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src/Cortex-M4-M3/FilteringFunctions/arm_fir_sparse_f32.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_fir_sparse_f32.c
simon	0:1014af42efd9	9	*
simon	0:1014af42efd9	10	* Description: Floating-point sparse FIR filter processing function.
simon	0:1014af42efd9	11	*
simon	0:1014af42efd9	12	* Target Processor: Cortex-M4/Cortex-M3
simon	0:1014af42efd9	13	*
simon	0:1014af42efd9	14	* Version 1.0.3 2010/11/29
simon	0:1014af42efd9	15	* Re-organized the CMSIS folders and updated documentation.
simon	0:1014af42efd9	16	*
simon	0:1014af42efd9	17	* Version 1.0.2 2010/11/11
simon	0:1014af42efd9	18	* Documentation updated.
simon	0:1014af42efd9	19	*
simon	0:1014af42efd9	20	* Version 1.0.1 2010/10/05
simon	0:1014af42efd9	21	* Production release and review comments incorporated.
simon	0:1014af42efd9	22	*
simon	0:1014af42efd9	23	* Version 1.0.0 2010/09/20
simon	0:1014af42efd9	24	* Production release and review comments incorporated
simon	0:1014af42efd9	25	*
simon	0:1014af42efd9	26	* Version 0.0.7 2010/06/10
simon	0:1014af42efd9	27	* Misra-C changes done
simon	0:1014af42efd9	28	* ------------------------------------------------------------------- */
simon	0:1014af42efd9	29	#include "arm_math.h"
simon	0:1014af42efd9	30
simon	0:1014af42efd9	31	/**
simon	0:1014af42efd9	32	* @ingroup groupFilters
simon	0:1014af42efd9	33	*/
simon	0:1014af42efd9	34
simon	0:1014af42efd9	35	/**
simon	0:1014af42efd9	36	* @defgroup FIR_Sparse Finite Impulse Response (FIR) Sparse Filters
simon	0:1014af42efd9	37	*
simon	0:1014af42efd9	38	* This group of functions implements sparse FIR filters.
simon	0:1014af42efd9	39	* Sparse FIR filters are equivalent to standard FIR filters except that most of the coefficients are equal to zero.
simon	0:1014af42efd9	40	* Sparse filters are used for simulating reflections in communications and audio applications.
simon	0:1014af42efd9	41	*
simon	0:1014af42efd9	42	* There are separate functions for Q7, Q15, Q31, and floating-point data types.
simon	0:1014af42efd9	43	* The functions operate on blocks of input and output data and each call to the function processes
simon	0:1014af42efd9	44	* <code>blockSize</code> samples through the filter. <code>pSrc</code> and
simon	0:1014af42efd9	45	* <code>pDst</code> points to input and output arrays respectively containing <code>blockSize</code> values.
simon	0:1014af42efd9	46	*
simon	0:1014af42efd9	47	* \par Algorithm:
simon	0:1014af42efd9	48	* The sparse filter instant structure contains an array of tap indices <code>pTapDelay</code> which specifies the locations of the non-zero coefficients.
simon	0:1014af42efd9	49	* This is in addition to the coefficient array <code>b</code>.
simon	0:1014af42efd9	50	* The implementation essentially skips the multiplications by zero and leads to an efficient realization.
simon	0:1014af42efd9	51	* <pre>
simon	0:1014af42efd9	52	* y[n] = b[0] * x[n-pTapDelay[0]] + b[1] * x[n-pTapDelay[1]] + b[2] * x[n-pTapDelay[2]] + ...+ b[numTaps-1] * x[n-pTapDelay[numTaps-1]]
simon	0:1014af42efd9	53	* </pre>
simon	0:1014af42efd9	54	* \par
simon	0:1014af42efd9	55	* \image html FIRSparse.gif "Sparse FIR filter. b[n] represents the filter coefficients"
simon	0:1014af42efd9	56	* \par
simon	0:1014af42efd9	57	* <code>pCoeffs</code> points to a coefficient array of size <code>numTaps</code>;
simon	0:1014af42efd9	58	* <code>pTapDelay</code> points to an array of nonzero indices and is also of size <code>numTaps</code>;
simon	0:1014af42efd9	59	* <code>pState</code> points to a state array of size <code>maxDelay + blockSize</code>, where
simon	0:1014af42efd9	60	* <code>maxDelay</code> is the largest offset value that is ever used in the <code>pTapDelay</code> array.
