aa52 13 *
emilmont 1:fdd22bb7aa52 14 * Version 1.1.0 2012/02/15
emilmont 1:fdd22bb7aa52 15 * Updated with more optimizations, bug fixes and minor API changes.
emilmont 1:fdd22bb7aa52 16 *
emilmont 1:fdd22bb7aa52 17 * -------------------------------------------------------------------- */
emilmont 1:fdd22bb7aa52 18
emilmont 1:fdd22bb7aa52 19
emilmont 1:fdd22bb7aa52 20 #include "arm_math.h"
emilmont 1:fdd22bb7aa52 21 #include "arm_common_tables.h"
emilmont 1:fdd22bb7aa52 22
emilmont 1:fdd22bb7aa52 23 /**
emilmont 1:fdd22bb7aa52 24 * @ingroup groupTransforms
emilmont 1:fdd22bb7aa52 25 */
emilmont 1:fdd22bb7aa52 26
emilmont 1:fdd22bb7aa52 27 /**
emilmont 1:fdd22bb7aa52 28 * @addtogroup Radix2_CFFT_CIFFT
emilmont 1:fdd22bb7aa52 29 * @{
emilmont 1:fdd22bb7aa52 30 */
emilmont 1:fdd22bb7aa52 31
emilmont 1:fdd22bb7aa52 32
emilmont 1:fdd22bb7aa52 33 /**
emilmont 1:fdd22bb7aa52 34 *
emilmont 1:fdd22bb7aa52 35 * @brief Initialization function for the Q31 CFFT/CIFFT.
emilmont 1:fdd22bb7aa52 36 * @param[in,out] *S points to an instance of the Q31 CFFT/CIFFT structure.
emilmont 1:fdd22bb7aa52 37 * @param[in] fftLen length of the FFT.
emilmont 1:fdd22bb7aa52 38 * @param[in] ifftFlag flag that selects forward (ifftFlag=0) or inverse (ifftFlag=1) transform.
emilmont 1:fdd22bb7aa52 39 * @param[in] bitReverseFlag flag that enables (bitReverseFlag=1) or disables (bitReverseFlag=0) bit reversal of output.
emilmont 1:fdd22bb7aa52 40 * @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.
emilmont 1:fdd22bb7aa52 41 *
emilmont 1:fdd22bb7aa52 42 * \par Description:
emilmont 1:fdd22bb7aa52 43 * \par
emilmont 1:fdd22bb7aa52 44 * The parameter <code>ifftFlag</code> controls whether a forward or inverse transform is computed.
emilmont 1:fdd22bb7aa52 45 * Set(=1) ifftFlag for calculation of CIFFT otherwise CFFT is calculated
emilmont 1:fdd22bb7aa52 46 * \par
emilmont 1:fdd22bb7aa52 47 * The parameter <code>bitReverseFlag</code> controls whether output is in normal order or bit reversed order.
emilmont 1:fdd22bb7aa52 48 * Set(=1) bitReverseFlag for output to be in normal order otherwise output is in bit reversed order.
emilmont 1:fdd22bb7aa52 49 * \par
emilmont 2:da51fb522205 50 * The parameter <code>fftLen</code> Specifies length of CFFT/CIFFT process. Supported FFT Lengths are 16, 64, 256, 1024.
emilmont 1:fdd22bb7aa52 51 * \par
emilmont 1:fdd22bb7aa52 52 * This Function also initializes Twiddle factor table pointer and Bit reversal table pointer.
