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CMSIS DSP Library from CMSIS 2.0. See http://www.onarm.com/cmsis/ for full details

Dependents: K22F_DSP_Matrix_least_square BNO055-ELEC3810 1BNO055 ECE4180Project--Slave2 ... more

src/Cortex-M4-M3/TransformFunctions/arm_rfft_q15.c@0:1014af42efd9, 2011-03-10 (annotated)

Committer:: simon
Date:: Thu Mar 10 15:07:50 2011 +0000
Revision:: 0:1014af42efd9

Who changed what in which revision?

User	Revision	Line number	New contents of line
simon	0:1014af42efd9	1	/* ----------------------------------------------------------------------
simon	0:1014af42efd9	2	* Copyright (C) 2010 ARM Limited. All rights reserved.
simon	0:1014af42efd9	3	*
simon	0:1014af42efd9	4	* $Date: 29. November 2010
simon	0:1014af42efd9	5	* $Revision: V1.0.3
simon	0:1014af42efd9	6	*
simon	0:1014af42efd9	7	* Project: CMSIS DSP Library
simon	0:1014af42efd9	8	* Title: arm_rfft_q15.c
simon	0:1014af42efd9	9	*
simon	0:1014af42efd9	10	* Description: RFFT & RIFFT Q15 process function
simon	0:1014af42efd9	11	*
simon	0:1014af42efd9	12	*
simon	0:1014af42efd9	13	* Target Processor: Cortex-M4/Cortex-M3
simon	0:1014af42efd9	14	*
simon	0:1014af42efd9	15	* Version 1.0.3 2010/11/29
simon	0:1014af42efd9	16	* Re-organized the CMSIS folders and updated documentation.
simon	0:1014af42efd9	17	*
simon	0:1014af42efd9	18	* Version 1.0.2 2010/11/11
simon	0:1014af42efd9	19	* Documentation updated.
simon	0:1014af42efd9	20	*
simon	0:1014af42efd9	21	* Version 1.0.1 2010/10/05
simon	0:1014af42efd9	22	* Production release and review comments incorporated.
simon	0:1014af42efd9	23	*
simon	0:1014af42efd9	24	* Version 1.0.0 2010/09/20
simon	0:1014af42efd9	25	* Production release and review comments incorporated
simon	0:1014af42efd9	26	*
simon	0:1014af42efd9	27	* Version 0.0.7 2010/06/10
simon	0:1014af42efd9	28	* Misra-C changes done
simon	0:1014af42efd9	29	* -------------------------------------------------------------------- */
simon	0:1014af42efd9	30
simon	0:1014af42efd9	31
simon	0:1014af42efd9	32	#include "arm_math.h"
simon	0:1014af42efd9	33
simon	0:1014af42efd9	34	/*--------------------------------------------------------------------
simon	0:1014af42efd9	35	* Internal functions prototypes
simon	0:1014af42efd9	36	--------------------------------------------------------------------*/
simon	0:1014af42efd9	37
simon	0:1014af42efd9	38	void arm_split_rfft_q15(
simon	0:1014af42efd9	39	q15_t * pSrc,
simon	0:1014af42efd9	40	uint32_t fftLen,
simon	0:1014af42efd9	41	q15_t * pATable,
simon	0:1014af42efd9	42	q15_t * pBTable,
simon	0:1014af42efd9	43	q15_t * pDst,
simon	0:1014af42efd9	44	uint32_t modifier);
simon	0:1014af42efd9	45
simon	0:1014af42efd9	46	void arm_split_rifft_q15(
simon	0:1014af42efd9	47	q15_t * pSrc,
simon	0:1014af42efd9	48	uint32_t fftLen,
simon	0:1014af42efd9	49	q15_t * pATable,
simon	0:1014af42efd9	50	q15_t * pBTable,
simon	0:1014af42efd9	51	q15_t * pDst,
simon	0:1014af42efd9	52	uint32_t modifier);
simon	0:1014af42efd9	53
simon	0:1014af42efd9	54	/**
simon	0:1014af42efd9	55	* @addtogroup RFFT_RIFFT
simon	0:1014af42efd9	56	* @{
simon	0:1014af42efd9	57	*/
simon	0:1014af42efd9	58
simon	0:1014af42efd9	59	/**
simon	0:1014af42efd9	60	* @brief Processing function for the Q15 RFFT/RIFFT.
simon	0:1014af42efd9	61	* @param[in] *S points to an instance of the Q15 RFFT/RIFFT structure.
