/* ----------------------------------------------------------------------
* Copyright (C) 2010 ARM Limited. All rights reserved.
*
* $Date: 15. February 2012
* $Revision: V1.1.0
*
* Project: CMSIS DSP Library
* Title: arm_cfft_radix4_init_f32.c
*
* Description: Radix-4 Decimation in Frequency Floating-point CFFT & CIFFT Initialization function
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Version 1.1.0 2012/02/15
* Updated with more optimizations, bug fixes and minor API changes.
*
* Version 1.0.3 2010/11/29
* Re-organized the CMSIS folders and updated documentation.
*
* Version 1.0.2 2010/11/11
* Documentation updated.
*
* Version 1.0.1 2010/10/05
* Production release and review comments incorporated.
*
* Version 1.0.0 2010/09/20
* Production release and review comments incorporated.
*
* Version 0.0.5 2010/04/26
* incorporated review comments and updated with latest CMSIS layer
*
* Version 0.0.3 2010/03/10
* Initial version
* -------------------------------------------------------------------- */
#include "arm_math.h"
#include "arm_common_tables.h"
/**
* @ingroup groupTransforms
*/
/**
* @addtogroup Radix2_CFFT_CIFFT
* @{
*/
/**
* @brief Initialization function for the floating-point CFFT/CIFFT.
* @param[in,out] *S points to an instance of the floating-point CFFT/CIFFT structure.
* @param[in] fftLen length of the FFT.
* @param[in] ifftFlag flag that selects forward (ifftFlag=0) or inverse (ifftFlag=1) transform.
* @param[in] bitReverseFlag flag that enables (bitReverseFlag=1) or disables (bitReverseFlag=0) bit reversal of output.
* @return The function returns ARM_MATH_SUCCESS if initialization is successful or ARM_MATH_ARGUMENT_ERROR if fftLen
is not a supported value.
*
* \par Description:
* \par
* The parameter ifftFlag
controls whether a forward or inverse transform is computed.
* Set(=1) ifftFlag for calculation of CIFFT otherwise CFFT is calculated
* \par
* The parameter bitReverseFlag
controls whether output is in normal order or bit reversed order.
* Set(=1) bitReverseFlag for output to be in normal order otherwise output is in bit reversed order.
* \par
* The parameter fftLen
Specifies length of CFFT/CIFFT process. Supported FFT Lengths are 16, 64, 256, 1024.
* \par
* This Function also initializes Twiddle factor table pointer and Bit reversal table pointer.
*/
arm_status arm_cfft_radix2_init_f32(
arm_cfft_radix2_instance_f32 * S,
uint16_t fftLen,
uint8_t ifftFlag,
uint8_t bitReverseFlag)
{
/* Initialise the default arm status */
arm_status status = ARM_MATH_SUCCESS;
/* Initialise the FFT length */
S->fftLen = fftLen;
/* Initialise the Twiddle coefficient pointer */
S->pTwiddle = (float32_t *) twiddleCoef;
/* Initialise the Flag for selection of CFFT or CIFFT */
S->ifftFlag = ifftFlag;
/* Initialise the Flag for calculation Bit reversal or not */
S->bitReverseFlag = bitReverseFlag;
/* Initializations of structure parameters depending on the FFT length */
switch (S->fftLen)
{
case 4096u:
/* Initializations of structure parameters for 4096 point FFT */
/* Initialise the twiddle coef modifier value */
S->twidCoefModifier = 1u;
/* Initialise the bit reversal table modifier */
S->bitRevFactor = 1u;
/* Initialise the bit reversal table pointer */
S->pBitRevTable = (uint16_t *) armBitRevTable;
/* Initialise the 1/fftLen Value */
S->onebyfftLen = 0.000244140625;
break;
case 2048u:
/* Initializations of structure parameters for 2048 point FFT */
/* Initialise the twiddle coef modifier value */
S->twidCoefModifier = 2u;
/* Initialise the bit reversal table modifier */
S->bitRevFactor = 2u;
/* Initialise the bit reversal table pointer */
S->pBitRevTable = (uint16_t *) & armBitRevTable[1];
/* Initialise the 1/fftLen Value */
S->onebyfftLen = 0.00048828125;
break;
case 1024u:
/* Initializations of structure parameters for 1024 point FFT */
/* Initialise the twiddle coef modifier value */
S->twidCoefModifier = 4u;
/* Initialise the bit reversal table modifier */
S->bitRevFactor = 4u;
/* Initialise the bit reversal table pointer */
S->pBitRevTable = (uint16_t *) & armBitRevTable[3];
/* Initialise the 1/fftLen Value */
S->onebyfftLen = 0.0009765625f;
break;
case 512u:
/* Initializations of structure parameters for 512 point FFT */
/* Initialise the twiddle coef modifier value */
S->twidCoefModifier = 8u;
/* Initialise the bit reversal table modifier */
S->bitRevFactor = 8u;
/* Initialise the bit reversal table pointer */
S->pBitRevTable = (uint16_t *) & armBitRevTable[7];
/* Initialise the 1/fftLen Value */
S->onebyfftLen = 0.001953125;
break;
case 256u:
/* Initializations of structure parameters for 256 point FFT */
S->twidCoefModifier = 16u;
S->bitRevFactor = 16u;
S->pBitRevTable = (uint16_t *) & armBitRevTable[15];
S->onebyfftLen = 0.00390625f;
break;
case 128u:
/* Initializations of structure parameters for 128 point FFT */
S->twidCoefModifier = 32u;
S->bitRevFactor = 32u;
S->pBitRevTable = (uint16_t *) & armBitRevTable[31];
S->onebyfftLen = 0.0078125;
break;
case 64u:
/* Initializations of structure parameters for 64 point FFT */
S->twidCoefModifier = 64u;
S->bitRevFactor = 64u;
S->pBitRevTable = (uint16_t *) & armBitRevTable[63];
S->onebyfftLen = 0.015625f;
break;
case 32u:
/* Initializations of structure parameters for 64 point FFT */
S->twidCoefModifier = 128u;
S->bitRevFactor = 128u;
S->pBitRevTable = (uint16_t *) & armBitRevTable[127];
S->onebyfftLen = 0.03125;
break;
case 16u:
/* Initializations of structure parameters for 16 point FFT */
S->twidCoefModifier = 256u;
S->bitRevFactor = 256u;
S->pBitRevTable = (uint16_t *) & armBitRevTable[255];
S->onebyfftLen = 0.0625f;
break;
default:
/* Reporting argument error if fftSize is not valid value */
status = ARM_MATH_ARGUMENT_ERROR;
break;
}
return (status);
}
/**
* @} end of Radix2_CFFT_CIFFT group
*/