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CMSIS DSP library

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cmsis_dsp/TransformFunctions/arm_cfft_radix2_init_q15.c@1:fdd22bb7aa52, 2012-11-28 (annotated)

Committer:
emilmont
Date:
Wed Nov 28 12:30:09 2012 +0000
Revision:
1:fdd22bb7aa52
Child:
2:da51fb522205
DSP library code

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 1:fdd22bb7aa52 5 * $Revision: V1.1.0
emilmont 1:fdd22bb7aa52 6 *
emilmont 1:fdd22bb7aa52 7 * Project: CMSIS DSP Library
emilmont 1:fdd22bb7aa52 8 * Title: arm_cfft_radix2_init_q15.c
emilmont 1:fdd22bb7aa52 9 *
emilmont 1:fdd22bb7aa52 10 * Description: Radix-2 Decimation in Frequency Q15 FFT & IFFT 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 * Version 1.0.10 2011/7/15
emilmont 1:fdd22bb7aa52 18 * Big Endian support added and Merged M0 and M3/M4 Source code.
emilmont 1:fdd22bb7aa52 19 *
emilmont 1:fdd22bb7aa52 20 * Version 1.0.3 2010/11/29
emilmont 1:fdd22bb7aa52 21 * Re-organized the CMSIS folders and updated documentation.
emilmont 1:fdd22bb7aa52 22 *
emilmont 1:fdd22bb7aa52 23 * Version 1.0.2 2010/11/11
emilmont 1:fdd22bb7aa52 24 * Documentation updated.
emilmont 1:fdd22bb7aa52 25 *
emilmont 1:fdd22bb7aa52 26 * Version 1.0.1 2010/10/05
emilmont 1:fdd22bb7aa52 27 * Production release and review comments incorporated.
emilmont 1:fdd22bb7aa52 28 *
emilmont 1:fdd22bb7aa52 29 * Version 1.0.0 2010/09/20
emilmont 1:fdd22bb7aa52 30 * Production release and review comments incorporated.
emilmont 1:fdd22bb7aa52 31 *
emilmont 1:fdd22bb7aa52 32 * Version 0.0.5 2010/04/26
emilmont 1:fdd22bb7aa52 33 * incorporated review comments and updated with latest CMSIS layer
emilmont 1:fdd22bb7aa52 34 *
emilmont 1:fdd22bb7aa52 35 * Version 0.0.3 2010/03/10
emilmont 1:fdd22bb7aa52 36 * Initial version
emilmont 1:fdd22bb7aa52 37 * -------------------------------------------------------------------- */
emilmont 1:fdd22bb7aa52 38
emilmont 1:fdd22bb7aa52 39 #include "arm_math.h"
emilmont 1:fdd22bb7aa52 40 #include "arm_common_tables.h"
emilmont 1:fdd22bb7aa52 41
emilmont 1:fdd22bb7aa52 42 /**
emilmont 1:fdd22bb7aa52 43 * @ingroup groupTransforms
emilmont 1:fdd22bb7aa52 44 */
emilmont 1:fdd22bb7aa52 45
emilmont 1:fdd22bb7aa52 46
emilmont 1:fdd22bb7aa52 47 /**
emilmont 1:fdd22bb7aa52 48 * @addtogroup Radix2_CFFT_CIFFT
emilmont 1:fdd22bb7aa52 49 * @{
emilmont 1:fdd22bb7aa52 50 */
emilmont 1:fdd22bb7aa52 51
emilmont 1:fdd22bb7aa52 52 /**
emilmont 1:fdd22bb7aa52 53 * @brief Initialization function for the Q15 CFFT/CIFFT.
emilmont 1:fdd22bb7aa52 54 * @param[in,out] *S points to an instance of the Q15 CFFT/CIFFT structure.
emilmont 1:fdd22bb7aa52 55 * @param[in] fftLen length of the FFT.
emilmont 1:fdd22bb7aa52 56 * @param[in] ifftFlag flag that selects forward (ifftFlag=0) or inverse (ifftFlag=1) transform.
emilmont 1:fdd22bb7aa52 57 * @param[in] bitReverseFlag flag that enables (bitReverseFlag=1) or disables (bitReverseFlag=0) bit reversal of output.
emilmont 1:fdd22bb7aa52 58 * @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 59 *
emilmont 1:fdd22bb7aa52 60 * \par Description:
emilmont 1:fdd22bb7aa52 61 * \par
emilmont 1:fdd22bb7aa52 62 * The parameter <code>ifftFlag</code> controls whether a forward or inverse transform is computed.
emilmont 1:fdd22bb7aa52 63 * Set(=1) ifftFlag for calculation of CIFFT otherwise CFFT is calculated
emilmont 1:fdd22bb7aa52 64 * \par
emilmont 1:fdd22bb7aa52 65 * The parameter <code>bitReverseFlag</code> controls whether output is in normal order or bit reversed order.