simon	0:1014af42efd9	61	* Some of the processing functions also require temporary working buffers.
simon	0:1014af42efd9	62	*
simon	0:1014af42efd9	63	* \par Instance Structure
simon	0:1014af42efd9	64	* The coefficients and state variables for a filter are stored together in an instance data structure.
simon	0:1014af42efd9	65	* A separate instance structure must be defined for each filter.
simon	0:1014af42efd9	66	* Coefficient and offset arrays may be shared among several instances while state variable arrays cannot be shared.
simon	0:1014af42efd9	67	* There are separate instance structure declarations for each of the 4 supported data types.
simon	0:1014af42efd9	68	*
simon	0:1014af42efd9	69	* \par Initialization Functions
simon	0:1014af42efd9	70	* There is also an associated initialization function for each data type.
simon	0:1014af42efd9	71	* The initialization function performs the following operations:
simon	0:1014af42efd9	72	* - Sets the values of the internal structure fields.
simon	0:1014af42efd9	73	* - Zeros out the values in the state buffer.
simon	0:1014af42efd9	74	*
simon	0:1014af42efd9	75	* \par
simon	0:1014af42efd9	76	* Use of the initialization function is optional.
simon	0:1014af42efd9	77	* However, if the initialization function is used, then the instance structure cannot be placed into a const data section.
simon	0:1014af42efd9	78	* To place an instance structure into a const data section, the instance structure must be manually initialized.
simon	0:1014af42efd9	79	* Set the values in the state buffer to zeros before static initialization.
simon	0:1014af42efd9	80	* The code below statically initializes each of the 4 different data type filter instance structures
simon	0:1014af42efd9	81	* <pre>
simon	0:1014af42efd9	82	*arm_fir_sparse_instance_f32 S = {numTaps, 0, pState, pCoeffs, maxDelay, pTapDelay};
simon	0:1014af42efd9	83	*arm_fir_sparse_instance_q31 S = {numTaps, 0, pState, pCoeffs, maxDelay, pTapDelay};
simon	0:1014af42efd9	84	*arm_fir_sparse_instance_q15 S = {numTaps, 0, pState, pCoeffs, maxDelay, pTapDelay};
simon	0:1014af42efd9	85	*arm_fir_sparse_instance_q7 S = {numTaps, 0, pState, pCoeffs, maxDelay, pTapDelay};
simon	0:1014af42efd9	86	* </pre>
simon	0:1014af42efd9	87	* \par
simon	0:1014af42efd9	88	*
simon	0:1014af42efd9	89	* \par Fixed-Point Behavior
simon	0:1014af42efd9	90	* Care must be taken when using the fixed-point versions of the sparse FIR filter functions.
simon	0:1014af42efd9	91	* In particular, the overflow and saturation behavior of the accumulator used in each function must be considered.
simon	0:1014af42efd9	92	* Refer to the function specific documentation below for usage guidelines.
simon	0:1014af42efd9	93	*/
simon	0:1014af42efd9	94
simon	0:1014af42efd9	95	/**
simon	0:1014af42efd9	96	* @addtogroup FIR_Sparse
simon	0:1014af42efd9	97	* @{
simon	0:1014af42efd9	98	*/
simon	0:1014af42efd9	99
simon	0:1014af42efd9	100	/**
simon	0:1014af42efd9	101	* @brief Processing function for the floating-point sparse FIR filter.
simon	0:1014af42efd9	102	* @param[in] *S points to an instance of the floating-point sparse FIR structure.