simon	0:1014af42efd9	62	* @param[in] *pSrc points to the input buffer.
simon	0:1014af42efd9	63	* @param[out] *pDst points to the output buffer.
simon	0:1014af42efd9	64	* @return none.
simon	0:1014af42efd9	65	*
simon	0:1014af42efd9	66	* \par Input an output formats:
simon	0:1014af42efd9	67	* \par
simon	0:1014af42efd9	68	* Internally input is downscaled by 2 for every stage to avoid saturations inside CFFT/CIFFT process.
simon	0:1014af42efd9	69	* Hence the output format is different for different RFFT sizes.
simon	0:1014af42efd9	70	* The input and output formats for different RFFT sizes and number of bits to upscale are mentioned in the tables below for RFFT and RIFFT:
simon	0:1014af42efd9	71	* \par
simon	0:1014af42efd9	72	* \image html RFFTQ15.gif "Input and Output Formats for Q15 RFFT"
simon	0:1014af42efd9	73	* \par
simon	0:1014af42efd9	74	* \image html RIFFTQ15.gif "Input and Output Formats for Q15 RIFFT"
simon	0:1014af42efd9	75	*/
simon	0:1014af42efd9	76
simon	0:1014af42efd9	77	void arm_rfft_q15(
simon	0:1014af42efd9	78	const arm_rfft_instance_q15 * S,
simon	0:1014af42efd9	79	q15_t * pSrc,
simon	0:1014af42efd9	80	q15_t * pDst)
simon	0:1014af42efd9	81	{
simon	0:1014af42efd9	82	const arm_cfft_radix4_instance_q15 *S_CFFT = S->pCfft;
simon	0:1014af42efd9	83
simon	0:1014af42efd9	84	/* Calculation of RIFFT of input */
simon	0:1014af42efd9	85	if(S->ifftFlagR == 1u)
simon	0:1014af42efd9	86	{
simon	0:1014af42efd9	87	/* Real IFFT core process */
simon	0:1014af42efd9	88	arm_split_rifft_q15(pSrc, S->fftLenBy2, S->pTwiddleAReal,
simon	0:1014af42efd9	89	S->pTwiddleBReal, pDst, S->twidCoefRModifier);
simon	0:1014af42efd9	90
simon	0:1014af42efd9	91	/* Complex readix-4 IFFT process */
simon	0:1014af42efd9	92	arm_radix4_butterfly_inverse_q15(pDst, S_CFFT->fftLen,
simon	0:1014af42efd9	93	S_CFFT->pTwiddle,
simon	0:1014af42efd9	94	S_CFFT->twidCoefModifier);
simon	0:1014af42efd9	95
simon	0:1014af42efd9	96	/* Bit reversal process */
simon	0:1014af42efd9	97	if(S->bitReverseFlagR == 1u)
simon	0:1014af42efd9	98	{
simon	0:1014af42efd9	99	arm_bitreversal_q15(pDst, S_CFFT->fftLen,
simon	0:1014af42efd9	100	S_CFFT->bitRevFactor, S_CFFT->pBitRevTable);
simon	0:1014af42efd9	101	}
simon	0:1014af42efd9	102	}
simon	0:1014af42efd9	103	else
simon	0:1014af42efd9	104	{
simon	0:1014af42efd9	105	/* Calculation of RFFT of input */
simon	0:1014af42efd9	106
simon	0:1014af42efd9	107	/* Complex readix-4 FFT process */
simon	0:1014af42efd9	108	arm_radix4_butterfly_q15(pSrc, S_CFFT->fftLen,
simon	0:1014af42efd9	109	S_CFFT->pTwiddle, S_CFFT->twidCoefModifier);
simon	0:1014af42efd9	110
simon	0:1014af42efd9	111	/* Bit reversal process */
simon	0:1014af42efd9	112	if(S->bitReverseFlagR == 1u)
simon	0:1014af42efd9	113	{
simon	0:1014af42efd9	114	arm_bitreversal_q15(pSrc, S_CFFT->fftLen,
simon	0:1014af42efd9	115	S_CFFT->bitRevFactor, S_CFFT->pBitRevTable);
simon	0:1014af42efd9	116	}
simon	0:1014af42efd9	117
simon	0:1014af42efd9	118	arm_split_rfft_q15(pSrc, S->fftLenBy2, S->pTwiddleAReal,
simon	0:1014af42efd9	119	S->pTwiddleBReal, pDst, S->twidCoefRModifier);
simon	0:1014af42efd9	120	}
simon	0:1014af42efd9	121
simon	0:1014af42efd9	122	}
simon	0:1014af42efd9	123
simon	0:1014af42efd9	124	/**
simon	0:1014af42efd9	125	* @} end of RFFT_RIFFT group
simon	0:1014af42efd9	126	*/
simon	0:1014af42efd9	127
simon	0:1014af42efd9	128	/**
simon	0:1014af42efd9	129	* @brief Core Real FFT process
simon	0:1014af42efd9	130	* @param *pSrc points to the input buffer.
