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Rev	Author	Line No.	Line
2	mjames	1	/* ----------------------------------------------------------------------
		2	* Project: CMSIS DSP Library
		3	* Title: arm_cfft_radix2_init_q15.c
		4	* Description: Radix-2 Decimation in Frequency Q15 FFT & IFFT initialization function
		5	*
		6	* $Date: 27. January 2017
		7	* $Revision: V.1.5.1
		8	*
		9	* Target Processor: Cortex-M cores
		10	* -------------------------------------------------------------------- */
		11	/*
		12	* Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
		13	*
		14	* SPDX-License-Identifier: Apache-2.0
		15	*
		16	* Licensed under the Apache License, Version 2.0 (the License); you may
		17	* not use this file except in compliance with the License.
		18	* You may obtain a copy of the License at
		19	*
		20	* www.apache.org/licenses/LICENSE-2.0
		21	*
		22	* Unless required by applicable law or agreed to in writing, software
		23	* distributed under the License is distributed on an AS IS BASIS, WITHOUT
		24	* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		25	* See the License for the specific language governing permissions and
		26	* limitations under the License.
		27	*/
		28
		29	#include "arm_math.h"
		30	#include "arm_common_tables.h"
		31
		32	/**
		33	* @ingroup groupTransforms
		34	*/
		35
		36
		37	/**
		38	* @addtogroup ComplexFFT
		39	* @{
		40	*/
		41
		42	/**
		43	* @brief Initialization function for the Q15 CFFT/CIFFT.
		44	* @deprecated Do not use this function. It has been superseded by \ref arm_cfft_q15 and will be removed
		45	* @param[in,out] *S points to an instance of the Q15 CFFT/CIFFT structure.
		46	* @param[in] fftLen length of the FFT.
		47	* @param[in] ifftFlag flag that selects forward (ifftFlag=0) or inverse (ifftFlag=1) transform.
		48	* @param[in] bitReverseFlag flag that enables (bitReverseFlag=1) or disables (bitReverseFlag=0) bit reversal of output.
		49	* @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.
		50	*
		51	* \par Description:
		52	* \par
		53	* The parameter <code>ifftFlag</code> controls whether a forward or inverse transform is computed.
		54	* Set(=1) ifftFlag for calculation of CIFFT otherwise CFFT is calculated
		55	* \par
		56	* The parameter <code>bitReverseFlag</code> controls whether output is in normal order or bit reversed order.
		57	* Set(=1) bitReverseFlag for output to be in normal order otherwise output is in bit reversed order.
		58	* \par
		59	* The parameter <code>fftLen</code> Specifies length of CFFT/CIFFT process. Supported FFT Lengths are 16, 64, 256, 1024.
		60	* \par
		61	* This Function also initializes Twiddle factor table pointer and Bit reversal table pointer.
		62	*/
		63
		64	arm_status arm_cfft_radix2_init_q15(
		65	arm_cfft_radix2_instance_q15 * S,
		66	uint16_t fftLen,
		67	uint8_t ifftFlag,
		68	uint8_t bitReverseFlag)
		69	{
		70	/* Initialise the default arm status */
		71	arm_status status = ARM_MATH_SUCCESS;
		72
		73	/* Initialise the FFT length */
		74	S->fftLen = fftLen;
		75
		76	/* Initialise the Twiddle coefficient pointer */
		77	S->pTwiddle = (q15_t *) twiddleCoef_4096_q15;
		78	/* Initialise the Flag for selection of CFFT or CIFFT */
		79	S->ifftFlag = ifftFlag;
		80	/* Initialise the Flag for calculation Bit reversal or not */
		81	S->bitReverseFlag = bitReverseFlag;
		82
		83	/* Initializations of structure parameters depending on the FFT length */
		84	switch (S->fftLen)
		85	{
		86	case 4096U:
		87	/* Initializations of structure parameters for 4096 point FFT */
		88
		89	/* Initialise the twiddle coef modifier value */
		90	S->twidCoefModifier = 1U;
		91	/* Initialise the bit reversal table modifier */
		92	S->bitRevFactor = 1U;
		93	/* Initialise the bit reversal table pointer */
		94	S->pBitRevTable = (uint16_t *) armBitRevTable;
		95
		96	break;
		97
		98	case 2048U:
		99	/* Initializations of structure parameters for 2048 point FFT */
		100
		101	/* Initialise the twiddle coef modifier value */
		102	S->twidCoefModifier = 2U;
		103	/* Initialise the bit reversal table modifier */
		104	S->bitRevFactor = 2U;
		105	/* Initialise the bit reversal table pointer */
		106	S->pBitRevTable = (uint16_t *) & armBitRevTable[1];
		107
		108	break;
		109
		110	case 1024U:
		111	/* Initializations of structure parameters for 1024 point FFT */
		112	S->twidCoefModifier = 4U;
		113	S->bitRevFactor = 4U;
		114	S->pBitRevTable = (uint16_t *) & armBitRevTable[3];
		115
		116	break;
		117
		118	case 512U:
		119	/* Initializations of structure parameters for 512 point FFT */
		120	S->twidCoefModifier = 8U;
		121	S->bitRevFactor = 8U;
		122	S->pBitRevTable = (uint16_t *) & armBitRevTable[7];
		123
		124	break;
		125
		126	case 256U:
		127	/* Initializations of structure parameters for 256 point FFT */
		128	S->twidCoefModifier = 16U;
		129	S->bitRevFactor = 16U;
		130	S->pBitRevTable = (uint16_t *) & armBitRevTable[15];
		131
		132	break;
		133
		134	case 128U:
		135	/* Initializations of structure parameters for 128 point FFT */
		136	S->twidCoefModifier = 32U;
		137	S->bitRevFactor = 32U;
		138	S->pBitRevTable = (uint16_t *) & armBitRevTable[31];
		139
		140	break;
		141
		142	case 64U:
		143	/* Initializations of structure parameters for 64 point FFT */
		144	S->twidCoefModifier = 64U;
		145	S->bitRevFactor = 64U;
		146	S->pBitRevTable = (uint16_t *) & armBitRevTable[63];
		147
		148	break;
		149
		150	case 32U:
		151	/* Initializations of structure parameters for 32 point FFT */
		152	S->twidCoefModifier = 128U;
		153	S->bitRevFactor = 128U;
		154	S->pBitRevTable = (uint16_t *) & armBitRevTable[127];
		155
		156	break;
		157
		158	case 16U:
		159	/* Initializations of structure parameters for 16 point FFT */
		160	S->twidCoefModifier = 256U;
		161	S->bitRevFactor = 256U;
		162	S->pBitRevTable = (uint16_t *) & armBitRevTable[255];
		163
		164	break;
		165
		166	default:
		167	/* Reporting argument error if fftSize is not valid value */
		168	status = ARM_MATH_ARGUMENT_ERROR;
		169	break;
		170	}
		171
		172	return (status);
		173	}
		174
		175	/**
		176	* @} end of ComplexFFT group
		177	*/

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