simon	0:1014af42efd9	103	* @param[in] *pSrc points to the block of input data.
simon	0:1014af42efd9	104	* @param[out] *pDst points to the block of output data
simon	0:1014af42efd9	105	* @param[in] *pScratchIn points to a temporary buffer of size blockSize.
simon	0:1014af42efd9	106	* @param[in] blockSize number of input samples to process per call.
simon	0:1014af42efd9	107	* @return none.
simon	0:1014af42efd9	108	*/
simon	0:1014af42efd9	109
simon	0:1014af42efd9	110	void arm_fir_sparse_f32(
simon	0:1014af42efd9	111	arm_fir_sparse_instance_f32 * S,
simon	0:1014af42efd9	112	float32_t * pSrc,
simon	0:1014af42efd9	113	float32_t * pDst,
simon	0:1014af42efd9	114	float32_t * pScratchIn,
simon	0:1014af42efd9	115	uint32_t blockSize)
simon	0:1014af42efd9	116	{
simon	0:1014af42efd9	117
simon	0:1014af42efd9	118	float32_t pState = S->pState; / State pointer */
simon	0:1014af42efd9	119	float32_t pCoeffs = S->pCoeffs; / Coefficient pointer */
simon	0:1014af42efd9	120	float32_t px; / Scratch buffer pointer */
simon	0:1014af42efd9	121	float32_t py = pState; / Temporary pointers for state buffer */
simon	0:1014af42efd9	122	float32_t pb = pScratchIn; / Temporary pointers for scratch buffer */
simon	0:1014af42efd9	123	float32_t pOut; / Destination pointer */
simon	0:1014af42efd9	124	int32_t pTapDelay = S->pTapDelay; / Pointer to the array containing offset of the non-zero tap values. */
simon	0:1014af42efd9	125	uint32_t delaySize = S->maxDelay + blockSize; /* state length */
simon	0:1014af42efd9	126	uint16_t numTaps = S->numTaps; /* Number of filter coefficients in the filter */
simon	0:1014af42efd9	127	int32_t readIndex; /* Read index of the state buffer */
simon	0:1014af42efd9	128	uint32_t tapCnt, blkCnt; /* loop counters */
simon	0:1014af42efd9	129	float32_t coeff = pCoeffs++; / Read the first coefficient value */
simon	0:1014af42efd9	130
simon	0:1014af42efd9	131
simon	0:1014af42efd9	132
simon	0:1014af42efd9	133	/* BlockSize of Input samples are copied into the state buffer */
simon	0:1014af42efd9	134	/* StateIndex points to the starting position to write in the state buffer */
simon	0:1014af42efd9	135	arm_circularWrite_f32((int32_t *) py, delaySize, &S->stateIndex, 1,
simon	0:1014af42efd9	136	(int32_t *) pSrc, 1, blockSize);
simon	0:1014af42efd9	137
simon	0:1014af42efd9	138
simon	0:1014af42efd9	139	/* Read Index, from where the state buffer should be read, is calculated. */
simon	0:1014af42efd9	140	readIndex = ((int32_t) S->stateIndex - (int32_t) blockSize) - *pTapDelay++;
simon	0:1014af42efd9	141
simon	0:1014af42efd9	142	/* Wraparound of readIndex */
simon	0:1014af42efd9	143	if(readIndex < 0)
simon	0:1014af42efd9	144	{
simon	0:1014af42efd9	145	readIndex += (int32_t) delaySize;
simon	0:1014af42efd9	146	}
simon	0:1014af42efd9	147
simon	0:1014af42efd9	148	/* Working pointer for state buffer is updated */
simon	0:1014af42efd9	149	py = pState;
simon	0:1014af42efd9	150
simon	0:1014af42efd9	151	/* blockSize samples are read from the state buffer */
simon	0:1014af42efd9	152	arm_circularRead_f32((int32_t *) py, delaySize, &readIndex, 1,
simon	0:1014af42efd9	153	(int32_t ) pb, (int32_t ) pb, blockSize, 1,
simon	0:1014af42efd9	154	blockSize);
simon	0:1014af42efd9	155
simon	0:1014af42efd9	156	/* Working pointer for the scratch buffer */
simon	0:1014af42efd9	157	px = pb;
simon	0:1014af42efd9	158
simon	0:1014af42efd9	159	/* Working pointer for destination buffer */
simon	0:1014af42efd9	160	pOut = pDst;
simon	0:1014af42efd9	161
simon	0:1014af42efd9	162	/* Loop over the blockSize. Unroll by a factor of 4.