simon	0:1014af42efd9	131	* @param fftLen length of FFT.
simon	0:1014af42efd9	132	* @param *pATable points to the A twiddle Coef buffer.
simon	0:1014af42efd9	133	* @param *pBTable points to the B twiddle Coef buffer.
simon	0:1014af42efd9	134	* @param *pDst points to the output buffer.
simon	0:1014af42efd9	135	* @param modifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table.
simon	0:1014af42efd9	136	* @return none.
simon	0:1014af42efd9	137	* The function implements a Real FFT
simon	0:1014af42efd9	138	*/
simon	0:1014af42efd9	139
simon	0:1014af42efd9	140	void arm_split_rfft_q15(
simon	0:1014af42efd9	141	q15_t * pSrc,
simon	0:1014af42efd9	142	uint32_t fftLen,
simon	0:1014af42efd9	143	q15_t * pATable,
simon	0:1014af42efd9	144	q15_t * pBTable,
simon	0:1014af42efd9	145	q15_t * pDst,
simon	0:1014af42efd9	146	uint32_t modifier)
simon	0:1014af42efd9	147	{
simon	0:1014af42efd9	148	uint32_t i; /* Loop Counter */
simon	0:1014af42efd9	149	q31_t outR, outI; /* Temporary variables for output */
simon	0:1014af42efd9	150	q15_t pCoefA, pCoefB; /* Temporary pointers for twiddle factors */
simon	0:1014af42efd9	151	q15_t pSrc1, pSrc2;
simon	0:1014af42efd9	152
simon	0:1014af42efd9	153
simon	0:1014af42efd9	154	pSrc[2u * fftLen] = pSrc[0];
simon	0:1014af42efd9	155	pSrc[(2u * fftLen) + 1u] = pSrc[1];
simon	0:1014af42efd9	156
simon	0:1014af42efd9	157	pCoefA = &pATable[modifier * 2u];
simon	0:1014af42efd9	158	pCoefB = &pBTable[modifier * 2u];
simon	0:1014af42efd9	159
simon	0:1014af42efd9	160	pSrc1 = &pSrc[2];
simon	0:1014af42efd9	161	pSrc2 = &pSrc[(2u * fftLen) - 2u];
simon	0:1014af42efd9	162
simon	0:1014af42efd9	163	i = 1u;
simon	0:1014af42efd9	164
simon	0:1014af42efd9	165	while(i < fftLen)
simon	0:1014af42efd9	166	{
simon	0:1014af42efd9	167	/*
simon	0:1014af42efd9	168	outR = (pSrc[2 * i] * pATable[2 * i] - pSrc[2 * i + 1] * pATable[2 * i + 1]
simon	0:1014af42efd9	169	+ pSrc[2 * n - 2 * i] * pBTable[2 * i] +
simon	0:1014af42efd9	170	pSrc[2 * n - 2 * i + 1] * pBTable[2 * i + 1]);
simon	0:1014af42efd9	171	*/
simon	0:1014af42efd9	172
simon	0:1014af42efd9	173	/* outI = (pIn[2 * i + 1] * pATable[2 * i] + pIn[2 * i] * pATable[2 * i + 1] +
simon	0:1014af42efd9	174	pIn[2 * n - 2 * i] * pBTable[2 * i + 1] -
simon	0:1014af42efd9	175	pIn[2 * n - 2 * i + 1] * pBTable[2 * i]); */
simon	0:1014af42efd9	176
simon	0:1014af42efd9	177	/* pSrc[2 * i] * pATable[2 * i] - pSrc[2 * i + 1] * pATable[2 * i + 1] */
