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CMSIS DSP library

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cmsis_dsp/TransformFunctions/arm_cfft_radix4_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_radix4_init_q15.c
emilmont 1:fdd22bb7aa52 9 *
emilmont 1:fdd22bb7aa52 10 * Description: Radix-4 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 Radix4_CFFT_CIFFT
emilmont 1:fdd22bb7aa52 49 * @{
emilmont 1:fdd22bb7aa52 50 */
emilmont 1:fdd22bb7aa52 51
emilmont 1:fdd22bb7aa52 52
emilmont 1:fdd22bb7aa52 53 /**
emilmont 1:fdd22bb7aa52 54 * @brief Initialization function for the Q15 CFFT/CIFFT.
emilmont 1:fdd22bb7aa52 55 * @param[in,out] *S points to an instance of the Q15 CFFT/CIFFT structure.
emilmont 1:fdd22bb7aa52 56 * @param[in] fftLen length of the FFT.
emilmont 1:fdd22bb7aa52 57 * @param[in] ifftFlag flag that selects forward (ifftFlag=0) or inverse (ifftFlag=1) transform.
emilmont 1:fdd22bb7aa52 58 * @param[in] bitReverseFlag flag that enables (bitReverseFlag=1) or disables (bitReverseFlag=0) bit reversal of output.
emilmont 1:fdd22bb7aa52 59 * @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 60 *
emilmont 1:fdd22bb7aa52 61 * \par Description:
emilmont 1:fdd22bb7aa52 62 * \par
emilmont 1:fdd22bb7aa52 63 * The parameter <code>ifftFlag</code> controls whether a forward or inverse transform is computed.
emilmont 1:fdd22bb7aa52 64 * Set(=1) ifftFlag for calculation of CIFFT otherwise CFFT is calculated
emilmont 1:fdd22bb7aa52 65 * \par
emilmont 1:fdd22bb7aa52 66 * The parameter <code>bitReverseFlag</code> controls whether output is in normal order or bit reversed order.
emilmont 1:fdd22bb7aa52 67 * Set(=1) bitReverseFlag for output to be in normal order otherwise output is in bit reversed order.
emilmont 1:fdd22bb7aa52 68 * \par
emilmont 1:fdd22bb7aa52 69 * The parameter <code>fftLen</code> Specifies length of CFFT/CIFFT process. Supported FFT Lengths are 16, 64, 256, 1024.
emilmont 1:fdd22bb7aa52 70 * \par
emilmont 1:fdd22bb7aa52 71 * This Function also initializes Twiddle factor table pointer and Bit reversal table pointer.
emilmont 1:fdd22bb7aa52 72 */
emilmont 1:fdd22bb7aa52 73
emilmont 1:fdd22bb7aa52 74 arm_status arm_cfft_radix4_init_q15(
emilmont 1:fdd22bb7aa52 75 arm_cfft_radix4_instance_q15 * S,
emilmont 1:fdd22bb7aa52 76 uint16_t fftLen,
emilmont 1:fdd22bb7aa52 77 uint8_t ifftFlag,
emilmont 1:fdd22bb7aa52 78 uint8_t bitReverseFlag)
emilmont 1:fdd22bb7aa52 79 {
emilmont 1:fdd22bb7aa52 80 /* Initialise the default arm status */
emilmont 1:fdd22bb7aa52 81 arm_status status = ARM_MATH_SUCCESS;
emilmont 1:fdd22bb7aa52 82 /* Initialise the FFT length */
emilmont 1:fdd22bb7aa52 83 S->fftLen = fftLen;
emilmont 1:fdd22bb7aa52 84 /* Initialise the Twiddle coefficient pointer */
emilmont 1:fdd22bb7aa52 85 S->pTwiddle = (q15_t *) twiddleCoefQ15;
emilmont 1:fdd22bb7aa52 86 /* Initialise the Flag for selection of CFFT or CIFFT */
emilmont 1:fdd22bb7aa52 87 S->ifftFlag = ifftFlag;
emilmont 1:fdd22bb7aa52 88 /* Initialise the Flag for calculation Bit reversal or not */