simon	0:1014af42efd9	163	* Compute 4 Multiplications at a time. */
simon	0:1014af42efd9	164	blkCnt = blockSize >> 2u;
simon	0:1014af42efd9	165
simon	0:1014af42efd9	166	while(blkCnt > 0u)
simon	0:1014af42efd9	167	{
simon	0:1014af42efd9	168	/* Perform Multiplications and store in destination buffer */
simon	0:1014af42efd9	169	pOut++ = px++ * coeff;
simon	0:1014af42efd9	170	pOut++ = px++ * coeff;
simon	0:1014af42efd9	171	pOut++ = px++ * coeff;
simon	0:1014af42efd9	172	pOut++ = px++ * coeff;
simon	0:1014af42efd9	173
simon	0:1014af42efd9	174	/* Decrement the loop counter */
simon	0:1014af42efd9	175	blkCnt--;
simon	0:1014af42efd9	176	}
simon	0:1014af42efd9	177
simon	0:1014af42efd9	178	/* If the blockSize is not a multiple of 4,
simon	0:1014af42efd9	179	* compute the remaining samples */
simon	0:1014af42efd9	180	blkCnt = blockSize % 0x4u;
simon	0:1014af42efd9	181
simon	0:1014af42efd9	182	while(blkCnt > 0u)
simon	0:1014af42efd9	183	{
simon	0:1014af42efd9	184	/* Perform Multiplications and store in destination buffer */
simon	0:1014af42efd9	185	pOut++ = px++ * coeff;
simon	0:1014af42efd9	186
simon	0:1014af42efd9	187	/* Decrement the loop counter */
simon	0:1014af42efd9	188	blkCnt--;
simon	0:1014af42efd9	189	}
simon	0:1014af42efd9	190
simon	0:1014af42efd9	191	/* Load the coefficient value and
simon	0:1014af42efd9	192	* increment the coefficient buffer for the next set of state values */
simon	0:1014af42efd9	193	coeff = *pCoeffs++;
simon	0:1014af42efd9	194
simon	0:1014af42efd9	195	/* Read Index, from where the state buffer should be read, is calculated. */
simon	0:1014af42efd9	196	readIndex = ((int32_t) S->stateIndex - (int32_t) blockSize) - *pTapDelay++;
simon	0:1014af42efd9	197
simon	0:1014af42efd9	198	/* Wraparound of readIndex */
simon	0:1014af42efd9	199	if(readIndex < 0)
simon	0:1014af42efd9	200	{
simon	0:1014af42efd9	201	readIndex += (int32_t) delaySize;
simon	0:1014af42efd9	202	}
simon	0:1014af42efd9	203
simon	0:1014af42efd9	204	/* Loop over the number of taps. */
simon	0:1014af42efd9	205	tapCnt = (uint32_t) numTaps - 1u;
simon	0:1014af42efd9	206
simon	0:1014af42efd9	207	while(tapCnt > 0u)
simon	0:1014af42efd9	208	{
simon	0:1014af42efd9	209
simon	0:1014af42efd9	210	/* Working pointer for state buffer is updated */
simon	0:1014af42efd9	211	py = pState;
simon	0:1014af42efd9	212
simon	0:1014af42efd9	213	/* blockSize samples are read from the state buffer */
simon	0:1014af42efd9	214	arm_circularRead_f32((int32_t *) py, delaySize, &readIndex, 1,
simon	0:1014af42efd9	215	(int32_t ) pb, (int32_t ) pb, blockSize, 1,
simon	0:1014af42efd9	216	blockSize);
simon	0:1014af42efd9	217
simon	0:1014af42efd9	218	/* Working pointer for the scratch buffer */
simon	0:1014af42efd9	219	px = pb;
simon	0:1014af42efd9	220
simon	0:1014af42efd9	221	/* Working pointer for destination buffer */
simon	0:1014af42efd9	222	pOut = pDst;
simon	0:1014af42efd9	223
simon	0:1014af42efd9	224	/* Loop over the blockSize. Unroll by a factor of 4.