simon	0:1014af42efd9	178	outR = __SMUSD(__SIMD32(pSrc1), __SIMD32(pCoefA));
simon	0:1014af42efd9	179
simon	0:1014af42efd9	180	/* pSrc[2 * n - 2 * i] * pBTable[2 * i] +
simon	0:1014af42efd9	181	pSrc[2 * n - 2 * i + 1] * pBTable[2 * i + 1]) */
simon	0:1014af42efd9	182	outR = __SMLAD(__SIMD32(pSrc2), __SIMD32(pCoefB), outR) >> 15u;
simon	0:1014af42efd9	183
simon	0:1014af42efd9	184	/* pIn[2 * n - 2 * i] * pBTable[2 * i + 1] -
simon	0:1014af42efd9	185	pIn[2 * n - 2 * i + 1] * pBTable[2 * i] */
simon	0:1014af42efd9	186	outI = __SMUSDX(__SIMD32(pSrc2)--, __SIMD32(pCoefB));
simon	0:1014af42efd9	187
simon	0:1014af42efd9	188	/* (pIn[2 * i + 1] * pATable[2 * i] + pIn[2 * i] * pATable[2 * i + 1] */
simon	0:1014af42efd9	189	outI = __SMLADX(__SIMD32(pSrc1)++, __SIMD32(pCoefA), outI);
simon	0:1014af42efd9	190
simon	0:1014af42efd9	191	/* write output */
simon	0:1014af42efd9	192	pDst[2u * i] = (q15_t) outR;
simon	0:1014af42efd9	193	pDst[(2u * i) + 1u] = outI >> 15u;
simon	0:1014af42efd9	194
simon	0:1014af42efd9	195	/* write complex conjugate output */
simon	0:1014af42efd9	196	pDst[(4u * fftLen) - (2u * i)] = (q15_t) outR;
simon	0:1014af42efd9	197	pDst[((4u * fftLen) - (2u * i)) + 1u] = -(outI >> 15u);
simon	0:1014af42efd9	198
simon	0:1014af42efd9	199	/* update coefficient pointer */
simon	0:1014af42efd9	200	pCoefB = pCoefB + (2u * modifier);
simon	0:1014af42efd9	201	pCoefA = pCoefA + (2u * modifier);
simon	0:1014af42efd9	202
simon	0:1014af42efd9	203	i++;
simon	0:1014af42efd9	204
simon	0:1014af42efd9	205	}
simon	0:1014af42efd9	206
simon	0:1014af42efd9	207	pDst[2u * fftLen] = pSrc[0] - pSrc[1];
simon	0:1014af42efd9	208	pDst[(2u * fftLen) + 1u] = 0;
simon	0:1014af42efd9	209
simon	0:1014af42efd9	210	pDst[0] = pSrc[0] + pSrc[1];
simon	0:1014af42efd9	211	pDst[1] = 0;
simon	0:1014af42efd9	212
simon	0:1014af42efd9	213	}
simon	0:1014af42efd9	214
simon	0:1014af42efd9	215
simon	0:1014af42efd9	216	/**
simon	0:1014af42efd9	217	* @brief Core Real IFFT process
simon	0:1014af42efd9	218	* @param[in] *pSrc points to the input buffer.
simon	0:1014af42efd9	219	* @param[in] fftLen length of FFT.
simon	0:1014af42efd9	220	* @param[in] *pATable points to the twiddle Coef A buffer.
simon	0:1014af42efd9	221	* @param[in] *pBTable points to the twiddle Coef B buffer.
simon	0:1014af42efd9	222	* @param[out] *pDst points to the output buffer.
simon	0:1014af42efd9	223	* @param[in] modifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table.
simon	0:1014af42efd9	224	* @return none.