emilmont 1:fdd22bb7aa52 53 */
emilmont 1:fdd22bb7aa52 54
emilmont 1:fdd22bb7aa52 55 arm_status arm_cfft_radix2_init_q31(
emilmont 1:fdd22bb7aa52 56 arm_cfft_radix2_instance_q31 * S,
emilmont 1:fdd22bb7aa52 57 uint16_t fftLen,
emilmont 1:fdd22bb7aa52 58 uint8_t ifftFlag,
emilmont 1:fdd22bb7aa52 59 uint8_t bitReverseFlag)
emilmont 1:fdd22bb7aa52 60 {
emilmont 1:fdd22bb7aa52 61 /* Initialise the default arm status */
emilmont 1:fdd22bb7aa52 62 arm_status status = ARM_MATH_SUCCESS;
emilmont 1:fdd22bb7aa52 63
emilmont 1:fdd22bb7aa52 64 /* Initialise the FFT length */
emilmont 1:fdd22bb7aa52 65 S->fftLen = fftLen;
emilmont 1:fdd22bb7aa52 66
emilmont 1:fdd22bb7aa52 67 /* Initialise the Twiddle coefficient pointer */
emilmont 1:fdd22bb7aa52 68 S->pTwiddle = (q31_t *) twiddleCoefQ31;
emilmont 1:fdd22bb7aa52 69 /* Initialise the Flag for selection of CFFT or CIFFT */
emilmont 1:fdd22bb7aa52 70 S->ifftFlag = ifftFlag;
emilmont 1:fdd22bb7aa52 71 /* Initialise the Flag for calculation Bit reversal or not */
emilmont 1:fdd22bb7aa52 72 S->bitReverseFlag = bitReverseFlag;
emilmont 1:fdd22bb7aa52 73
emilmont 1:fdd22bb7aa52 74 /* Initializations of Instance structure depending on the FFT length */
emilmont 1:fdd22bb7aa52 75 switch (S->fftLen)
emilmont 1:fdd22bb7aa52 76 {
emilmont 1:fdd22bb7aa52 77 /* Initializations of structure parameters for 4096 point FFT */
emilmont 1:fdd22bb7aa52 78 case 4096u:
emilmont 1:fdd22bb7aa52 79 /* Initialise the twiddle coef modifier value */
emilmont 1:fdd22bb7aa52 80 S->twidCoefModifier = 1u;
emilmont 1:fdd22bb7aa52 81 /* Initialise the bit reversal table modifier */
emilmont 1:fdd22bb7aa52 82 S->bitRevFactor = 1u;
emilmont 1:fdd22bb7aa52 83 /* Initialise the bit reversal table pointer */
emilmont 1:fdd22bb7aa52 84 S->pBitRevTable = (uint16_t *) armBitRevTable;
emilmont 1:fdd22bb7aa52 85 break;
emilmont 1:fdd22bb7aa52 86
emilmont 1:fdd22bb7aa52 87 /* Initializations of structure parameters for 2048 point FFT */
emilmont 1:fdd22bb7aa52 88 case 2048u:
emilmont 1:fdd22bb7aa52 89 /* Initialise the twiddle coef modifier value */
emilmont 1:fdd22bb7aa52 90 S->twidCoefModifier = 2u;
emilmont 1:fdd22bb7aa52 91 /* Initialise the bit reversal table modifier */
emilmont 1:fdd22bb7aa52 92 S->bitRevFactor = 2u;
emilmont 1:fdd22bb7aa52 93 /* Initialise the bit reversal table pointer */
emilmont 1:fdd22bb7aa52 94 S->pBitRevTable = (uint16_t *) & armBitRevTable[1];
emilmont 1:fdd22bb7aa52 95 break;
emilmont 1:fdd22bb7aa52 96
emilmont 1:fdd22bb7aa52 97 /* Initializations of structure parameters for 1024 point FFT */
emilmont 1:fdd22bb7aa52 98 case 1024u:
emilmont 1:fdd22bb7aa52 99 /* Initialise the twiddle coef modifier value */
emilmont 1:fdd22bb7aa52 100 S->twidCoefModifier = 4u;
emilmont 1:fdd22bb7aa52 101 /* Initialise the bit reversal table modifier */
emilmont 1:fdd22bb7aa52 102 S->bitRevFactor = 4u;
emilmont 1:fdd22bb7aa52 103 /* Initialise the bit reversal table pointer */
emilmont 1:fdd22bb7aa52 104 S->pBitRevTable = (uint16_t *) & armBitRevTable[3];
emilmont 1:fdd22bb7aa52 105 break;
emilmont 1:fdd22bb7aa52 106