emilmont 1:fdd22bb7aa52 66 * Set(=1) bitReverseFlag for output to be in normal order otherwise output is in bit reversed order.
emilmont 1:fdd22bb7aa52 67 * \par
emilmont 1:fdd22bb7aa52 68 * The parameter <code>fftLen</code> Specifies length of CFFT/CIFFT process. Supported FFT Lengths are 16, 64, 256, 1024.
emilmont 1:fdd22bb7aa52 69 * \par
emilmont 1:fdd22bb7aa52 70 * This Function also initializes Twiddle factor table pointer and Bit reversal table pointer.
emilmont 1:fdd22bb7aa52 71 */
emilmont 1:fdd22bb7aa52 72
emilmont 1:fdd22bb7aa52 73 arm_status arm_cfft_radix2_init_q15(
emilmont 1:fdd22bb7aa52 74 arm_cfft_radix2_instance_q15 * S,
emilmont 1:fdd22bb7aa52 75 uint16_t fftLen,
emilmont 1:fdd22bb7aa52 76 uint8_t ifftFlag,
emilmont 1:fdd22bb7aa52 77 uint8_t bitReverseFlag)
emilmont 1:fdd22bb7aa52 78 {
emilmont 1:fdd22bb7aa52 79 /* Initialise the default arm status */
emilmont 1:fdd22bb7aa52 80 arm_status status = ARM_MATH_SUCCESS;
emilmont 1:fdd22bb7aa52 81
emilmont 1:fdd22bb7aa52 82 /* Initialise the FFT length */
emilmont 1:fdd22bb7aa52 83 S->fftLen = fftLen;
emilmont 1:fdd22bb7aa52 84
emilmont 1:fdd22bb7aa52 85 /* Initialise the Twiddle coefficient pointer */
emilmont 1:fdd22bb7aa52 86 S->pTwiddle = (q15_t *) twiddleCoefQ15;
emilmont 1:fdd22bb7aa52 87 /* Initialise the Flag for selection of CFFT or CIFFT */
emilmont 1:fdd22bb7aa52 88 S->ifftFlag = ifftFlag;
emilmont 1:fdd22bb7aa52 89 /* Initialise the Flag for calculation Bit reversal or not */
emilmont 1:fdd22bb7aa52 90 S->bitReverseFlag = bitReverseFlag;
emilmont 1:fdd22bb7aa52 91
emilmont 1:fdd22bb7aa52 92 /* Initializations of structure parameters depending on the FFT length */
emilmont 1:fdd22bb7aa52 93 switch (S->fftLen)
emilmont 1:fdd22bb7aa52 94 {
emilmont 1:fdd22bb7aa52 95 case 4096u:
emilmont 1:fdd22bb7aa52 96 /* Initializations of structure parameters for 4096 point FFT */
emilmont 1:fdd22bb7aa52 97
emilmont 1:fdd22bb7aa52 98 /* Initialise the twiddle coef modifier value */
emilmont 1:fdd22bb7aa52 99 S->twidCoefModifier = 1u;
emilmont 1:fdd22bb7aa52 100 /* Initialise the bit reversal table modifier */
emilmont 1:fdd22bb7aa52 101 S->bitRevFactor = 1u;
emilmont 1:fdd22bb7aa52 102 /* Initialise the bit reversal table pointer */
emilmont 1:fdd22bb7aa52 103 S->pBitRevTable = (uint16_t *) armBitRevTable;
emilmont 1:fdd22bb7aa52 104
emilmont 1:fdd22bb7aa52 105 break;
emilmont 1:fdd22bb7aa52 106
emilmont 1:fdd22bb7aa52 107 case 2048u:
emilmont 1:fdd22bb7aa52 108 /* Initializations of structure parameters for 2048 point FFT */
emilmont 1:fdd22bb7aa52 109
emilmont 1:fdd22bb7aa52 110 /* Initialise the twiddle coef modifier value */
emilmont 1:fdd22bb7aa52 111 S->twidCoefModifier = 2u;
emilmont 1:fdd22bb7aa52 112 /* Initialise the bit reversal table modifier */
emilmont 1:fdd22bb7aa52 113 S->bitRevFactor = 2u;
emilmont 1:fdd22bb7aa52 114 /* Initialise the bit reversal table pointer */
emilmont 1:fdd22bb7aa52 115 S->pBitRevTable = (uint16_t *) & armBitRevTable[1];
emilmont 1:fdd22bb7aa52 116
emilmont 1:fdd22bb7aa52 117 break;
emilmont 1:fdd22bb7aa52 118
emilmont 1:fdd22bb7aa52 119 case 1024u:
emilmont 1:fdd22bb7aa52 120 /* Initializations of structure parameters for 1024 point FFT */