simon	0:1014af42efd9	225	* The function implements a Real IFFT
simon	0:1014af42efd9	226	*/
simon	0:1014af42efd9	227
simon	0:1014af42efd9	228	void arm_split_rifft_q15(
simon	0:1014af42efd9	229	q15_t * pSrc,
simon	0:1014af42efd9	230	uint32_t fftLen,
simon	0:1014af42efd9	231	q15_t * pATable,
simon	0:1014af42efd9	232	q15_t * pBTable,
simon	0:1014af42efd9	233	q15_t * pDst,
simon	0:1014af42efd9	234	uint32_t modifier)
simon	0:1014af42efd9	235	{
simon	0:1014af42efd9	236	uint32_t i; /* Loop Counter */
simon	0:1014af42efd9	237	q31_t outR, outI; /* Temporary variables for output */
simon	0:1014af42efd9	238	q15_t pCoefA, pCoefB; /* Temporary pointers for twiddle factors */
simon	0:1014af42efd9	239	q15_t pSrc1, pSrc2;
simon	0:1014af42efd9	240	q15_t *pDst1 = &pDst[0];
simon	0:1014af42efd9	241
simon	0:1014af42efd9	242	pCoefA = &pATable[0];
simon	0:1014af42efd9	243	pCoefB = &pBTable[0];
simon	0:1014af42efd9	244
simon	0:1014af42efd9	245	pSrc1 = &pSrc[0];
simon	0:1014af42efd9	246	pSrc2 = &pSrc[2u * fftLen];
simon	0:1014af42efd9	247
simon	0:1014af42efd9	248	i = fftLen;
simon	0:1014af42efd9	249
simon	0:1014af42efd9	250	while(i > 0u)
simon	0:1014af42efd9	251	{
simon	0:1014af42efd9	252
simon	0:1014af42efd9	253	/*
simon	0:1014af42efd9	254	outR = (pIn[2 * i] * pATable[2 * i] + pIn[2 * i + 1] * pATable[2 * i + 1] +
simon	0:1014af42efd9	255	pIn[2 * n - 2 * i] * pBTable[2 * i] -
simon	0:1014af42efd9	256	pIn[2 * n - 2 * i + 1] * pBTable[2 * i + 1]);
simon	0:1014af42efd9	257
simon	0:1014af42efd9	258	outI = (pIn[2 * i + 1] * pATable[2 * i] - pIn[2 * i] * pATable[2 * i + 1] -
simon	0:1014af42efd9	259	pIn[2 * n - 2 * i] * pBTable[2 * i + 1] -
simon	0:1014af42efd9	260	pIn[2 * n - 2 * i + 1] * pBTable[2 * i]);
simon	0:1014af42efd9	261
simon	0:1014af42efd9	262	*/
simon	0:1014af42efd9	263
simon	0:1014af42efd9	264	/* pIn[2 * n - 2 * i] * pBTable[2 * i] -
simon	0:1014af42efd9	265	pIn[2 * n - 2 * i + 1] * pBTable[2 * i + 1]) */
simon	0:1014af42efd9	266	outR = __SMUSD(__SIMD32(pSrc2), __SIMD32(pCoefB));
simon	0:1014af42efd9	267
simon	0:1014af42efd9	268	/* pIn[2 * i] * pATable[2 * i] + pIn[2 * i + 1] * pATable[2 * i + 1] +
simon	0:1014af42efd9	269	pIn[2 * n - 2 * i] * pBTable[2 * i] */
simon	0:1014af42efd9	270	outR = __SMLAD(__SIMD32(pSrc1), __SIMD32(pCoefA), outR) >> 15u;
simon	0:1014af42efd9	271
simon	0:1014af42efd9	272	/*
simon	0:1014af42efd9	273	-pIn[2 * n - 2 * i] * pBTable[2 * i + 1] +
simon	0:1014af42efd9	274	pIn[2 * n - 2 * i + 1] * pBTable[2 * i] */
simon	0:1014af42efd9	275	outI = __SMUADX(__SIMD32(pSrc2)--, __SIMD32(pCoefB));
simon	0:1014af42efd9	276
simon	0:1014af42efd9	277	/* pIn[2 * i + 1] * pATable[2 * i] - pIn[2 * i] * pATable[2 * i + 1] */
simon	0:1014af42efd9	278	outI = __SMLSDX(__SIMD32(pCoefA), __SIMD32(pSrc1)++, -outI);
simon	0:1014af42efd9	279
simon	0:1014af42efd9	280	/* write output */
simon	0:1014af42efd9	281	*__SIMD32(pDst1)++ =
simon	0:1014af42efd9	282	(q31_t) ((outI << 1u) & 0xFFFF0000) \| (outR & 0x0000FFFF);
simon	0:1014af42efd9	283
simon	0:1014af42efd9	284	/* update coefficient pointer */
simon	0:1014af42efd9	285	pCoefB = pCoefB + (2u * modifier);
simon	0:1014af42efd9	286	pCoefA = pCoefA + (2u * modifier);
simon	0:1014af42efd9	287
simon	0:1014af42efd9	288	i--;
simon	0:1014af42efd9	289
simon	0:1014af42efd9	290	}
simon	0:1014af42efd9	291
simon	0:1014af42efd9	292	}

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Type:	Library
Created:	10 Mar 2011
Imports:	907
Forks:	1
Commits:	3
Dependents:	5
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Followers:	35

src/Cortex-M4-M3/TransformFunctions/arm_rfft_q15.c@0:1014af42efd9, 2011-03-10 (annotated)

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