emilmont 1:fdd22bb7aa52 89 S->bitReverseFlag = bitReverseFlag;
emilmont 1:fdd22bb7aa52 90
emilmont 1:fdd22bb7aa52 91 /* Initializations of structure parameters depending on the FFT length */
emilmont 1:fdd22bb7aa52 92 switch (S->fftLen)
emilmont 1:fdd22bb7aa52 93 {
emilmont 1:fdd22bb7aa52 94 case 4096u:
emilmont 1:fdd22bb7aa52 95 /* Initializations of structure parameters for 4096 point FFT */
emilmont 1:fdd22bb7aa52 96
emilmont 1:fdd22bb7aa52 97 /* Initialise the twiddle coef modifier value */
emilmont 1:fdd22bb7aa52 98 S->twidCoefModifier = 1u;
emilmont 1:fdd22bb7aa52 99 /* Initialise the bit reversal table modifier */
emilmont 1:fdd22bb7aa52 100 S->bitRevFactor = 1u;
emilmont 1:fdd22bb7aa52 101 /* Initialise the bit reversal table pointer */
emilmont 1:fdd22bb7aa52 102 S->pBitRevTable = (uint16_t *) armBitRevTable;
emilmont 1:fdd22bb7aa52 103
emilmont 1:fdd22bb7aa52 104 break;
emilmont 1:fdd22bb7aa52 105
emilmont 1:fdd22bb7aa52 106 case 1024u:
emilmont 1:fdd22bb7aa52 107 /* Initializations of structure parameters for 1024 point FFT */
emilmont 1:fdd22bb7aa52 108 S->twidCoefModifier = 4u;
emilmont 1:fdd22bb7aa52 109 S->bitRevFactor = 4u;
emilmont 1:fdd22bb7aa52 110 S->pBitRevTable = (uint16_t *) & armBitRevTable[3];
emilmont 1:fdd22bb7aa52 111
emilmont 1:fdd22bb7aa52 112 break;
emilmont 1:fdd22bb7aa52 113
emilmont 1:fdd22bb7aa52 114 case 256u:
emilmont 1:fdd22bb7aa52 115 /* Initializations of structure parameters for 256 point FFT */
emilmont 1:fdd22bb7aa52 116 S->twidCoefModifier = 16u;
emilmont 1:fdd22bb7aa52 117 S->bitRevFactor = 16u;
emilmont 1:fdd22bb7aa52 118 S->pBitRevTable = (uint16_t *) & armBitRevTable[15];
emilmont 1:fdd22bb7aa52 119
emilmont 1:fdd22bb7aa52 120 break;
emilmont 1:fdd22bb7aa52 121
emilmont 1:fdd22bb7aa52 122 case 64u:
emilmont 1:fdd22bb7aa52 123 /* Initializations of structure parameters for 64 point FFT */
emilmont 1:fdd22bb7aa52 124 S->twidCoefModifier = 64u;
emilmont 1:fdd22bb7aa52 125 S->bitRevFactor = 64u;
emilmont 1:fdd22bb7aa52 126 S->pBitRevTable = (uint16_t *) & armBitRevTable[63];
emilmont 1:fdd22bb7aa52 127
emilmont 1:fdd22bb7aa52 128 break;
emilmont 1:fdd22bb7aa52 129
emilmont 1:fdd22bb7aa52 130 case 16u:
emilmont 1:fdd22bb7aa52 131 /* Initializations of structure parameters for 16 point FFT */
emilmont 1:fdd22bb7aa52 132 S->twidCoefModifier = 256u;
emilmont 1:fdd22bb7aa52 133 S->bitRevFactor = 256u;
emilmont 1:fdd22bb7aa52 134 S->pBitRevTable = (uint16_t *) & armBitRevTable[255];
emilmont 1:fdd22bb7aa52 135
emilmont 1:fdd22bb7aa52 136 break;
emilmont 1:fdd22bb7aa52 137
emilmont 1:fdd22bb7aa52 138 default:
emilmont 1:fdd22bb7aa52 139 /* Reporting argument error if fftSize is not valid value */
emilmont 1:fdd22bb7aa52 140 status = ARM_MATH_ARGUMENT_ERROR;
emilmont 1:fdd22bb7aa52 141 break;
emilmont 1:fdd22bb7aa52 142 }
emilmont 1:fdd22bb7aa52 143
emilmont 1:fdd22bb7aa52 144 return (status);
emilmont 1:fdd22bb7aa52 145 }
emilmont 1:fdd22bb7aa52 146
emilmont 1:fdd22bb7aa52 147 /**
emilmont 1:fdd22bb7aa52 148 * @} end of Radix4_CFFT_CIFFT group
emilmont 1:fdd22bb7aa52 149 */