emilmont 1:fdd22bb7aa52 121 S->twidCoefModifier = 4u;
emilmont 1:fdd22bb7aa52 122 S->bitRevFactor = 4u;
emilmont 1:fdd22bb7aa52 123 S->pBitRevTable = (uint16_t *) & armBitRevTable[3];
emilmont 1:fdd22bb7aa52 124
emilmont 1:fdd22bb7aa52 125 break;
emilmont 1:fdd22bb7aa52 126
emilmont 1:fdd22bb7aa52 127 case 512u:
emilmont 1:fdd22bb7aa52 128 /* Initializations of structure parameters for 512 point FFT */
emilmont 1:fdd22bb7aa52 129 S->twidCoefModifier = 8u;
emilmont 1:fdd22bb7aa52 130 S->bitRevFactor = 8u;
emilmont 1:fdd22bb7aa52 131 S->pBitRevTable = (uint16_t *) & armBitRevTable[7];
emilmont 1:fdd22bb7aa52 132
emilmont 1:fdd22bb7aa52 133 break;
emilmont 1:fdd22bb7aa52 134
emilmont 1:fdd22bb7aa52 135 case 256u:
emilmont 1:fdd22bb7aa52 136 /* Initializations of structure parameters for 256 point FFT */
emilmont 1:fdd22bb7aa52 137 S->twidCoefModifier = 16u;
emilmont 1:fdd22bb7aa52 138 S->bitRevFactor = 16u;
emilmont 1:fdd22bb7aa52 139 S->pBitRevTable = (uint16_t *) & armBitRevTable[15];
emilmont 1:fdd22bb7aa52 140
emilmont 1:fdd22bb7aa52 141 break;
emilmont 1:fdd22bb7aa52 142
emilmont 1:fdd22bb7aa52 143 case 128u:
emilmont 1:fdd22bb7aa52 144 /* Initializations of structure parameters for 128 point FFT */
emilmont 1:fdd22bb7aa52 145 S->twidCoefModifier = 32u;
emilmont 1:fdd22bb7aa52 146 S->bitRevFactor = 32u;
emilmont 1:fdd22bb7aa52 147 S->pBitRevTable = (uint16_t *) & armBitRevTable[31];
emilmont 1:fdd22bb7aa52 148
emilmont 1:fdd22bb7aa52 149 break;
emilmont 1:fdd22bb7aa52 150
emilmont 1:fdd22bb7aa52 151 case 64u:
emilmont 1:fdd22bb7aa52 152 /* Initializations of structure parameters for 64 point FFT */
emilmont 1:fdd22bb7aa52 153 S->twidCoefModifier = 64u;
emilmont 1:fdd22bb7aa52 154 S->bitRevFactor = 64u;
emilmont 1:fdd22bb7aa52 155 S->pBitRevTable = (uint16_t *) & armBitRevTable[63];
emilmont 1:fdd22bb7aa52 156
emilmont 1:fdd22bb7aa52 157 break;
emilmont 1:fdd22bb7aa52 158
emilmont 1:fdd22bb7aa52 159 case 32u:
emilmont 1:fdd22bb7aa52 160 /* Initializations of structure parameters for 32 point FFT */
emilmont 1:fdd22bb7aa52 161 S->twidCoefModifier = 128u;
emilmont 1:fdd22bb7aa52 162 S->bitRevFactor = 128u;
emilmont 1:fdd22bb7aa52 163 S->pBitRevTable = (uint16_t *) & armBitRevTable[127];
emilmont 1:fdd22bb7aa52 164
emilmont 1:fdd22bb7aa52 165 break;
emilmont 1:fdd22bb7aa52 166
emilmont 1:fdd22bb7aa52 167 case 16u:
emilmont 1:fdd22bb7aa52 168 /* Initializations of structure parameters for 16 point FFT */
emilmont 1:fdd22bb7aa52 169 S->twidCoefModifier = 256u;
emilmont 1:fdd22bb7aa52 170 S->bitRevFactor = 256u;
emilmont 1:fdd22bb7aa52 171 S->pBitRevTable = (uint16_t *) & armBitRevTable[255];
emilmont 1:fdd22bb7aa52 172
emilmont 1:fdd22bb7aa52 173 break;
emilmont 1:fdd22bb7aa52 174
emilmont 1:fdd22bb7aa52 175 default:
emilmont 1:fdd22bb7aa52 176 /* Reporting argument error if fftSize is not valid value */
emilmont 1:fdd22bb7aa52 177 status = ARM_MATH_ARGUMENT_ERROR;
emilmont 1:fdd22bb7aa52 178 break;
emilmont 1:fdd22bb7aa52 179 }
emilmont 1:fdd22bb7aa52 180
emilmont 1:fdd22bb7aa52 181 return (status);
emilmont 1:fdd22bb7aa52 182 }
emilmont 1:fdd22bb7aa52 183
emilmont 1:fdd22bb7aa52 184 /**
emilmont 1:fdd22bb7aa52 185 * @} end of Radix2_CFFT_CIFFT group
emilmont 1:fdd22bb7aa52 186 */