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Rev	Author	Line No.	Line
2	mjames	1	/* ----------------------------------------------------------------------
		2	* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
		3	*
		4	* $Date: 19. March 2015
		5	* $Revision: V.1.4.5
		6	*
		7	* Project: CMSIS DSP Library
		8	* Title: arm_cfft_radix2_init_q15.c
		9	*
		10	* Description: Radix-2 Decimation in Frequency Q15 FFT & IFFT initialization function
		11	*
		12	* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
		13	*
		14	* Redistribution and use in source and binary forms, with or without
		15	* modification, are permitted provided that the following conditions
		16	* are met:
		17	* - Redistributions of source code must retain the above copyright
		18	* notice, this list of conditions and the following disclaimer.
		19	* - Redistributions in binary form must reproduce the above copyright
		20	* notice, this list of conditions and the following disclaimer in
		21	* the documentation and/or other materials provided with the
		22	* distribution.
		23	* - Neither the name of ARM LIMITED nor the names of its contributors
		24	* may be used to endorse or promote products derived from this
		25	* software without specific prior written permission.
		26	*
		27	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
		28	* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
		29	* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
		30	* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
		31	* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
		32	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
		33	* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
		34	* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
		35	* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
		36	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
		37	* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
		38	* POSSIBILITY OF SUCH DAMAGE.
		39	* -------------------------------------------------------------------- */
		40
		41	#include "arm_math.h"
		42	#include "arm_common_tables.h"
		43
		44	/**
		45	* @ingroup groupTransforms
		46	*/
		47
		48
		49	/**
		50	* @addtogroup ComplexFFT
		51	* @{
		52	*/
		53
		54	/**
		55	* @brief Initialization function for the Q15 CFFT/CIFFT.
		56	* @deprecated Do not use this function. It has been superseded by \ref arm_cfft_q15 and will be removed
		57	* @param[in,out] *S points to an instance of the Q15 CFFT/CIFFT structure.
		58	* @param[in] fftLen length of the FFT.
		59	* @param[in] ifftFlag flag that selects forward (ifftFlag=0) or inverse (ifftFlag=1) transform.
		60	* @param[in] bitReverseFlag flag that enables (bitReverseFlag=1) or disables (bitReverseFlag=0) bit reversal of output.
		61	* @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.
		62	*
		63	* \par Description:
		64	* \par
		65	* The parameter <code>ifftFlag</code> controls whether a forward or inverse transform is computed.
		66	* Set(=1) ifftFlag for calculation of CIFFT otherwise CFFT is calculated
		67	* \par
		68	* The parameter <code>bitReverseFlag</code> controls whether output is in normal order or bit reversed order.
		69	* Set(=1) bitReverseFlag for output to be in normal order otherwise output is in bit reversed order.
		70	* \par
		71	* The parameter <code>fftLen</code> Specifies length of CFFT/CIFFT process. Supported FFT Lengths are 16, 64, 256, 1024.
		72	* \par
		73	* This Function also initializes Twiddle factor table pointer and Bit reversal table pointer.
		74	*/
		75
		76	arm_status arm_cfft_radix2_init_q15(
		77	arm_cfft_radix2_instance_q15 * S,
		78	uint16_t fftLen,
		79	uint8_t ifftFlag,
		80	uint8_t bitReverseFlag)
		81	{
		82	/* Initialise the default arm status */
		83	arm_status status = ARM_MATH_SUCCESS;
		84
		85	/* Initialise the FFT length */
		86	S->fftLen = fftLen;
		87
		88	/* Initialise the Twiddle coefficient pointer */
		89	S->pTwiddle = (q15_t *) twiddleCoef_4096_q15;
		90	/* Initialise the Flag for selection of CFFT or CIFFT */
		91	S->ifftFlag = ifftFlag;
		92	/* Initialise the Flag for calculation Bit reversal or not */
		93	S->bitReverseFlag = bitReverseFlag;
		94
		95	/* Initializations of structure parameters depending on the FFT length */
		96	switch (S->fftLen)
		97	{
		98	case 4096u:
		99	/* Initializations of structure parameters for 4096 point FFT */
		100
		101	/* Initialise the twiddle coef modifier value */
		102	S->twidCoefModifier = 1u;
		103	/* Initialise the bit reversal table modifier */
		104	S->bitRevFactor = 1u;
		105	/* Initialise the bit reversal table pointer */
		106	S->pBitRevTable = (uint16_t *) armBitRevTable;
		107
		108	break;
		109
		110	case 2048u:
		111	/* Initializations of structure parameters for 2048 point FFT */
		112
		113	/* Initialise the twiddle coef modifier value */
		114	S->twidCoefModifier = 2u;
		115	/* Initialise the bit reversal table modifier */
		116	S->bitRevFactor = 2u;
		117	/* Initialise the bit reversal table pointer */
		118	S->pBitRevTable = (uint16_t *) & armBitRevTable[1];
		119
		120	break;
		121
		122	case 1024u:
		123	/* Initializations of structure parameters for 1024 point FFT */
		124	S->twidCoefModifier = 4u;
		125	S->bitRevFactor = 4u;
		126	S->pBitRevTable = (uint16_t *) & armBitRevTable[3];
		127
		128	break;
		129
		130	case 512u:
		131	/* Initializations of structure parameters for 512 point FFT */
		132	S->twidCoefModifier = 8u;
		133	S->bitRevFactor = 8u;
		134	S->pBitRevTable = (uint16_t *) & armBitRevTable[7];
		135
		136	break;
		137
		138	case 256u:
		139	/* Initializations of structure parameters for 256 point FFT */
		140	S->twidCoefModifier = 16u;
		141	S->bitRevFactor = 16u;
		142	S->pBitRevTable = (uint16_t *) & armBitRevTable[15];
		143
		144	break;
		145
		146	case 128u:
		147	/* Initializations of structure parameters for 128 point FFT */
		148	S->twidCoefModifier = 32u;
		149	S->bitRevFactor = 32u;
		150	S->pBitRevTable = (uint16_t *) & armBitRevTable[31];
		151
		152	break;
		153
		154	case 64u:
		155	/* Initializations of structure parameters for 64 point FFT */
		156	S->twidCoefModifier = 64u;
		157	S->bitRevFactor = 64u;
		158	S->pBitRevTable = (uint16_t *) & armBitRevTable[63];
		159
		160	break;
		161
		162	case 32u:
		163	/* Initializations of structure parameters for 32 point FFT */
		164	S->twidCoefModifier = 128u;
		165	S->bitRevFactor = 128u;
		166	S->pBitRevTable = (uint16_t *) & armBitRevTable[127];
		167
		168	break;
		169
		170	case 16u:
		171	/* Initializations of structure parameters for 16 point FFT */
		172	S->twidCoefModifier = 256u;
		173	S->bitRevFactor = 256u;
		174	S->pBitRevTable = (uint16_t *) & armBitRevTable[255];
		175
		176	break;
		177
		178	default:
		179	/* Reporting argument error if fftSize is not valid value */
		180	status = ARM_MATH_ARGUMENT_ERROR;
		181	break;
		182	}
		183
		184	return (status);
		185	}
		186
		187	/**
		188	* @} end of ComplexFFT group
		189	*/

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