/* ----------------------------------------------------------------------
* Copyright (C) 2010-2013 ARM Limited. All rights reserved.
*
* $Date: 17. January 2013
* $Revision: V1.4.1
*
* Project: CMSIS DSP Library
* Title: arm_cfft_radix2_init_q15.c
*
* Description: Radix-2 Decimation in Frequency Q15 FFT & IFFT initialization function
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* - Neither the name of ARM LIMITED nor the names of its contributors
* may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* -------------------------------------------------------------------- */
#include "arm_math.h"
#include "arm_common_tables.h"
/**
* @ingroup groupTransforms
*/
/**
* @addtogroup ComplexFFT
* @{
*/
/**
* @brief Initialization function for the Q15 CFFT/CIFFT.
* @param[in,out] *S points to an instance of the Q15 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_q15(
arm_cfft_radix2_instance_q15 * 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 = (q15_t *) twiddleCoefQ15;
/* 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;
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];
break;
case 1024u:
/* Initializations of structure parameters for 1024 point FFT */
S->twidCoefModifier = 4u;
S->bitRevFactor = 4u;
S->pBitRevTable = (uint16_t *) & armBitRevTable[3];
break;
case 512u:
/* Initializations of structure parameters for 512 point FFT */
S->twidCoefModifier = 8u;
S->bitRevFactor = 8u;
S->pBitRevTable = (uint16_t *) & armBitRevTable[7];
break;
case 256u:
/* Initializations of structure parameters for 256 point FFT */
S->twidCoefModifier = 16u;
S->bitRevFactor = 16u;
S->pBitRevTable = (uint16_t *) & armBitRevTable[15];
break;
case 128u:
/* Initializations of structure parameters for 128 point FFT */
S->twidCoefModifier = 32u;
S->bitRevFactor = 32u;
S->pBitRevTable = (uint16_t *) & armBitRevTable[31];
break;
case 64u:
/* Initializations of structure parameters for 64 point FFT */
S->twidCoefModifier = 64u;
S->bitRevFactor = 64u;
S->pBitRevTable = (uint16_t *) & armBitRevTable[63];
break;
case 32u:
/* Initializations of structure parameters for 32 point FFT */
S->twidCoefModifier = 128u;
S->bitRevFactor = 128u;
S->pBitRevTable = (uint16_t *) & armBitRevTable[127];
break;
case 16u:
/* Initializations of structure parameters for 16 point FFT */
S->twidCoefModifier = 256u;
S->bitRevFactor = 256u;
S->pBitRevTable = (uint16_t *) & armBitRevTable[255];
break;
default:
/* Reporting argument error if fftSize is not valid value */
status = ARM_MATH_ARGUMENT_ERROR;
break;
}
return (status);
}
/**
* @} end of ComplexFFT group
*/