emilmont 1:fdd22bb7aa52 107 /* Initializations of structure parameters for 512 point FFT */
emilmont 1:fdd22bb7aa52 108 case 512u:
emilmont 1:fdd22bb7aa52 109 /* Initialise the twiddle coef modifier value */
emilmont 1:fdd22bb7aa52 110 S->twidCoefModifier = 8u;
emilmont 1:fdd22bb7aa52 111 /* Initialise the bit reversal table modifier */
emilmont 1:fdd22bb7aa52 112 S->bitRevFactor = 8u;
emilmont 1:fdd22bb7aa52 113 /* Initialise the bit reversal table pointer */
emilmont 1:fdd22bb7aa52 114 S->pBitRevTable = (uint16_t *) & armBitRevTable[7];
emilmont 1:fdd22bb7aa52 115 break;
emilmont 1:fdd22bb7aa52 116
emilmont 1:fdd22bb7aa52 117 case 256u:
emilmont 1:fdd22bb7aa52 118 /* Initializations of structure parameters for 256 point FFT */
emilmont 1:fdd22bb7aa52 119 S->twidCoefModifier = 16u;
emilmont 1:fdd22bb7aa52 120 S->bitRevFactor = 16u;
emilmont 1:fdd22bb7aa52 121 S->pBitRevTable = (uint16_t *) & armBitRevTable[15];
emilmont 1:fdd22bb7aa52 122 break;
emilmont 1:fdd22bb7aa52 123
emilmont 1:fdd22bb7aa52 124 case 128u:
emilmont 1:fdd22bb7aa52 125 /* Initializations of structure parameters for 128 point FFT */
emilmont 1:fdd22bb7aa52 126 S->twidCoefModifier = 32u;
emilmont 1:fdd22bb7aa52 127 S->bitRevFactor = 32u;
emilmont 1:fdd22bb7aa52 128 S->pBitRevTable = (uint16_t *) & armBitRevTable[31];
emilmont 1:fdd22bb7aa52 129 break;
emilmont 1:fdd22bb7aa52 130
emilmont 1:fdd22bb7aa52 131 case 64u:
emilmont 1:fdd22bb7aa52 132 /* Initializations of structure parameters for 64 point FFT */
emilmont 1:fdd22bb7aa52 133 S->twidCoefModifier = 64u;
emilmont 1:fdd22bb7aa52 134 S->bitRevFactor = 64u;
emilmont 1:fdd22bb7aa52 135 S->pBitRevTable = (uint16_t *) & armBitRevTable[63];
emilmont 1:fdd22bb7aa52 136 break;
emilmont 1:fdd22bb7aa52 137
emilmont 1:fdd22bb7aa52 138 case 32u:
emilmont 1:fdd22bb7aa52 139 /* Initializations of structure parameters for 32 point FFT */
emilmont 1:fdd22bb7aa52 140 S->twidCoefModifier = 128u;
emilmont 1:fdd22bb7aa52 141 S->bitRevFactor = 128u;
emilmont 1:fdd22bb7aa52 142 S->pBitRevTable = (uint16_t *) & armBitRevTable[127];
emilmont 1:fdd22bb7aa52 143 break;
emilmont 1:fdd22bb7aa52 144
emilmont 1:fdd22bb7aa52 145 case 16u:
emilmont 1:fdd22bb7aa52 146 /* Initializations of structure parameters for 16 point FFT */
emilmont 1:fdd22bb7aa52 147 S->twidCoefModifier = 256u;
emilmont 1:fdd22bb7aa52 148 S->bitRevFactor = 256u;
emilmont 1:fdd22bb7aa52 149 S->pBitRevTable = (uint16_t *) & armBitRevTable[255];
emilmont 1:fdd22bb7aa52 150 break;
emilmont 1:fdd22bb7aa52 151
emilmont 1:fdd22bb7aa52 152
emilmont 1:fdd22bb7aa52 153 default:
emilmont 1:fdd22bb7aa52 154 /* Reporting argument error if fftSize is not valid value */
emilmont 1:fdd22bb7aa52 155 status = ARM_MATH_ARGUMENT_ERROR;
emilmont 1:fdd22bb7aa52 156 break;
emilmont 1:fdd22bb7aa52 157 }
emilmont 1:fdd22bb7aa52 158
emilmont 1:fdd22bb7aa52 159 return (status);
emilmont 1:fdd22bb7aa52 160 }
emilmont 1:fdd22bb7aa52 161
emilmont 1:fdd22bb7aa52 162 /**
emilmont 1:fdd22bb7aa52 163 * @} end of Radix2_CFFT_CIFFT group
emilmont 1:fdd22bb7aa52 164 */