simon	0:1014af42efd9	225	* Compute 4 MACS at a time. */
simon	0:1014af42efd9	226	blkCnt = blockSize >> 2u;
simon	0:1014af42efd9	227
simon	0:1014af42efd9	228	while(blkCnt > 0u)
simon	0:1014af42efd9	229	{
simon	0:1014af42efd9	230	/* Perform Multiply-Accumulate */
simon	0:1014af42efd9	231	pOut++ += px++ * coeff;
simon	0:1014af42efd9	232	pOut++ += px++ * coeff;
simon	0:1014af42efd9	233	pOut++ += px++ * coeff;
simon	0:1014af42efd9	234	pOut++ += px++ * coeff;
simon	0:1014af42efd9	235
simon	0:1014af42efd9	236	/* Decrement the loop counter */
simon	0:1014af42efd9	237	blkCnt--;
simon	0:1014af42efd9	238	}
simon	0:1014af42efd9	239
simon	0:1014af42efd9	240	/* If the blockSize is not a multiple of 4,
simon	0:1014af42efd9	241	* compute the remaining samples */
simon	0:1014af42efd9	242	blkCnt = blockSize % 0x4u;
simon	0:1014af42efd9	243
simon	0:1014af42efd9	244	while(blkCnt > 0u)
simon	0:1014af42efd9	245	{
simon	0:1014af42efd9	246	/* Perform Multiply-Accumulate */
simon	0:1014af42efd9	247	pOut++ += px++ * coeff;
simon	0:1014af42efd9	248
simon	0:1014af42efd9	249	/* Decrement the loop counter */
simon	0:1014af42efd9	250	blkCnt--;
simon	0:1014af42efd9	251	}
simon	0:1014af42efd9	252
simon	0:1014af42efd9	253	/* Load the coefficient value and
simon	0:1014af42efd9	254	* increment the coefficient buffer for the next set of state values */
simon	0:1014af42efd9	255	coeff = *pCoeffs++;
simon	0:1014af42efd9	256
simon	0:1014af42efd9	257	/* Read Index, from where the state buffer should be read, is calculated. */
simon	0:1014af42efd9	258	readIndex = ((int32_t) S->stateIndex -
simon	0:1014af42efd9	259	(int32_t) blockSize) - *pTapDelay++;
simon	0:1014af42efd9	260
simon	0:1014af42efd9	261	/* Wraparound of readIndex */
simon	0:1014af42efd9	262	if(readIndex < 0)
simon	0:1014af42efd9	263	{
simon	0:1014af42efd9	264	readIndex += (int32_t) delaySize;
simon	0:1014af42efd9	265	}
simon	0:1014af42efd9	266
simon	0:1014af42efd9	267	/* Decrement the tap loop counter */
simon	0:1014af42efd9	268	tapCnt--;
simon	0:1014af42efd9	269	}
simon	0:1014af42efd9	270
simon	0:1014af42efd9	271	}
simon	0:1014af42efd9	272
simon	0:1014af42efd9	273	/**
simon	0:1014af42efd9	274	* @} end of FIR_Sparse group
simon	0:1014af42efd9	275	*/

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Type:	Library
Created:	10 Mar 2011
Imports:	907
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src/Cortex-M4-M3/FilteringFunctions/arm_fir_sparse_f32.c@0:1014af42efd9, 2011-03-10 (annotated)

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