WebSVN – dashGPS – Blame – /branches/dashGPS-bmp/Drivers/CMSIS/DSP/Source/TransformFunctions/arm_cfft_radix2_init_f32.c

Rev	Author	Line No.	Line
2	mjames	1	/* ----------------------------------------------------------------------
		2	* Project: CMSIS DSP Library
		3	* Title: arm_cfft_radix2_init_f32.c
		4	* Description: Radix-2 Decimation in Frequency Floating-point CFFT & CIFFT 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	* @addtogroup ComplexFFT
		38	* @{
		39	*/
		40
		41	/**
		42	* @brief Initialization function for the floating-point CFFT/CIFFT.
		43	* @deprecated Do not use this function. It has been superseded by \ref arm_cfft_f32 and will be removed
		44	* in the future.
		45	* @param[in,out] *S points to an instance of the floating-point 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	arm_status arm_cfft_radix2_init_f32(
		64	arm_cfft_radix2_instance_f32 * S,
		65	uint16_t fftLen,
		66	uint8_t ifftFlag,
		67	uint8_t bitReverseFlag)
		68	{
		69	/* Initialise the default arm status */
		70	arm_status status = ARM_MATH_SUCCESS;
		71
		72	/* Initialise the FFT length */
		73	S->fftLen = fftLen;
		74
		75	/* Initialise the Twiddle coefficient pointer */
		76	S->pTwiddle = (float32_t *) twiddleCoef;
		77
		78	/* Initialise the Flag for selection of CFFT or CIFFT */
		79	S->ifftFlag = ifftFlag;
		80
		81	/* Initialise the Flag for calculation Bit reversal or not */
		82	S->bitReverseFlag = bitReverseFlag;
		83
		84	/* Initializations of structure parameters depending on the FFT length */
		85	switch (S->fftLen)
		86	{
		87
		88	case 4096U:
		89	/* Initializations of structure parameters for 4096 point FFT */
		90
		91	/* Initialise the twiddle coef modifier value */
		92	S->twidCoefModifier = 1U;
		93	/* Initialise the bit reversal table modifier */
		94	S->bitRevFactor = 1U;
		95	/* Initialise the bit reversal table pointer */
		96	S->pBitRevTable = (uint16_t *) armBitRevTable;
		97	/* Initialise the 1/fftLen Value */
		98	S->onebyfftLen = 0.000244140625;
		99	break;
		100
		101	case 2048U:
		102	/* Initializations of structure parameters for 2048 point FFT */
		103
		104	/* Initialise the twiddle coef modifier value */
		105	S->twidCoefModifier = 2U;
		106	/* Initialise the bit reversal table modifier */
		107	S->bitRevFactor = 2U;
		108	/* Initialise the bit reversal table pointer */
		109	S->pBitRevTable = (uint16_t *) & armBitRevTable[1];
		110	/* Initialise the 1/fftLen Value */
		111	S->onebyfftLen = 0.00048828125;
		112	break;
		113
		114	case 1024U:
		115	/* Initializations of structure parameters for 1024 point FFT */
		116
		117	/* Initialise the twiddle coef modifier value */
		118	S->twidCoefModifier = 4U;
		119	/* Initialise the bit reversal table modifier */
		120	S->bitRevFactor = 4U;
		121	/* Initialise the bit reversal table pointer */
		122	S->pBitRevTable = (uint16_t *) & armBitRevTable[3];
		123	/* Initialise the 1/fftLen Value */
		124	S->onebyfftLen = 0.0009765625f;
		125	break;
		126
		127	case 512U:
		128	/* Initializations of structure parameters for 512 point FFT */
		129
		130	/* Initialise the twiddle coef modifier value */
		131	S->twidCoefModifier = 8U;
		132	/* Initialise the bit reversal table modifier */
		133	S->bitRevFactor = 8U;
		134	/* Initialise the bit reversal table pointer */
		135	S->pBitRevTable = (uint16_t *) & armBitRevTable[7];
		136	/* Initialise the 1/fftLen Value */
		137	S->onebyfftLen = 0.001953125;
		138	break;
		139
		140	case 256U:
		141	/* Initializations of structure parameters for 256 point FFT */
		142	S->twidCoefModifier = 16U;
		143	S->bitRevFactor = 16U;
		144	S->pBitRevTable = (uint16_t *) & armBitRevTable[15];
		145	S->onebyfftLen = 0.00390625f;
		146	break;
		147
		148	case 128U:
		149	/* Initializations of structure parameters for 128 point FFT */
		150	S->twidCoefModifier = 32U;
		151	S->bitRevFactor = 32U;
		152	S->pBitRevTable = (uint16_t *) & armBitRevTable[31];
		153	S->onebyfftLen = 0.0078125;
		154	break;
		155
		156	case 64U:
		157	/* Initializations of structure parameters for 64 point FFT */
		158	S->twidCoefModifier = 64U;
		159	S->bitRevFactor = 64U;
		160	S->pBitRevTable = (uint16_t *) & armBitRevTable[63];
		161	S->onebyfftLen = 0.015625f;
		162	break;
		163
		164	case 32U:
		165	/* Initializations of structure parameters for 64 point FFT */
		166	S->twidCoefModifier = 128U;
		167	S->bitRevFactor = 128U;
		168	S->pBitRevTable = (uint16_t *) & armBitRevTable[127];
		169	S->onebyfftLen = 0.03125;
		170	break;
		171
		172	case 16U:
		173	/* Initializations of structure parameters for 16 point FFT */
		174	S->twidCoefModifier = 256U;
		175	S->bitRevFactor = 256U;
		176	S->pBitRevTable = (uint16_t *) & armBitRevTable[255];
		177	S->onebyfftLen = 0.0625f;
		178	break;
		179
		180
		181	default:
		182	/* Reporting argument error if fftSize is not valid value */
		183	status = ARM_MATH_ARGUMENT_ERROR;
		184	break;
		185	}
		186
		187	return (status);
		188	}
		189
		190	/**
		191	* @} end of ComplexFFT group
		192	*/

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