WebSVN – dashGPS – Blame – /trunk/Drivers/CMSIS/DSP/Source/TransformFunctions/arm_cfft_radix2_init_q31.c

Rev	Author	Line No.	Line
2	mjames	1	/* ----------------------------------------------------------------------
		2	* Project: CMSIS DSP Library
		3	* Title: arm_cfft_radix2_init_q31.c
		4	* Description: Radix-2 Decimation in Frequency Fixed-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	/**
		43	*
		44	* @brief Initialization function for the Q31 CFFT/CIFFT.
		45	* @deprecated Do not use this function. It has been superseded by \ref arm_cfft_q31 and will be removed
		46	* @param[in,out] *S points to an instance of the Q31 CFFT/CIFFT structure.
		47	* @param[in] fftLen length of the FFT.
		48	* @param[in] ifftFlag flag that selects forward (ifftFlag=0) or inverse (ifftFlag=1) transform.
		49	* @param[in] bitReverseFlag flag that enables (bitReverseFlag=1) or disables (bitReverseFlag=0) bit reversal of output.
		50	* @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.
		51	*
		52	* \par Description:
		53	* \par
		54	* The parameter <code>ifftFlag</code> controls whether a forward or inverse transform is computed.
		55	* Set(=1) ifftFlag for calculation of CIFFT otherwise CFFT is calculated
		56	* \par
		57	* The parameter <code>bitReverseFlag</code> controls whether output is in normal order or bit reversed order.
		58	* Set(=1) bitReverseFlag for output to be in normal order otherwise output is in bit reversed order.
		59	* \par
		60	* The parameter <code>fftLen</code> Specifies length of CFFT/CIFFT process. Supported FFT Lengths are 16, 64, 256, 1024.
		61	* \par
		62	* This Function also initializes Twiddle factor table pointer and Bit reversal table pointer.
		63	*/
		64
		65	arm_status arm_cfft_radix2_init_q31(
		66	arm_cfft_radix2_instance_q31 * S,
		67	uint16_t fftLen,
		68	uint8_t ifftFlag,
		69	uint8_t bitReverseFlag)
		70	{
		71	/* Initialise the default arm status */
		72	arm_status status = ARM_MATH_SUCCESS;
		73
		74	/* Initialise the FFT length */
		75	S->fftLen = fftLen;
		76
		77	/* Initialise the Twiddle coefficient pointer */
		78	S->pTwiddle = (q31_t *) twiddleCoef_4096_q31;
		79	/* Initialise the Flag for selection of CFFT or CIFFT */
		80	S->ifftFlag = ifftFlag;
		81	/* Initialise the Flag for calculation Bit reversal or not */
		82	S->bitReverseFlag = bitReverseFlag;
		83
		84	/* Initializations of Instance structure depending on the FFT length */
		85	switch (S->fftLen)
		86	{
		87	/* Initializations of structure parameters for 4096 point FFT */
		88	case 4096U:
		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	break;
		96
		97	/* Initializations of structure parameters for 2048 point FFT */
		98	case 2048U:
		99	/* Initialise the twiddle coef modifier value */
		100	S->twidCoefModifier = 2U;
		101	/* Initialise the bit reversal table modifier */
		102	S->bitRevFactor = 2U;
		103	/* Initialise the bit reversal table pointer */
		104	S->pBitRevTable = (uint16_t *) & armBitRevTable[1];
		105	break;
		106
		107	/* Initializations of structure parameters for 1024 point FFT */
		108	case 1024U:
		109	/* Initialise the twiddle coef modifier value */
		110	S->twidCoefModifier = 4U;
		111	/* Initialise the bit reversal table modifier */
		112	S->bitRevFactor = 4U;
		113	/* Initialise the bit reversal table pointer */
		114	S->pBitRevTable = (uint16_t *) & armBitRevTable[3];
		115	break;
		116
		117	/* Initializations of structure parameters for 512 point FFT */
		118	case 512U:
		119	/* Initialise the twiddle coef modifier value */
		120	S->twidCoefModifier = 8U;
		121	/* Initialise the bit reversal table modifier */
		122	S->bitRevFactor = 8U;
		123	/* Initialise the bit reversal table pointer */
		124	S->pBitRevTable = (uint16_t *) & armBitRevTable[7];
		125	break;
		126
		127	case 256U:
		128	/* Initializations of structure parameters for 256 point FFT */
		129	S->twidCoefModifier = 16U;
		130	S->bitRevFactor = 16U;
		131	S->pBitRevTable = (uint16_t *) & armBitRevTable[15];
		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	break;
		140
		141	case 64U:
		142	/* Initializations of structure parameters for 64 point FFT */
		143	S->twidCoefModifier = 64U;
		144	S->bitRevFactor = 64U;
		145	S->pBitRevTable = (uint16_t *) & armBitRevTable[63];
		146	break;
		147
		148	case 32U:
		149	/* Initializations of structure parameters for 32 point FFT */
		150	S->twidCoefModifier = 128U;
		151	S->bitRevFactor = 128U;
		152	S->pBitRevTable = (uint16_t *) & armBitRevTable[127];
		153	break;
		154
		155	case 16U:
		156	/* Initializations of structure parameters for 16 point FFT */
		157	S->twidCoefModifier = 256U;
		158	S->bitRevFactor = 256U;
		159	S->pBitRevTable = (uint16_t *) & armBitRevTable[255];
		160	break;
		161
		162
		163	default:
		164	/* Reporting argument error if fftSize is not valid value */
		165	status = ARM_MATH_ARGUMENT_ERROR;
		166	break;
		167	}
		168
		169	return (status);
		170	}
		171
		172	/**
		173	* @} end of ComplexFFT group
		174	*/

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